The Rakhine Coastal

Both on land and offshose continental shelf of this belt are narrow in the south and become wider in the north because they are controlled by underlying structures and prevaitling tectonic stress regions. They are underlain by deformed Indoburman Flysch tectonically inter-mixed with mélanges, comprising exotic blocks of limestone and mafic volcanic and ultramafic rock of phiolite affinity, particularly in its southern part. The upper tertiary strata of molasse facies overlap the deformed flysch strata of loder age in the north and east. The molasse strata of this belt belong to the Bangal Bain to the west, a kind of fore-deep Basin beneath west-vergant fold and thrust fault of WR. Containtal shelf offshore to the west of the Rakhin coast is narrow in the south. The Wr and the Rakhin Coastal Belt (RCB) are sparated by series of faults mark by the topographic breaks.

The Arakan Costal Belts in the narrow southern part of the Assam trough, and the lithological types deposited there are similar to those the Central Belts. The Arakan Costal Area extends west of the Indoburman Ranges. Geologically, this area has much in common with the Arakan Yoma because it is part of the same fold belt. Upper Cretaceous (?) and Eocene, and also – unlike in the Arakan Yoma – Oligocene and Miocene sediments are exposed. The sedimentary sequences are cut in places by volcanic dykes.  On the island of Ramree and Cheduba, as well as on smaller neighbouring island and further north on the mainland, natural gas seepages have formed mud volcanoes of sometime considerable size (Bender, 1983).

In the offshorse area, seismic reflection survey revealed narrow 30 to 80 km long, often faults and offset anticlinal trends with special culminations of Pre-Paleozoic rocks. They run generally in S-N and SSW-NNE directions. In the coastal area, Miocene sequences are frequently steeply tilted, intensively faulted, locally fold and overthrusted. The pre-Miocene flysch rocks occurring below the transgressive Miocene Beds show the structural style of the Indo-Burma Ranges (Atlas Of Mineral Resources of the Escap Region, 1996).

reference: 

Atlas of Mineral Resources of the Escpe Region Volume 12, 1996

The Western Ranges

The Western Ranges consists of two different geological units, namely a board flysch range, which constitutes the main section, and a narrow, intermittently outcropping zone of metamorphic rocks, ophiolite, Triassic Halobia schist and an Upper Cretaceous sequence at their E margin. Flysch-type sediment characteristics, such as alternating beds of greywackey, sandstone, siltstone, claystone and shale, graded bedding, rhythmic interbedding of sandstone and schists, and sole marks can be observed in this rock sequence. The Naga metamorphic Complex contains meso-metamorphic rocks, i.e dark and sometimes graphitic, biotite-muscovite and biotite-muscovite-sillimantie schist, frequently in association with banded paragneiss, sericitic quartzite and the carbonatic Pansat Series.  

The Western Belt of the Indoburman Ranges consists of deformed Senonian mudstone and pelagic limestones, or Chin Flysch, and overlying Eocene and younger clastics (United Nations, 1978b) and is faulted against the Eastern Belt. The surface trace of the active subduction zone between the Indain Plate Myanmar lies west of the Chin Flysch, which can be projected into the Yarlung suture zone in Tebit. Small of less deformed strata of molasse facies were probably deposited in shallower water above the rising flysch strata probably in Late Eocene or Early Oligocene while their coal non-marine strata were laid down in the adjancet tough above the trench, like Yaw and part of Pondaung Formations. The flysch strata were deformed and weekly metamorphosed in the trench environment be north the frontal edge of overriding continental plate.

Within the Pondaung Formation of Late Eocene age some possible small non-marine subunits are exposed. The overlying uppermost Eocene unit, the Yaw Formations is composed of numerous commercial coal seams indicating the non-marines deposition. Line of the western outcrop, exposed as isolated hills of big mountain masses like Paungmin Taung near Htelin, Pyarnattaung near Gangaw and Geiksgoke taung southeast of Kalemyo or as several small Low Hill, lense and individual beds intercalated with flyschoid mudstone and sandstone of comparable age, along the eastern margin of Myittha and Kabaw valleys of the CMB.

Within the Pondaung formation of Late Eocene age some possible small non-marine subunits are exposed. The overlying upper most Eocene unit, the Yaw Formation is composed of numerous commerciate coal seams indicating the non-marine deposition.

reference: 

Atlas of Mineral Resources of the Escpe Region Volume 12, 1996

The Central Lowlands

The Central Lowlands are made up of Triassic, Cretaceous-Tertiary marine and non-marine strata that are bounded in the east by the Easter Highlands and the west by the Western Ranges (Indo-Burma Ranges). They are filled with more than 60,000 ft (2500 m) of Triassic, Cretaceous, Tertiary and Quaternary deposits (Than Nyunt & Chit Saing, 1978) among the Eocene sediments constitute 50% of the Tertiary sequence, with a whole Eocene thickness of 27,700 ft (8445 m) (Aung Khin & Kyaw Win, 1969). The Central Myanmar Block with the Wuntho Salingyi-Mesozoic Arc extending in a north-south direction along its medial axis. There are at least four uplifts and the five basins in the Central Cenozoic Belt. The four uplifts are (from north to south) Kumon ridge uplift, Wuntho mass uplift, Salingyi uplift, Peguyoma uplift. The five Basins are Hukawng Basin, Chindwin Basin, Shwebo Monywa Basin, Minbu Basin, Pathain Basin.

Pre-Albin rocks are intruded by andesite sills, by the early Upper Cretaceous granodioritic Kanza Chaung batholiths and by Tertiary minor intrusions, including those with associated copper deposits at Monywa (Win and Kirwin, 1998). Between Mt Popa and Sagaing Fault only post-Oligocene sediments are exposed.

Tne Inner Burmar Tertiary Basin consists of tow major north-south oriented sedimentary throughs spreaded by a central line of volcanic rocks. The entire fault system is characterized by a Znoe of Basic and ulterbasic igneous of Mesozoic-Cenozoic age. These volcanic belong to the inner volcanic arc, individual occurrences of which can be traced along the entire belt extending for the same distance in a SSW-NNE-N direction in the Inner Tertiary Basin. The arc has been found magnetic and in the seismic reflection survey in the Golf of Martaban, also in the coarse of oil exploratory drilling in the Ayeyarwady Delta Basin. It run vir Mt Popa the volcanic of Shinmataung range, salingyi and the Wuntho Massif through to the eastern border of the Hugaung Basin. The arc is made up of granodioritic, andesitic and basaltic rock of Late Mesozoic to Cenozoic volcanism (Bender, 1983). The Central Myanmar Block with the Wuntho Salingyi-Mesozoic Arc extending in a north-south direction along its medial axis. The Basin are formed north to south Hukawng Basin, Chindwin Basin, Minbu Basin, Ayeyawady Delta Basin, all o force side of Wuntho-Salingyi Magmatic Arce. In the Wuntho –banmauk-Pinlebu Area, the CMB is under lain by pre-Albin andesitic basaltic with pillow stractures, intruded by mid-Cretaceous granodiorite batho-litho, which are exposed discontiously wouth ward along the medial exis of the CMB, form Wuntho-Bamauk are to Salingyi Area southwest of Monywa.

In the Tagaung-Myitkyina belt of northern Myanmar, granodioritic plutons and the Katha-Gangaw Range kyanite-bearing schists may be equilivalents of the Wuntho-Popa Upper cretaceous magmatic arc and Kanpetlet Schists offset on the Sagaing Fault (Mitchell. 1993). The schist dip steeply east beneath the Mogok Metamorphic belt on the Kyaukphyu Fault. North of Singu, the eastern volcanic line makes a curve to the north-east, folloeing Kumon Ranges. 

reference: 

Atlas of Mineral Resources of the Escpe Region Volume 12, 1996