This document summarizes a study on the Neogene siliciclastic sequences in the Arakan Coastal Ranges of western Myanmar. Through detailed outcrop mapping, facies analysis, and provenance studies, the authors aimed to better understand basin evolution and provide insights into the tectonic evolution of the Himalaya-Bengal system. Key findings include identification of submarine slope deposits and evidence for episodic uplift of the Himalayas recorded in the sedimentary sequences. Provenance data found indications of increasing erosion of the Himalayas over time. The basin evolution appears to have been controlled by subsidence over the continent-ocean boundary and oblique convergence, with sediment influx influenced by Himalayan

1. Geology and provenance of Neogene siliciclastic sequences, Arakan
Coastal Ranges in Western Myanmar:
Implications for the tectonic evolution of the Himalaya-Bengal System
Kyi Khin* and Khin Zaw**
50km
Baronga Islands
N
*PUB, Singapore, **UTAS, Australia
10/30/2017 MAESA 2017 CONFERENCE, YANGON,
MYANMAR
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2. Outline of Presentation
 Purpose and Method of Study
 Regional Geology and Tectonics
 Detail Outcrop Mapping and Stratigraphy
 Outcrop Sequence Stratigraphy
 Sedimentary Provenance Study
 Structural Analysis on Folds and Faults
 Conclusion
10/30/2017
MAESA 2017 CONFERENCE, YANGON,
MYANMAR
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3. Purpose
 To provide important information to link the syntectonic sedimentation in the proximal
foreland basins and deep marine sedimentations in distal parts
 To shad some lights on episodic uplifting of Himalayas and resulted erosional fluxes
derived from the India-Asia collision
 To understand basin evolution and find Key Performant Indicators (KPI) for Hydrocarbon
exploration in Bengal offshore and Arakan on-land Areas
Method
 Geological Mapping : Detailed Outcrop Mapping with Measured Sections (45 Nos.)
 Facies Analysis and Sequence Stratigraphy
 Age resolution by Foraminifera Interpretation
 Sandstone Petrography: Microscopic Thin section Analysis, 60-Point counting Model
Analysis and Provenance Study (38 - Laung Fm, 11 -Yezaw Fm, and 11-Mayu Fm)
 Geochemical Analysis on Mudstone: XRF (major and trace elements geochemistry of 133
samples were analyzed (80 Siltstone, 53 Mudstone)
 Zircon chronology and Sr isotope study
Purpose and Method of Study
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4. Regional Geology and Tectonics
 Situated in the Western most part of Myanmar and
Subduction and Collision zone between the Indian
and Asian continents.
 Indo-Burman belt has been accreted onto the Indian
Craton margin after the collision indicates east-west
crustal shortening.
 Zone of plate convergence between India and
Burma, with Bengal basin strata overlying the
subducting oceanic crust of Indian plate.
o S: Bengal Bay, Arakan Coastal Ranges, which occupies western part of the Indo-Burman Ranges.
o N: Chittagong-Tripura Folds Belt plunge northward into the Sylhet Trough.
o Far N: Main Boundary thrust faults (late Miocene or Pliocene) are separated from the Bengal
Basin by Shillong Plateau.
o Subduction zone between the Indian Plate and Burma Plate to the East.
o The collisional history of Himalayas is recorded in sediments deposited in subsiding foreland basins
to the south.
o Bengal-Arakan Basin is a large remnant basin occupied dominantly by the Paleo-Ganges-
Brahmaputra delta since earliest Miocene.
Kyi Khin et al. (2014, 2017a, b)
w
E
Bertrand & Rangin, 2003; Uddin & Lundberg, 2004; Rangin et. al., 2013
S
N
4

5. 1
1
2
2
3
3
4
4
5
5
6
6
Detail Outcrop Mapping and Stratigraphy
Sittwe
Pauktaw
 NNW-SSE trending tight anticlines and broad synclines
 Strong East–West shortening and composed with slumped beds
(Lower Miocene) and major Sandstone and Shale interbeds of
Middle to Upper Miocene Sequences.
5

6. Stratigraphy
Kyi Khin et al. (2014, 2017a, b)
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7. Outcrop Sequence Stratigraphy
 Homogenized chaotic Mudstone (Hm) cut by slide scars and listric faults
 Slumped shale with minor sandstone blocks in early Lower Miocene (ML1)
 Dislocated sandstone gutter-cast (gs) overlying the deformed mudstone (dm)
 Amalgamated sandstone irregularly stepped basal contact underlying chaotic mud units in late
Lower Miocene (ML3)-Stranded Parasequences
 (FA-5) in Middle Miocene (Lower Yezaw Fm.) (MM1) Large-scale slump underlies the undisturbed
thickening upward sandstone-shale
 Large-scaled Cross laminated Sandstone with Scoured-channel Thick swaley cross laminated sandstone
dipping low angle
 Sandstone and Shale interbeds with shallow water traces (e.g. Skolithos, Scolicia, Ophiomorpha ichnosp.)
Hm
Hm
gs
Lower to Middle Miocene
Upper Miocene
Deltaic
Slope and Shelf
7

8. DF: Debris Flow
Conglomerates
CS: Channel Sandbody
AS: Alternated Sandstones
(Levee deposits)
Interpretation
Submarine slope
deposits containing
submarine channels
based with debris flows
and, levee deposits
Laychat Taung Island (off-Sittwe Point)
DF
DF
N
DF
Lower Miocene (Laung Fm.)
*N4 Foraminifera in TST
*
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9. Sedimentary Provenance Study
Modification ProcessControlling factors
Paleocurrent
Paleo-sea water chemistry
TectonicsHinterland structural condition
Sandstone Composition and QFL Triangular diagrams
Clay Mineralogy and Alteration Index
Heavy Minerals Analysis/Chronology
Hinterland
Foreland
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10. Laung Formation (Lower Miocene)
10

11. Mayu Formation (Upper Miocene)Yezaw Formation (Middle Miocene)
Yezaw Formation (Middle Miocene)
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12. Dickinson (1985)Roser and Korsch (1986)
Ternary DiagramsGeochemical parameters
K-Rich in younger age
Collision suture belts
Rifted Continental margins
Increasing meta-sediments (Lsm)
Active continental margin (ACM)
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13. DF1=0.303–0.0447SiO2–0:972TiO2+0.008Al2O3–
0.267Fe2O3+0:208FeO–3.082MnO+0.14MgO+0.195CaO
+0.719Na2O–0.032K2O+7.51P2O5
DF2=43.57–0.421SiO2+1.988TiO2–0.526Al2O3–
0.551Fe2O3–1.61FeO+2.72MnO+0.881MgO–0.907CaO–
0.177Na2O–1.84K2O+7.244P2O5
Sandstones
Shales
Rock Types Tectonic Settings
Bhatia (1983)
Scattered in all fields
Recycled field
Felsic & Interm. fields
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14. McLennan et al. 1993
Paleoweathering and Sequence Stratigraphy
High
Low
High
Low
* High Feldspar and Low Paleo-weathering in late Early Miocene to early Middle Miocene (ML3-MM1) and Highstand Systems Tracts (HST)
14

15. Geochronologic constraints of Provenance
U-Pb dating on Monazite and Thorite minerals
STDS=South Tibetan Detachment System; MBT=Main Boundary Thrust; MCT=Main Central Thrust; N-S=Nouth-South Trended
Faults. CIA = A/[A + K + N + C] * 100 (Nesbitt &Young, 1982)
Correlation of Arakan Miocene basin with Evolution of Himalaya-Bengal System
Kyi Khin et al. (2014, 2017b)
High
Low
High
Basin/Thrusting/Uplifting
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16. Minor Cross-Faults at Middle Baronga and Clastic dyke near Cross-Fault at East Baronga Island
Structural Analysis on Folds and Faults
Strike-slip Faults at eastern part of Middle Baronga Island
1
234
Middle Baronga
Syncline
10km
East Baronga Island
West Baronga Island
1
3
2
4
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17. Basin and Dome Formation
Kyi Khin & Aung Moe (2015)
Syn-sedimentary folds in Lower Miocene
Aligned N-NE
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18. Strike-slip motion (Extension)
Oblique Motion (Crustal shortening)
Sketches showing NW-SE trend double plunging Folds which as a model
of the slump structures development in Syn-Sedimenatary deposition of
paleo-submarine slope deposits in Baronga Islands , Yakhine, Myanmar
Paleo-Slope trends from Gutter Casts direction
SSE
SW
Lr. Mio
Mid. Mio
Bangladesh
N
Kyi Khin & Aung Moe (2015)
Slump folds were
formed by syn-
sedimentary
deformation
including gravity
sliding at eastern
Bengal paleo-slope
F1
F2
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19. Ch: Chittagaung Hills, Sch: Schuppen Belt, Ng: Naga Hills, As:
Assam Basin, Ak: Arakan Basin
Opposite to the pattern normally
seen in foreland basins.
Due to the continent–ocean
boundary, sedimentary loading
and basin-ward down-faulting
from Early Miocene to early
Middle Miocene.
Kyi Khin et. al., 2014, GR 26, P. 89-111
Early Miocene
Late Miocene
Backbulge
Sediments-Accumulation Curves of Assam-
Arakan-Bengal Basins
Bay of Bengal
Himalayas
India 7
5
8
6
Ak
foredeep
forebulge
backbulge
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20. Conclusion
 Proto-Bengal-Arakan Basin is remnant Ocean Basin formed during tectonic loading
at foreland area and backbulge subsidence with force regression since Early
Miocene
 Uplifting and denudation of the Himalayan Orogen generated huge amount of
sediments and accumulated in the Himalayan foreland basins and accelerated the
continuous progradation of the Bengal fan southward
 Episodes based on the geochemical and provenance data proxy for the unroofing of
Himalayas are related to the interactions between the timing of Himalayas
thrusting, tectonic denudation and palaeo-weathering, migration of foreland
fluvial system and the rate of base-level changes in the Arakan Miocene Basin,
Myanmar
 These new information based on sequence stratigraphy and provenance data
indicate that sedimentary lithofacies in the fill of this asymmetric basin were
controlled mainly by subsidence over the continent/ocean boundary, overprinted
by tectonic loading and oblique convergence along its eastern boundary
10/30/2017
MAESA 2017 CONFERENCE, YANGON,
MYANMAR
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21. REFERENCES
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MYANMAR
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22. Thank You!
Q & A
For more Information and Question, Please email to
Dr. Kyi Khin:kyikyaw2@gmail.com, Subject: MAESA 2017-PRESENTATION (Arakan Basin)23