A STUDY OF OPEN COAST TIDAL FLAT SEDIMENTOLOGY BASED … SPB-03 A Study... · 2017-08-10 ·...

PROCEEDING, SEMINAR NASIONAL KEBUMIAN KE-9 PERAN PENELITIAN ILMU KEBUMIAN DALAM PEMBERDAYAAN MASYARAKAT

6 - 7 OKTOBER 2016; GRHA SABHA PRAMANA

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A STUDY OF OPEN COAST TIDAL FLAT SEDIMENTOLOGY BASED ON

OUTCROP DATA IN NGRAYONG FORMATION, KADIWONO AREA, CENTRAL

JAVA

Rifqi Zakaria1*, Rian Cahya Romana2, Rivandi Taufik1, Tara Shinta Dewi2, Putri Ramadhina3 1Dept. of Geology, UPN “Veteran” Yogyakarta

2GeoPangea Research Group (GPRG) 3Sedimentology Lab, UPN “Veteran” Yogyakarta

*Email : [email protected]

SARI

This study employs sedimentological analysis and basic principles of sequence stratigraphy to correlate

sedimentary log and try to reveal the sedimentology of open coast tidal flat outcrop in Middle Miocene

Ngrayong Formation, Kadiwono Area, Blora Regency, Central Java. Open coast tidal flat is unique

system in its wave and tide dominated physical setting.Ngrayong Formation deposited in North East

Java Basin and one of the giant reservoir in Indonesia. In the study area, Middle Miocene Ngrayong

Formation with the thickness >400 meter which is dominated by sandstone, siltstone, and claystone.

Based on the physical aspects, such as lithology, texture and sedimentary structure in the field, there

are 12lithofacies. These lithofacies is spread in the 4 facies association, there are mud flat, mixed flat,

sand flat and subtidal flat. Mud flat is dominated by fine grain (mud) which is showed the low energy

that affect to the depositional of mud flat. Mixed flat are composed by mud and sand, that is happened

because of medium tide level, therefore that founded a contact between sandstones and mudstone, which

is interpreted as flooding surface. Sand flat is dominated by sand, but there is a few layer of mud. Lateral

accretion is often occurring in sand flat, the evidence is the domination of planar and trough cross

stratification. In the subtidal flat, lateral accretion is also occurring, and hummocky cross stratification

is constructed because of the influence of sea waves. Moreover, there are limestone which is interpreted

as a sequence boundary type 2 the product of transgressive surface deposits.

Keywords: Ngrayong Formation, Tidal Flat, Sedimentology, Stratigraphy.

I. INTRODUCTION

Ngrayong Formation is part of North East

Java Basin in the Rembang Zone. This

formation is commonly deposited with

progradingfluvio-deltaic lowstand system

and shallow-marine systems (Johnstone et.

al., 2006) and composed by interbedded of

quartz sandstone with claystone, siltstone,

lignite, and bioclastic limestone

(Pringgoprawiro and Sukido, 1992).

Furthermore, Ngrayong Formation is one of

the potential oil reservoir in Northe East Java

Basin, this can be seen from Ngrayong quartz

sandstone that has a good porosity and

permeability.

The purpose of this research is to employs

sedimentological analysis and basic

principles of sequence stratigraphy to

correlate sedimentary log and try to reveal the

sedimentology of open coast tidal flat outcrop

by integrating of all data fields that have been

investigated by researcher.

II. REGIONAL GEOLOGICAL

SETTING

North East Java Basin stretches from West to

East from Semarang to Surabaya 250 km

(width of 60-70 km). Tectonic phase in North

East Java Basin are divided into 4 phase. The

first phase happened during Tertiary to Early

Oligocene, where Ngimbang Formation and

Kujung Formation are deposited. In this

phase the work force is predominantly

extensional force and this force formed fore

arc basin. The second stage happened during

Middle Oligocene to Late Miocene. In this

phase, Hindia plate subducted to Java Island.

This oblique subduction forming folds and

faults that trend to Northeast-Southwest

(Meratus pattern). Fore arc basin has entered

a phase of sagging-inverse and at this time,



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Prupuh Formation, Tawun Formation,

Ngrayong Formation, Bulu Formation,

Wonocolo Formation and Ledok Formation

are deposited. Top notch sea level at this

stage is relatively regression and

progradational occurs. This caused changes

in facies

Laterally towards the ground to the north.

This matter evidenced by the changes in

facies of limestone (Prupuh Formation) to

sandstone, mudstone mineral-rich glauconite

(Ngrayong Formation and Ledok Formation).

Sandstone is likely deposited in delta. The

third phase occured in the Late Miocene to

Early Pleistocene. In this phase, transgression

occured which caused the sea level rise

relatively which Mundu Formation, Paciran

Formation, Selorejo Formation and Lidah

Formation deposited. In the fourth phase

occured during Late Pleistocene to Holocene.

In this phase, subductionHindia Plate formed

structures that trend East-West. This

subduction caused partial melting, and

occured volcanism in south Rembang Zone

(Figure 1).

Ngrayong Formation is composed by

interbedded of quartz sandstone with

claystone, siltstone, lignite, and bioclastic

limestone. This formation deposited on

shallow marine and progradely the

depositional environment change into

lagoonal to Outer Sublitoral. The thickness of

Ngrayong Formation up to 900 meters, and

this formation is one of the potential oil

reservoir.

III. DATA & METHODS

Methods in this research are divided into

three stage.

The first stage is observation stage. Primary

data acquired from observation including

field orientation, rock description along with

rock sampling, and measuring section.

The second stage is analysis. Various analysis

has been done with petrographic analysis,

microfossil analysis, and measuring section

analysis.

The last stage is interpretation for all data that

has been analyzed. The researcher employs

sedimentological analysis and basic

principles of sequence stratigraphy to

correlate sedimentary log and interprete the

sedimentology of open coast tidal flat

outcrop.

IV. DEPOSITIONAL

ENVIRONTMENT ANALYSIS

a. Lithofacies

Lithofacies defined as subdivisions of a

sedimentary sequence based on lithology,

grain size, physical and biogenic sedimentary

structures, and stratification that bear a direct

relationship to the depositional processes that

produced them. Lithofacies and lithofacies

associations (groups of related lithofacies)

are the basic units for the interpretation of

depositional environments.

As the identifying of depositional

environment analysis, there are 12 lithofacies

of object study of Ngrayong Formation that

was observed ;

1. Parallel lamination claystone (Clm)

This consist of grey to brownish claystone

with 10 – 20 cm of thickness. In several

place of outcrops, this unit consists of

siderite noduls. Parallel lamination was

observed as sedimentary structures. This

unit associates with lenticular bedding

claystone and flasher bedding

sandstone.This unit was deposited by

effect of lower energy current or with lack

of mud concentration while depositional

process by suspension current.

2. Lenticular Bedding Claystone (Cln)

Grey to brownish claystone and lens of

fine grain sandstone with 40 cm of

thickness dominated this unit. Lenticular

bedding was observed as sedimentary

structures. This unit associates with

lenticular bedding siltstone.The

comprising of claystone and fine grain

sandstone in this unit indicated that this

unit was deposited by decreasing energy

current which affect of tidal process.

Therefore, fine grain sandstone stuck

inside of claystone which called as

lenticular bedding sedimentary structure.

This sedimentary structure is produced in

the environment which depositional

condition and preservation of mud was

more than sand.



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3. Parallel lamination Siltstone (Llm)

This consist of brownish siltstone with

parallel lamination of sedimentary

structure and 20- 40 cm of thickness. This

unit associates with lencicular bedding

siltstone. This unit was deposited by effect

of lower energy current or with lack of

mud concentration while depositional

process by suspension current.

4. Lenticular bedding siltstone (Lln)

Brownish siltstone and lens of fine grain

sandtone with 40 – 100 of thickness

dominated this unit. Lenticular bedding

was observed as sedimentary structures.

This unit associates with parallel

lamination siltstone.The comprising of

siltstone and fine grain sandstone in this

unit indicated that this unit was deposited

by decreasing energy current which affect

of tidal process. Therefore, fine grain

sandstone stuck inside of siltstone which

called as lenticular bedding sedimentary

structure. This sedimentary structure is

produced in the environment which

depositional condition and preservation of

mud was more than sand.

5. Flasher Bedding Sandstone (Sfl)

This consist of very fine grain to fine grain

brownish sandstone that were dominate

composed by quartz and k-feldspar.

Sediment structure was identified as

flasher bedding with dominated by

sandstone and lens of siltstone to

claystone. This unit has 50 – 100 cm of

thickness and associates with wavy

lamination sandstone and planar cross-

bedding sandstone.This unit can be

formed by lower energy of suspension and

traction mechanism with fluctuative

hydraulic condition.

6. Hummocky Cross-Stratification

Sandstone (Shc)

This consist of medium grain brownish

sandstone. The characteristic of this

sandstone are subrounded – rounded of

grain, well sorted, composed by quartz

and k-feldspar minerals, hummocky

cross-stractification of sedimentary

structure. This unit has 100 cm of

thickness and associates with planar cross-

bedding sandstone.This unit is formed by

wave and storm activities which can be

made by combination of unidirectional

current that linked of storm activity.

7. Parallel Lamination Sandstone (Slm)

This consist of brownish very fine grain

sandstone that were dominate composed

by quartz and k-feldspar. Sediment

structure was identified as parallel

lamination. This unit has 40 cm of

thickness and associates with lencticular

bedding siltstone and wavy lamination

sandstone. This unit is formed by high

energy depositional current as upper

plane-bed phase lamination and by low

energy depositional current as lower

plane-bed phase lamination.

8. Planar Cross-Bedding Sandstone (Spc)

This consist of fine to coarse grain

sandstone. The characteristics of this unit

are brownish of colour, subrounded to

rounded of grain, well sorted,composed

by quartz and k-feldspar minerals, planar

cross-bedding of sedimentary structure.

This unit has 30-100 cm of thickness and

associates with planar stratified sandstone,

hummocky cross-stratification sandstone,

trough cross-bedding sandstone, and

flasher bedding sandstone.

Cross-bedding is formed by the

downstream migration of bedforms such

as ripples or dunes in a flowing fluid. The

fluid flow causes sand grains to saltate up

the upstream ("stoss") side of the bedform

and collect at the peak until the angle of

repose is reached. At this point, the crest

of granular material has grown too large

and will be overcome by the force of the

depositing fluid, falling down the

downstream ("lee") side of the dune.

Repeated avalanches will eventually form

the sedimentary structure known as cross-

bedding, with the structure dipping in the

direction of the paleocurrent.

9. Planar Stratified Sandstone (Ss)



are brownish of colour, composed by

quartz and k-feldspar minerals,and

parallel lamination of sedimentary



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structure. This unit has 30-100 cm of

thickness and associates with planar

stratified packstone and planar cross-

bedding sandstone.This unit is formed by

high energy depositional current as upper

plane-bed phase lamination and by low

energy depositional current as lower

plane-bed phase lamination.The

association with planar cross-bedding

sandstone identified that there was

increasing of current velocity which

planar stratified sandstone facies eroded

planar cross-bedding sandstone facies that

early formed.

10. Trough Cross-Bedding Sandstone (Stc)

This consist of coarse grain sandstone.

The characteristics of this unit are

brownish of colour, subrounded to

rounded of grain, well sorted, composed

by quartz and k-feldspar minerals, trough

cross-bedding of sedimentary structure.

This unit has 60 cm of thickness and

associates with planar stratified sandstone.

11. Wavy Lamination Sandstone (Sw)



are brownish of colour, composed by

quartz and k-feldspar minerals,and wavy

lamination of sedimentary structure. This

unit has 40 cm of thickness and associates

with flasher bedding sandstone and

parallel lamination sandstone.

This unit is formed by the process in quiet

water current. Fine grain sediment is

deposited by traction transported while

depositional process of ripple is formed

which alternately change to quiet period

for mud deposit.

12. Planar Stratified Packstone (Ps)

This consist of calcarenite which has

characteristic white colour, poor sorted,

dominated by skeletal, and planar

stratified of sedimentary structure. This

unit has 30 cm of thickness and associates

with planar stratified sandstone.This unit

can be formed by high energy depositional

current as upper plane (flat) bed. Existing

of skeletal of this unit identified that the

depositional procces formed by high

energy current which formed planar

stratified of sedimentary structure. This

unit occur as sequence boundary (sb)

b. Facies Association

Facies Association is a combination of two or

more lithofacies that forms the body of rock

in a variety of scales and combinations that

are genetically interconnected in the

depositional environment. Facies association

reflects the depositional environment or

fasies process whereby fasies were formed

(Mutti Ricci Luchi, 1972). In the

determination of facies association and

depositional facies of the Ngrayong

formation, the author refers to the tidal flat

depositional facies models that have been

created by the Boggs (1995), Dalrymple

(1992) and the model of the open coast tidal

flats by Kim et al (1999); The et al (2006b),

in Fan Daidu (2012). (Figure 4)

From the results of the analysis on the

Ngrayong sandstone unitsfasies, the

faciessssociationNgrayong Formation in the

study area is divided into four facies

associations, namely:

1. Mudflat

The suspension occurs frequently, thus

producing facies association Clm and Llm.

The influence of tidal (wave fluctuations)

with a constant low energy formed lenticular

bedding of sedimentary structure which is the

facies Association of Cln and Lln.

2. Mixed Flat

Faices association of Sfl, Sw, Lln, Llm and

Slm are on this zone. Current activity eroded

the ripple crest sediment which formed first,

that causing the rippled sand recently buried

and preserved layers of ripple with mud

which formed flasher bedding. When the

current activity increases will form Sw (wavy

lamination) facies which still preserve a layer

of mud between SW facies. While on the

conditions of deposition and preservation of

mud is larger than sand, it will make the sand

stuck between silt (lens of sandstone) and will

form Llnfacies.

3. Sand Flat

SPC Facies is formed by migration of ripple

and dune which effect by a current that is

formed during lower flow regime conditions



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(lower flow regime). In other conditions, it

can also be formed during the process of

erosional and scour which will form trough

cross-bedding of sedimentary structure

(Stcfasies).

4. Subtidal Flat

This zone formed Spcfacies which associate

with Ssfacies. It occurs because Ssfacies

formed when the speed of the current

increases, and forms the upper plane (flat)

bed) which eroding Spc (Sand dune waves)

facies which earlier formed. Because of this

zone is affected by ocean waves, it will form

deposits of storm (Shcfacies). PC facies is the

last facies which is formed when the speed of

the current is increasing that bringing with

many of skeletal sediment that preserve into

the layers.

c. Architectural-Element

Architectural element is a large of facies

association which group of facies association

in the system of depositional environment

(Allen, 1983 in walker, 1992). In the

development of the relation of facies

association, the definition of architectural

elements is a morphology from the specific

depositional system characterized by

grouping of facies,facies geometry, and the

process of deposition.

As we know that, facies association in study

area of Ngrayong formation are divided into

4 groups namely mudflat, mixed flat, sand

flat in intertidal and subtidal flat.

Mud flat is a part of the intertidal at tidal flats.

In the intertidal, mud flat is a part that has

high rate of tidal wave. Facies that contains in

the mudflat is Clm, Cln, LlmdanLln. The

thickness of the mud flat association on the

study area was

RCR-1: > 3.14 m

RCR-2: > 2.48 m,

RCR-3: > 3.66 m

RCR-4: > 1.71 m

Changes of the sediment mud flat to mixed

flat was characterized by a relatively

coarsening upward sequence. This occurs

because the sea level relatively increase (HST

phase) and produce a retrograding mud to

mixed flat.

Mixed flat is a part of intertidal at tidal flats

which has a medium tide level. This can be

explained by the presence of granules 2

mixing mud (clay-silt) and sand which is

evidenced by the presence of faciesLln, Llm,

Slm, Sfl and Sw. The thickness of the mixed

flat association on the study area was

RCR-1: 3.14 m,

RCR-2: 2.83 m,

RCR-3: 3 m

RCR-4: 2.92 m

Changes of the sediment mixed to flat sand

flats, characterized by a relatively coarsening

upward sequence. This occurs because the

sea level relatively increase (phase HST) and

formed retrograding Sand flats. In this zone

there was contact between the sandstones

with claystone, which is interpreted as

flooding surface (FS), which was used as one

of the datum in the facies correlation of tidal

deposit in the study area.

Sand flats is a part of intertidal at tidal flats

which has a medium – low tide level. Sand is

dominating of the granules in this part

although there is little inserts a layer of mud

(Sflfcies). On the sand flats of this activity the

suspension have been very rare, whereas

lateral accretion of a lot going on. Evidence

of the presence of lateral accretion is Spc and

Stcfacies. The thickness of the sand flat

association on the study area was

RCR-1: 3.29 m,

RCR-2: 3.21 m,

RCR-3: 3.52 m,

RCR-4: 3.78 m.

Changes of the sediment mixed to flat sand

flats was also characterized by a relatively

coarsening upward sequence. This occurs

because the sea level relatively increase

(phase HST) and there was a lateral accretion

which caused of forming retrograding

Subtidal flat.

Subtidal flat is a part of tidal flat which has a

low tide level. In this zone the process was



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strongly influenced sedimentation of sea

waves,which were no longer influenced by

the tides (tidal). There were occur many of

lateral accretion. Because of greatly

influenced the waves of sea water,it formed

Shcfasies which were formed because of the

existence of a combination of direct current

or the existence of the storm. The other of

facies association are Ss, Spc and Pc facies.

Pc facies occurs as a contact of sequence

boundary type 2 and as a result of

transgressive surface deposits. This sequence

boundary type 2 is characterized by a

minimum of erosion on the contact between

the Pc and Ssfacies which in this phase of the

environmental change because the sea level is

relatively increase (TS) which can be formed

the limestone (Pc fasies) that covering sand

facies below.

The thickness of the subtidal flat association

on the study area was

RCR-1: 4.19 m,

RCR-2: 6.6 m,

RCR-3: 6.6 m,

RCR-4: 6.42 m.

V. CONCLUSIONS

There are 12 lithofacies at study area,

namely Parallel lamination claystone

(Clm), Lenticular Bedding Claystone

(Cln), Parallel lamination Siltstone

(Llm), Lenticular bedding siltstone (Lln),

Flasher Bedding Sandstone (Sfl),

Hummocky Cross-Stratification

Sandstone (Shc), Parallel Lamination

Sandstone (Slm), Planar Cross-Bedding

Sandstone (Spc), Planar Stratified

Sandstone (Ss), Trough Cross-Bedding

Sandstone (Stc), Wavy Lamination

Sandstone (Sw) and Planar Stratified

Packstone (Ps).

12 lithofacies that interpreted at study

area divided into 4 facies association,

namely Mud Flat (Clm, Cln, Llm and

Lmnfacies), Mixed Flat (Clm, Lmn,

SflSlm, and Swfacies), Sand Flat (Sfl,

Spc, and Stcfacies) and Subtidal Flat

(Shc, Spc, Ss, and Ps facies).

Mud flat is dominated by fine grain

(mud) which is showed the low energy

that affect to the depositional of mud flat.

Mixed flat are composed by mud and

sand, that is happened because of

medium tide level, therefore that founded

a contact between sandstones and

mudstone, which is interpreted as

flooding surface (FS). Sand flat is

dominated by sand, but there is a few

layer of mud. Lateral accretion is often

occurring in sand flat, the evidence is the

domination of planar and trough cross

bedding sedimentary structures. In the

subtidal flat, lateral accretion is also

occurring, and hummocky cross

stratification structure is constructed

because of the influence of sea waves.

VI. ACKNOWLEDGMENT

We would to thank all Seminar

NasionalKebumian UGM committee for

publishing this paper, and Ir. Sugeng Widada,

M.Sc, and Ir. BambangTriwibowo, M.T, and

also all of GPRG Indonesia member for

valuable discussion.

REFERENCES

Ardhana, W. 1993, A Depositional Model For The Early Middle Miocene Ngrayong Formation And

Implications For Exploration In The East Java Basin,Proceedings Indonesian Petroleum

Association.

Boggs, S.,1987, Principles of Sedimentary and Stratigraphy, Merril Publishing Company, a Bdl and

Howel Company, Columbus, Ohio.

Daidu, Fan. 2012. Classifications, sedimentary features and facies associations of tidal flats. Journal of

Palaeogeography. Volume 2, Issue 1, January 2013, Pages 66–80.

Davis, Jr, Richard A and Dalrymple, Robert W, 2012, Principles of Tidal Sedimentology, Springer

Dordrecht Heidelberg London New York.



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Mutti, E., and F. Ricci Lucchi, 1972, Turbidites of the northern Apennines: Introduction to facies

analysis (English translation by T.H. Nilson, 1978): International Geology Review, v. 20, p.

125-166.

Selley, R.C.,1970, Ancient Sedimentary Environment and their sub-surface diagnosis, Cornell

University Press, Ithaca, New York.

Sribudiyani, Muchsin N, Ryacudu R, Kunto T, Astono P, Prasetya I, Benyamin S, Asikin S,

HarsolumaksoAgus H, Yulianto I, 2003, The Collision Of The EastJava Microplate And Its

Implication For Hydrocarbon Occurrences In TheEast Java Basin, Proceedings Indonesian

Petroleum Association.

Walker,R.G.,James,N.P.,1992, Facies Models Response to Sea Level Change,Geological Association

of Canada.



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FIGURES

Figure 1. The correlation between tectonic and stratigraphy at North East Java Basin (Sribudiyani et

al, 2003)

Figure 2. Work flow of study area



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Figure 3. Several outcrops of lithofacies in the study area

Figures 4. Profile of Ngrayong sands groups in Sendangharjo with the depositional facies models

(without scale)



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Figure 5. Interpretation of facies model in the study area based on tidal flat model (Darlrymple, 1992

with modified)

Figure 6. Depositional facies correlation and architectural elements of tidal flat deposit at study area

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