Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains

Bauer, Wilfried; Siemes, Heinrich; Spaeth, Gerhard; Jacobs, Joachim

doi:10.3402/polar.v35.25420

Cited by 6 publications

(5 citation statements)

References 42 publications

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“…This originated within the Maud Belt from the oblique collision between the volcanic arc and the Kaapvaal Craton at ∼1,080 Ma (Jacobs et al., 1993; Jacobs & Thomas, 2004). It was reactivated during dextral transpressional tectonics in Ediacaran/Cambrian times that affected the East African Antarctic Orogen (EAAO; Bauer et al., 2016). Aeromagnetic data (Golynsky & Jacobs, 2001) reveal that the HF shear zone separates high amplitude aeromagnetic anomalies over largely unreworked ca 1.2 Ga arc crust similar to the Namaqua‐Natal belt (Wang et al., 2020) from a long‐wavelength low over the EAAO.…”

Section: Te Resultsmentioning

confidence: 99%

Effective Elastic Thickness Map Reveals Subglacial Structure of East Antarctica

Swain

Kirby

2021

Geophysical Research Letters

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East Antarctica is the least well‐exposed Precambrian shield on Earth. What is known, or surmised, of its geological structure comes from extrapolation over large distances and from geophysics. Here, we present a map of effective elastic thickness, Te, computed from Antarctic bedrock topography and both terrestrial and satellite gravity data. Te is directly related to lithospheric strength and can distinguish domains of differing tectonic history. Our map reveals a broad region of high Te in Wilkes Land, interpreted as a craton, while elsewhere a corridor of low Te meanders between areas of higher Te. The low‐Te belt follows the trend of prominent linear magnetic anomalies identified in the Gamburtsev and Dronning Maud Land provinces, two of which have previously been identified as possible Grenville or Pan‐African age sutures.

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Section: Te Resultsmentioning

confidence: 99%

Effective Elastic Thickness Map Reveals Subglacial Structure of East Antarctica

Swain

Kirby

2021

Geophysical Research Letters

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“…Recent accumulation of petrological, geochemical, and geochronological data on high-grade metamorphic rocks from Sri Lanka, southern India, East Antarctica, Madagascar, and East Africa regions, which corresponds to the junction of the N-S trending East African-Antarctic Orogen (EAAO; Jacobs & Thomas, 2004;Baba et al, 2015;Bauer, Siemes, Spaeth, & Jacobs, 2016;Tsunogae, Yang, & Santosh, 2016) and the E-W trending Kuunga Orogen (Boger, 2011;Grantham et al, 2013;Kuribara, Tsunogae, Takamura, & Tsutsumi, 2019;Meert & Lieberman, 2008;Meert, van der Voo, & Ayub, 1995), indicates that the Gondwana supercontinent was formed by a series of collision of continental fragments or magmatic arcs between 750 and 530 Ma (e.g., Collins & Pisarevsky, 2005;Jacobs & Thomas, 2004;Meert, 2003;Meert & Lieberman, 2008;Meert & van der Voo, 1997;Santosh, Tsunogae, Tsutsumi, & Iwamura, 2009) rather than a simple collision of East and West Gondwana continents. Although the timing of peak metamorphism related to the final collisional event in these regions has been roughly inferred as about 600-550 Ma (e.g., Kröner et al, 1987;Santosh, Yokoyama, Biju-Sekhal, & Rogers, 2003;Shiraishi et al, 1994), recent studies reported various metamorphic ages from 650 to 500 Ma.…”

Section: Introductionmentioning

confidence: 99%

Prolonged Neoproterozoic high‐grade metamorphism of the Wanni Complex, Sri Lanka: New insights from petrology, phase equilibria modelling, and zircon U–Pb geochronology of partially melted cordierite gneiss from Walpita

et al. 2020

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We report new petrological and geochronological data of garnet‐cordierite (Grt‐Crd) gneiss as well as two types of leucocratic rocks (garnet‐bearing and cordierite‐bearing leucosomes) crystallized during prograde and near‐peak metamorphisms of the Wanni Complex (WC) in Sri Lanka, and investigate the pressure–temperature–time evolution of granulite‐facies metamorphism for unravelling the timing and tectonics of the Neoproterozoic collisional processes related to Gondwana amalgamation. Grt‐Crd gneiss, garnet‐biotite (Grt‐Bt) gneiss, garnet‐bearing leucocratic rock (Grt‐L), and cordierite‐bearing leucocratic rock (Crd‐L) discussed in this study were collected from Walpita in the margin of the WC along the boundary with the Highland Complex (HC). Grt‐L occurs as thin layers parallel to the foliation of matrix Grt‐Bt and Grt‐Crd gneisses. The occurrences of porphyroblastic garnet in quartzo‐feldspathic matrix and crystallised melt inclusions within the garnet suggest that the Grt‐L could have formed by partial melting of host Grt‐Bt gneiss during prograde to peak metamorphism. Crd‐L is coarse‐grained and massive, lacks obvious foliation, and crosscuts the foliation of host Grt‐Bt gneiss. These observations suggest that the Crd‐L could have intruded after the crystallization of the Grt‐L. Application of phase equilibria modelling in the system NCKFMASHTO for the rocks yielded three discrete thermal events: 600–800°C/4.0–6.0 kbar (Stage 1 from Grt‐L), 700–840°C/5.5–7.0 kbar (Stage 2 from Grt‐Crd gneiss), and 840–880°C/4.5–5.5 kbar (Stage 3 from Crd‐L), suggesting a clockwise P–T evolution. LA‐ICP‐MS zircon U–Pb dating of the leucosomes yielded several metamorphic events: >577 Ma (partial melting of Grt‐L), ~562 Ma (crystallization of Grt‐L), 537 ± 14 Ma (peak metamorphism and crystallization of Crd‐L), and 507–503 Ma (post‐peak cooling event). The results of this study therefore confirmed prolonged (>70 Myr) high‐grade metamorphism of the WC, although the duration might be shorter than that of the HC (>100 Ma). The continuous heat supply necessary for such long‐lived high‐grade metamorphism is explained by a recent tectonic model of Sri Lanka. The model suggests double‐sided subduction and continent‐continent collision, which could have given rise to subsequent slab delamination and differential heating of lower to middle crust. Such complex subduction–collision processes possibly controlled the difference in the style of P–T path and the duration of high‐grade metamorphism between the HC and the WC.

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“…Weyprechtfjella; ZH-Zwieselhøgda. Lineaments after Jacobs and Lisker [11], Bauer et al [34] and Jacobs et al [36].…”

Section: Regional Geologymentioning

confidence: 99%

“…The Late Mesoproterozoic metamorphic event is associated with the incorporation of Dronning Maud Land into Rodinia, while the two Late Neoproterozoic-Early Cambrian metamorphic events are related to the collisional phase during Gondwana assembly, resulting in the major East African-Antarctic Orogen (EAAO; e.g., [31]), and the subsequent extensional collapse of this orogen [30], respectively. To the west, the orogenic front of the EAAO is exposed as the 20 km wide, dextral Heimefront Shear Zone in Heimefrontfjella, e.g., [32][33][34].…”

Section: Regional Geologymentioning

confidence: 99%

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Tectono-Thermal Evolution and Morphodynamics of the Central Dronning Maud Land Mountains, East Antarctica, Based on New Thermochronological Data

et al. 2018

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The lack of preserved Mesozoic–Cenozoic sediments and structures in central Dronning Maud Land has so far limited our understanding of the post-Pan-African evolution of this important part of East Antarctica. In order to investigate the thermal evolution of the basement rocks and place constraints on landscape evolution, we present new low-temperature thermochronological data from 34 samples. Apatite fission track ages range from 280–85 Ma, while single-grain (U-Th)/He ages from apatite and zircon range from 305–15 and 420–340 Ma, respectively. Our preferred thermal history models suggest late Paleozoic–early Mesozoic peneplanation and subsequent burial by 3–6 km of Beacon sediments. The samples experienced no additional burial in the Jurassic, thus the once voluminous continental flood basalts of western Dronning Maud Land did not reach central Dronning Maud Land. Mesozoic–early Cenozoic cooling of the samples was slow. Contrary to western Dronning Maud Land, central Dronning Maud Land lacks a mid-Cretaceous cooling phase. We therefore suggest that the mid-Cretaceous cooling of western Dronning Maud Land should be attributed to the proximity to the collapse of the orogenic plateau at the Panthalassic margin of Gondwana. Cooling rates accelerated considerably with the onset of glaciation at 34 Ma, due to climate deterioration and glacial denudation of up to 2 km.

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Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains

Cited by 6 publications

References 42 publications

Effective Elastic Thickness Map Reveals Subglacial Structure of East Antarctica

Effective Elastic Thickness Map Reveals Subglacial Structure of East Antarctica

Prolonged Neoproterozoic high‐grade metamorphism of the Wanni Complex, Sri Lanka: New insights from petrology, phase equilibria modelling, and zircon U–Pb geochronology of partially melted cordierite gneiss from Walpita

Tectono-Thermal Evolution and Morphodynamics of the Central Dronning Maud Land Mountains, East Antarctica, Based on New Thermochronological Data

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