ORCID Profile
0000-0002-6542-7908
Current Organisations
Australian National University
,
University of Melbourne
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Publisher: Wiley
Date: 03-06-2023
DOI: 10.1111/JMG.12734
Abstract: The Dom Feliciano Belt of southern Brazil and Uruguay represents part of a larger Neoproterozoic orogenic system formed during the amalgamation of Western Gondwana. The hinterland and foreland domains in parts of the belt preserve deformation structures and metamorphic assemblages that developed during early crustal thickening from c. 650 Ma. However, the metamorphic history of the southern foreland, in Uruguay, and its relationship with the hinterland, is not so well understood. We show that metamorphism in the southern hinterland is characterized by near‐isothermal decompression from ~10 kbar (~770°C) down to ~6 kbar, reflecting exhumation from depths of ~40 km during convergent thrusting and crustal thickening. This metamorphic event and associated magmatism is constrained by garnet Lu–Hf and zircon U–Pb dating to c. 655–640 Ma, supporting age and P–T constraints from previous studies. In contrast, prograde metamorphism in the foreland supracrustal rocks reached maximum lower‐ hibolite facies conditions (~6–7 kbar and ~550–570°C) and is constrained by garnet Lu–Hf dating to 582 ± 23 Ma. An exposed sheet of imbricated foreland basement rocks reached partial melting at upper‐ hibolite facies conditions, and metamorphism is similarly constrained to c. 585–570 Ma by monazite U–Pb dating. The data indicate that metamorphism in the foreland occurred during a sinistral transpressional event c. 55–85 Ma after the start of crustal thickening recorded in the hinterland, whereby strain partitioning during sinistral transpression led to imbrication in the foreland and oblique thrusting of the basement over more distal supracrustal rocks. This event is coeval with transpressional deformation in the Kaoko and Gariep belts, indicating a distinct two‐stage tectonic history driven by the three‐way convergence between the Congo, Kalahari, and South American cratons.
Publisher: American Geophysical Union (AGU)
Date: 02-2022
DOI: 10.1029/2021TC007014
Abstract: The Dom Feliciano Belt in southern Brazil and Uruguay represents the western half of a Neoproterozoic orogenic belt located in the southern portion of the South Atlantic Neoproterozoic Orogenic System. Current interpretations are ided as to the nature of orogenesis in this belt, in part owing to lacking geochronological constraints. Metamorphosed and deformed supracrustal sequences of the Brusque Complex in the northern Dom Feliciano Belt, representing part of the orogenic foreland, record the onset and duration of crustal thickening. Structural analysis and pressure–temperature estimates indicate that the complex reached peak regional metamorphic conditions of 540–570°C and 5.5–6.7 kbar during thrusting and burial, consistent with orogenic metamorphism and early crustal thickening. Garnet–whole rock Lu–Hf and Sm–Nd isochron ages date this event to between circa 660–650 Ma. Ar–Ar dating of mica suggests thrust‐controlled exhumation and partial cooling by circa 635 Ma, and that localized deformation occurred into the late Ediacaran. Our results show that the orogenic foreland reached metamorphic conditions typical for crustal thickening 20–30 million years prior to the onset of massive magmatic activity in the hinterland. Such a delay is typical of hot, internal parts of orogens, which supports interpretations that hinterland magmatism in the northern Dom Feliciano Belt represents post‐collisional magmatism and not arc magmatism above a subduction zone. Instead, we suggest that orogenesis in the northern Dom Feliciano Belt was initiated by rift‐basin inversion driven by far‐field forces transmitted through the crust in an intracontinental rift or back‐arc rift setting.
Publisher: Elsevier BV
Date: 03-2021
No related grants have been discovered for Jack Percival.