New U-Pb zircon ages from the Denman Glacier area, East Antarctica, and their significance for Gondwana reconstruction

1992 ◽  
Vol 4 (4) ◽  
pp. 447-460 ◽  
Author(s):  
Lance P. Black ◽  
John W. Sheraton ◽  
Robert J. Tingey ◽  
Malcolm T. Mcculloch
Keyword(s):  
Western Australia ◽  
East Antarctica ◽  
Mobile Belt ◽  
High Grade ◽  
Glacier Area ◽  
Geological History ◽  
Entire Region ◽  
Grade Metamorphism ◽  
High Grade Metamorphism ◽  
Indirect Relationship

Two new U-Pb zircon ages from the area immediately west of Denman Glacier in Antarctica show that its geological history differs from that of the Obruchev Hills and Bunger Hills, to the east of the glacier. A crystallization age of 516.0 ± 1.5 Ma for syenite is by far the youngest primary age reported for this region, whereas tonalitic orthogneiss from Cape Charcot, the oldest known local rock, was derived by the high-grade metamorphism and deformation at 2889 ± 9 Ma of a 3003 ± 8 Ma igneous precursor. Both major populations of zircon in this rock lost Pb at 500–600 Ma. Although the Sm-Nd characteristics of the entire region resemble those of the Albany Mobile Belt of Western Australia, the Sm-Nd systematics of the felsic gneisses and plutonics are too old to allow direct correlation with the rocks of the Naturaliste Block (Western Australia), a potential key element for Gondwana reconstruction. However, the possibility exists that there is an indirect relationship between the Naturaliste Block and the region immediately west of Denman Glacier.

scholarly journals Rb/Sr whole rock isochron age determinations on metamorphosed acid volcanic rocks and granitic gneisses from the Ketilidian mobile belt, South-East Greenland

1974 ◽  
Vol 66 ◽  
pp. 12-20
Author(s):  
S Pedersen ◽  
O Larsen ◽  
D Bridgwater ◽  
J Watterson
Keyword(s):  
Volcanic Rocks ◽  
Mobile Belt ◽  
High Grade ◽  
East Greenland ◽  
Volcanic Material ◽  
Grade Metamorphism ◽  
The North ◽  
Acid Volcanic ◽  
High Grade Metamorphism ◽  
Age Determinations

The metamorphosed supracrustal rocks and paragneisses studied were collected during a reconnaissance traverse across the trend of the Ketilidian mobile belt in South-Bast Greenland (Andrews et al., 1971, 1973). All the samples are taken from gneisses regarded as derived from supracrustal material which was originally composed of acid volcanic material deposited as lavas, ignimbrites or sediments with a large volcanic component. Sample localities are shown in fig. 2. All the rocks have been affected by at least one metamorphic episode during the formation of the Ketilidian mobile belt. All are regarded as deposited after the end of regional high grade metamorphism in the Archaean block to the north (which has yielded a U/Pb zircon diffusion age of 2808 m.y.) and are intruded by a variety of synto late tectonic granites within the Ketilidian mobile belt which have yielded U/Pb diffusion and concordia ages between 1850 and 1770 m.y. in this area (Gulson & Krogh, 1972).

scholarly journals Prolonged high-grade metamorphism of supracrustal gneisses from Mühlig-Hofmannfjella, central Dronning Maud Land (East Antarctica)

2020 ◽  
Vol 339 ◽  
pp. 105618 ◽  
Author(s):  
Synnøve Elvevold ◽  
Ane K. Engvik ◽  
Tamer S. Abu-Alam ◽  
Per Inge Myhre ◽  
Fernando Corfu
Keyword(s):  
East Antarctica ◽  
High Grade ◽  
Grade Metamorphism ◽  
Dronning Maud Land ◽  
High Grade Metamorphism

scholarly journals Tectonic evolution of the southern margin of the Amazonian craton in the late Mesoproterozoic based on field relationships and zircon U-Pb geochronology

2014 ◽  
Vol 86 (1) ◽  
pp. 57-84 ◽  
Author(s):  
GILMAR J. RIZZOTTO ◽  
LÉO A. HARTMANN ◽  
JOÃO O.S. SANTOS ◽  
NEAL J. MCNAUGHTON
Keyword(s):  
Tectonic Evolution ◽  
High Grade ◽  
Geological History ◽  
Short Sequence ◽  
Geochronological Data ◽  
Mafic Rocks ◽  
Grade Metamorphism ◽  
Amazonian Craton ◽  
High Grade Metamorphism ◽  
Wilson Cycle

New U-Pb zircon geochronological data integrated with field relationships and an airborne geophysical survey suggest that the Nova Brasilândia and Aguapeí belts are part of the same monocyclic, metaigneous and metasedimentary belt formed in the late Mesoproterozoic (1150 Ma-1110 Ma). This geological history is very similar to the within-plate origin of the Sunsás belt, in eastern Bolivia. Thus, we propose that the Nova Brasilândia, Aguapeí and Sunsás belts represent a unique geotectonic unit (here termed the Western Amazon belt) that became amalgamated at the end of the Mesoproterozoic and originated through the reactivation of a paleo-suture (Guaporé suture zone) in an intracontinental rift environment. Therefore, its geological history involves a short, complete Wilson cycle of ca. 40 Ma. Globally, this tectonic evolution may be related with the final breakup of the supercontinent Columbia. Mafic rocks and trondhjemites in the northernmost portion of the belt yielded U-Pb zircon ages ca. 1110 Ma, which dates the high-grade metamorphism and the closure of the rift. This indicates that the breakup of supercontinent Columbia was followed in short sequence by the assembly of supercontinent Rodinia at ca. 1.1-1.0 Ga and that the Western Amazon belt was formed during the accretion of the Arequipa-Antofalla basement to the Amazonian craton.

Neoproterozoic extension in the Greater Dharwar Craton: a reevaluation of the “Betsimisaraka suture” in MadagascarThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.

2011 ◽  
Vol 48 (2) ◽  
pp. 389-417 ◽  
Author(s):  
R. D. Tucker ◽  
J.-Y. Roig ◽  
C. Delor ◽  
Y. Amelin ◽  
P. Goncalves ◽  
...  
Keyword(s):  
Dharwar Craton ◽  
High Grade ◽  
Grade Metamorphism ◽  
Continental Extension ◽  
Shrimp Geochronology ◽  
Igneous Activity ◽  
High Grade Metamorphism ◽  
Local Inversion ◽  
Metaigneous Rocks ◽  
Eastern Domain

The Precambrian shield of Madagascar is reevaluated with recently compiled geological data and new U–Pb sensitive high-resolution ion microprobe (SHRIMP) geochronology. Two Archean domains are recognized: the eastern Antongil–Masora domain and the central Antananarivo domain, the latter with distinctive belts of metamafic gneiss and schist (Tsaratanana Complex). In the eastern domain, the period of early crust formation is extended to the Paleo–Mesoarchean (3.32–3.15 Ga) and a supracrustal sequence (Fenerivo Group), deposited at 3.18 Ga and metamorphosed at 2.55 Ga, is identified. In the central domain, a Neoarchean period of high-grade metamorphism and anatexis that affected both felsic (Betsiboka Suite) and mafic gneisses (Tsaratanana Complex) is documented. We propose, therefore, that the Antananarivo domain was amalgamated within the Greater Dharwar Craton (India + Madagascar) by a Neoarchean accretion event (2.55–2.48 Ga), involving emplacement of juvenile igneous rocks, high-grade metamorphism, and the juxtaposition of disparate belts of mafic gneiss and schist (metagreenstones). The concept of the “Betsimisaraka suture” is dispelled and the zone is redefined as a domain of Neoproterozoic metasedimentary (Manampotsy Group) and metaigneous rocks (Itsindro–Imorona Suite) formed during a period of continental extension and intrusive igneous activity between 840 and 760 Ma. Younger orogenic convergence (560–520 Ma) resulted in east-directed overthrusting throughout south Madagascar and steepening with local inversion of the domain in central Madagascar. Along part of its length, the Manampotsy Group covers the boundary between the eastern and central Archean domains and is overprinted by the Angavo–Ifanadiana high-strain zone that served as a zone of crustal weakness throughout Cretaceous to Recent times.

scholarly journals Timing of High-Grade Metamorphism in Madurai Block, South India: Insights from New U-Pb Zircon & Monazite Ages

2020 ◽  
Author(s):  
J Amal Dev ◽  
J K Tomson ◽  
K Anto Francis ◽  
Nilanjana Sorcar ◽  
V Nandakumar
Keyword(s):  
South India ◽  
High Grade ◽  
Grade Metamorphism ◽  
High Grade Metamorphism
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