Geology of Myanmar

To the west, a highly oblique subduction zone separates the offshore Indian Plate from the Burma microplate, which underlies most of the country.

[7] A large amount of potential energy stored within the thickened Tibetan crust was released, and resulted in a crustal flow around the eastern Himalaya Syntaxis.

This crustal flow, along with the accretionary wedge in the subduction system, may have participated in the late Neogene uplift of Indo-Burman Range.

The subduction between the two plates resulted in the development of accretionary wedges, in order to accommodate the EW shortening along the convergent boundary.

[7] This arc-shaped structure implies restriction on the convergent motion along the Indian-Burma boundary, therefore the collision intensity varies along the range.

[11] The 1000 km Myanmar Central Belt consists of a series of Cenozoic sub-basins between the Indo-Burman Range (west) and Sagaing Fault (east).

[7] The eight major tertiary sub-basins within the Myanmar Central Belt are Hukwang, Chindwin, Shwebo, Salin, Pyay Embayment, Irrawaddy Delta, Bago-Yoma, and Sittaung Basin.

The exposed metamorphic lineation along the belt[14] indicates different motions within the central belt: (1) dextral pull apart geometry trending in a north-northwest direction during Oligocene to early Miocene forming an "en-echelon" pull-apart basin:[12] (2) fault-propagated folds cored in a west-dipping thrust fault in the basin center implies an east-west trending transpressional deformation from Pliocene-Pleistocene onwards.

[16] The plateau, unlike other regions Myanmar, comprises thick successions of Paleozoic, Mesozoic and even Precambrian sedimentary rocks.

[15] The folding, thrusting and uplifting of the Shan Plateau is probably coeval with the transpressional deformation along the Myanmar Central Belt during the commencement of the India-Eurasia collision.

[4] The meta-sedimentary and meta-intrusive belt is composed of marbles, schists, gneisses of upper amphibolite, with locally granulite facies intruded by a deformed granodiorite pluton and pegmatites.

[6] The obduction of ophiolites is interpreted as the closure of several Neo-Tethys between the Shan-Thai block, Burma microplate and Indian Plate.

[21] Northward, the Sagaing fault terminates at the Jade Mine belt (~ 24.5°N) and splays into a 200 km width compressive horsetail structure.

[21] Along the foothills of the Shan Scarp, steady-state stretching ductile deformation trending in NNW-SSE direction was identified and is compatible with the extensive force that generates the en-echelon pull apart basin in Myanmar Central Belt (MCB).

[7] The rifted Burma-microplate from Gondwanaland also docked against Shan-Thai block and together formed part of the Sunda plate approximately in the period.

[29] In early Eocene, the start of a hard continent-to-continent collision between India and the Eurasia Plate led to the formation of the Himalayan Orogeny.

[31] Between late Eocene to Miocene, the Burma and Shan-Thai block rotated 30° to 40° clockwise, to accommodate the major collision along the plate boundary.

[32] In the late Miocene (10 million years ago), the Myanmar Central Belt underwent a major regional plate kinematic reorganization transition.

[16] The tectonic regimes transform from northwest-southeast extensional force to basin inversion and was followed by a major uplift event caused by east-west compression during Plio-Pleistocene period.

[43] The formations that compose the hydrocarbon basins are sedimentary rocks of Eocene through mid-Mioceneand sealed with interbedded Oligocene and Miocene shales and clays.

The picture shows the location of Myanmar in Southeast Asia .
The figure shows a simplified version of the regional features in Myanmar. The three physiographical region from west to east: Indo-Burman Range, Myanmar Central Belt and Shan Plateau. The Mogok Metamorphic Belt (MMB) is expressed with dashed lines. Modified from Bender (1983). [ 6 ]
Simplified geological cross section of Myanmar at latitude 21°N. SG refers to Sagaing fault. Inspired and modified from Rangin et al. (2013) and Mitchell (1989). [ 7 ] [ 15 ]
Arakan Mountains in Maungdaw district .
Hills, Kalaw area, Shan Plateau
The figure shows the location of plates around Myanmar. Myanmar is traced in dotted red lines, where the strike slip fault is the Sagaing fault and the thrust fault is the Kabaw fault. Modified with Alam et al. (2003) [ 6 ]
This figure shows the India plate motion with reference to the Shan Thai (Sunda) plate. The N10°E 35 mm/yr convergence is accommodated by the 20 mm/yr right lateral Sagaing strike slip fault, the 9 mm/yr convergent Kabaw thrust fault and 14 mm/yr subduction the Andaman Trench. Modified from Socquet et al. 2006. [ 20 ]
Simplified diagram showing the tectonic deformation along Shan Plateau and the Sagaing fault. 1) The NE-SW extensional ductile deformation along this region was dated prior to Late Miocene . 2) The brittle dextral strike slip fault and thrust fault along the Shan Scarp and the Sagaing fault is dated back to Plio-Pleistocene period. Modified from Bertrand et al. (2003) [ 25 ]
A simplified geological evolution of Myanmar. (ST=South Tibet; B= Burma; IC=Indochina; S=Sumatra; RRF=Red River Fault; SB= Shan-Thai Block). (a) The rifting of Gondwana (b) The start of "soft collision" between India and Southeast Asia. (c) The start of "hard collision" between India and South Asia. (d) The time for major collision between India, South Tibet and Burma; where Burma, Shan-Thai Block rotates clockwise to the present position. Modified from Alam et al. (2003). [ 25 ]