Update: 2018-03-04 04:30 AM -0500

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Geology of Myanmarpré

myn-geol.htm

from: Wikipedia:
1. https://en.wikipedia.org/wiki/Geology_of_Myanmar 180203
2. https://en.wikipedia.org/wiki/Lithology 180205

Downloaded and edited by U Kyaw Tun (UKT) (M.S., I.P.S.T., USA), and staff of Tun Institute of Learning (TIL) . Not for sale. No copyright. Free for everyone. Prepared for students and staff of TIL Research Station, Yangon, MYANMAR 
 - http://www.tuninst.net , www.romabama.blogspot.com

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geol-indx.htm

Contents of this page

Introduction
UKT 180215: Myanmarpré is a part of Asia. However, my motherland and the continent of Asia have never been the same throughout geological time stretching for about 4 billion years. To appreciate the changes, see downloaded videos in the TIL HD-VIDEO and SD-VIDEO libraries, in the folder GEOLOGY:
- Geological History of the World<Ô> / Bkp<Ô> (link chk 180215)
- A Brief History of Geologic Time<Ô> / Bkp<Ô> (link chk 180215)

1.0. Regional geology
1.1. Arc-shaped structure of Myanmarpré
1.2. Indo-Burman Ranges
1.3. Myanmar Central Belt
1.4. Shan Plateau
1.5. Mogok Metamorphic Belt

2.0. Lithology
Introduction
2.1. Indo-Burman Range: Rakhine Yoma
2.2. Myanmar Central Belt
2.3. The Shan Plateau

3.0. Tectonic settings
3.1.0. Highly oblique Indo-Burma Boundary (Arakan Trench and Andaman Trench)
3.2.0. Fault systems
3.2.1. Sagaing Fault
3.2.2.
Shan Scarp

4.0. Geological evolution of Myanmarpré

4.1.0 Paleozoic Era
4.1.1. Permian Period (~ 300 Ma)

4.2.0. Mesozoic Era
4.2.1. Late Triassic to Jurassic Period (~ 235-145ma)
4.2.2. Cretaceous Period (~ 145-65ma)

4.3.0. Cenozoic Era
4.3.1. Early Eocene to Miocene (~ 55-10ma)
4.3.2. Late Miocene onwards (~ 10ma)

5.0. Geological resources
5.1. Mineral belts
5.2.
Petroleum basin

6.0. Reference
UKT to TIL editor 180209: Original references with active links to Wikipedia intact. I've cleaned up the Code view, removing the Table to make my editing from Code view easier. There are only 46 references. Look for ^ mark which stands for beginning of a reference. I've added my number such as 01, 02, 03 ... to ^, so that I can separate the individual references. Clicking on my number (in parenthesis) will take you to the reference on this page. Wiki references are in [...]. There are articles on this page which were not part of the original Wiki article. You'll not find links to their references in this Reference.
Remember, I am not a geologist: my training is in chemistry and chemical engineering. Geology is a new discipline for me, and references are important for a new comer.

 

UKT notes
 

 

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Introduction

From: Wikipedia: https://en.wikipedia.org/wiki/Geology_of_Myanmar 180203
UKT: To appreciate the maps given, I always refer to the latitude 20°N where we find the most prominent landmark of the region, Mount Popa {poap~pa:taún}, 20.92°N 95.25°E, summit elevation 4,980 feet (1518 m).  The name is a combination of two words {poap~pa:} + {taún} 'mountain'.

UKT 180203: Wikipedia has followed the current spellings, e.g. Myanmar for Burma, which I have corrected to Myanmarpré because the word "Myanmar" is ambiguous. It could refer to the country, to the peoples, or to the written language or script.

Downloaded Geology of Burma by F. Bender is available in TIL HD-PDF and SD-PDF libraries:
- FBender-GeolBurma<Ô> / Bkp<Ô> (link chk 180203)

The geology of Myanmarpré is shaped by dramatic, ongoing tectonic processes controlled by shifting tectonic components as the Indian plate slides northwards and towards southeastern Asia. [1](TIL01)[UKT ¶]

Myanmarpré spans across parts of three tectonic plates (the Indian Plate, Burma microplate and Shan Thai Block) separated by north-trending faults. To the west, a highly oblique subduction zone separates the offshore Indian plate from the Burma microplate, which underlies most of the country. In the center-east of Myanmarpré, a right lateral strike slip fault extends from south to north across more than 1000 km. [2](TIL02) These tectonic zones are responsible for large earthquakes in the region. [1](TIL01)[UKT ¶]

The India-Eurasia plate collision which initiated in the Eocene provides the last geological pieces of Myanmarpré, [3](TIL03) and thus Myanmar preserves a more extensive Cenozoic geological record as compared to records of the Mesozoic and Paleozoic eras. [UKT ¶]

UKT 180203: "The Eocene Epoch, lasting from 56 to 33.9 Ma (million years ago), is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. ... The name Eocene comes from the Ancient Greek ἠώς (ēṓs, "dawn") and καινός (kainós, "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. [5] " - https://en.wikipedia.org/wiki/Eocene 180203

UKT 180204: [Geologically] "Eons are divided into eras, which are in turn divided into periods, epochs and ages. The terms eonothem, erathem, system, series, and stage are used to refer to the layers of rock that correspond to these periods of geologic time. Years are expressed as MYA or MA, meaning “million years ago.” - Google

Myanmarpré is physiographically divided into three regions: the Indo-Burman Range, Myanmar Central Belt and the Shan Plateau; [4](TIL04) these all display an arcuate shape bulging westwards. The varying regional tectonic settings of Myanmarpré not only give rise to disparate regional features, but they also foster the formation of petroleum basins and a diverse mix of mineral resources. [5](TIL05)

UKT 180204: The word "basin" here means the structural basin.
"A structural basin is a large-scale structural formation of rock strata formed by tectonic warping of previously flat-lying strata. Structural basins are geological depressions, and are the inverse of domes. Some elongated structural basins are also known as synclines.

Structural basins may also be sedimentary basins, which are aggregations of sediment that filled up a depression or accumulated in an area; however, many structural basins were formed by tectonic events long after the sedimentary layers were deposited.
  "Basins may appear on a geologic map as roughly circular or elliptical, with concentric layers. Because the strata dip toward the center, the exposed strata in a basin are progressively younger from the outside in, with the youngest rocks in the center. Basins are often large in areal extent, often hundreds of kilometers across.
  "Structural basins are often important sources of coal, petroleum, and groundwater."
- https://en.wikipedia.org/wiki/Structural_basin (180204)

 

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1.0. Regional geology

Inset pix from Wikipedia: The figure shows a simplified version of the regional features in Myanmarpré. The three physiographical region from west to east:
1. Indo-Burman Range,
2. Myanmar Central Belt and
3. Shan Plateau. The Mogok Metamorphic Belt (MMB) is expressed with dashed lines. Modified from Bender (1983). [6](TIL06)

UKT 180204: Refer to F. Bender, - FBender-GeolBurma<Ô> / Bkp<Ô> (link chk 180203)
p017-042

Myanmarpré is classified into three physiographical regions, each region spans over Myanmarpré in near NS direction, from west to east is: the Indo-Burman folded mountain ranges, the Myanmar Central Belt (MCB) and the Shan Plateau. [4](TIL04) To the north of Myanmar, the eastern Himalaya syntaxis bounds the three physiographical region. [7](TIL07)

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Arc-shaped structure of Myanmarpré

Myanmar has a complex arc-shaped deformation structure, which is probably due to the a combination of various forces. [8](TIL08) Aside from the subduction system on the west and the strike-slip fault system in the central Myanmarpré, another major contribution may be the crustal flow from the Tibet Plateau. [8](TIL08) [UKT ¶]

UKT 180210: See Topographic ooze: Building the eastern margin of Tibet by lower crustal flow - by Marin Kristen Clark* and Leigh Handy Royden, in Geology August 2000; v. 28; no. 8; p. 703–706 in downloaded paper in TIL HD-PDF and SD-PDF libraries:
- MKClark-LHRoyden-TibetCrustalFlow<Ô> / Bkp<Ô> (link chk 180210).

The Tibet Plateau is located at the north of Myanmarpré and has been considerably thickened since the Eocene. [8](TIL08) 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. [9](TIL09) The crustal flow runs towards west and into the central region of Myanmarpré. This crustal flow, along the with accretionary wedge in the subduction system, may have participated in the late Neogene uplift of Indo-Burman Range. [8](TIL08)

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Indo-Burman Ranges

The Indo-Burman Range sits at the convergent boundary of the Indian and Burma-micro Plates in Myanmarpré. The subduction between the two plates resulted in the development of accretionary wedges, in order to accommodate the EW shortening along the convergent boundary. Later, thrusting, folding and uplifting formed the Indo-Burman Ranges. [10](TIL10) [UKT ¶]

The mountain belt comprises various mountains: the Arakan-Yoma mountains and the Chin, Naga, Maniour, Lushai and Patkai hills. [11](TIL11) The Indo-Burman Range merged with Eastern Himalayan Syntaxis further north, submerged into the Andaman Sea, and resurfaced as Andaman Islands further south. [4](TIL04)

The Indo-Burman Range bulges towards the west at the center (about 22°N), forming an arc-shaped structure. [8](TIL08) This arc-shaped structure implies restriction on the convergent motion along the Indian-Burma boundary, therefore the collision intensity varies along the range. [11](TIL11).

The collision is at a maximum at the center of the Indo-Burman Range around 24°N, which is presented with a broad, high range (up to 20 km wide) and evolves to narrow, low hills in the south (16°N). [11](TIL11) The collision strikes in NW-SE at the northern part of the Indo-Burman Range (Naga Domain). [12](TIL12)

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Myanmar Central Belt

The 1000 km Myanmar Central Belt consists of a series of Cenozoic sub-basins between the Indo-Burman Range (west) and Sagaing Fault (east). [13] These basins are generally considered as forearc/back arc basin couplet of the Indo-Burma subduction system. [8] 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. [14]

A variety of structural features — such as oblique-reverse faults, strike slip faults and normal faults — can be found within the central belt. [13] The abundant evidence of shear zones suggests the Myanmar Central Belt has undergone severe internal deformation. The exposed metamorphic lineation along the belt [15] 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: [13]
  (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. [13]

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Shan Plateau

The Shan Plateau, with an average elevation of 1 kilometre (0.62 mi), forms the eastern highlands of Myanmar. [16] It provides the major topographic relief in Myanmar and it extends towards the southeast to Thailand. [17] The plateau, unlike other regions Myanmar, comprises thick successions of Paleozoic, Mesozoic and even Precambrian sedimentary rocks. [16] 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. [17]

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Mogok Metamorphic Belt

Situated on the east of the Sagaing fault and the west of Shan plateau, the Mogok Metamorphic Belt (MMB) lies at the foothill of Shan Scarp. It runs in a near north-south direction and extends over 1500 km with an average width of 24–40 km. [4] The meta-sedimentary and meta-intrusive belt is comprised of marbles, schists, gneisses of upper amphibolite, with locally granulite facies intruded by a deformed granodiorite pluton and pegmatites. [2] The belt also shows evidence for ductile stretching along the north-northwest-south-southeast direction, e.g. lineation, sheath folds and “pencil-like” mullions. [2] Various radiometric dating confirms the age of Mogok Metamorphic Belt predates the Sagaing Fault, and the shear heating of Sagaing Fault has no contribution to the formation of Mogok Metamorphic Belt. [2]

Searle (2007) suggested a five-phased metamorphism and magmatism along the Mogok Metamorphic Belt. [2]

1. Jurassic- Early Cretaceous I-Type intrusion and metamorphism (171–120 Ma)

2. Paleocene- Early Eocene metamorphism of biotite granite sill injection (~59 Ma)

3. Late Eocene- Oligocene metamorphism of sillimanite (37–29 Ma)

4. Late Oligocene- Early Miocene granite magmatism (22–16 Ma)

5. Pliocene- Quaternary volcanism (0–6 Ma)
Note: Ma (mega-annum) is a million years

Inset pix shows: Simplified geological cross section of Myanmar at latitude 21°N. SG refers to Sagaing fault. Inspired and modified from C. Rangin et al. (2013) and A. H. T. G. Mitchell (1989). [8] [16]
See downloaded pdf pages in TIL HD-PDF and SD-PDF libraries:
1. Rigid and non-rigid microplates: Phillipines, and Myanmar-Andaman case studies, by C. Rangin, 2016
- CRangin-MicroplatesPhillipinesMyanmarAdaman<Ô> / Bkp<Ô> (link chk 180204)
2. UKT 180205: I am unable to get Mitchell.

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2.0. Lithology

From Wikipedia: https://en.wikipedia.org/wiki/Lithology 180205
For the study of rocks and their formation, see Petrology.

Introduction

The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples or with low magnification microscopy, such as colour, texture, grain size, or composition. [1](TIL01) [2](TIL02) [3](TIL03) It may be either a detailed description of these characteristics or be a summary of the gross physical character of a rock. [4](TIL04) It is the basis of subdividing rock sequences into individual lithostratigraphic units for the purposes of mapping and correlation between areas. In certain applications, such as site investigations, lithology is described using a standard terminology such as in the European geotechnical standard Eurocode 7.

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Indo-Burman Range : Rakhine Yoma

UKT 180205: Refer to pdf downloads in TIL HD-PDF and SD-PDF libraries:

Provenance of Tertiary sedimentary rocks of the Indo-Burman Ranges, Burma (Myanmar): Burman arc or Himalayan derived?, by R. Allen, Y. Najman, A. Carter, D. Barfod, M. J. Bickle, H. J. Chapman, E. Garzanti, G. Vezzoli, S. Ando & R. R. Parrish, J. Geological Soc., London, vol. 165, 2008, pp 1045-1057
- RAllenEtAl-IndoBurmanRanges<Ô> / Bkp<Ô> (link chk 180205)
Abstract: The Indo-Burman Ranges in western Myanmar extend along the Sunda Arc subduction zone and may be divided into a western portion of Neogene sedimentary rocks and an eastern portion of Palaeogene sedimentary rocks, separated by the Kaladan Fault. Both Himalayan and Burman sources have been proposed for these sediments. Our thermochronological analyses on detrital grains, isotopic analyses on bulk rock, and petrographic and heavy mineral data indicate that the Palaeogene Indo-Burman Ranges contain a significant component of arc-derived material, interpreted as derived from the Burmese portion of the Mesozoic–Tertiary arc to the east. And older crustal component is also identifiable, which may have been sourced from the Himalaya or the Burmese margin. By contrast, the Neogene Indo-Burman Ranges show dominant derivation from the Himalaya. A minor arc-derived component may have been sourced from the Trans-Himalaya, or recycled from the arc-derived Paleogene Indo-Burman Ranges."

The Indo-Burman Range is an sedimentary belt mainly consisted of Cenozoic flysch sediments [18] and a core of Mesozoic ophiolites dated back to late Jurassic overlain on a thick Mesozoic sequence. All the above unconformity lies on a metamorphic basement dated back to pre- Triassic. [19]

Inset pix: Arakan Mountains in  Maungdaw district.

The core Mesozoic ophiolites consists of serpentinite peridotites, pillow basalts and red cherts etc. [19] The obduction of ophiolites is interpreted as the closure of several Neo-Tethys between the Shan-Thai block, Burma microplate and Indian Plate. [8]

The sedimentary sequence overlain by the ophiolites ranges from Late Triassic to Orbitoides-bearing Late Cretaceous carbonates and shales [8], where part of the sedimentary sequence has undergone high pressure/low temperature blue-schist metamorphism. [18]

The pre-Triassic metamorphic basement comprised of Kampetlet schist and gneisses were exposed in the Mount Victoria area in Myanmar. [19] The flysch type sediments in the western flank of the Indo-Burman Range are relatively younger than the folded and thrusted eastern flank. [20]

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Myanmar Central Belt (MCB)

UKT 180205: Refer to pdf downloads in TIL HD-PDF and SD-PDF libraries:

Cenozoic Evolution of the Central Myanmar drainage system: insights from sediment provenance in the Minbu Sub-Basin , by A. Litcht, L. Reisberg, Christian France-Lanord, Aung Naing Soe and Jean-Jacques Jaeger, Basin Research (2014) 1–15.
- ALitchEtAl-CenozoicEvolCentralMyanDrainSyst<Ô> / Bkp<Ô> (link chk 180205)
Abstract: Located at the southern edge of the eastern Himalayan syntaxis, the Central Myanmar Basin (CMB) is divided into several Tertiary sub-basins that have been almost continuously filled since the Indo-Asia collision. They are currently drained by the Irrawaddy River, which flows down the eastern Tibetan Plateau and the Sino-Burman Ranges. Tracing sediment provenance from the CMB is thus critical for reconstructing the past denudation of the Himalayan-Tibetan orogen; it is especially relevant since a popular drainage scenario involves the capture of the Tsangpo drainage system in Tibet by a precursor to the Irrawaddy River [UKT ¶].

UKT 180210: Tsangopo River is now known as "Yarlung Tsangpo (sometimes called Yarlung Zangbo or Yarlung Zangbo Jiang (Tibetan: ཡར་ཀླུངས་གཙང་པོ་,  Wylie-transliteration: yar kLungs gTsang po,) - https://en.wikipedia.org/wiki/Yarlung_Tsangpo_River 180210

UKT 180210: The precursor to the Irrawaddy River known as Proto-Irrawaddy River, had flowed from Myitkyina area in the north to discharge into the Gulf of Martaban in the south. The Proto-Irrawaddy River had broken into two when Mount Popa rose from the flat land and erupted - presumably due to the Sagaing fault. The upper portion has become the Samoan River - the only river in Myanmarpré flowing from south to north: the lower portion - the Sittang River discharging into the Gulf of Mataban. Samoan River joins the Irrawaddy River somewhere south of Mandalay. The Irrawaddy River turns westward to join with the Chindwin River, washing down the soil to build the Irrawaddy Delta.

Here, we document the provenance of sediment samples from the Minbu Sub-Basin at the southern edge of the CMB, which is traversed by the modern stream of the Irrawaddy River. Samples ranging in age from middle Eocene to Pleistocene were investigated using Nd isotopes, trace element geochemistry and sandstone modal compositions. Our data provide no evidence of a dramatic provenance shift; however, sandstone petrography, trace element ratios and isotopic values display long-term trends indicating a gradual decrease of the volcanic input and its replacement by a dominant supply from the Burmese basement. These trends are interpreted to reflect the progressive denudation of the Andean-type volcanic arc that extended onto the Burmese margin, along the flank of the modern Sino-Burman Ranges, where most of the post-collisional deformation of central Myanmar is located. Though our results do not exclude an ephemeral or diluted contribution from a past Tsangpo-Irrawaddy connection, sedimentation rates suggest that this hypothesis is unlikely before the development of a stable Tsangpo-Brahmaputra River in the Miocene. These results thus suggest that the central Myanmar drainage basin has remained restricted to the Sino-Burman Ranges since the beginning of the India-Asia collision.

The Cenozoic pull-apart basins along the Myanmar Central Belt (MCB) are filled-up with 15 km thick Late Cretaceous and Eocene to Late Miocene sediments. [19]

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The Shan Plateau

Belonging to the rigid Shan-Thai block, the Shan Plateau is comprised of consolidated partially low-grade metamorphic and Precambrian crystalline rocks [19] overlain with a thick succession of Palaeozoic and Mesozoic sedimentary rocks. [16]

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3.0. Tectonic settings

The tectonic setting of Myanmar consists of a highly oblique convergence on the western boundary, a dextral (right lateral) strike-slip fault in the centre of Myanmarpré defining the Burma-Sunda boundary and the spreading of Andaman Sea Ridge in the south. [3]

Inset pix: 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) [7]

UKT 180205: See downloaded pdf pages in TIL HD-PDF and SD-PDF libraries
¤ - SPramumijoho-RegionalGeolMyanmar<Ô> / Bkp<Ô> (link chk 180205)
¤ - SoeThuraTunEtAl-Ch5TarlayEquake<Ô> / Bkp<Ô> (link chk 180206)

 

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Highly oblique Indo-Burma Boundary (Arakan Trench and Andaman Trench)

From the Eocene epoch onward, the northward movement of Indian Plate collided with the Eurasian Plate and generated the Himalaya Orogenic belt. [21] The relative motion of the Indian plate against the Eurasian plate (Sunda) has two components (1) 36 mm/year right lateral strike-slip, trending in N10°E direction; (2) 7-9 mm/year east-west convergence. [22] The convergent motion is absorbed by a highly oblique subduction zone between the Indian plate and Burma-micro plate and internal deformation in the centre of Myanmarpré on the Sagaing Fault. [8]

The obliquity of the Indo-Burma convergent plate boundary (Arakan Trench and Andaman Trench) increases further northwards, with a minimum angle of 58° at 20°N latitude to 70° near 22°N latitude, and rapidly increases to 90° near 24°N latitude and over 90° to further North. [3] The boundary between Indo-Burma region runs furter southward into the Bay of Bengal and joins the Sumatra Trench. [3]

Insert 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. [22]
See downloaded papers in TIL HD-PDF & SD-PDF libraries:
- ASocquetEtAl-IndiaSundaPlatesGPS<Ô> / Bkp<Ô> (link chk 180206)
Note: Wiki's figure is blurred: see my reproduction from downloaded PDF paper.

 

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Fault systems

In order to accommodate the India-Eurasia collision, extensive fault systems can be found in Myanmar. The following introduces two of the major fault systems.

The Sagaing Fault

The 20mm/yr dextral (right lateral) strike slip Sagaing Fault detaches the Burma microplate from the Sunda plate. [23] The arc-parallel fault spans over 1400 km in a north-south direction, remarkably linear for the central 700 km (at 17°N to 23°N latitude) and forms a slight arc shape swinging N10°E and N170°E direction at the north and south ends of the fault respectively. [23] Northward, the Sagaing fault terminates at the Jade Mine belt (~ 24.5°N) and splays into a 200 km width compressive horsetail structure. [23] Southward, it is connected to the active Andaman spreading rift. [23] The onset of seafloor spreading on the Andaman rift puts a minimum 4.5 Ma age constraint on the Sagaing Fault. [24]

The total displacement of the right lateral strike slip fault remains controversial. Curray et al. (1979) suggested a total 460 km of displacement since Miocene [25]; whereas Khin Zaw (1990) proposed 250 km since post Lower Miocene. [26] Guillaume & Rangin (2003) deduced approximately 100km by constraining a continuous 20mm/yr right lateral strike slip since 4-5Ma. [17]

Shan Scarp

The topographic boundary separating the Myanmar Central Basin (MCB) and the Shan Plateau (or Eastern Highland) [17] is referred as the Shan Scarp. The abrupt elevation over a short distance (up to 1.8km over few km) harbors the trace of reverse faults and largely overturned folds. [17] The Shan Scarp aligns parallel to the Sagaing fault on the east. [17] The general trend of reverse fault strikes is N20°W and dips in the east-northeast direction; where some N20°E striking normal faults were identified along the fault scarp (at 21°N to 22°N latitude), north of Mandalay. [17] Dextral (right lateral) strike slip motion is also observed along the fault scarp, this motion is reasonably expected due to the nearby right lateral Sagaing fault. Southward, the Shan Scarp ends at the junction with the Three Pagodas fault. [23]

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). [17]

The above evidence suggests ductile deformation along Myanmar Central Belt (MCB) should occur prior to the brittle deformation along Sagaing fault and the Shan Scarp fault.

Inset pix: 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) [27]

 

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4.0. Geological evolution of Myanmarpré

Myanmar lies on the boundary of three tectonic plates (India, Burma-micro and Sunda Plate), thus its geological evolution is highly dependent on the plate tectonic events in this region. In the following, the geological evolution of Myanmar will be explained in the order of geological timescale. Only major tectonic events are recorded with some missing timescale where no major events occurred.

Inset pix: A simplified geological evolution of Myanmarpré. (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). [28]

UKT 180207: See also downloaded paper in TIL HD-PDF and SD-PDF libraries:
A tectonic model reconciling evidence for the collisions between India, Eurasia and intra-oceanic arcs of the central-eastern Tethys, by A.D. Gibbons, S. Zahirovic, R.D. Muller, J.M. Whittaker, V. Yatheesh, Gondwana Research , 2015
- ADGibbonsEtAl-CollisionIndiaEurasiaTethys<Ô> / Bkp<Ô> (link chk 180207)

 

 

 

 

 

 

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Paleozoic Era

 

Permian Period (~ 300 ma.)

In the early Permian, a continental block rifted from Gondwanaland. [29] The continental plate has been variously termed: Shan-Thai [29], Sibumasu [30], or Sinoburmalaya. This continental block harbors features of glaciogenic marine diamictite unit, indicating its origin from Gondwanaland [27]. The Shan-Thai block was probably located northwest of Australia plate during the Gondwanaland period. [27]

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Mesozoic Era

 

Late Triassic to Jurassic Period (~ 235-145ma)

In the mid- late Triassic, the Shan-Thai block collided with the Indo-China block, and under-thrusted an ophiolite and associated arc system in the northeast. [16] A foreland thrust belt developed along the collision of the two blocks and laid the foundation of the Shan Plateau. [16]

A thick flysch unit with fossils and deltaic sediments were deposited along the northeastern Shan-Thai block (now Shan Plateau) with the closing of a shallow sea region between the two blocks prior to collision. [19] Large-scale intrusion of granitoid plutons and batholiths were induced by oceanic subduction [19]; and partial melting of metasedimentary rocks within the foreland thrust belt led to tin-tungsten mineralization (the Central Tin Belt). [16]

 

Cretaceous Period (~ 145-65ma)

The India Plate departed from the Gondwanaland and headed northwards at a rate of 10cm/yr during the Cretaceous Period. [8]

The rifted Burma-microplate from Gondwanaland also docked against Shan-Thai block and together formed part of the Sunda plate approximately in the period. [16] There is a discrepancy for the time of the Burma-Shan-Thai collision: Mitchell (1989) says Early Cretaceous yet changes to Mid-Eocene in 1993 [20]; Hutchison (1989) says Late Cretaceous [31]; and Acharyya (1998) says late Oligocene. [32]

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Cenozoic Era

 

Early Eocene to Miocene (~ 55-10ma)

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. [33] On the eastern margin of the India plate, high oblique subduction occurs between the boundary of India and the Burma-micro plate. [34]

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. [33] This resulted in the trend of arc shifting from east-west to the north-south direction.

The subduction boundary forms an accretionary prism [33] and eventually with thrusting and folding forms the Indo-Burma Range. [20]

 

Late Miocene onwards (~ 10ma)

In late Miocene to Pliocene, the slab detachment of Burma-microplate beneath the Shan-Thai block induced in a mantle window into the slab and resulted in alkaline and calk-alkaline volcanism along the Myanmar Central Belt. [35]

In the late Miocene (10ma), the Myanmar Central Belt underwent a major regional plate kinematic reorganization transition. [17] 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. [36]

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5.0. Geological resources

 

Mineral belts

Myanmar hosts a variety of ore-deposits with economic significance and global recognition. It is a global source of true jade and produces some of the world’s finest rubies, [5] with mines in the Mogok Valley providing the bulk of the world's supply for centuries. [37]

Myanmar’s mineral deposits into different distinct metallogenic provinces by various workers. [5] The following outlines the nine major ones:

1. Magmatic-hydrothermal granite and pegmatite-hosted minerals: World-class tin and tungsten mineralization can be found in the southern Myanmar. These mineralizations are often associated with Late Cretaceous-Eocene intrusive granites. [38] It is dated around 45-62 Ma. [39] [5]

2. Skarn: Found along the Mogok Metamorphic belt, the native gold and base metal sulfide is hosted within phlogopite-bearing amphibolite-grade marbles. [5] The age of the granite is dated back to 17Ma [5] with zircon U-Pb geochronology.

3. Porphyry: The base metal sulphide and Au deposits are associated with magmatic intrusions. [40] The mineralization at Shangalon in Myanmarpré is related with fine-grained diorite intrusion into the hosting batholith at 40Ma. [5]

4. Epithermal: The epithermal Au-Cu mineralization along with auriferous quartz veins are hosted by Cretaceous granodiorite and diorite magmatic rocks. [41]

5. Ultramafic: The ultramafic-hosted deposits are discovered along with ophiolite fragments within the Myanmar. [5] The Tagaung-Myitkyina Belt (TMB) comprises ophiolitic mantle peridotite and is a source of nickel laterite. [42] In the Hpakant region, extensive pure | jade can be found. [43] The Indo-Burman Range (e.g. Chin and Naga Hills) also harbors many Chromite and nickel deposits. [19]

6. Orogenic Au: Gold mineralization in Myanmarpré is inferred as Orogenic type and or Cretaceous–Paleogene fault zone related. [44]

7. Sediment-hosted Pb-Zn: Several lead-zinc sulphide deposits hosted in carbonate rocks were found in the Upper Palaeozoic carbonate sequence of Shan Plateau. [44]

8. Gemstone: The finest rubies are sourced from Mogok Metamorphic Belt derived from marbles. The gem-quality rubies are formed under an Eocene-Oligocene high temperature metamorphism. [42]

9. Sediment hosted Epithermal Au: The Kyaukpahto Mine is the largest gold-producing mine located around the Sagaing Division in Myanmarpé. Gold mineralization here is formed during extensional faulting (probably due to Sagaing fault) and intense hydrothermal alteration and silicification in late Eocene. [45]

 

Petroleum basin

The hydrocarbon basins in Myanmarpré are mostly situated in the Central Myanmar Belt, e.g. Salin Basin, Chindwin Basin and Hukawng Basin over 1000km. [46] The formations that comprise the hydrocarbon basins are sedimentary rocks of Eocene through mid-Miocene and sealed with interbedded Oligocene and Miocene shales and clays. [46]

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UKT notes

 

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End of TIL file