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Burma Terrane part of the Trans-Tethyan Arc during collision with India according to palaeomagnetic data - PubMed

Burma Terrane part of the Trans-Tethyan Arc during collision with India according to palaeomagnetic data

Jan Westerweel et al. Nat Geosci. 2019 Oct.

Abstract

Convergence between the Indian and Asian plates has reshaped large parts of Asia, changing regional climate and biodiversity. Yet geodynamic models fundamentally diverge on how convergence was accommodated since the India-Asia collision. Here we report paleomagnetic data from the Burma Terrane, at the eastern edge of the collision zone and famous for its Cretaceous amber biota, to better determine the evolution of the India-Asia collision. The Burma Terrane was part of a Trans-Tethyan island arc and stood at a near-equatorial southern latitude at ~95 Ma, suggesting island endemism for the Burmese amber biota. The Burma Terrane underwent significant clockwise rotation between ~80-50 Ma, causing its subduction margin to become hyper-oblique. Subsequently, it was translated northward on the Indian Plate, by an exceptional distance of at least 2000 km, along a dextral strike-slip fault system in the east. Our reconstructions are only compatible with geodynamic models involving a first collision of India with a near-equatorial Trans-Tethyan subduction system at ~60 Ma, followed by a later collision with the Asian margin.

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Conflict of interest statement

Competing interests The authors declare no competing financial interests.

Figures

Figure 1
Figure 1

Alternative plate reconstructions of India-Asia paleogeography at 60 Ma with GPlates (See also Methods): a) Reconstruction with a nearly linear subduction zone and significant extrusion of Indochina blocks ,; b) Reconstruction with a Greater India Basin ; c) Reconstruction with a second Trans-Tethyan subduction zone . Abbreviations: BT = Burma Terrane, GI(B) = Greater India (Basin), IB = Indochina Blocks, KA = Kohistan Arc, LT = Lhasa Terrane, RRF = Red River Fault (accommodating Indochina extrusion), SL = Sundaland, TTS = Trans-Tethyan subduction system, WA = Woyla Arc.

Figure 2
Figure 2

Generalized Myanmar geologic map . Localities: 1 = Kawlin, 2 = Pinlebu, 3 = Banmauk, 4 = Kyaung Le, 5 = Shinpa, 6 = Kalewa, 7 = Burmese ambers ,. Abbreviations: AI = Cretaceous-Paleogene Asian intrusives, CB = Chindwin Basin, GA = Cretaceous Gangdese Arc, IBRB: Indo-Burman Ranges basement, KF = Kabaw Fault, MMMB = Mogok–Mandalay–Mergui Belt (including Jurassic Eastern Belt Ophiolites & Jade Belt Ophiolite), SF = Sagaing Fault, SPG = Songpan Ganze & Yangtze complexes, WBO = Cretaceous Western Belt Ophiolite, WPA = Wuntho-Popa Arc, YTSZ = Yarlung-Tsangpo Suture Zone. Dashed black lines: Central Myanmar Basins.

Figure 3
Figure 3

Equal-area projections of interpretable paleomagnetic results: a) Tilt-corrected characteristic directions (squares) of samples from upper Eocene sediments from Kalewa and mean direction (blue); b) Early Late Cretaceous Wuntho Range site means with 95% confidence angles in in-situ coordinates, coloured by locality: Pinlebu (purple), Shinpa (dark green), Banmauk (blue), Kawlin (black) and Kyaung Le (green) and mean direction (red); c) Early Late Cretaceous/late Eocene (red/blue circles) final mean directions compared with the stable Eurasia APWP in the early Late Cretaceous/late Eocene (red/blue diamonds) . Corresponding paleolatitudes and rotation magnitudes are indicated with 95% confidence angles. Open/closed symbols denote negative/positive inclinations.

Figure 4
Figure 4

Reconstructions of the Burma Terrane and Asia at 95 Ma (left) and 40 Ma (right) with GPlates (See also Methods). Abbreviations: BT = Burma Terrane, EA = Eastern Andaman Basins, IB = Indochina Blocks, GI = Greater India, KA = Kohistan Arc, LT = Lhasa Terrane, SB = Sibumasu Block, SL = Sundaland, WA = Woyla Arc.

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