Eastern Highlands

The Shan-Tenasserim Highland is constituted of the Precambrian, Paleozoic and Mesozoic rocks, were formed partly in mobile belts and partly on unstable shelves, which were later deformed and partly metamorphosed. The eastern mountainous tract of Kachin State belongs to the Sino-Myanmar Ranges which together with their southward continuations in Myanmar are generally referred to the Eastern Highlands (Win Swe, 1981), or the eastern most geotectonic belt of Myanmar or restricted east Kachin/Shan Unit by (Bender et al 1983). The eastern highland belt extends southward through the Shan Plateau and the ranges southward to those Tanintharyi reagion, and father, southward into those of Malay Peninsula and eastern Sumata. The Eastern Highlands Belts is also considered to be the southern continuation of the Lhasa block of south Tibet through the Yunnan Plateau (Tapponnier et al, 1986). The Chaung Magyi Group is uncomformably overline by fossiliferous Ordovician to Middle Devonian sequence of Carbonate and fine-grained indurated clastic sedimentary strata, successively overline by fossiliferous Upper Palezoic to Middle Triassic turbiditte strata and Upper Jurassic shallow marine strata. The rock types exposed in the region include gneiss, schist, calx-silicate rock and marble some of whichare very coarse grained. They are indurated by ignerous rocks like lucogranite, syenite,and gneiss, garnet biotite gneiss, biotite silliminite gneiss.

The Shan-Thai succession is characterized by a distinctive Upper Cambrian to Devonian and late Lower Permian to Mesozoic stratigraphy (Boucot, 2002). Within the block, amphibolites facies schist and gneisses occur on the Shan Plateau, to the south in Thailand where there was a major end-Triassic metamorphic event (Hansen et al, 2002).

The Mogok Belt contains medium to high-grade metamorphic rocks including banded gneiss, crystalline schist, crystalline limestone or coarse-grained marble, calcsilcate granulites and quartzite which are closely associated with foliated and nonfoliated in metamorphic grade and are more pervasively deformed than those of the Chaung Magyi Group of northern Shan State, believed to be late Proterozoic in age, crystalline rocks of the Mogok area are generally regarded as of Archean age, like those of the Dhawar system of peninsular Indian an those of the crystalline rocks of the Himalayas (La Touche, 1913, Chhibber, 1934). Clegg (1941) believed that this belt contains metamorphosed sediment and tuffs which may range in age from Ordovician to Cretaceous. Searle and Ba Than Haq (1964) discovered that a limited K/Ar radiogenic date from the Kabaing granite near Mogok is only 15 Ma. Limited K/Ar radiogenic dates from the metamorphic rocks of the Mogok Metamorphic Belt along the west margin to the eastern Highland and the Mogok area indicate early Oligocene to late Miocene age (GIAC, 2002). Barley et al., 2003) further discovered the Jurassic to Miocene age for the magmatism and metamorphism of the Mogok Metamorphism Belt. The Chaung Magyi Group which is unconformably overlain by fossiliferous Ordovician to Middle Devonian sequence of carbonate and fine-grained indurated clastic sedimendary strata, successively overlain by spreadly fossiliferous Upper Palezoic to Middle Triassic turbiditte Strata and Upper Jurassic shallow marine strata.

The rock type exposed in the region include gneiss, schist, calc-silicate rocks and marble some of which are very coarse-grained. They are intruded by igneous rocks like Lucogranite, syenite, and alaskite and gneiss, garnet biotite gneiss, biotite-silliminite gneiss. The Sagaing fault System is younger, initiated probably in late Oliocene to Miocene time. (curry, 2005).

The Mergui Group is also exposed extensively on the islands of the Myeik (Mergui) Archipelago of Tenintharyi Division. The Belt which is now more well known as the Slate Belt (Mitchell et. al., 2004) as the diamicrite and associated strata are dominated by fine-grained sediments regionally metamorphosed to slate, phyllite, greenshist and marble, and locally were intruded by granitoid plutons along the belt. It has been of special interest in recent years because of its gold deposits at Moditaung, Phayaung Taung and other occurrences and resources in the north and in the south particularly in Toungo, Shwegyin and Kyaikto areas.

The western margin of Eastern Highland is fringed by narrow belt of Late Carboniferous-Early Permian Mergui Group of pebbly mudstone and siltstone (diamicite), grewackey, orthoquartzite, volacanoclastic sandstone and minor carbonate strata, all of which were deformed and weakely metamorphosed, more or less continuously, from Phayaung Taung area about 30km NNE of Mandalay, southward up to Kawthoung area at the Thai-Myanmar border. Further southward in Thailand this group is known as the Phuket Group.  

 reference: 

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