ORCID Profile
0000-0001-5626-4521
Current Organisation
Curtin University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Geochronology | Geology | Extraterrestrial Geology | Inorganic Geochemistry | Isotope Geochemistry | Planetary Science (excl. Extraterrestrial Geology) | Astronomical and Space Sciences | Geophysics | Geomagnetism | Geochronology And Isotope Geochemistry | Geomorphology and Regolith and Landscape Evolution | Igneous and Metamorphic Petrology | Structural Geology | Volcanology | Tectonics
Expanding Knowledge in the Earth Sciences | Mineral Exploration not elsewhere classified | Energy Exploration not elsewhere classified | Oil and gas | Earth sciences | Expanding Knowledge in Technology | Education and Training not elsewhere classified | Climate and Climate Change not elsewhere classified | Expanding Knowledge in the Environmental Sciences | Environment not elsewhere classified |
Publisher: Canadian Science Publishing
Date: 2022
Abstract: A large dyke of quartz tholeiitic gabbronorite has been mapped for 59 km in southern New Brunswick, Canada, between Lepreau River in the northeast and Indian Island in the southwest. Scattered outcrops occur along a positive aeromagnetic lineament, providing a dyke strike of N42°E overall (segments N30°E to N72°E), dips of 80° to 90°NNW, and widths of 4 to 30 m. A new 40 Ar/ 39 Ar plagioclase age of 201.67 ± 0.35 Ma for the Lepreau River Dyke is similar to dates for the massive North Mountain Basalt in the Fundy Basin to the east. The dyke is associated with the Ministers Island and Christmas Cove dykes, which are indistinguishable in chemistry, petrology, and probable age, and we regard them as segments of the same co-magmatic dyke system. In addition, their petrology is similar to that of the basalts of the adjacent Early Mesozoic Fundy and Grand Manan basins. We propose that the Lepreau River and associated dykes were sources for the regional basin basalts, which in turn are part of the Central Atlantic Magmatic Province (CAMP) that overlaps the Triassic–Jurassic boundary and associated mass extinction event.
Publisher: Elsevier BV
Date: 03-2018
Publisher: Geological Society of America
Date: 2022
DOI: 10.1130/G49457.1
Abstract: Subduction of oceanic lithosphere is a diagnostic characteristic of plate tectonics. However, the geodynamic processes from initiation to termination of subduction zones remain enigmatic mainly due to the scarcity of appropriate rock records. We report the first discovery of early Paleozoic boninitic blueschists and associated greenschists from the eastern Proto-Tethyan North Qilian orogenic belt, northeastern Tibet, which have geochemical affinities that are typical of forearc boninites and island arc basalts, respectively. The boninitic protoliths of the blueschists record intra-oceanic subduction initiation at ca. 492–488 Ma in the eastern North Qilian arc/forearc–backarc system, whereas peak blueschist facies metamorphism reflects subsequent subduction of the arc/forearc complex to high pressure at ca. 455 Ma. These relations therefore record the life circle of an intra-oceanic subduction zone within the northeastern Proto-Tethys Ocean. The geodynamic evolution provides an early Paleozoic analogue of the early development of the Izu–Bonin–Mariana arc and its later subduction beneath the extant Japanese arc margin. This finding highlights the important role of subduction of former upper plate island arc/forearcs in reducing the likelihood of preservation of initial subduction-related rock records in ancient orogenic belts.
Publisher: Elsevier BV
Date: 04-2016
Publisher: Geological Society of America
Date: 06-2014
DOI: 10.1130/G35434.1
Publisher: American Geophysical Union (AGU)
Date: 08-2019
DOI: 10.1029/2019JB017713
Publisher: Informa UK Limited
Date: 17-02-2014
Publisher: Elsevier BV
Date: 03-2015
Publisher: Elsevier BV
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 14-07-2012
Publisher: IOP Publishing
Date: 24-08-2023
Abstract: Experiments have been conducted in the DIII-D tokamak to explore the in-situ growth of silicon-rich layers as a potential technique for real-time replenishment of surface coatings on plasma-facing components (PFCs) during steady-state long-pulse reactor operation. Silicon (Si) pellets of 1 mm diameter were injected into low- and high-confinement (L-mode and H-mode) plasma discharges with densities ranging from 3.9– 7.5 × 10 19 m −3 and input powers ranging from 5.5 to 9 MW. The small Si pellets were delivered with the impurity granule injector at frequencies ranging from 4 to 16 Hz corresponding to mass flow rates of 5–19 mg s −1 (1– 4.2 × 10 20 Si s −1 ) at cumulative amounts of up to 34 mg of Si per five-second discharge. Graphite s les were exposed to the scrape-off layer and private flux region plasmas through the ertor material evaluation system to evaluate the Si deposition on the ertor targets. The Si II emission at the s le correlates with silicon injection and suggests net surface Si-deposition in measurable amounts. Post-mortem analysis showed Si-rich coatings containing silicon oxides, of which SiO 2 is the dominant component. No evidence of SiC was found, which is attributed to low ertor surface temperatures. The in-situ and ex-situ analysis found that Si-rich coatings of at least 0.4–1.2 nm thickness have been deposited at 0.4–0.7 nm s −1 . The technique is estimated to coat a surface area of at least 0.94 m 2 on the outer ertor. These results demonstrate the potential of using real-time material injection to form Si-enriched layers on ertor PFCs during reactor operation.
Publisher: Elsevier BV
Date: 07-2013
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 09-2019
Publisher: Geological Society of America
Date: 25-08-2020
DOI: 10.1130/G48149.1
Abstract: The First Bend on the Yangtze River (China), the point where the river ceases flowing toward the south and heads toward the northeast, has been one of the most strongly debated geomorphic features in Asia because it holds the key to understanding the history of the Yangtze River and is linked to the tectonically driven surface uplift of the southeastern Tibetan Plateau. Mid- to upper Eocene sedimentary rocks preserved in the Jianchuan Basin located immediately southwest of the First Bend demonstrate that a large river system, presumably the paleo–Jinshajiang River (the upper Yangtze), used to flow south through that region. Provenance analysis of sediments over the wider region, based mostly on U-Pb dating of detrital zircon grains, confirms that the once south-flowing paleo–Yangtze River originated in the Tibetan Plateau and flowed into the South China Sea. Inversion of the Jianchuan Basin, starting in or after the latest Eocene and associated with wider plateau surface uplift at that time, caused the river to be erted toward the northeast where it was confined along tectonic lineaments associated with strike-slip faulting, giving birth to the First Bend, a major step in the formation of the modern Yangtze River.
Publisher: Springer Science and Business Media LLC
Date: 26-01-2012
Publisher: Springer Science and Business Media LLC
Date: 29-11-2021
Publisher: Springer Science and Business Media LLC
Date: 29-05-2015
Publisher: Elsevier BV
Date: 2018
Publisher: Geological Society of London
Date: 06-01-2022
Abstract: Starting in the early 1950s, palaeontologists began to discover a wide range of Cretaceous terrestrial fossils in the Laiyang, Qingshan and Wangshi groups of the Jiaolai Basin, which resides in the eastern part of the Shandong Peninsula of northern China. Significant specimens from these deposits include various dinosaur eggs, footprints and fossils, including hadrosauroids, tyrannosaurids and ankylosaurids. These expanded the understanding of evolution, bio ersity and palaeoecology in East Asia. While many ex les of the Jehol Biota from this area are not well constrained in terms of their stratigraphy and geochronology, previous studies have generally suggested that fossils from this region represent the second or third phase of Jehol Biota development. This paper reviews fossils, stratigraphic correlations, tectonic history and age estimates for the less well-studied outcrops of the Shandong Peninsula that host the Jehol Biota. We report three new 40 Ar/ 39 Ar ages for the Qingshang Group and discuss how these somewhat imprecise ages still constrain chronostratigraphic interpretation for the fossil-rich units.
Publisher: American Geophysical Union (AGU)
Date: 06-2012
DOI: 10.1029/2011TC003085
Publisher: Elsevier BV
Date: 03-2020
Publisher: Mineralogical Society of America
Date: 02-2012
Publisher: Geological Society of America
Date: 29-12-2016
DOI: 10.1130/B31541.1
Publisher: Elsevier BV
Date: 12-2017
Publisher: Oxford University Press (OUP)
Date: 21-11-2013
Publisher: Elsevier BV
Date: 10-2007
Publisher: Informa UK Limited
Date: 03-06-2018
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 06-2009
Publisher: Elsevier BV
Date: 06-2007
Publisher: Elsevier BV
Date: 06-2022
Publisher: American Journal of Science (AJS)
Date: 03-2016
DOI: 10.2475/03.2016.01
Publisher: Springer Science and Business Media LLC
Date: 08-11-2016
Publisher: Geological Society of South Africa
Date: 03-2007
Publisher: Wiley
Date: 11-02-2019
DOI: 10.1111/MAPS.13244
Publisher: Elsevier BV
Date: 03-2017
Publisher: Informa UK Limited
Date: 08-08-2022
Publisher: Society of Economic Geologists
Date: 30-09-2013
Publisher: Elsevier BV
Date: 07-2015
Publisher: Elsevier BV
Date: 08-2015
Publisher: Universidade de Sao Paulo, Agencia USP de Gestao da Informacao Academica (AGUIA)
Date: 22-12-2020
DOI: 10.11606/ISSN.2316-9095.V20-151049
Abstract: This article presents geochemical characteristics of the alkaline rocks of Rio Bonito intrusive complex, State of Rio de Janeiro, Brazil, which is constituted mainly by nepheline syenite. The fractional crystallisation of this magma decreases K2O/(Na2O + K2O) and increases (Na + K)/Al. The TiO2, Fe2O3*, MgO, CaO, and P2O5 contents indicate fractionation of titanite, ilmenite, and clinopyroxene or hibole. The total rare earth elements (REEs) are high, and the REE pattern is linear with negative gradient. The nepheline syenite aplite has low REEs, concave REE pattern, and positive Eu anomaly. The ultrabasic and basic mela-nepheline syenite s les have total REEs and light REEs higher than the felsic alkaline rocks. Therefore, the nepheline syenite magma is not derived directly from the alkaline ultrabasic magma. Laser-spot step‑heating 40Ar/39Ar ages for biotite and hibole are 65.03 ± 0.70 and 65.03 ± 0.46. U-Pb ages LA-ICP-MS for two s les are 65.49 ± 0.30 and 65.18 ± 0.30. Values of εHf are negative for both s les, indicating an important crustal component in the evolution of Rio Bonito.
Publisher: Wiley
Date: 27-02-2017
DOI: 10.1111/MAPS.12838
Publisher: Society of Economic Geologists
Date: 12-12-2020
DOI: 10.5382/ECONGEO.4755
Abstract: New geochronological data provide evidence for Permo-Triassic low-sulfidation epithermal gold-silver mineralization in the Cordillera Frontal, Argentina. The U-Pb sensitive high-resolution ion microprobe (SHRIMP) analyses on zircons and titanite gave the following results: (1) andesite and rhyolite volcanic host rocks of the Casposo Au-Ag deposit yielded a range of ages between 267.1 ± 0.7 and 241.7 ± 2.2 Ma (2) two composite plutons located near Casposo yielded ages of 268.2 ± 1.5 and 265.1 ± 1.5 Ma for the Colorado syenogranite-granite pluton and 266.6 ± 1.4 and 254.0 ± 2.4 Ma for the Casposo granodiorite-tonalite pluton (3) a trachyandesite dike emplaced at 265.7 ± 1.2 Ma that is crosscut by mineralized quartz-adularia-calcite-gold veins in the Kamila East area (4) felsite intrusions, interpreted to be temporally related to the emplacement of mineralized veins at 261.1 ± 3.5 Ma and (5) composite rhyolite/andesite dikes that crosscut all other lithostratigraphic units and mineralized veins at 238.4 ± 1.6 Ma. The 40Ar/39Ar dates on hydrothermal adularia within quartz-adularia-calcite-gold veins of the Casposo deposit revealed at least three, likely discreet, hydro-thermal fluid pulses and associated periods of vein formation during extensional events between 280–274, 262–258, and 250–246 Ma. Relative and absolute timing of volcanic host rocks, plutons, postmineralization felsic dikes, and gold-bearing veins of the Casposo epithermal vein system suggest the presence of significant Permian (Cisuralian)-Lower Triassic low-sulfidation epithermal-style gold-silver mineralization at the eastern flank of the Cordillera Principal in Argentina. The existence of this epithermal Au-Ag system opens the potential for a significant magmatic-hydrothermal system in a part of the Andes that previously was considered to be of low prospectivity.
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 04-2016
Publisher: Elsevier BV
Date: 09-2009
Publisher: Mineralogical Society of America
Date: 09-2020
DOI: 10.2138/AM-2020-7608
Abstract: The Miocene Cuonadong leucogranites in the easternmost section of the Tethyan Himalaya, Southern Tibet, are characterized by two types of tourmaline. Tourmaline occurs as needle-like crystals in the two-mica ± tourmaline granites (Tur G) and large patches in the pegmatites (Tur P). Both the granite and the pegmatites yield Miocene ages (ca. 20 Ma) based on monazite U(-Th)-Pb dating, whereas 40Ar/39Ar geochronology of the coarse-grained tourmalines (Tur P) crosscut by pegmatite veins yielded an Eocene mini-plateau age of 43 ± 6 Ma. Major element concentrations of tourmaline indicate that both Tur P and Tur G belong to the schorl group with a magmatic origin, but trace elements such as V indicate that they are not cogenetic. Boron isotopes suggest that Tur P (average –9.76‰) was derived from typical crustal sources, whereas Tur G (average –7.65‰) contains relatively more mafic input. The capture of Eocene tourmaline by the Miocene leucogranites at Cuonadong suggests that the crustally derived Eocene magmatism may have occurred in the southern Tethyan Himalaya. Identification of the inherited magmatic tourmaline (Tur P), although not common, challenges the current application of tourmaline chemistry to the investigation of magmatic-hydrothermal systems.
Publisher: Elsevier BV
Date: 07-2006
Publisher: American Journal of Science (AJS)
Date: 2021
DOI: 10.2475/01.2021.05
Publisher: American Geophysical Union (AGU)
Date: 08-2019
DOI: 10.1029/2018TC005417
Publisher: Elsevier BV
Date: 11-2016
Publisher: Geological Society of London
Date: 30-01-2014
DOI: 10.1144/JGS2013-005
Publisher: Elsevier BV
Date: 04-2019
Publisher: Oxford University Press (OUP)
Date: 05-2015
Publisher: Elsevier BV
Date: 04-2018
Publisher: Elsevier BV
Date: 12-2021
Publisher: American Geophysical Union (AGU)
Date: 2021
DOI: 10.1029/2020GC009485
Abstract: The Macquarie Ridge Complex (MRC) on the Australia‐Pacific plate boundary south of New Zealand is an extinct mid‐ocean ridge that has experienced a complex tectonic history and produced highly heterogeneous mid‐ocean ridge basalts (MORBs). When and how seafloor spreading ceased along the proto‐Macquarie mid‐ocean ridge remain elusive, and it is unclear how the mantle source of MORBs is affected by the gradual cessation of seafloor spreading at mid‐ocean ridges. To constrain the tectonic evolution of the MRC, the mantle source variations for MORBs at dying mid‐ocean ridges, and the mechanisms of mantle enrichment and asthenospheric heterogeneities, we report 11 pyroxene, plagioclase, basaltic glass, groundmass, and sericite 40 Ar/ 39 Ar and one zircon U‐Pb ages for the MRC MORBs. Our data reveal that basalts from the MRC seamounts were erupted between 25.9 and 1.6 Ma and Macquarie Island at ∼10 Ma. Combined age and plate reconstruction results reveal that the cessation of seafloor spreading at the MRC generally propagated from south to north along the ridge. Basalts produced by the then dying Macquarie mid‐ocean ridge at different times on different seamounts/island show a large variation in isotopic compositions and there is no clear correlation between ages and isotopic ratios. The heterogeneity of mantle source for MORBs from the proto‐Macquarie mid‐ocean ridge suggests that the upper asthenospheric mantle is heterogeneous, and such heterogeneity becomes most obvious at dying mid‐ocean ridges where the degrees of partial melting are low and a large range of melt compositions are produced.
Publisher: Wiley
Date: 02-2021
DOI: 10.1111/MAPS.13615
Publisher: American Geophysical Union (AGU)
Date: 12-2019
DOI: 10.1029/2019JE006053
Publisher: Elsevier BV
Date: 06-2017
Publisher: AIP Publishing
Date: 02-2022
DOI: 10.1063/5.0080385
Abstract: The first dynamic (time-dependent) measurements of impurity ion radial (cross field) and parallel (along-field) diffusion coefficients for post-disruption runaway electron plateaus are presented. Small (∼1 mm diameter) carbon or silicon pellets are fired into the edge of steady-state runaway electron (RE) plateaus, and the resulting radial and toroidal transport of singly charged impurity ions (C+ or Si+) is monitored with spatially distributed visible spectrometers. Consistent with previous steady-state particle balance estimates of Ar+ radial transport, radial (cross field) diffusion coefficients D⊥≈2–5 m2/s are obtained, about 10× larger than expected from neo-classical theory. Parallel diffusion coefficients D∥≈30–80 m2/s are estimated, also much (≈50×) larger than classical. It is speculated at present that these large diffusion coefficients may be due to turbulent transport. Indications of fairly significant (almost 2×) toroidal variation in electron density are seen in the RE plateaus, and this appears to cause some toroidal variation in impurity radial diffusion rates. Indications of slow (≈1 Hz) toroidal rotation in the impurity ions are observed, although the uncertainty in this measurement is large.
Publisher: Mineralogical Society of America
Date: 02-2012
Publisher: Elsevier BV
Date: 11-2016
Publisher: Geological Society of America
Date: 08-04-2020
DOI: 10.1130/B35353.1
Abstract: The Central Asian Orogenic Belt, as the largest accretionary orogen on Earth, is an ideal candidate to study the geodynamics of convergent plate boundaries through a prolonged period. The evolution of this orogen has been explained by different tectonic models, which incorporated one, or a combination, of the following mechanisms: lateral stacking of arc systems along major shear zones, arc amalgamation, oroclinal bending, and trench migration. Here we elucidate major mechanisms responsible for the tectonic evolution of the Central Asian Orogenic Belt, focusing on the Chinese Tianshan Orogen in the southern Central Asian Orogenic Belt. Structural observations from the ∼50-km-long Gangou section show evidence of polyphase deformation. The earliest episode of orogen-parallel sinistral shearing, constrained to the Early Devonian (ca. 399 Ma) by syn-deformational intrusions, was possibly controlled by oblique subduction. This was followed by an episode of ∼NE–SW contractional deformation, dated at ca. 356 Ma (40Ar/39Ar age of syn-deformational hornblende), and likely associated with an episode of trench advance. The third stages of deformation during the latest Carboniferous and Permian involved ∼NE-SW contraction, orogen-parallel extension, and dextral transpression. Our new geochronological data constrain the timing of orogen-parallel extension to ca. 303–293 Ma, and confirm that dextral activation along shear zones occurred during the Permian. The results highlight the role of trench migration, oblique tectonics, and syn-collisional orogen-parallel extension in the build-up of the Central Asian Orogenic Belt, and contribute to the pre-collisional reconstruction of this orogenic system.
Publisher: Geological Society of America
Date: 07-2020
DOI: 10.1130/B35560.1
Abstract: The 40Ar/39Ar dating method is among the most versatile of geochronometers, having the potential to date a broad variety of K-bearing materials spanning from the time of Earth’s formation into the historical realm. Measurements using modern noble-gas mass spectrometers are now producing 40Ar/39Ar dates with analytical uncertainties of ∼0.1%, thereby providing precise time constraints for a wide range of geologic and extraterrestrial processes. Analyses of increasingly smaller subs les have revealed age dispersion in many materials, including some minerals used as neutron fluence monitors. Accordingly, interpretive strategies are evolving to address observed dispersion in dates from a single s le. Moreover, inferring a geologically meaningful “age” from a measured “date” or set of dates is dependent on the geological problem being addressed and the salient assumptions associated with each set of data. We highlight requirements for collateral information that will better constrain the interpretation of 40Ar/39Ar data sets, including those associated with single-crystal fusion analyses, incremental heating experiments, and in situ analyses of micros led domains. To ensure the utility and viability of published results, we emphasize previous recommendations for reporting 40Ar/39Ar data and the related essential metadata, with the amendment that data conform to evolving standards of being findable, accessible, interoperable, and reusable (FAIR) by both humans and computers. Our ex les provide guidance for the presentation and interpretation of 40Ar/39Ar dates to maximize their interdisciplinary usage, reproducibility, and longevity.
Publisher: Elsevier BV
Date: 11-2019
Publisher: Elsevier BV
Date: 09-2019
Publisher: Springer Science and Business Media LLC
Date: 17-05-2021
DOI: 10.1038/S43247-021-00155-1
Abstract: Tektites are terrestrial impact-generated glasses that are ejected long distance (up to 11,000 km), share unique characteristics and have a poorly understood formation process. Only four tektite strewn-fields are known, and three of them are sourced from known impact craters. Here we show that the recently discovered Pantasma impact crater (14 km diameter) in Nicaragua is the source of an impact glass strewn-field documented in Belize 530 km away. Their cogenesis is documented by coincidental ages, at 804 ± 9 ka, as well as consistent elemental compositions and isotopic ratios. The Belize impact glass share many characteristics with known tektites but also present several peculiar features. We propose that these glasses represent a previously unrecognized tektite strewn-field. These discoveries shed new light on the tektite formation process, which may be more common than previously claimed, as most known Pleistocene km diameter cratering events have generated tektites.
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 2006
Publisher: Geological Society of London
Date: 25-04-2018
DOI: 10.1144/JGS2017-139
Publisher: Proceedings of the National Academy of Sciences
Date: 23-01-2023
Abstract: Rubble piles asteroids consist of reassembled fragments from shattered monolithic asteroids and are much more abundant than previously thought in the solar system. Although monolithic asteroids that are a kilometer in diameter have been predicted to have a lifespan of few 100 million years, it is currently not known how durable rubble pile asteroids are. Here, we show that rubble pile asteroids can survive ambient solar system bombardment processes for extremely long periods and potentially 10 times longer than their monolith counterparts. We studied three regolith dust particles recovered by the Hayabusa space probe from the rubble pile asteroid 25143 Itokawa using electron backscatter diffraction, time-of-flight secondary ion mass spectrometry, atom probe tomography, and 40 Ar/ 39 Ar dating techniques. Our results show that the particles have only been affected by shock pressure of ca. 5 to 15 GPa. Two particles have 40 Ar/ 39 Ar ages of 4,219 ± 35 and 4,149 ± 41 My and when combined with thermal and diffusion models these results constrain the formation age of the rubble pile structure to ≥4.2 billion years ago. Such a long survival time for an asteroid is attributed to the shock-absorbent nature of rubble pile material and suggests that rubble piles are hard to destroy once they are created. Our results suggest that rubble piles are probably more abundant in the asteroid belt than previously thought and provide constrain to help develop mitigation strategies to prevent asteroid collisions with Earth.
Publisher: Elsevier BV
Date: 06-2022
Publisher: Springer Science and Business Media LLC
Date: 10-2021
Publisher: Oxford University Press (OUP)
Date: 09-2017
Publisher: Elsevier BV
Date: 09-2014
Publisher: Oxford University Press (OUP)
Date: 04-2018
Publisher: Geological Society of America
Date: 2005
DOI: 10.1130/G21632.1
Publisher: Elsevier BV
Date: 06-2017
Publisher: Geological Society of London
Date: 17-06-2021
Publisher: Elsevier BV
Date: 06-2009
Publisher: Springer Science and Business Media LLC
Date: 27-04-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 12-11-2021
Abstract: Measuring physical s les of Solar System bodies in the laboratory provides more information than is possible from remote sensing alone. In December 2020, the Chang’e-5 mission landed on the Moon, collected s les, and returned them to Earth. Che et al . analyze two fragments of volcanic lunar basalt collected by Chang’e-5. Radiometric dating using lead isotopes indicated that the rocks formed from magma that erupted about 2 billion years ago, later than other volcanic lunar s les. The abundance of extinct radioactive elements in the rock is too low for radioactive heating to have produced the magma. Another, thus far unknown, source must be responsible for the late lunar volcanism. —KTS
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 08-2017
Publisher: Elsevier BV
Date: 05-2020
Publisher: Elsevier BV
Date: 11-2017
Publisher: Edicions de la Universitat de Barcelona
Date: 21-05-2021
DOI: 10.1344/GEOLOGICAACTA2021.19.5
Abstract: The Lipovany and Mučín paleobotanical localities contain important floral associations within the tuff horizons, which were used for determination of subtropical to tropical climatic conditions during the Early Miocene. Based on the combination of results from plagioclase and biotite 40Ar/39Ar dating, the age of the tuff deposition is around 17.3Ma. For the Lipovany locality, single-grain 40Ar/39Ar convergent ages of 17.49±0.54Ma and 17.28±0.06Ma, for plagioclase and biotite were obtained, respectively. The Mučín locality only provide an imprecise convergent age of 16.5±1.4Ma due to the small size of the analyzed plagioclase crystals. The results thus allowed to include the fossil subtropical flora of the studied localities in the late Ottnangian regional stage (upper part of the Burdigalian). Additionally, these age data indicate that deposition of the overlaying Salgótarján Formation starts much later than originally thought (during Ottnangian-Karpatian boundary).
Publisher: Elsevier BV
Date: 10-2019
Publisher: Wiley
Date: 10-2016
Publisher: Proceedings of the National Academy of Sciences
Date: 22-04-2013
Abstract: The development of fluvial systems in East Asia is closely linked to the evolving topography following India–Eurasia collision. Despite this, the age of the Yangtze River system has been strongly debated, with estimates ranging from 40 to 45 Ma, to a more recent initiation around 2 Ma. Here, we present 40 Ar/ 39 Ar ages from basalts interbedded with fluvial sediments from the lower reaches of the Yangtze together with detrital zircon U–Pb ages from sand grains within these sediments. We show that a river containing sediments indistinguishable from the modern river was established before ∼23 Ma. We argue that the connection through the Three Gorges must postdate 36.5 Ma because of evaporite and lacustrine sedimentation in the Jianghan Basin before that time. We propose that the present Yangtze River system formed in response to regional extension throughout eastern China, synchronous with the start of strike–slip tectonism and surface uplift in eastern Tibet and fed by strengthened rains caused by the newly intensified summer monsoon.
Publisher: Elsevier BV
Date: 11-2015
Publisher: Elsevier BV
Date: 03-2017
Publisher: Geological Society of America
Date: 10-07-2017
DOI: 10.1130/G39138.1
Publisher: American Geophysical Union (AGU)
Date: 17-09-2011
DOI: 10.1029/2011JB008379
Publisher: Wiley
Date: 08-12-2021
DOI: 10.1002/GJ.4328
Abstract: Geochronological 40 Ar/ 39 Ar investigations in the São Gabriel Terrane, Dom Feliciano Belt, Brazil, associated with previous structural geology and geochronology studies, allow for a better understanding of Neoproterozoic events in this region. The Sanga da Cachoeira Complex and metasedimentary rocks of Arroio Marmeleiro Complex (U–Pb provenance age 1.5 Ga) show 40 Ar/ 39 Ar spectra with no successful plateau age, attributed to the alteration or excess 40 Ar. Tonian (ca. 729 ± 9 Ma) 40 Ar/ 39 Ar hornblende age of metadiorites of the Cambaí Complex (U–Pb protolith age ca. 750 Ma) is interpreted to register the age of an early structure in this unit, where hornblende is a mineral of the composite banding fabric formed by remnants of original bedding, locally preserved, and added by metamorphic recrystallization. A cooling rate of at least 5°C/Ma is suggested for the Cambaí Complex, from its crystallization to its metamorphic event. The Cryogenian ( ± 8 Ma) 40 Ar/ 39 Ar hornblende and muscovite ages belonging to the Imbicuí Complex (protolith age ca. 869 Ma) whose ages are related to the late structure formed by a short and intense activity of the Cerro Branco Shear Zone, which experienced a rapid cooling of 12°C/Ma. The ages from the rocks belonging to such a erse tectonic setting, including continental and intraoceanic island arc, oceanic crust low‐K hibolites and meta‐harzburgites, and metasediments, presenting similar nature and fabric orientation, indicate that major tectonic‐magmatic–metamorphic activity was responsible for the accretion of these lithotectonic units that gave rise to the São Gabriel Terrane in southern Brazil.
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 12-2014
Publisher: Elsevier BV
Date: 07-2015
Publisher: Elsevier BV
Date: 10-2020
Publisher: Proceedings of the National Academy of Sciences
Date: 08-06-2015
Abstract: The formation of the Taklimakan Desert marked a major geological event in central Asia during the Cenozoic, with far-reaching impacts. Deposition of both eolian sand dunes in the basin center and the genetically equivalent loessite along the basin margins provide evidence for the birth of the Taklimakan Desert. This paper resolves a long-standing debate concerning the age of the Taklimakan Desert, specifically whether it dates to ∼3.4–7 Ma, currently the dominant view. Our result shows that the desert came into existence during late Oligocene–early Miocene, between ∼26.7 Ma and 22.6 Ma, as a result of widespread regional aridification and increased erosion in the surrounding mountain fronts, both of which are closely linked to the tectonic uplift of the Tibetan–Pamir Plateau and Tian Shan.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Springer Science and Business Media LLC
Date: 19-12-2018
Publisher: Elsevier BV
Date: 03-2021
Publisher: Geological Society of America
Date: 15-06-2021
DOI: 10.1130/B35851.1
Abstract: The evolution of the Yangtze River, the longest river in Asia, provides a spectacular ex le for understanding the Cenozoic interaction between tectonics, climate, and surficial processes. The oldest Lower Yangtze deposits, characterized by ~100-m-thick sequences of unconsolidated conglomerate, sandstone, and siltstone, referred to as “Yangtze Gravel,” have been recently dated & Ma, indicating a pre-Miocene establishment of a through-going river. However, the link between river integration and tectonic evolution has never been established due to the limited study of these sediments. Here, we report sedimentology, geochronology, and provenance of the Yangtze Gravel based on 17 stratigraphic sections exposed along the Lower Yangtze River. Our new chronostratigraphic results, including 40Ar/39Ar ages from the overlying basalt and fossil-based stratigraphic correlation, suggest an early-middle Miocene age for these sediments. Detailed analysis of lithofacies reveals several sequences of coarse-grained channel-belt deposits (channel fills and bars), indicating braided alluvial deposition across the Jianghan Basin, North Jiangsu-South Yellow Sea Basin, and East China Sea Shelf Basin. This ancient Lower Yangtze River is further characterized by petrography and detrital zircon U-Pb geochronology results which show similar provenance and erosion pattern as the present-day Yangtze River. However, the ancient river in early-middle Miocene is an alluvial, bedload-dominated braided river with higher stream power and a more prolonged course flowing into the East China Sea Shelf Basin. These differences between ancient and modern Lower Yangtze River reflect varied climate and paleogeography in southeast China during the late Cenozoic. Compared with the Paleogene red-colored, halite-bearing, Ephedripite pollen-dominated, lacustrine deposits in Jianghan Basin and North Jiangsu-South Yellow Sea Basin, the deposition of yellow to green-colored, coarse-grained, arboreal pollen, and wood-dominated Yangtze Gravel indicates a drainage reorganization from hydrologically closed lakes to a through-going river system during late Oligocene to early Miocene. During Paleogene, rift basins were filled by alluvial and fluvial-lacustrine deposition with restricted flow distance and local sources. From late Oligocene to early-middle Miocene, the post-rift subsidence opens a path for the ancient Lower Yangtze River connecting the Jianghan Basin, North Jiangsu-South Yellow Sea Basin, and East China Sea Shelf Basin. We attribute the drainage reorganization of the Lower Yangtze River to be a surficial response to Cenozoic tectonics, particularly the western Pacific subduction, in southeast China. The deposition of the widespread, coarse-grained Yangtze Gravel is probably due to the combined effects of catchment expansion and strong monsoonal climate in East Asia.
Publisher: Elsevier BV
Date: 10-2019
Publisher: Elsevier BV
Date: 05-2013
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 11-2014
Publisher: American Geophysical Union (AGU)
Date: 10-2018
DOI: 10.1029/2018TC005170
Publisher: Oxford University Press (OUP)
Date: 09-03-2020
DOI: 10.1017/S1431927620000136
Abstract: Atom probe tomography (APT) is used to quantify atomic-scale elemental and isotopic compositional variations within a very small volume of material (typically .01 µ m 3 ). The small analytical volume ideally contains specific compositional or microstructural targets that can be placed within the context of the previously characterized surface in order to facilitate a correct interpretation of APT data. In this regard, careful targeting and preparation are paramount to ensure that the desired target, which is often smaller than 100 nm, is optimally located within the APT specimen. Needle-shaped specimens required for atom probe analysis are commonly prepared using a focused ion beam scanning electron microscope (FIB-SEM). Here, we utilize FIB-SEM-based time-of-flight secondary ion mass spectrometry (ToF-SIMS) to illustrate a novel approach to targeting nm compositional and isotopic variations that can be used for targeting regions of interest for subsequent lift-out and APT analysis. We present a new method for high-spatial resolution targeting of small features that involves using FIB-SEM-based electron deposition of platinum “buttons” prior to standard lift-out and sharpening procedures for atom probe specimen manufacture. In combination, FIB-ToF-SIMS analysis and application of the “button” method ensure that even the smallest APT targets can be successfully captured in extracted needles.
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 12-2015
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 06-2012
Publisher: Informa UK Limited
Date: 16-03-2023
Publisher: University of Chicago Press
Date: 09-2012
DOI: 10.1086/666876
Publisher: Wiley
Date: 03-10-2014
DOI: 10.1111/SED.12143
Publisher: Geological Society of America
Date: 07-2011
DOI: 10.1130/G31888.1
Abstract: Asteroid impacts play an important role in the evolution of planetary surfaces. In the inner solar system, the large majority of impacts occur on bodies (e.g., asteroids, the Moon, Mars) covered by primitive igneous rocks. However, most of the impacts recorded on Earth occur on different rock types and are poor proxies for planetary impacts. The Lonar crater is a 1.88-km-diameter, Quaternary age crater (Fig. 1) located on the ca. 66 Ma Deccan basaltic traps in Maharashtra (India), and is one of the very few craters on Earth emplaced directly on basaltic lava flows. We carried out 12 40Ar/39Ar step-heating experiments on 4 melt rock s les in order to (1) obtain a precise age for the Lonar crater (2) study the response of isotopic chronometers during impacts on mafic target rocks and (3) better understand the dating of extraterrestrial impact craters. We obtained 10 plateau and 9 inverse isochron ages on various aliquots. Combination of selected data into a global inverse isochron yielded an age of 570 ± 47 ka (MSWD = 1.1 P = 0.24). In comparison, previous nonisotopic investigations on rocks thought to be affected by secondary processes yielded a range of much younger ages (ca. 12–62 ka). The measured 40Ar/36Ar trapped values offer a direct comparison with the atmospheric benchmark value and allow us to test the inherited 40Ar* degassing capacity of basaltic impact melt rocks. The 40Ar/36Ar ratio of 296.5 ± 1.7 is indistinguishable from the atmospheric composition and suggests that inherited 40Ar* is absent from the melt rock. This result substantiates diffusion models that predict a near-complete degassing of low-viscosity melt (e.g., basalts) during impact, and demonstrates for the first time that inherited 40Ar* is less problematic for 40Ar/39Ar dating of impact events in basaltic igneous rocks compared to Si-rich rocks. These results provide direct evidence that basaltic melt rocks are excellent candidates for recording the timing of planetary impact events and, as far as dating is concerned, should be the preferred targets of s le recovery by future missions.
Publisher: Elsevier BV
Date: 09-2002
Publisher: Oxford University Press (OUP)
Date: 19-04-2019
Abstract: The Central Atlantic Magmatic Province (CAMP) is a large igneous province (LIP) composed of basic dykes, sills, layered intrusions and lava flows emplaced before Pangea break-up and currently distributed on the four continents surrounding the Atlantic Ocean. One of the oldest, best preserved and most complete sub-provinces of the CAMP is located in Morocco. Geochemical, geochronologic, petrographic and magnetostratigraphic data obtained in previous studies allowed identification of four strato-chemical magmatic units, i.e. the Lower, Intermediate, Upper and Recurrent units. For this study, we completed a detailed s ling of the CAMP in Morocco, from the Anti Atlas in the south to the Meseta in the north. We provide a complete mineralogical, petrologic (major and trace elements on whole-rocks and minerals), geochronologic (40Ar/39Ar and U–Pb ages) and geochemical set of data (including Sr–Nd–Pb–Os isotope systematics) for basaltic and basaltic–andesitic lava flow piles and for their presumed feeder dykes and sills. Combined with field observations, these data suggest a very rapid ( ·3 Ma) emplacement of over 95% of the preserved magmatic rocks. In particular, new and previously published data for the Lower to Upper unit s les yielded indistinguishable 40Ar/39Ar (mean age = 201·2 ± 0·8 Ma) and U–Pb ages (201·57 ± 0·04 Ma), suggesting emplacement coincident with the main phase of the end-Triassic biotic turnover (c.201·5 to 201·3 Ma). Eruptions are suggested to have been pulsed with rates in excess of 10 km3/year during five main volcanic pulses, each pulse possibly lasting only a few centuries. Such high eruption rates reinforce the likelihood that CAMP magmatism triggered the end-Triassic climate change and mass extinction. Only the Recurrent unit may have been younger but by no more than 1 Ma. Whole-rock and mineral geochemistry constrain the petrogenesis of the CAMP basalts. The Moroccan magmas evolved in mid-crustal reservoirs (7–20 km deep) where most of the differentiation occurred. However, a previous stage of crystallization probably occurred at even greater depths. The four units cannot be linked by closed-system fractional crystallization processes, but require distinct parental magmas and/or distinct crustal assimilation processes. EC-AFC modeling shows that limited crustal assimilation (maximum c.5–8% assimilation of e.g. Eburnean or Pan-African granites) could explain some, but not all the observed geochemical variations. Intermediate unit magmas are apparently the most contaminated and may have been derived from parental magmas similar to the Upper basalts (as attested by indistinguishable trace element contents in the augites analysed for these units). Chemical differences between Central High Atlas and Middle Atlas s les in the Intermediate unit could be explained by distinct crustal contaminants (lower crustal rocks or Pan-African granites for the former and Eburnean granites for the latter). The CAMP units in Morocco are likely derived from 5–10% melting of enriched peridotite sources. The differences observed in REE ratios for the four units are attributed to variations in both source mineralogy and melting degree. In particular, the Lower basalts require a garnet peridotite source, while the Upper basalts were probably formed from a shallower melting region straddling the garnet–spinel transition. Recurrent basalts instead are relatively shallow-level melts generated mainly from spinel peridotites. Sr–Nd–Pb–Os isotopic ratios in the CAMP units from Morocco are similar to those of other CAMP sub-provinces and suggest a significant enrichment of the mantle-source regions by subducted crustal components. The enriched signature is attributed to involvement of about 5–10% recycled crustal materials introduced into an ambient depleted or PREMA-type mantle, while involvement of mantle-plume components like those s led by present-day Central Atlantic Ocean Island Basalts (OIB, e.g. Cape Verde and Canary Islands) is not supported by the observed compositions. Only Recurrent basalts may possibly reflect a Central Atlantic plume-like signature similar to the Common or FOZO components.
Publisher: Elsevier BV
Date: 07-2015
Publisher: American Geophysical Union (AGU)
Date: 2014
DOI: 10.1002/2013TC003398
Publisher: Elsevier BV
Date: 06-2004
Publisher: Informa UK Limited
Date: 02-01-2017
Publisher: Society of Economic Geologists
Date: 03-04-2017
Publisher: Elsevier BV
Date: 06-2009
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 2009
Publisher: Wiley
Date: 26-11-2018
DOI: 10.1002/GJ.3375
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 12-2021
Publisher: Wiley
Date: 29-05-2019
DOI: 10.1111/MAPS.13305
Publisher: Oxford University Press (OUP)
Date: 22-09-2016
Publisher: American Geophysical Union (AGU)
Date: 09-2018
DOI: 10.1029/2018TC005008
Publisher: Geological Society of London
Date: 18-09-2020
DOI: 10.1144/JGS2020-120
Publisher: Elsevier BV
Date: 12-2015
Publisher: Wiley
Date: 29-05-2019
DOI: 10.1111/MAPS.13309
Publisher: Elsevier BV
Date: 03-2015
Publisher: Elsevier BV
Date: 2010
Publisher: Elsevier BV
Date: 08-2014
Publisher: Elsevier BV
Date: 03-2012
Publisher: Wiley
Date: 25-06-2015
DOI: 10.1111/MAPS.12463
Publisher: Elsevier BV
Date: 02-2020
Publisher: American Geophysical Union (AGU)
Date: 27-01-2011
DOI: 10.1029/2009TC002656
Publisher: Oxford University Press (OUP)
Date: 03-2017
Publisher: Elsevier BV
Date: 10-2014
Publisher: Oxford University Press (OUP)
Date: 17-08-2017
Publisher: Elsevier BV
Date: 11-2014
Publisher: MDPI AG
Date: 09-09-2021
DOI: 10.3390/MIN11090988
Abstract: The composite Albian–Eocene orogenic wedge of the northern part of the Inner Western Carpathians (IWC) comprises the European Variscan basement with the Upper Carboniferous–Triassic cover and the Jurassic to Upper Cretaceous sedimentary successions of a large oceanic–continental Atlantic (Alpine) Tethys basin system. This paper presents an updated evolutionary model for principal structural units of the orogenic wedge (i.e., Fatricum, Tatricum and Infratatricum) based on new and published white mica 40Ar/39Ar geochronology and P–T estimates by Perple_X modeling and geothermobarometry. The north-directed Cretaceous collision led to closure of the Jurassic–Early Cretaceous basins, and incorporation of their sedimentary infill and a thinned basement into the Albian–Cenomanian/Turonian accretionary wedge. During this compressional D1 stage, the subautochthonous Fatric structural units, including the present-day higher Infratatric nappes, achieved the metamorphic conditions of ca. 250–400 °C and 400–700 MPa. The collapse of the Albian–Cenomanian/Turonian wedge and contemporary southward Penninic oceanic subduction enhanced the extensional exhumation of the low-grade metamorphosed structural complexes (D2 stage) and the opening of a fore-arc basin. This basin hemipelagic Coniacian–C anian Couches-Rouges type marls (C.R.) spread from the northern Tatric edge, throughout the Infratatric Belice Basin, up to the peri-Pieniny Klippen Belt Kysuca Basin, thus tracing the south-Penninic subduction. The ceasing subduction switched to the compressional regime recorded in the trench-like Belice “flysch” trough formation and the lower anchi-metamorphism of the C.R. at ca. 75–65 Ma (D3 stage). The Belice trough closure was followed by the thrusting of the exhumed low-grade metamorphosed higher Infratatric complexes and the anchi-metamorphosed C.R. over the frontal unmetamorphosed to lowest anchi-metamorphosed Upper C anian–Maastrichtian “flysch” sediments at ca. 65–50 Ma (D4 stage). Phengite from the Infratatric marble s le SRB-1 and meta-marl s le HC-12 produced apparent 40Ar/39Ar step ages clustered around 90 Ma. A mixture interpretation of this age is consistent with the presence of an older metamorphic Ph1 related to the burial (D1) within the Albian–Cenomanian/Turonian accretionary wedge. On the contrary, a younger Ph2 is closely related to the late- to post-C anian (D3) thrust fault formation over the C.R. Celadonite-enriched muscovite from the subautochthonous Fatric Zobor Nappe meta-quartzite s le ZI-3 yielded a mini-plateau age of 62.21 ± 0.31 Ma which coincides with the closing of the Infratatric foreland Belice “flysch” trough, the accretion of the Infratatricum to the Tatricum, and the formation of the rear subautochthonous Fatricum bivergent structure in the Eocene orogenic wedge.
Publisher: Informa UK Limited
Date: 03-2012
Publisher: Elsevier BV
Date: 06-2018
Publisher: American Association of Petroleum Geologists AAPG/Datapages
Date: 12-2011
DOI: 10.1306/03241110115
Publisher: Geological Society of London
Date: 18-05-2015
DOI: 10.1144/SP420.7
Publisher: Elsevier BV
Date: 2005
Publisher: Geological Society of America
Date: 2010
Publisher: Wiley
Date: 03-2021
DOI: 10.1111/MAPS.13640
Publisher: Elsevier BV
Date: 09-2020
Publisher: Wiley
Date: 10-2020
Publisher: Elsevier BV
Date: 11-2018
Publisher: Elsevier BV
Date: 2008
Publisher: Elsevier BV
Date: 03-2011
Publisher: Elsevier BV
Date: 11-2017
Publisher: Proceedings of the National Academy of Sciences
Date: 10-2015
Publisher: American Geophysical Union (AGU)
Date: 06-2008
DOI: 10.1029/2008GC001994
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 02-2014
Publisher: Elsevier BV
Date: 06-2019
Publisher: Cambridge University Press (CUP)
Date: 07-06-2012
DOI: 10.1017/S0016756812000088
Abstract: The Madagascar Cretaceous igneous province exposed in the Mahajanga basin is represented by basalt and basaltic andesite lavas. New 40 Ar– 39 Ar plateau ages (92.3 ± 2.0 Ma and 91.5 ± 1.3 Ma) indicate that the magmatism in the Mahajanga basin started about 92 Ma ago. Four geochemically distinct magma types (Groups A–D) are present. Group A and C rocks have low to moderate TiO 2 (1.2–2.6 wt%), Nb (3–9 μg g −1 ) and Zr (82–200 μg g −1 ), and show large variations in ɛNd i (+0.1 to −10.8), 206 Pb/ 204 Pb (15.28 to 16.33) and γ Os (+11.4 to +7378). The large isotopic variations, particularly in Os, Nd and Pb isotopic compositions, are likely due to crustal contamination. The low Pb isotope ratios observed in the Group A and C rocks suggest involvement of continental crust with low μ ( 238 U/ 204 Pb). Group B and D rocks have moderate to high TiO 2 (2.2–4.9 wt%), Nb (8–24 μg g −1 ) and Zr (120–327 μg g −1 ). Age-corrected isotopes of Group B and D lavas show a small range in ɛNd i (+1.0 to +4.0) and a wide range in γ Os (+128 to +1182). Values of 207 Pb/ 204 Pb are within the range for Groups A and C, but the Group D 206 Pb/ 204 Pb (16.52–17.08) and 208 Pb/ 204 Pb (37.51–38.01) values are higher, indicating a different crustal contaminant. Pb isotopic values of the Group B rocks seem to reflect the isotopic features of their mantle source. The magma groups of Mahajanga display a wide range of trace element and isotopic compositions that cannot be explained only by open-system crystallization processes but, rather, by distinct mantle sources.
Publisher: Elsevier BV
Date: 02-2022
Publisher: American Geophysical Union (AGU)
Date: 05-2012
DOI: 10.1029/2011GC004017
Publisher: Elsevier BV
Date: 05-2022
Publisher: Geological Society of America
Date: 12-2021
DOI: 10.1130/B36200.1
Abstract: To understand the origin of curved subduction zones has been one of the major challenges in plate tectonics. The Mongol-Okhotsk Orogen in Central Asia is characterized by the development of a U-shaped oroclinal structure that was accompanied by the continuous subduction of the Mongol-Okhotsk oceanic plate. Therefore, it provides a natural laboratory to understand why and how a subduction system became tightly curved. In this study, we provide the first structural observation around the hinge of the Mongolian Orocline (the Zag zone in Central Mongolia), with an aim to constrain the oroclinal geometry and to link hinge zone structures with the origin of the orocline. Our results show that rocks in the Zag zone are characterized by the occurrence of a penetrative foliation that is commonly subparallel to bedding. Both bedding and dominant fabric in the Zag zone are steeply dipping, and their strike orientations in a map view follow a simple curve around the hinge of the Mongolian Orocline, thus providing the first structural constraint for 3D geometry of the orocline. A secondary penetrative fabric parallel to the axial plane of the orocline was not observed, indicating a low degree of orogen-parallel shortening during oroclinal bending. Combining with available geological and geophysical data, we conclude that the Mongolian Orocline was developed in a period of Permian to Jurassic, and its origin was linked to the subduction of the Mongol-Okhotsk oceanic slab. We consider that the low-strain oroclinal bending likely resulted from the along-strike variation in trench retreat, which was either triggered by the negative buoyancy of the Mongol-Okhotsk oceanic slab, or driven by the relative rotation of the Siberian and North China cratons. Our results shed a light on 3D geometry and geodynamic mechanisms of large-scale oroclinal bending in an accretionary orogen.
Publisher: American Geophysical Union (AGU)
Date: 02-2007
DOI: 10.1029/2006GC001392
Publisher: Elsevier BV
Date: 11-2018
Publisher: Geological Society of London
Date: 09-03-2016
DOI: 10.1144/JGS2015-133
Publisher: Informa UK Limited
Date: 22-05-2012
Publisher: Elsevier BV
Date: 03-2010
Publisher: Springer Science and Business Media LLC
Date: 16-02-2022
DOI: 10.1186/S40645-022-00470-X
Abstract: Although there is increasing evidence for wet, monsoonal conditions in Southeast Asia during the late Eocene, it has not been clear when this environment became established. Cenozoic sedimentary sequences constrained by radiometrically dated igneous rocks from the Jianchuan Basin in the southeast flank of Tibetan Plateau now provide a section whose facies and climatic proxies determine this evolution. Semi-arid conditions had dominated the region since Paleocene controlled by the northern sub-tropical high pressure system, culminating in mid Eocene when desert dunes developed. From 36 Ma, the basin began to accumulate sw sediments with coals, together with synchronous braided river deposits and ersified pollen assemblages, indicating significant increase in precipitation. This remarkable transition from dry to wet conditions precedes the Eocene/Oligocene boundary at 34 Ma, thus excluding general global cooling as the prime driver. We propose that uplift of Tibetan Plateau might have reached a threshold elevation by that time, operating through thermal and dynamic forcing, causing the inception or significant intensification of monsoonal rains to penetrate into this downwind locality.
Publisher: Geological Society of London
Date: 25-07-2013
DOI: 10.1144/SP378.14
Publisher: Geological Society of London
Date: 25-07-2013
DOI: 10.1144/SP378.15
Publisher: Elsevier BV
Date: 2021
Publisher: American Geophysical Union
Date: 2003
DOI: 10.1029/136GM011
Publisher: Copernicus GmbH
Date: 13-12-2021
DOI: 10.5194/GCHRON-3-545-2021
Abstract: Abstract. The Salt Range Formation is an extensive evaporite sequence in northern Pakistan that has acted as the primary detachment accommodating Himalayan orogenic deformation from the north. This rheologically weak formation forms a mylonite in the Khewra Mine, where it accommodates approximately 40 km displacement and is comprised of intercalated halite and potash salts and gypsiferous marls. Polyhalite [K2Ca2Mg(SO4)4⚫2H2O] grains taken from potash marl and crystalline halite s les are used as geochronometers to date the formation and identify the closure temperature of the mineral polyhalite using the 40Ar/39Ar step-heating laser and furnace methods. The diffusion characteristics measured for two s les of polyhalite are diffusivity (D0), activation energy (Ea), and %39Ar. These values correspond to a closure temperature of ca. 254 and 277 ∘C for a cooling rate of 10 ∘C Myr−1. 40Ar/39Ar age results for both s les did not return any reliable crystallisation age. This is not unexpected as polyhalite is prone to 40Ar* diffusion loss and the evaporites have experienced numerous phases of deformation resetting the closed K/Ar system. An oldest minimum heating step age of ∼514 Ma from s le 06-3.1 corresponds relatively well to the established early Cambrian age of the formation. S les 05-P2 and 05-W2 have measured step ages and represent a deformation event that partially reset the K/Ar system based on oldest significant ages between ca. 381 and 415 Ma. We interpret the youngest measured step ages, between ca. 286 and 292 Ma, to represent the maximum age of deformation-induced recrystallisation. Both the youngest and oldest measured step ages for s les 05-P2 and 05-W2 occur within the time of a major unconformity in the area. These dates may reflect partial resetting of the K/Ar system from meteoric water infiltration and recrystallisation during this non-depositional time. Otherwise, they may result from mixing of Ar derived by radiogenic decay after Cambrian precipitation with partially reset Ar from pervasive Cenozoic deformation and physical recrystallisation.
Publisher: Geological Society of America
Date: 02-01-2018
DOI: 10.1130/B31626.1
Publisher: Elsevier BV
Date: 03-2010
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 08-2013
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 08-2009
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 04-2022
Publisher: American Geophysical Union (AGU)
Date: 03-2017
DOI: 10.1002/2016GC006601
Publisher: Elsevier BV
Date: 02-2009
Publisher: Elsevier BV
Date: 08-2015
Publisher: GeoScienceWorld
Date: 19-08-2016
DOI: 10.1130/L561.1
Publisher: Geological Society of London
Date: 2014
DOI: 10.1144/SP378.24
Publisher: Elsevier BV
Date: 09-2018
Publisher: Elsevier BV
Date: 09-2002
Publisher: Elsevier BV
Date: 03-2011
Publisher: Elsevier BV
Date: 07-2013
Publisher: Wiley
Date: 11-04-2019
DOI: 10.1111/JMG.12480
Publisher: Informa UK Limited
Date: 23-04-2015
Publisher: Geological Society of America
Date: 2007
DOI: 10.1130/G23593Y.1
Publisher: Geological Society of London
Date: 19-08-2009
Publisher: Elsevier BV
Date: 11-2022
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 09-2016
Publisher: Elsevier BV
Date: 04-2021
Publisher: Wiley
Date: 02-2016
DOI: 10.1111/MAPS.12593
Publisher: Informa UK Limited
Date: 30-11-2022
Publisher: Wiley
Date: 02-2016
DOI: 10.1111/MAPS.12594
Publisher: Proceedings of the National Academy of Sciences
Date: 25-07-2022
Abstract: The emplacement of large igneous provinces (LIPs) has been linked to catastrophic mass extinctions in Earth’s history, but some LIPs are only associated with less severe oceanic anoxic events, and others have negligible environmental effects. Although it is widely accepted that massive magma outpouring can affect the environment through volatile degassing, it remains debated what controls the severity of environmental crises. Here, we demonstrate that the second-most-voluminous Phanerozoic LIP, the Kerguelen LIP, may have contributed to the early Aptian oceanic anoxic event 1a, a global event previously believed to have been caused by the Ontong Java LIP. Geochronological data show that the earliest eruptions of the Kerguelen LIP preceded the onset of oceanic anoxic event 1a by at least ∼5 million years. Analyses of CO 2 abundances in melt inclusions combined with Monte Carlo simulations reveal that the volume and degassing rate of CO 2 emissions from the Kerguelen LIP are an order of magnitude lower compared to LIPs that caused severe mass extinctions. We propose that the severity of volcanism-related environmental and biotic perturbations is positively correlated with the volume and rate of CO 2 emissions. Our results highlight the significant importance of reducing and slowing down CO 2 emission in preventing future disastrous environmental consequences.
Publisher: Elsevier BV
Date: 08-2016
Publisher: Elsevier BV
Date: 05-2019
Publisher: Elsevier BV
Date: 03-2020
Publisher: Geological Society of America
Date: 10-2015
DOI: 10.1130/G37044.1
Publisher: Elsevier BV
Date: 12-2019
Publisher: Geological Society of America
Date: 06-02-2020
DOI: 10.1130/G47166.1
Abstract: In Australia, the onset of human occupation (≥65 ka?) and dispersion across the continent are the subjects of intense debate and are critical to understanding global human migration routes. New-generation multi-collector mass spectrometers capable of high-precision 40Ar/39Ar dating of young (& ka) s les provide unprecedented opportunities to improve temporal constraints of archaeological events. In southeastern Australia, a novel approach to improving understanding of occupation involves dating key volcanic eruptions in the region, referenced to stone artifacts and Aboriginal oral traditions. The current study focuses on two monogenetic volcanoes in the Newer Volcanic Province of southeastern Australia: Budj Bim (previously Mount Eccles) and Tower Hill. Budj Bim and its surrounding lava landforms are of great cultural significance and feature prominently in the oral traditions of the Gunditjmara people. Tower Hill is of archaeological significance due to the occurrence of a stone tool beneath tephra. 40Ar/39Ar eruption ages of 36.9 ± 3.1 ka (95% confidence interval) and 36.8 ± 3.8 ka (2σ) were determined for the Budj Bim and Tower Hill volcanic complexes, respectively. The Tower Hill eruption age is a minimum age constraint for human presence in Victoria, consistent with published optically stimulated luminescence and 14C age constraints for the earliest known occupation sites in Tasmania, New South Wales, and South Australia. If aspects of oral traditions pertaining to Budj Bim or its surrounding lava landforms reflect volcanic activity, this could be interpreted as evidence for these being some of the oldest oral traditions in existence.
Publisher: Geological Society of America
Date: 07-10-2021
DOI: 10.1130/G47850.1
Abstract: Large igneous provinces (LIPs) typically form in one short pulse of ∼1–5 Ma or several punctuated ∼1–5 Ma pulses. Here, our 25 new 40Ar/39Ar plateau ages for the main construct of the Kerguelen LIP—the Cretaceous Southern and Central Kerguelen Plateau, Elan Bank, and Broken Ridge—show continuous volcanic activity from ca. 122 to 90 Ma, a long lifespan of & Ma. This suggests that the Kerguelen LIP records the longest, continuous high-magma-flux emplacement interval of any LIP. Distinct from both short-lived and multiple-pulsed LIPs, we propose that Kerguelen is a different type of LIP that formed through long-term interactions between a mantle plume and mid-ocean ridge, which is enabled by multiple ridge jumps, slow spreading, and migration of the ridge. Such processes allow the transport of magma products away from the eruption center and result in long-lived, continuous magmatic activity.
Publisher: Elsevier BV
Date: 10-2018
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 04-2012
Publisher: Elsevier BV
Date: 02-2012
Publisher: American Geophysical Union (AGU)
Date: 12-2020
DOI: 10.1029/2020TC006129
Publisher: Geological Society of America
Date: 16-09-2014
DOI: 10.1130/B31068.1
Publisher: Cambridge University Press (CUP)
Date: 07-03-2018
DOI: 10.1017/S0016756817000061
Abstract: The Omani basement is located spatially distant from the dominantly juvenile Arabian–Nubian Shield (ANS) to its west, and its relationship to the amalgamation of those arc terranes has yet to be properly constrained. The Jebel Ja'alan (NE Oman) basement inlier provides an excellent opportunity to better understand the Neoproterozoic tectonic geography of Oman and its relationship to the ANS. To understand the origin of this basement inlier, we present new radiogenic isotopic data from igneous bodies in Jebel Ja'alan. U–Pb and 40 Ar/ 39 Ar geochronological data are used to constrain the timing of magmatism and metamorphism in the jebel. Positive εHf and εNd values indicate a juvenile origin for the igneous lithologies. Phase equilibria modelling is used to constrain the metamorphic conditions recorded by basement. Pressure–temperature ( P – T ) pseudosections show that basement schists followed a clockwise P–T path, reaching peak metamorphic conditions of c. 650–700°C at 4–7.5 kbar, corresponding to a thermal gradient of c. 90–160°C/kbar. From the calculated thermal gradient, in conjunction with collected trace-element data, we interpret that the Jebel Ja'alan basement formed in an arc environment. Geochronological data indicate that this juvenile arc formed during Tonian time and is older than basement further west in Oman. We argue that the difference in timing is related to westwards arc accretion and migration, which implies that the Omani basement represents its own tectonic domain separate to the ANS and may be the leading edge of the Neoproterozoic accretionary margin of India.
Publisher: Oxford University Press (OUP)
Date: 28-04-2007
Publisher: Elsevier BV
Date: 12-2016
Publisher: Elsevier BV
Date: 2007
Publisher: Elsevier BV
Date: 03-2007
Publisher: Elsevier BV
Date: 12-2018
Publisher: Elsevier BV
Date: 04-2021
Location: United States of America
Start Date: 2011
End Date: 2013
Funder: Australian Research Council
View Funded ActivityStart Date: 2013
End Date: 2015
Funder: Australian Research Council
View Funded ActivityStart Date: 2009
End Date: 2012
Funder: Australian Research Council
View Funded ActivityStart Date: 2010
End Date: 2013
Funder: Australian Research Council
View Funded ActivityStart Date: 2011
End Date: 2011
Funder: Australian Research Council
View Funded ActivityStart Date: 10-2021
End Date: 09-2024
Amount: $455,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2011
End Date: 06-2014
Amount: $170,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2013
End Date: 12-2016
Amount: $370,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2020
End Date: 06-2023
Amount: $610,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 10-2010
End Date: 12-2013
Amount: $192,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2010
End Date: 12-2013
Amount: $510,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 10-2011
End Date: 10-2012
Amount: $420,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2021
End Date: 06-2023
Amount: $905,654.00
Funder: Australian Research Council
View Funded Activity