Early Palaeozoic orogenic collapse and voluminous late-tectonic magmatism in Dronning Maud Land and Mozambique: Insights into the partially delaminated orogenic root of the East African-Antarctic Orogen?

Joachim Jacobs, Bernard Bingen, Robert J. Thomas, Wilfried Bauer, Michael T D Wingate, Paulino Feitio

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Abstract

The late tectonic history of the southern part of the Late Neoproterozoic-Early Palaeozoic East African-Antarctic Orogen (EAAO) is characterized by lateral extrusion, extensional collapse and large volumes of high-temperature A2-type granitoids. This late-tectonic igneous province covers an area more than 15 000 km2 of the EAAO in Dronning Maud Land (East Antarctica) and its northerly continuation as the Nampula Complex of NE Mozambique. The magmatic province is bounded in the north by the Lurio Belt. New secondary ionization mass spectrometry (SIMS) U-Pb analyses of zircons from two major late-tectonic granitoid intrusions from Dronning Maud Land indicate crystallization ages of 501 + 7 and 499 + 4 Ma, whereas a major extensional shear zone was dated at 507 + 9 Ma. New SIMS zircon U-Pb analyses of late-tectonic granitoid sheets and plutons from the Nampula Province indicate ages of 512 + 4, 508 + 4, 508 + 2 and 507 + 3 Ma. Consequently, the late-tectonic magmatism can be bracketed between c. 530 and 485 Ma. It started with small gabbro bodies emplaced at c. 530-520 Ma, culminated with the intrusion of major granite-charnockite plutons at c. 510-500 Ma and terminated with the introduction of small volumes of sheet-like granite at c. 485 Ma. The new dates demonstrate that extensional shearing and granitoid intrusion are synchronous, and that orogenic collapse and the magmatism are related. We ascribe the distribution, structural style, geochemical composition and age of the late magmatic province to a process of partial delamination of the orogenic root in the southern third of the EAAO. It remains to be tested whether there is a relationship between orogenic collapse-granitoid magmatism and south-directed escape tectonics in the southernmost EAAO.

Original languageEnglish
Pages (from-to)69-90
Number of pages22
JournalGeological Society Special Publication
Volume308
DOIs
Publication statusPublished - 2008
Externally publishedYes

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Tectonics
magmatism
Paleozoic
granitoid
tectonics
Zircon
Granite
pluton
Ionization
Mass spectrometry
zircon
ionization
granite
mass spectrometry
igneous province
charnockite
delamination
extrusion
Shearing
gabbro

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@article{f6442f27c30049b9a1128836b975ce0a,
title = "Early Palaeozoic orogenic collapse and voluminous late-tectonic magmatism in Dronning Maud Land and Mozambique: Insights into the partially delaminated orogenic root of the East African-Antarctic Orogen?",
abstract = "The late tectonic history of the southern part of the Late Neoproterozoic-Early Palaeozoic East African-Antarctic Orogen (EAAO) is characterized by lateral extrusion, extensional collapse and large volumes of high-temperature A2-type granitoids. This late-tectonic igneous province covers an area more than 15 000 km2 of the EAAO in Dronning Maud Land (East Antarctica) and its northerly continuation as the Nampula Complex of NE Mozambique. The magmatic province is bounded in the north by the Lurio Belt. New secondary ionization mass spectrometry (SIMS) U-Pb analyses of zircons from two major late-tectonic granitoid intrusions from Dronning Maud Land indicate crystallization ages of 501 + 7 and 499 + 4 Ma, whereas a major extensional shear zone was dated at 507 + 9 Ma. New SIMS zircon U-Pb analyses of late-tectonic granitoid sheets and plutons from the Nampula Province indicate ages of 512 + 4, 508 + 4, 508 + 2 and 507 + 3 Ma. Consequently, the late-tectonic magmatism can be bracketed between c. 530 and 485 Ma. It started with small gabbro bodies emplaced at c. 530-520 Ma, culminated with the intrusion of major granite-charnockite plutons at c. 510-500 Ma and terminated with the introduction of small volumes of sheet-like granite at c. 485 Ma. The new dates demonstrate that extensional shearing and granitoid intrusion are synchronous, and that orogenic collapse and the magmatism are related. We ascribe the distribution, structural style, geochemical composition and age of the late magmatic province to a process of partial delamination of the orogenic root in the southern third of the EAAO. It remains to be tested whether there is a relationship between orogenic collapse-granitoid magmatism and south-directed escape tectonics in the southernmost EAAO.",
author = "Joachim Jacobs and Bernard Bingen and Thomas, {Robert J.} and Wilfried Bauer and Wingate, {Michael T D} and Paulino Feitio",
year = "2008",
doi = "10.1144/SP308.3",
language = "English",
volume = "308",
pages = "69--90",
journal = "Geological Society Special Publication",
issn = "0305-8719",
publisher = "Geological Society of London",

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TY - JOUR

T1 - Early Palaeozoic orogenic collapse and voluminous late-tectonic magmatism in Dronning Maud Land and Mozambique

T2 - Insights into the partially delaminated orogenic root of the East African-Antarctic Orogen?

AU - Jacobs, Joachim

AU - Bingen, Bernard

AU - Thomas, Robert J.

AU - Bauer, Wilfried

AU - Wingate, Michael T D

AU - Feitio, Paulino

PY - 2008

Y1 - 2008

N2 - The late tectonic history of the southern part of the Late Neoproterozoic-Early Palaeozoic East African-Antarctic Orogen (EAAO) is characterized by lateral extrusion, extensional collapse and large volumes of high-temperature A2-type granitoids. This late-tectonic igneous province covers an area more than 15 000 km2 of the EAAO in Dronning Maud Land (East Antarctica) and its northerly continuation as the Nampula Complex of NE Mozambique. The magmatic province is bounded in the north by the Lurio Belt. New secondary ionization mass spectrometry (SIMS) U-Pb analyses of zircons from two major late-tectonic granitoid intrusions from Dronning Maud Land indicate crystallization ages of 501 + 7 and 499 + 4 Ma, whereas a major extensional shear zone was dated at 507 + 9 Ma. New SIMS zircon U-Pb analyses of late-tectonic granitoid sheets and plutons from the Nampula Province indicate ages of 512 + 4, 508 + 4, 508 + 2 and 507 + 3 Ma. Consequently, the late-tectonic magmatism can be bracketed between c. 530 and 485 Ma. It started with small gabbro bodies emplaced at c. 530-520 Ma, culminated with the intrusion of major granite-charnockite plutons at c. 510-500 Ma and terminated with the introduction of small volumes of sheet-like granite at c. 485 Ma. The new dates demonstrate that extensional shearing and granitoid intrusion are synchronous, and that orogenic collapse and the magmatism are related. We ascribe the distribution, structural style, geochemical composition and age of the late magmatic province to a process of partial delamination of the orogenic root in the southern third of the EAAO. It remains to be tested whether there is a relationship between orogenic collapse-granitoid magmatism and south-directed escape tectonics in the southernmost EAAO.

AB - The late tectonic history of the southern part of the Late Neoproterozoic-Early Palaeozoic East African-Antarctic Orogen (EAAO) is characterized by lateral extrusion, extensional collapse and large volumes of high-temperature A2-type granitoids. This late-tectonic igneous province covers an area more than 15 000 km2 of the EAAO in Dronning Maud Land (East Antarctica) and its northerly continuation as the Nampula Complex of NE Mozambique. The magmatic province is bounded in the north by the Lurio Belt. New secondary ionization mass spectrometry (SIMS) U-Pb analyses of zircons from two major late-tectonic granitoid intrusions from Dronning Maud Land indicate crystallization ages of 501 + 7 and 499 + 4 Ma, whereas a major extensional shear zone was dated at 507 + 9 Ma. New SIMS zircon U-Pb analyses of late-tectonic granitoid sheets and plutons from the Nampula Province indicate ages of 512 + 4, 508 + 4, 508 + 2 and 507 + 3 Ma. Consequently, the late-tectonic magmatism can be bracketed between c. 530 and 485 Ma. It started with small gabbro bodies emplaced at c. 530-520 Ma, culminated with the intrusion of major granite-charnockite plutons at c. 510-500 Ma and terminated with the introduction of small volumes of sheet-like granite at c. 485 Ma. The new dates demonstrate that extensional shearing and granitoid intrusion are synchronous, and that orogenic collapse and the magmatism are related. We ascribe the distribution, structural style, geochemical composition and age of the late magmatic province to a process of partial delamination of the orogenic root in the southern third of the EAAO. It remains to be tested whether there is a relationship between orogenic collapse-granitoid magmatism and south-directed escape tectonics in the southernmost EAAO.

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U2 - 10.1144/SP308.3

DO - 10.1144/SP308.3

M3 - Article

VL - 308

SP - 69

EP - 90

JO - Geological Society Special Publication

JF - Geological Society Special Publication

SN - 0305-8719

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