lithofacies analysis and depositional environments of...
TRANSCRIPT
448 The Second Myanmar National Conference on Earth Sciences (MNCES, 2018)
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
1Lecturer and Head, Dr., Department of Geology, Yenangyaung Degree College
2Demonstrator, Department of Geology, Magway Univerity
#Corresponding author: [email protected]
Lithofacies Analysis and Depositional Environments of Tilin Formation in
Taing Da area, Mindon Township, Magway Region
Paing Soe1#
and Kyaw Min Oo2
Abstract
The Eocene sedimentary rocks, exposed in the southwest of Minbu Basin, central part of
Myanmar, are characterized by continental clastic units of sandstones and deltaic to
shallow shelf sediments of sand-shale and mudstone. Taing Da area is located in
northwest of Mindon and southwestern part of Magway Region. Six stratigraphic units
can be classified in Taing Da area. They are (1) Kabaw Formation (Late Cretaceous), (2)
Paunggyi Formation (Late Paleocene), (3) Laungshe Formation (Early Eocene), (4) Tilin
Formation (Early Eocene), (5) Tabyin Formation (Middle Eocene) and (6) Alluvium
(Holocene). Present study for lithofacies analysis is only one formation of Tilin Formation exposed in Taing Da and its environs. According to the distinctive lithologic
features including colour, bedding, composition, texture, fossils and sedimentary
structures, (12) lithofacies are recognized and (4) lithofacies associations were
distinguished. Based on the field observations and lithofacies analysis, the most of the
sediments and rocks of lower member of Tilin Formation in Taing Da area were probably
deposited under shoreface, tidal channel and tidal flat environments and upper member of
Tilin Formation were deposited under tidal flat and delta front environments during Early
Eocene Epoch.
Keywords: Eocene, shelf, lithofacies analysis, Tilin Formation
Introduction
Location, size and Accessibility
The study area is located in the Mindon Township, Magway Region and especially
lies in the southwestern part of the Magway Region. This area is situated between Latitude
19˚ 27΄ to 19˚ 34΄ N and longitude 94˚ 35΄ and 94˚ 44΄ E in one inch topographic maps of
85I/10 and 85I/11. The eastern part of the study area is low land and the western part of the
study is rugged terrain. The study area, Taing Da area can be reached from Yangon, Magway,
Monywa, Pathein, Pyay, Minbu and Mindon by car throughout the year. The location map of
the study area is shown in figure (1).
Previous Work
The study area lies in the western margins of Minbu Basin which includes the study
area was paid much attention by many geologists. Theobald (1871, 1873) reported the
western part of the Mindon area was shown as Axial (Triassic) and overlain by the
Nummulitic Series (Eocene). Chibber (1934) described briefly the geology of the upper
Chindwin Area. He reported that the flysch of Western Ranges in rocks that range in age
from Middle Triassic to Late Eocene. Maung Maung Gyi (1983) reported the Geology of the
northwestern part of Mindon Area, for his M.Sc thesis.
The Second Myanmar National Conference on Earth Sciences (MNCES, 2018) 449
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Figure (1). Locatoion map of the study area.
Materials and Methods
The geological map of the study area was resulted from the fieldwork carried out
during November, 2014. The field work was carried out along the exposure of the Eocene to
recent rock units of the Taing Da area. Detail sections measurements were carried out along
the stream sections and car road cuts section. These sections have been measured bed by bed,
and samples have been taken every few centimeters or tens of centimeters, depending on
facies changes. The lithology, texture, sedimentary structures, fossil content and tectonic
deformation were checked and recorded in note book during measurements. Based on the
field works, detail stratigraphic columns were reproduced by Surfer 10 software. The
lithofacies were classified based on particular set of sediments characteristics, lithology,
texture, suite of sedimentary structures, fossil content, colour, geometry and paleocurrent
pattern of the sedimentary rock.
Geological Setting and Stratigraphy
The Central Myanmar Basin (CMB) lies between the Indo-Burman Ranges (IBR) in
the west and the Shan Plateau in the east Metcalfe (2011, 2013). The Central Myanmar Basin
(CMB) is divided into the eastern (backarc) and the western (forearc) troughs particularly
after the late Miocene when the Central Volcanic Line (CVL) became well established. The
western trough of the CMB is further subdivided into a few sub-basin, namely (from north to
south) the Hukaung, Chindwin, Minbu/Salin, Pyay and Irrawaddy sub-basins.
The present Taing Da area is situated a small segment of the south-western margin in
Minbu/Salin sub-basin. The study area can be said distinct morphological break between the
mountain ranges in the west and the ridges and valleys of the Central Basin in east
450 The Second Myanmar National Conference on Earth Sciences (MNCES, 2018)
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
corresponds to a stratigraphic discontinuity. The ridges of high relief occurred in the western
part of the area. The oldest rock unit by the Kabaw Formation covered the western part and
the youngest rock units by the Alluvium toward the east. Satellite 3D image of the present
area is shown in figure (2). Geological map of the Zingyan - Taing Da - Mothauk area of the
northwestern part of the Mindon Township is shown in figure (3). Topographic features of
this area are from east to west, Mu chaung Valley, Kyaukkyi-aing Ridge, Thaminkadok-
Zawgyi valley, Zindaung-Sinza Taung, Kalan Taung Ridge, Kywedu Taung, and Kyaukpya
Taung. Mu chaung is distinct stream of the area which drain NW to SE direction. The
principal streams of the study area are Mu chaung.
On the basis of lithology, stratigraphic position, and faunal content, six stratigraphic
units can be classified in the study area which is explained in ascending order as follows;
6. Alluvium (Holocene)
5. Tabyin Formation (Middle Eocene)
4. Tilin Formation (Early Eocene)
3. Laungshe Formation (Early Eocene)
2. Paunggyi Formation (Late Paleocene)
1. Kabaw Formation (Late Cretaceous)
The generalized stratigraphic succession is shown in table (1). There are six
lithostratigraphic units are exposed in the area, the present study is carried out especially
onthe Tilin Formation. The present study is mainly emphasized on the Sedimentary
lothofacies analysis of the Tilin Formation.
Figure (2). 3D image of the study area: facing to northwest (source; Google map)
Tha Min Ka Dok Village
Taing Da Village
The Second Myanmar National Conference on Earth Sciences (MNCES, 2018) 451
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Figure (3). Geological Map of the Zingyan - Taing Da - Mothauk Area, Northwestern Part of
the Mindon Township, Magway Region ( Modified after Maung Maung Gyi,
1983)
Stratigraphy of Tilin Formation
Cotter (1912) was firstly introduced the name of Tilin Formation in the area between
75 and 81 miles on the Pakokku-Tilin Road, from the Western Outcrops of the Minbu
Basin. The sandstones occur below Tabyin clays and above the laungshe shales (1912). The
name Tilin Formation was proposed by Aung Khin and Kyaw Win (1969). Tilin Formation
can be divided into two members according to the difference of lithology and topography by
Maung Maung Gyi (1983).
The Tilin Formation is well exposed in the stream section of the study area. The lower
member of Tilin Formation occupies N-S trending and small ridge between the Laungshe
Valley in the west and the upper Tilin Valley in the east. This Formation is well exposed
along the Mu chaung, located from the north-eastern part of the Thamingadok village to the
west of the Taing Da village. Along Mu chaung, SSE of the Taing Da village and
Meinmahla chaung near the Htanbingaing village can be seen upper member of the Tilin
Formation. The average thickness of Tilin Formation is 3600m.
Lower Member The lower member is mainly occurred alternation of buff- to grey-colored,
thin-bedded calcareous sandstone and bluish grey shale. Bluish grey shale interbedded with
thin-bedded sandstone (Fig. 4.a). Medium-to thick-bedded sandstones with bioturbation and
shell fragments are occurred (Fig. 4.b). Wavy bedding, lenticular bedding, flaser bedding,
planar type and trough type cross-beddings are occurred in the lower member of the Tilin
Formation. Bluish grey, thin to medium-bedded sandstone with load cast are also observed at
Units
Upper Member
Lower Member
452 The Second Myanmar National Conference on Earth Sciences (MNCES, 2018)
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
the lower member (Fig. 4.c). The sandstone content of the lower member of the Tilin
Formaion is more prominent than the upper member of Tilin Formation.
Upper Member The upper member is composed of grey-colored, medium-bedded sandstone
interbedded with bluish grey clay along the Meinmahla chaung section (Fig. 4.d). Buff-
colored, thin- to medium-bedded lenticular and wavy bedded sandstone are intercalated
between the bluish grey clay (massive type) can be seen in this Formation (Fig. 4.e). In the
upper member of Tilin Formation, thin- to medium-bedded, cone-in-cone structures and disc-
shaped concretions are also intercalated between the massive mudstone (Fig. 4.f). In some
places, concretionary mudstone and soft sediment folding are observed. At the upper most of
the Tilin Formation, medium-bedded friable sandstone and cone in cone structures are
occurred. The contact with overlying Tabyin Formation is gradational and it can be seen the
east part of Taing Da- Htinnyauktin- Mindon- Padan Junction road. On the basic of lithology
and stratigraphic position, Tilin Formation may be regarded as Early Eocene age.
Table (1). Generalized stratigraphic succession of the Zingyan - Taing Da - Mothauk Area.
Age Formatio
n Lithology Thickness
Holocene Alluvium light brown colored of sandy soil, silt and clay, and often contains organic matter that makes as a
fertile soil
About 400 m (Kyaw Min Oo,
2015)
Middle Eocene
Tabyin Formation
Yellow to yellowish shale and clay interbedded with bluish grey,thin- bedded, medium-grained
sandstone.
963 m (Maung Maung
Gyi,1983)
Early
Eocene
Tilin
Formation
Lower Member- Yellowish brown to brownish
grey, medium-grained, thin- to medium-bedded sandstone and bluish grey shale.
Upper Member- Bluish grey shale and thin- to
medium-bedded, compact and hard sand band.
3600 m
(present study)
Early
Eocene
Laungshe
Formation
Light-grey to grey-colored, fine- to medium-grained sandstone interbedded with greenish grey
to bluish grey shale; minor amount of tuff bed and
limestone lens.
1918 m
(Kyaw Min Oo, 2015)
Late
Paleocene
Paunggyi
Formation
Greenish grey to grey colored, coarse-grained,medium- to thick- beddedsandstones and
bluish-grey shale; grey to reddish brown, thick-
bedded to massive conglomerate; grits and gritty sandstone.
1950 m
(Kyaw Min Oo,
2015)
Late Cretaceous
Kabaw Formation
medium- to coarse-grained, Medium- tothick-bedded, sandstoneinterbedded with bluish grey
shale
2569 m (Maung Maung
Gyi, 1983)
Stratigraphic Relationship
The lower stratigraphic contact between Tilin Formation (Early Eocene) and
underlying Laungshe Formation (Early Eocene) is graditional contact. It is characterized by
the presence of sand-shale alternation. The lower contact can be seen along the Mu chaung,
north-eastern of Thamingadok village and the upper contact with overlying Tabyin Formation
is gradational. Its contact can be seen at the junction of the Htinnyauktin-Taing Da- Mindon
car road.
The Second Myanmar National Conference on Earth Sciences (MNCES, 2018) 453
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Faunal, Age and Correlation
Tilin Formation of the present study area is fairly fossiliferous. The Lepidocyclina sp.,
Nummulities sp. and Camerina sp. are preserved (Htay Sandar Soe, 2015). The above faunal
assemblages indicate that the Tilin Formation may belong to Early Eocene age.
Depositional Environment
Tilin Formation of the present area is characterized by the following;
(1) This formation composed of alternated sandstones and shales.
(2) Light-grey, thick-bedded sandstone, calcareous sandstone with load cast, wave ripple
mark are present.
(3) Sedimentary structures such as small scale trough type cross-bedding, wavy bedding,
lenticular bedding, flaser bedding, cone-in-cone structure and burrow structure are also
common.
Figure (4). (a). Thin-bedded sandstone beds are interbedded with bluish grey shale (19˚ 32'
14.8''N and 94˚ 39' 44.5''E), (b). medium-to thick-bedded sandstones (19˚ 32'
29''N and 94˚ 39' 4.1''E), (c). sandstone with load cast (19˚ 32' 54''N and 94˚ 39'
11''E), and in the lower member of Tilin Formation, (d). medium-bedded
sandstone interbedded with massive clay at Meinmahla chaung section, (e).
massive type or crudely bedded mudstone (19˚ 31' 10.731''N and 94˚ 40'
47.424''E), and (f). massive clay with thin- to medium-bedded cone-in-cone
sandstone and disc-shaped concretions at the upper member of Tilin Formation
The above characteristics are strongly indicated that Tilin Formation was deposited
under the shallow marine condition. The presence of worm burrows indicate that the littoral
depositional environment.
a b c
d e f
454 The Second Myanmar National Conference on Earth Sciences (MNCES, 2018)
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Lithofacies Analysis and Lithofacies Association
General Statement
A facies is a body of rock and it is defined on the basis of its distinctive lithologic
features including color, bedding, composition, texture, fossils and sedimentary structures
(Reading, 1996). A facies is defined by Tucker (2001) as a particular set of sediment
attributes a characteristic lithology, texture, suit of sedimentary structure, fossil content,
color, geometry and paleocurrent patterns, etc. Each lithofacies represents on individual
depositional event. Therefore, lithofacies may be grouped into lithofacies associations or
assemblages, which are characteristics of particular depositional environment (Miall, 1984).
The term ‘Facies Association’ was defined by Potter (1959) as a collection of
commonly associated sedimentary attributes, including gross-geometry (thickness and areal
extent), continuity and shape of lithologic units, rock types, sedimentary structures and fauna
(type and abundance). In the study area, at least (12) lithofacies are recognized for Tilin
Formation. Their brief descriptions with interpretations are given in table (2). Detail
sedimentological log of the Tilin Formation (Fig. 7). The four lithofacies associations were
distinguished with respect to their lithology, facies successions and bed geometry. They are
shoreface facies association, tidal channel facies association, tidal flat facies association and
delta front facies association in table (3).
Lithofacies Characteristics
Facies A: Quartz Pebbles conglomerate
This facies is distributed in upper member of the Tilin Formation. The thickness of
each bed varies from 15 to 30 centimeters. The diameter of quartz pebble range from 0.5 cm
to 7 cm and most of the quartz pebbles are rounded (Fig. 5.a). This facies is associated and
sandstone with Thick-bedded gritty sandstone of Facies-C and trough type cross-stratification
of Facies D. The upper boundary and lower boundary are sharp.
Interpretation
Most of the quartz pebbles in this facies are rounded. Facies A is regarded as lag
deposit at the base of tidal channel that occurs at the coastal area.
Facies B: Sandstone with Mud Clasts
This facies is distributed in the upper member of the Tilin Formation. It is mainly
composed of buff colored, medium-grained sandstone with mud clasts (Fig. 5.b).The
thickness of each bed varies from 7-30 cm. The diameter of mud clasts range from 0.5cm to
4cm and most of mud clasts are rounded. This facies is associated with sandstone with trough
type cross-stratification of Facies D. The upper boundary and lower boundary are sharp.
Interpretation
Facies B may be regarded as lag deposit at the base of tidal channel that occurs at the
delta front of the coastal area.
Facies C: Thick-bedded gritty sandstone
This facies is distributed in the upper member of the Tilin Formation. It consists of
grey colored, medium-grained, thick-bedded gritty sandstone (Fig. 5.c). The upper boundary
and lower boundary are graditional.
The Second Myanmar National Conference on Earth Sciences (MNCES, 2018) 455
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Interpretation
Facies C may be regarded as lag deposit at the base of tidal channel.
Facies D: Sandstone with Trough Cross-stratification
This facies is distributed in the lower member of the Tilin Formation. It consists of
buff colored, medium-grained, trough type cross-stratification sandstone (Fig. 5.d). The
nature of boundaries with the underlying and overlying units is sharp.
Interpretation
The most common sedimentary structures in the tidal channel deposits are channel lag
deposit overlain by bidirectional trough and planar cross-bedding, parallel laminated
sandstone and shells (Walker and James, 1992). Facies D is deposited in subaqueous topset
deposits of tidal channel.
Facies E: Sandstone with Planar Cross-stratification
This facies is distributed in the lower member of Tilin Formation. This facies occurs
in grouped with planar-type cross bedding. This occurrence is small scale and distributed
through the area. (Fig. 5.e).This facie is variable in relationship associated with facies. Most
of them have erosion tops, but in rare cases they have transitional tops. The nature of
boundaries with the underlying unit is graditional and overlying unit is sharp.
Interpretation
This facies may be interpreted as upper shoreface deposits (Reineck and Singh, 1980).
Facies F: Sandstone with Burrow Structure
This facies is distributed in lower member of Tilin Formation. It consists of light grey,
medium-bedded sandstone with burrow structure (Fig. 5.f). The presence of evidence of
organisms disturbing sediment is known as bioturbation (Nichols, 2009).
Interpretation
Toward the deeper part of the shoreface, the degree of bioturbation is incresess. This
facies may be interpreted as lower shore face environment (Reineck and Singh, 1980).
Facies G: Sandstone with Wavy/Lenticular Bedding
This facies is distributed in Tilin Formation. It is composed of grey colored, medium-
bedded sandstone with wavy and lenticular bedding (Fig. 5.g). Based on nature of lenses,
lenticular bedding can be subdivided into two types. They are lenticular bedding with
connected lenses and lenticular bedding with single (Isolated lenses). The type of lenticular
bedding is second type. The nature of boundary is graditional.
Interpretation
This facies may be formed in tidal flat (sand flat) environment (Reineck and Singh,
1980).
Facies H: Sandstone with Flaser Bedding
This facies is also distributed in Tilin Formation. It is composed of grey coloured,
medium-grained sandstone with flaser bedding (Fig. 5.h). This facies is associated with
sandstone with wavy and lenticular bedding of Facies G and crudely bedded mudstone facies.
The nature of boundary is graditional.
456 The Second Myanmar National Conference on Earth Sciences (MNCES, 2018)
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Figure (5). (a). Quartz pebbles conglomerate of facies A, (b) Sandstone with mud clasts of
facies B, (c) Thick-bedded gritty sandstone of facies C, (d) Sandstone with
Trough Cross-stratification of facies D, (e) Sandstone with Planar Cross-
stratification of facies E, (f) Sandstone with Burrow Structure of facies F, (g)
Sandstone with Wavy and Lenticular bedding, (h) Sandstone with Flaser Bedding
of facies H were preserved in Tilin Formation of Taing Da area.
a b
c d
e f
g h
The Second Myanmar National Conference on Earth Sciences (MNCES, 2018) 457
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Figure (6). (a) Sandstone with Wave Ripple of facies I, (b) Sand-shale Interbed Sequence of
facies J, (c) Massive Concretionary Mudstone of facies K, (d) Crudely bedded
Mudstone of facies L were preserved in Tilin Formation of Taing Da area.
Interpretation
This structure implies that both sand and mud are available and that periods of current
activity alternate with period of quiescence. This facies may be formed in tidal flat (sand flat)
environment (Reineck and Singh, 1980).
Facies I: Sandstone with Wave Ripple
This facies is distributed in the lower and upper member of Tilin Formation. This
facies is mainly composed of light grey, medium- grained sandstone with ripple marks
(Fig. 6.a). The thickness of ripple mark sandstone is about from 15 to 30 cm. The nature of
boundary is graditional.
Interpretation
This ripple type occurs in wave-dominated, tidal influenced environments (Reineck
and Singh, 1980) described interfering ripple systems formed on the North Sea tidal flat by
the interaction of wave activity and currents. So, this Facies I may be deposited under the
wave activity tidal flat (sand flat) environment.
Facies J: Sand-shale Interbed Sequence
This facies is distributed in the lower member of the Tilin Formation. It is composed
of buff colored, thin- to medium-bedded sandstone interbedded with bluish grey shale
(Fig. 6.b). The nature of boundaries with the underlying unit is graditional and overlying unit
is sharp.
a b
c d
458 The Second Myanmar National Conference on Earth Sciences (MNCES, 2018)
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Interpretation
In this facies, the sandy layers are deposited during periods of current activity, and
shale/mud content during slack water periods. This alternate bedding is mostly to the
alternation of tidal current and slack water phases (Reineck and Singh, 1980). This facies
may be deposited in the tidal falt (mixed flat) environment.
Facies K: Massive Concretionary Mudstone
This facies is distributed in upper member of Tilin Formation. It is composed of
bluish grey colored, massive concretionary mudstone and thickness is about 170 to 3000 cm
(Fig. 6.c). This facies is associated with gritty sandstone of Facies C and crudely bedded
mudstone of Facies L. The nature of boundary is gradational.
Interpretation
Fine sediments are deposited under relatively quite water condition. This facies may
be deposited in the delta front environment.
Table (2). Lithofacies identification for Tilin Formation, in the Mindon Township, Magway
Region
Lithofacies Sedimentary
Structures Interpretation
A Quartz Pebbles
conglomerate
Lack of internal
structure the base of tidal channel deposits
B Sandstone with Mud Clasts Lack of internal
structure
Lag deposit at the base of the tidal
channel
C Thick-bedded gritty
sandstone
Lack of internal
structure
Lag deposit at the base of the tidal
channel
D Sandstone with Trough
Cross-stratification
Small scale trough cross
stratification
deposited in subaqueous topset
deposits of tidal channel
E Sandstone with Planar
Cross-stratification
Small scale planar cross
stratification upper shoreface deposits
F Sandstone with Burrow
Structure
Burrow Structure, Shell
Fragments lower shore face environment
G Sandstone with
Wavy/Lenticular Bedding
Wavy bedding,
Lenticular bedding tidal flat environment
H Sandstone with Flaser
Bedding Flaser bedding tidal flat environment
I Sandstone with Wave
Ripple Wave ripple marks wave activity tidal flat environment
J Sand-shale Interbed
Sequence Organic debris
tidal falt and upper shoreface
environments
K Massive Concretionary
Mudstone Concretions delta front environment
L Crudely bedded Mudstone cone-in-cone structures,
disc-shaped concretions delta front environment
The Second Myanmar National Conference on Earth Sciences (MNCES, 2018) 459
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Table (3). Identification of Lithofacies Association for Tilin Formation in the Mindon
Township, Magway Region
Facies Association Lithofacies
Shoreface E, F, J
Sandstone with Planar Cross-stratification
Sandstone with Burrow Structure
Sand-shale Interbed Sequence
Tidal Channel A, B, C, D, L
Quartz Pebbles conglomerate
Sandstone with Mud Clasts
Thick-bedded gritty sandstone
Sandstone with Trough Cross-stratification
Crudely bedded Mudstone
Tidal Flat G, H, I, J, L
Sandstone with Wavy/Lenticular Bedding
Sandstone with Flaser Bedding
Sandstone with Wave Ripple
Sand-shale Interbed Sequence
Crudely bedded Mudstone
Delta Front B, K, L
Sandstone with Mud Clasts
Massive Concretionary Mudstone
Crudely bedded Mudstone
Facies L: Crudely bedded Mudstone
This facies is distributed in lower and upper member of Tilin Formation. This facies
mainly composed of bluish grey colored, massive or crudely bedded mudstone and about 170
to 3000 cm in thick (Fig. 6.d). The nature of boundary is gradational.
Interpretation
This facies may be deposited under the tidal channel and tidal mud flat environments
(Reineck and Singh, 1980).
Lithofacies Association
The combination of two or more facies, which were formed in a single depositional
environment at the same time, is grouped into a facies association. A facies association can
thus be used for more detailed interpretation of depositional environments. (12) lithofacies
have been classified on the basis of sedimentary structures, lithology and fossils. (4)
lithofacies associations were distinguished with respect to their lithology, facies successions
and bed geometry table (3). They are;
(1) Shoreface facies association
(2) Tidal channel facies association
(3) Tidal flat facies association and
(4) Delta front facies association
1. Shoreface facies association
The shoreface is always submerged under water, and the surface is usually made up of
submerged long shore bars with channels on their landward side. Generally, the structures
460 The Second Myanmar National Conference on Earth Sciences (MNCES, 2018)
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
identified in lower shore face were planner cross-bedded sandstone of Facies E, bioturbated
sandstone of Facies F and sand-shale interbed sequence of Facies J. The upper shoreface
structures were.
Toward the deeper part of shoreface, cross-bedding is very rare and degree of
bioturbation is incresess (Reineck and Singh, 1980). Storm-dominated sandstone is underlain
by offshore mudstone and overlain by tidal channel or tidal flats. Lower shoreface and upper
shoreface can be seen in (Figs. 7 & 8).
2. Tidal channel facies association
The outer part of a tide-dominated estuary is the zone of strongest tidal currents,
which transport and deposit both fluvial derived sediment and material brought in from the
sea. In macro tidal regions the currents will be strong enough to cause local scouring and to
move both sand and gravel: quartz pebbles conglomerate (Facies-A) is common among the
gravelly detritus deposited as a lag on the channel floor (Reinson, 1992). Horizontal
laminated sandstone of facies-F, thick-bedded gritty sandstone facies-C and trough type
cross-laminated sandstone of facies-E are also indicated as tidal channel character. This
facies association is well defined as tidal channel facies (Figs. 7 & 8).
3. Tidal flat facies association
Tidal flats develop along the gently dipping sea coasts with marked tidal rhythms,
where enough dipping sea coasts with marked tidal rhythms, where enough sediment is
available and strong wave action is not present. The main part of the tidal flat is located
between intertidal zone and into the shallow portion of the subtidal zone. Consequently, the
sediments adjacent to the channel are typically sandy, and pass gradually into muds near the
high-tide line (Walker & James, 1992). There are three sub-environments of (1) sand flat, (2)
mixed flat and (3) mud flat in the intertidal zone.
The primary sedimentary structures of tidal flats association included flaser bedding,
interference ripples and lenticular bedding which were formed under tidal flat condition.
Facies G, H and I are as sandflat deposits. Facies J may be assigned to be deposited mixed
flat deposit and Facie L may be assigned to be deposited in the mud flat deposit (Reineck &
Singh, 1980) (Figs. 7 & 8).
Sand flat sub-environment: The sand flats which occupy the lower portion of most tidal
flats. Commonly contain flaser bedded sandstone of Facies H, interference ripples of Facies I
and lenticular bedding of Facies G (Walker and James, 1992).
Mixed flat sub-environment: The mixed flat are deposited when the fluvial and marine
influence both act in short period of time to deposit sediments. The structure identified in this
sub-environment is sand-shale interbed sequence of Facies J. The mixed flat are mostly
underlain by the sand flat or tidal channel and overlain by the mud flat or supratidal.
Mud flat sub-environment: The sediments deposition in muddy tidal flat in the studied
outcrop are characterized by area of inter-tidal mudflats that are covered at high tide and
exposed at low tide at the time of deposition. Generally, muddy tidal flat sediment was
deposited by massive or crudely bedded mudstone of Facies L.
4. Delta front facies association
Deltaic deposits are a substantial amount of coastal sediments incorporate deltaic deposits.
However, the recognization of deltaic deposits in ancient sediments may be very difficult,
because for definite recognization of a delta a regional variation in depositional
The Second Myanmar National Conference on Earth Sciences (MNCES, 2018) 461
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
environments. The thickness of modern delta deposits varies from a few meters to several
tens of meters. Delta Front association include; Sandstone with mud clasts of Facies B,
massive concretionary mudstone of Facies K and crudely bedded mudstone of Facies L. Delta
front association can be seen deltaic depositional environment (Figs. 7 & 8).
Figure (7). Detailed sedimentological log of the Tilin Formation along Mu chaung and
Meinmahla chaung exposed at west and southeast of Taing Da village, Mindon
Township, Magway Region.
Depositional Environments
The Tertiary sediments recorded a history of infilling of the fore arc basin by marine
sediments from the south and non- marine deposits from the north. The process was
interrupted by marine transgressions and regressions, resulting in intertonguing of continental
and marine units (Chibber, 1934). Depositional environment of study the area may be
interpreted on the basis of sedimentary structures, texture and sedimentary facies. There are
four lithofacies association in the study area.
Lower part of Tilin Formation may also be deposited in shoreface, tidal channel and
tidal flat environments and upper part of the Tilin Formation may be deposited under the tidal
flat and delta front environments during the Early Eocene time.
462 The Second Myanmar National Conference on Earth Sciences (MNCES, 2018)
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
Figure (8). Probable depositional facies model of the Tilin Formation in Taing Da area
(modified after internet image: www.google image/depositional
environments.com)
Summary and Conclusion
Tilin Formation is 3600m thick based on the stratigraphic measured sections. Twelve
lithofacies, which were grouped into four facies associations, were recognized. The base of
the Tilin Formation (lower member) represents a sequence deposited of shorefae deposits of
small scale planar type cross-bedding, bioturbation and sand-shale interbed sequence. Tidal
channel environment may be represent as quartz pebbles conglomerate, mud clasts, gritty
sandstone and trought cross-bedding. Tidal flat environment of wavy bedding, lenticular
bedding, flaser bedding, wave ripple and crudely bedded mudstone were deposited in lower
member of the Tilin Formation. The deposition of upper member of Tilin Formation
represents a sequence being formed from tidal flat to delta front environments. The crudely
stratified mudstone, concretionary mudstoneand mud clasts of delta front deposits and tidal
flat deposits were preserved in the upper member of the Tilin Formation. The upper part of
the Tilin Formation was deposited during Late Eocene Epoch.
Acknowledgements
First I would like to thank Dr Maung Maung, Principal of Myin Gyan Degree College for giving me a
seed of research minded to me. And the persons I ought to thank are my parents and the teachers from kindergarten to University.
Study Area
The Second Myanmar National Conference on Earth Sciences (MNCES, 2018) 463
November 29-30, 2018, Hinthada University, Hinthada, Myanmar
References
Aung Khin and Kyaw Win, (1969). Geology and hydrocarbon prospects of the Burma.
Brunnschweiller, R.O., (1966). On the Geology of the Indoburman Ranges: Geol. SOC. Australia Jour.,
V.13,p. 137-194
Chhibber, H. L., (1934). The geology of Burma. Macmillan London.
Cotter, G. de P., (1912). Notes on some Nummulites from the Burma Tertiaries. Rec. Geol. Surv. Ind., V. 41, P. 322 – 323.
Htay Sandar Soe, (2015). Petrography and Diagenesis of Tiin Formation exposed Zingyan-Mothauk Area, For
her M.Sc (thesis), unpub Thesis, University of Magway.
Kyaw Min Oo, (2015). Facies Analysis Of The Tilin Formation Exposed At The Zingyan-Mothauk Area,
Mindon Township, Magway Region, For his M.Sc (thesis), unpub Thesis, University of
Magway.
Kyaw Win and Thit Wai, (1971), The Geology of the Chin Ranges. Burma Research Cong. Rgn.
Maung Maung, (1994). Petrology of Shwezettaw-Kyauk-O-Ngape area, Ngape-Minbu Township, Magway
Division: M.Sc., unpub Thesis, University of Mandalay.
Maung Maung Gyi, (1983). Geology of northwestern part of Mindon area, For his M.Sc., unpub. Thesis,
University of Mandalay.
Maung Thein, (1972). The Geological evolution of Burma: a preliminaty synthesis. SE Asia Geol;Congr., Malaysia.
Maung Thein, (2010). The Geology evolution of Burma. Unpub.,Department Report, University of Mandalay.
Metcalfe, I., (2011). Tectonic framework and Phanerozoic evolution of Sundaland. Gondwana Res. 19, 3–21.
Metcalfe, I., (2013). Gondwana dispersion and Asian accretion: tectonic and palaeogeographic evolution of
eastern Tethys. J. Asian Earth Sci. 66, 1–33
Miall, A.D., (1984). Principles Basin Analysis, 490 pp. Springer-Verlag, New York.1.1,11.5.2.
Nichols, G.J., (2009). Sedimentology and Stratigraphy, 2 nd edn. United Kingdom, p 179-214.
Potter, P.E., (1959). Facies model conference, Science. Geol. 71, 41-471.
Reading, H.G., ed., (1996). Sedimentary Environments and Facies. Third Edition., Oxford Blackwell Scientific
Publications, pp. 154-228.
Reineck, H.E. and Singh, I.B., (1980). Depositional Sedimentary Environments. 2nd edition. Springer, New York.
Reinson, G. E., (1992). Tranfressive barrier island and estuarine systems. In: Facies Models:Response to Sea
Level Change (Ed. by R. G. Walker and N. P. James), pp 179-194.Geol. Ass. Can, St John’s,
Newfoundland.6.7.5, 6.7.6, Fig.6.8., 9.4.2.
Than Tun, (1967). Geological report on part of Western Outcrops, Tilin-Pauk-Kyauktu Area, Pakokku Dist.,
Peoples Oil Industry, unpub.
Than Tun, (1977). Stratigraphy and age of the Kaw Formation, Kabaw valley, Burma. Paper read at XII Burma
Research Congress.
Theobald, W., (1871-1873). The geology of Pegu: Mem. Geol. Surv. India, 10, 2, P. 189-359.
Tucker, M.E., (2001). Sedimentary Petrology: An introduction to the Origin of Sedimentary Rocks (3rd Edition)
Blackwell Science Ltd.,UK.
Walker, R .G. and James, N.P., (1992). Facies Models: Geological association of Canada. 157-218 pp. Geol. Ass. Canada, St John’s, Newfoundland.