ORCID Profile
0000-0003-2289-2903
Current Organisation
National Taiwan Normal University
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Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 12-2013
Publisher: Geological Society of London
Date: 08-07-2021
Publisher: Elsevier BV
Date: 05-2018
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 2014
Publisher: Elsevier BV
Date: 2013
Publisher: Cambridge University Press (CUP)
Date: 06-05-2015
DOI: 10.1017/S0016756815000217
Abstract: The Doba gabbro was collected from an exploration well through the Cretaceous Doba basin of southern Chad. The gabbro is composed mostly of plagioclase, clinopyroxene and Fe–Ti oxide minerals and displays cumulus mineral textures. Whole-rock 40 Ar– 39 Ar step-heating geochronology yielded a Late Permian plateau age of 257 ± 1 Ma. The major and trace elemental geochemistry shows that the gabbro is tholeiitic in composition and has trace element ratios (i.e. La/Yb N 7 Sm/Yb PM 3.4 Nb/Y 1 Zr/Y 5) indicative of a basaltic melt derived from a garnet-bearing mantle source. The moderately enriched Sr–Nd isotopes (i.e. I Sr = 0.70495 to 0.70839 ɛNd (T) = −1.0 to −1.3) fall within the mantle array (i.e. OIB-like) and are similar to other Late Permian plutonic rocks of North-Central Africa (i.e. I Sr = 0.7040 to 0.7070). The enriched isotopic composition of the Doba gabbro contrasts with the more depleted compositions of the spatially associated Neoproterozoic post-Pan-African within-plate granites. The contrasting Nd isotope composition between the older within-plate granites and the younger Doba gabbro indicates that different mantle sources produced the rocks and thus may mark the southern boundary of the Saharan Metacraton.
Publisher: Geological Society of America
Date: 06-02-2020
DOI: 10.1130/G47076.1
Abstract: The eruption of Emeishan lava in southwestern China and northern Vietnam is considered to be a contributing factor to the Capitanian mass extinction and subsequent global cooling event, but the duration of volcanism is uncertain. The difficulty in assessing the termination age is, in part, due to the lack of high-precision age data for late-stage volcanic rocks. The Tu Le rhyolite of northern Vietnam is the most voluminous silicic unit of the Emeishan large igneous province (ELIP) and is spatially associated with the Muong Hum and Phan Si Pan hypabyssal plutons. Chemical abrasion–isotope dilution–thermal ionization mass spectrometry U-Pb dating of zircons from the Tu Le rhyolite (257.1 ± 0.6 Ma to 257.9 ± 0.3 Ma) and Muong Hum (257.3 ± 0.2 Ma) and Phan Si Pan (256.3 ± 0.4 Ma) plutons yielded the youngest high-precision ages of the ELIP yet determined. The results demonstrate that Emeishan lavas erupted over a period of ∼6 m.y,. with plutonism ending shortly thereafter. Thus, it is possible that Emeishan volcanism contributed to global cooling into the middle Wuchiapingian. It appears that these rocks represent a distinct period of ELIP magmatism, as they are young and were emplaced oblique to the main north-south–trending Panxi rift.
Publisher: Elsevier BV
Date: 10-2017
Publisher: Informa UK Limited
Date: 24-06-2014
Publisher: Elsevier BV
Date: 05-2019
Publisher: Frontiers Media SA
Date: 21-01-2021
Publisher: Elsevier BV
Date: 07-2012
Location: Taiwan, Province of China
No related grants have been discovered for J. Gregory Shellnutt.