Journal of Geosciences, Osaka City UniversityVol. 43, Art. 2, p. 2]-30, March, 2000

Biostratigraphy of Calcareous Nannofossils in the Paleogenechaotic sediment in the Karangsambung area,

Central Java, Indonesia

HADIWISASTRA Sapri I and KUMAI Hisao2

1 Research and Development Center for Geotechnology, Indonesian Institute of Sciences,

Bandung, Indonesia2 Department of Geosciences, Faculty of Science, Osaka City University, Osaka 558 - 8585, Japan

AbstractThe Paleogene sediments of the Loh Ulo Region consist mainly of mudstones and scaly clays, with exotic

fragments of limestone, conglomerate and sandstone, deposited in a tectonically active basin. This sediment is

distributed along the middle part of an anticline oriented in an E-W direction following the Welaran river flowing

westwardly in the area of Karangsambung. The impact of tectonic development on the basin is reflected by both the

types of deposit and the nannofossil association developed during the Paleogene.

The assemblage of calcareous nannofossils in the lower part consists mainly of Reticulofenestra umbilica,

Discoaster saipanensis, Reticulofenestra dictyoda, Helicosphaera lophota and Cribrocentrum reticulatum, indicating

Zones NP 16-NP 17/Zones CP 14, or Late Middle Eocene age. The upper part is dominated by Cyclicargolithus

floridanus, Cyclicargolithus abisectus, Ericsonia fOlmosa and Discoaster deflandrei, indicating an Oligocene age.

Delineation of the lithological boundary in the Karangsambung area based on the nannoplankton association is

discussed.

Key words: Tectonic melange, olistostrome, calcareous nannofossil, local zonal marker, deep marine environment

Introduction

Physiographically, the study area belongs to the South

Serayu Mountains (Bemmelen, 1948) reflecting geanticline

morphology oriented E - W (Fig.1). The area ofLoh Dlo is

characterized by a very complex structural and stratigraphic

setting, and some hypotheses and speculation have been

suggested to explain the complexity of the region. The

crystalline Pre Tertiary basement complex is overlain

unconformably by Tertiary sediments.The Loh Dlo Melange Complex is believed to be the

product of subduction following the collision between the

Indo-Australian oceanic crust and continental crust of the

Asian plate during Late Cretaceous times. The early EarlyTertiary sediment is characterized by gravity sliding andmixed sedimentation of various types of sediment.

Many papers have been published on the geology of

the Kebumen area, mostly regarding tectonics and

sedimentation during Mesozoic and Tertiary times (Tjia,1966; Asikin, 1974; Baumann et al., 1972). Whereaspaleontological study in this area has been very scanty,

severals authors have contributed publications about the

biostratigraphy of the Mesozoic and Early Tertiary on the

basis of radiolaria and planktonic foraminifera (Sunarti,

1973; Djoehanah, 1973; Paltriniery et al., 1976; Kadar,

1986; Wakita et al., 1990).

Three columnar sections with a total of 38 samples are

examined, of which 23 samples are recognized as suitable

for the present study.

Previously, the age of the Eocene sediments in the Loh

Dlo area was based on the planktonic and large benthic

foraminifera. However, that mixed faunal content has not

been described clearly or well.

The main purpose of the present study is to describe

the calcareous nannofossil assemblage, and to discuss theapplication of nannofossil biostratigraphy of a Paleogeneevent in a chaotic sediment.

Geologic setting

The geology of the Loh Ulo area is very complex, both

in structure and sratigraphy. The Pre-Tertiary is represented

22 Calcareous Nannnofossiis in the Paleogene Karangsambung, Indonesia

6()0 gOO 1000 11 OO 1200 1300 1400 1500 1600 1700 1800

- - -'-,

-, - - - I. I-r----

D Studied area

o 40kmI I

100

JAVA

,J----\-,

INDIAN OCEAN

II, ..

", ,- - - - ',1..'" - - - t

'. ,(1,\.... I II \ ,::.. _ ... - ...,

, -_ ... _: ;:<_I\.:,~,,:, __:__ - :~-:- - \ I

~u;;'-_~~__"L-\---\ ~-~\J: ~ .'., :,': '-~", ~"> ~ __ 100____ ~ _ ~"'- ........... -~ I I _ ... =-1': _ - .. -"I ..

, - .. - -,- - - - -,"'~ - - - -.- - - - - '-I', j

, ', .

40'

80

20'

20' 40' 20' 40' 20' 40'

Fig. 1. Location index of the study area.

by a mixture of different rock types, conslstmg of

greywackes, argillites, pillow basalts with red cherts,

dismembered ophiolites and metamorphic rocks, showing a

high degree of deformation in different environments.

Exotic rock assemblages are seen to be floating in a matrixof highly sheared black shale. The rock units of the Pre­

Tertiary have been classified as a type of melange called

the Loh Ulo Melange (Asikin, 1974). The study of

radiolarian fossils in the area of Karangsambung (Wakita et

al., 1994) proved that tectonic mixing of all components,

ranging from early Cretaceous to Paleocene, occurred

during the Paleocene.

The Pre-Tertiary rocks are overlain unconformably by

Tertiary sediments, which represents a characteristic

sedimentation influenced by tectonics 111 an active

sedimentary basin. The tectonic development causes the

structural complexity of the area, where units of Paleogene

occur as a mixture of fragmental sedimentary rocks withheterogeneous lithology dispersed in a matrix as described

below.

The Paleogene sediments in the area of

Karangsambung are distributed along the axis of an

anticline oriented E-W. The mentioned sediments consist

mainly of olistostrome deposits and turbidites, in which

conglomerate and limestone blocks are embedded in a

matrix of grey mudstone. Two rock units of the Paleogene

HADIWISASTRA Sapri and KUMA! Hisao

Legend

N D EJ-_ ....- 5

+ " " "~~AAAA ....."" 2 6

",.A A A

LA..-A....A-

........... me" " " 3 72m ... ... ...." " ""-~

" ""m [[[]] B' D ShtdHl.,..

4 8

"'. '''''",. "'. .,.

r....... ", ......... h

'w-~~~~~~~..--'.A A "" A A "".... A A A A A A A A A A .... A A A .... .... ....

... A .... A A .... A A ... A A A A ... A ... A ........ .... A A .... A .... A .... .... .... .... .... ... .... .... .... .... ~ ....

A A .... '" A A A A .... A A .... A ... .... ... A .... A A.... A A .... A .... .... .... '" ... A A .... A .... .... A A A A A ~

A A .... A .... A A A .... A A A A A A A A A A A A A

Fig. 2. Geologic map of the Karangsambung area.1. Alluvial sediment, 2. Waturanda Formation, 3. Diabas intrusion, 4. Totogan Formation, 5. Karangsambung

Formation, 6,7,8. Loh Vlo Melange Complex

23

sediments may be arbitrarily distinguished by the rock type

of the exotic blocks. The lower part, known as the

Karangsambung Formation, consists mainly of limestones

and conglomerate blocks, and the upper part, called the

Totogan Formation, consists mostly of sandstone blocks

and nodules. The matrix of both formations IS

characteristically scaly, with contorted innerbeds, and as awhole forming a chaotic structure. At some places, thematrix shows flow structure, indicating mass flow or

gravity flow.The Karangsarnbung Formation consists mainly of

grey mudstones, scaly clay with limestone blocks,

conglomerate and nodules of claystone. The unclear

stratification, flow structures and chaotic distribution of

exotic blocks reflect a slumping sedimentation on the

submarine basement. The limestone blocks contain

abundant large foraminifers, including Nummulites javana,

Alveolina sp. and Discocyclina sp., indicating an Upper

Eocene age. Similar to the Karangsarnbung Formation, the

Totogan Formation also shows a chaotic distribution ofrock units containing abundant allochthonous debris ofvarious sizes. Based on the content of foraminifers such as

Globoquadrina praedehischens, Globigerina binaensis, andon the absence of Globigerinoides in the matrix, theTotogan Formation is correlated to Zones N 2 - N 3 or Late

Oligocene in age.

24 Calcareous Nannnofossils in the Paleogene Karangsambung, Indonesia

Quaternary Sand and gravel Fluvial

PlioceneHa/ang Fm

Fine grained tUffs interbedded with marl

• .............0.0.0 '0 •

1----------,-------1

Miocene

Late

Middle

Early~ ~ ~ ~ ~ ~ h A A A A

A A hAn A h n nAnh A h A A h A A h h h

A A A h h A h A h A Ah h h h h h h h h h h

h h h h h h h A hAn

Panosogan FmNternating layers of marl,tuff,sandstone,claystone and calcaren~e

Waturanda FmVolcanic Breccia interbeddedgreywacke.

Turbidite

Olistostrome

Totogan FmSandtone blocks embedded in claymatrix

Karangsambung FmExotic block of conglomerate,limestone embedded in clay matrix

.~... ... . ~.~..... .... .-:..:.:-:..-.- :-:..: - :~_ .. :.

Eocene

Oligocene............. ••• M ••

B$~:::::::::::\\--------------4:::::::.Yo•••::::::::::.

CretaceousLoh Ufo Melange Complex

Greywacke,argillltes,red chert,greenschist toblueschist metamorphic

Melange

Fig. 3. Stratigraphic column and succession of rock units in the Kebumen Basin.

The Miocene sediments were deposited on the top of

olistostrome rock units along a boundary of uncertain

relationship, which suggests an erosional unconformity.

This formation consists mainly of volcanoclastic and flysch

turbidites. The lower unit, called the Waturanda Formation,

consists of volcanoclastic turbidites dominated by

greywacke at the top of the Fonnation. The Waturanda

Formation is essentially made up of breccias consisting of

andesitic rocks and sandstones embedded in a fine sandy

matrix.In the upper part of the basinal deposit a plain turbidite

sequence is observed and it is called the Penosogan

Formation. This unit is made up mainly of alternating

layers of marls, tuffs, sandstones, tuffaceous marls and

calcarenites. On the basis of sedimentary structure,

lithologic type and depositional environment, the

Penosogan Formation is recognized as the onlapping of a

turbidite sequence deposited m an upper bathyalenvironment.

The general geology and stratigraphy of the Loh UtoRegion are shown in Figures 2 and 3.

Calcareous nannoplankton distribution

A number of samples was randomly collected along

the river traverse and from a well-exposed surface sediment,

as shown in FigA. Sampling were taken along a N-S

direction across the orientation of the anticline, and parallel

to the distribution of the Paleogene sediments in the

Karangsambung area.Some samples of Paleogene sediments in the area of

Karangsanlbung generally contain abundant calcareous

nannoplanktons, with good to moderate preservation. The

general distribution and occurences of nannofossil

assemblages in the Paleogene sediments is presented in

Tables 1 and 2.All samples predominantly show such nannofossil

assemblages as Discoasteraceae, Coccolithoceace and

Prinsiaceae, consisting of Discoaster saipanensis,

Coccolithus pelagicus, Ericsonia formosa, Reticulofenestra

umbilica and Cyclicargolithus floridanus. Among them,

Discoaster saipanensis and Reticulofenestra umbilica are

very common in the lower part, and drastically decrease in

the middle part. The calcareous nannoplankton contentfrom the southern flank of the anticline, located close to

Jatibungkus Hill, shows a variety of nannofossilassemblages. One bluish clay sample (Jtb-3), collected fromthe western side of Jatibungkus Hill, presents some taxa ofMesozoic nannofossils, such as Watznaueria barnesae,

Watznaueria biporta, Cretarhabdus crenulatus, Miculaconcava, Haqius circumradiatus, Manivitella pemmatoidea,Prediscosphaera cretacea and Quadrum trifidum, with

oI

HADlWISASTRA Sapri and KUMA! Hisao

Fig. 4. Locality of samples from the Karangsambung Formation.

oKs 9Ks 12

Ks 14o Ks 10Ks 15Ks 16

11

25

predominant taxa of Watznaueria bamesae, Watznaueria

biporta and Micula concava. This nannofossil assemblage

indicates an Upper Cretaceous age. In the surrounding site

(Jtb-S and Jtb-6), the nannoplankton assemblage consists

mostly of Eocene nannofossils, such as Reticulofenestra

umbilica, Reticulofenestra dictyoda, Reticulofenestra

bisecta, Sphenolithus pseudoradians, Helicosphaeraseminulum, Helicosphaera lophota, Discoaster saipanensis

and Discoaster barbadiensis .

In the exposed axis of the anticline, the Karangsam­

bung Formation contains a Reticulofenestra dictyoda - Dis­

coaster saipanensis assemblage, and diagnostic species of

Reticulofenestra dictyoda, Reticulofenestra umbilica, Dis-

coaster saipanensis, Coccolithus pelagicus and Cribrocen­

trum reticulatum.

In the northern flank of the anticline, the diagnostic

nannofossils are Discoaster saipanensis, Reticulofenestra

umbilica, Reticulofenestra dictyoda, Reticulofenestra

bisecta, Cribrocentrum reticulatum, Coccolithus pelagicus,

Helicosphaera bramlettei and Helicosphaera lophota.Among these species, the dominant and well-preserved

ones are Discoaster saipanensis, Reticulofenestra umbilica

and Reticulofenestra dictyoda. The floral content and

reworked nannofossil taxa of Discoaster elegans and

Cribrosphaerella ehrenbergi occur commonly (Table I,Fig.S).

26 Calcareous Nannnofossils in the Paleogene Ka.rangsambung, Indonesia

Table 1. Distribution of calcareous nannofossils from the

northern area of the anticline.

~Ie K,2 K.3 K.4 K,S Ksa K.7b K.7c KsaSpecies

AbundancelPreservation CIM CIM ClM CIM FIP C/M CIP FIP

ChillSlnOithus nitidus

Hekosphaefll hezeeni_me peppi/Blum

Hefcosph8818 _lelle

ChillSlnOithus gmndi,PontOSph8818 multipol8

BirlcelundiesillUrion

Discosster bBrbadiensis

Zygrhllbithus bijugBIus

Discos,l., dellandrsi A

Helicosphaef'8 bramlett9l'

DllidyIelhl8 punclu/e'e

Cyc6ca1pOlifhus fIoridanus C

Sphenolthus belemnos C

Sphenolithus moriformis R F R RSphenolithus pseudoradians R R F REricsonia formosus F F

DisCOBs/er lam nodifer R RReliculohmestrB bisecla F F

Cribrocenfrum nJ6cuIatum R A A RRe#culofenestf8 dictyoda F F C A

Hefcosph88I8/opho/e F F

Discoss1er sapanensis C C A CRsticuIoI8II8SItaumbikus A F C FCoccoithus pelsgicus F R F F RReliculofsnes1l8 hillae R R RCtibrosphll8fll88 Bhl8nbBrfi RDisrosster eleg8flS F

A- abundant; C- commoo; F: few; R: rare; M: moderate; p: poor

+ = pcesent; . = absent

In the southern flank of the anticline, the nannofossil

association also shows a variety of taxa. The stratigraphic

section along the Klepoh river consists of gray scaly clay

with nodules of fine, calcareous sandstone. The species of

nannofossils from this section are as follows: Ericsonia

formosa, Coccolithus pelagicus, Cribrocentrum reticulatum,

Discoaster barbadiensis, Discoaster saipanensis, Discoaster

tanj nodifer, Helicosphaera lophota, Helicosphaera hezeenii,

Helicosphaera paralella , Reticulifenestra umbilica,

Reticulofenestra hampdenensis, Sphenolithus moriformis,

Sphenolithus pseudoradians , Chiasmolithus grandis ,

Chiasmolithus njtidus, Birkelundia staurion, Daktylethra

punctulata, Pontosphaera multipora, Pemma pappilattum,

Zygrhablithus bijugatus (Table 2, Fig.6) .

In the lower part of this section, the nannoplankton

association is dominated by Discoaster saipanensis,

Ericsonia formosa, Coccolithus pelagicus, Reticulofenestraumbilica and Helicosphaera lophota, whereas in the upper

part, the dominant taxa are Ericsonia formosa, Coccolithuspelagicus, Cribrocentrum reticulatum Discoaster deflandrei,

Sphenolithus moriformis and Reticulofenestra umbilica.

The nannofossils observed near Clebok village, thewestern site of the Loh Ulo River, contain a fairly wellpreserved and low-diversity nannofossil association,dominated by Discoaster saipanensis, Reticulofenestra

umbilica , Coccolithus pelagicus , Cyclicargolithus

f10ridanus and Cribrocentrum reticulatum. The distribution

of the nannofossil association from tills sequence is shown

in Table 3. The interesting nannoflora found in this section

occur as reworked fossils of Heliolithus kJeinpelli and

Discoaster elegans. Both species are commonly Paleocene

in age (Martini and Muller,1986; Wuchang Wei and Wise,

1989).

Discussion

In the Loh Ulo region, during the transition event from

Late Mesozoic to Tertiary, the Loh Ulo Melange Complex

was related to the collision of the Indo-Australian and

Asian plates. It was formed by a tectonic event, during

which assemblages of tectonic slabs and blocks of

sedimentary, igneous and metamorphjc rocks were mixed

together during Paleocene time (Wakita et aI., 1994). This

complex is overlain unconformably by the Karangsambung

Formation.

The basement of the Tertiary basin in the

Karangsambung area is the Loh Ulo Melange Complex.

The distribution of the Paleogene sediments is well exposed

along the Welaran river and its tributaries, where bioclastic

limestone layers and polymjct conglomerate boulders

floating in a scaly clay matrix are observed. An E-Woriented anticline follows the course of the Welaran river

(Fig.2). Sedimentary events during the Paleogene include

slumping and other gravity flows, thus causing the chaotic

distribution of rock units. The biostratigraphical evidence

for this is the common appearance of Discoastersaipanensis, Reticulofenestra umbilica, Cribrocentrum

reticulatum and Reticulofenestra dictyoda.

The anticlinal axis samples and samples collected from

the surrounding area (Ks-7 b,Ks-7 c,Ks-8) are mostly dark­

grey mudstone containing some nannofossil taxa of

Discoaster saipanensis , Discoaster barbadiensis ,

Reticulofenestra umbilica, Reticulofenestra dictyoda and

Cribrocentrurn reticulatum. Tills assemblage ranges in age

from Zones NP 16 to NP 17 (CP 14 of Okada & Bukry's,

1980) or Late Middle Eocene. The interesting species found

in the Karangsambung Formation is Reticulofenestra

umbilica willch commonly show a more elliptical outline,forming a wide central opening, and is relatively large in

size. The size and ancestral form of Reticulofenestra um­

bilica support the age of the assemblage. Reticulofenestraumbilica are typically known from Zone CP 14, whereas

the ancestral type is more rounded and small in form, and isknown from Zone CP II (Backman and Hermelin, 1986;Perch-Nielsen, 1986). The Karangsambung Formationcontains Reticulofenestra umbilica with a wide central

HADIWISASTRA Sapri and KUMAr Hisao

Table 2 . Distribution of calcareous nannofossils in the outcrop samples from the southern area of the anticline.

~e Jib 3 Jib 2 Jib 5 Jtb6 Ks 9 Ks 12 Ks 10 Ks 15 Ks 16 Ks 11a Ks 11bSpecies

Abundance/PreseNation F/M F/P C/P C/M C/M AlP F/P C/P C/P AIM AIM

Watznaueria bamesae A

Watznaueria biporta F

Cretarhabdus crenulatus F

Micula concava C

Markalius circumradiafus F

Markalius pemmatoidea R

Prediscosphaere cretacea F

Quadrum trifidum R

Discoaster deflandrei A R

Discoaster muHirediatus F

Discoaster barbadiensis R F R R R R F

Discoaster saipanensis C C C C F C R F

Discoaster tani noditer R

Reticulotenestra bisecla C R

Reticu/oteneslre umbilicus A C A A F R F A

Rebculotenestre dictyoda A C

Helicosphaera lophota C A F F F F C F

Helicosphaera seminu/um R R F

Helicosphaera bramlettei F F

Helicosphaera parelella R

Helicosphaera inteooedia A R R R

Helicosphaera hezeenii F F

Coccolffhus pe/agicus F A C F C F A F C C

Cyclicargolithus floridanus A C F

Ericsonia toooosus C C C C C F F F

Cribrocentrum reticulatum C R C R R C C

Spheno/ithus morifooois R R C R R

Sphenolffhus pseudoradians R R C

SjJhenolffhus belemnos R

Pemma basquensis R R

Pontosphaere muHipora R R F F

Chiasmo/ithus nitidus +

Chiasmolithus grandis R R

A= abundant; C= common; F = few; R= rare; M= moderat; P= poor

+ = present; • =absent

27

opening, so the lower sequence of the Karangsambung

Formation should be not older Zone CP 14. Presence of

Chiasmolithus grandis which exists in the middle of the

north anticline section (Table 1) also supports the

suggestion of Zone CP 14. The last occurrence of this

species is used to separate Zones CP 14 and CP 15 (Martiniand Muller, 1986).

The middle sequence of the Karangsambung Fonna­

tion (Ks-9, Ks-10 and Ks-11) is dominated by Discoaster

saipanensis, Reticulofenestra umbilica, Helicosphaera

lophota and Helicosphaera intermedia, which indicate ZoneCP 15 a or early Middle Eocene (Fig.6).

This result, dated by nannofossils, is assigned to anearlier age than that by micro-foraminiferal dating at P 14 ­

P 17 (Belon et al.,1989). The range of nannofossils fromZone CP 14 to Zone CP 15 a is correlated with P 12 tomiddle P 15 of planktonic foraminifera (Berggren et aI.,

1985).

The conventional zonal marker of the Eocene - Oligo­

cene boundary is defined by the extinction of Discoaster

saipanensis and Discoaster barbadiensis (Wuchang Wei &

Sherwood W.Wise, 1989; Beckman et al.,1981; Monechi,

1986), whereas the presence of Latemithus minutus, Cycli­

cargolithus abisectus, Isthmolithus recurvus and Reticu­

lofenestra umbilica suggest early Oligocene (Shafik, 1983).

In the area of Karangsambung, calcareous nannofossil

associations are characterized by the extinction of

Discoaster saipanensis and Discoaster barbadiensis at the

upper Eocene boundary. According to Monechi (1986), theDiscoaster barbadiensis were more abundant than theDiscoaster saipanensis, but the present study indicates that

the Discoaster saipanensis is more dominant than the

Discoaster barbadiensis. The development of Discoastersaipanensis has an important role to playas a localboundary characteristic in the Karangsambung area.

Several samples of the Totogan Formation, taken from

28

zo~:::iE0::ou..

r::::::·..·:..::f·:·:·:-:·:·:-:·:·:·:·:

~~~~~~~~~~0~..........................................= .~ _ ................................................ -­......... _.. _..--_ .. _.. _-_ ..­.............................. __ ...... ....................._.. _...... _.. - ..----_ .. _-_ ..­......................... - ..

~..._-------........................................._.. _.. _.. - ...........................-- ..

f::·-::::::::....................

:-:·(tw:·.........................................

• Ks6

• Ks7b

• Ks 7c

• KsB

Calcareous Nannnofossils in the Paleogene Karangsambung, Indonesia

-I~---------~

~

------

- -J'.:.. --I

i Rarey

~ Few~

Fig.5. Stratigraphic distribution of calcareous nannoplankton taxa from the Karangsambung Formation in the northern part of the ill'ea.

.:.;:~@:

............................... -­............ _.. _............ -.......

............................. _......

... ...-_ ......................

............................- ......

...• ........• ..':'......- .."':........00

-_ ....... -- .. -.

• Ks12

• Ks9

~ Rare

~ Few

Common

Abundant

Fig. 6, Stratigraphic distribution of calcareous nannoplankton taxa from the Karangsambung Formation in the southern part of the area.

HADIWISASTRA Sapri and KUMA! Hisao 29

Table 3. Distribution of calcareous nannofossils from Clebok

village on the western side of the Loh Vlo river.

~e Clb 2 Clb3 Clb4 Clb5 Clb 6Species

Abundance/Preservation AIM C/P AIM AIM AIM

Discoas/er elegans R

Discoaster barbadiensis C R A F R

Discoaster saipanensis C F A R A

Discoaster tani nodifer F

Reticu/ofenestra bisecta R R F C A

Reticulofenestra umbilicus A R F C A

Reticulofenes/ra samodurovi R C R A C

Reticulofenes/ra dictyoda C F A C

Reticulofenes/ra hillea F F R F

Helicosphaera lophota R R F F

He/icosphaera selebrosa R R F

Helicosphaera bramlettei R

CIlCcolffhus eope/agicus R F R F

Coccolffhus pelagicus C C R C A

Ericsonia formosus A C

Ericsonia subdisticha R

Cyclicargolilhus fIoridanus A F F F A

Cribrocen/rum reticula/um A A F A A

Sphenolffhus moriformis R F F C C

Sphenolffhus pseudoradians R R R F R

Sphenolffhus distensus R

Heliolithus kleinpelli R F R

Coronocyclus pr%anu/a R R

Coronocyclus nifescen F R

A=abundant; C=common; F=few; R=rare; M=madera!; P=poor

+ =pres8flt; - =abS8flt

Clebok village on the western side of Loh Ulo River,

contains well-preserved nannofossils. However, the assem­

blage still indicates a Late Eocene age, as it consists domi­

nantly of Discoaster saipanensis, Discoaster barbadiensis,

Cribrocentrum reticulatum, Reticulofenestra umbilica and

Cyclicargolithus f1oridanus.

The sample locations of Ks-ll a+b in the southern part,

and Ks-3 in the northern part of the anticline contain

several nannofossils, such as Discoaster saipanensis,

Discoaster barbadiensis, Reticulofenestra umbilica, Cribro­

centrum reticulatum, Helicosphaera lophota, Chiasmolithus

grandis, Birkelundia staurion and Helicosphaera heezenii

which indicate a Late Eocene age. But at the locations ofKs-6 and Jt-2, the samples contain a nannofossil assem­

blage dominated by Discoaster adamanteus, Discoaster

deflandrei, Cyclicargolithus floridanus (Table 2). The dis­

appearance of Discoaster saipanensis and Discoasterbarbadiensis and the occurrence of Discoaster deflandreiand Cyclicargolithus floridanus, suggest an Oligocene age.

The assemblage of nannofossils from the Totogan

Formation in Clebok village indicates a Late Eocene age(Table 3). The age of this section is based on the associa­tion of Discoaster saipanensis, Discoaster barbadiensis Cri-

brocentrum reticulatum and Reticulofenestra umbilica.

From this point of view, it is suggested that the deposition

of the Totogan FOImation took place during the upper

Eocene to Oligocene.Nannofossils are useful for assessing the variations of

temperature, and the susceptibility to dissolution in depth of

water. Therefore, the presence of different nannofossil taxa

indicate paleoenvironmental changes (Shafik, 1983; Perch

-Nielsen, 1985; Backman and Hermelin, 1986).

Some nannofossil taxa, such as Daktylethra punctulata

and Cribrocentrum reticulatum, are restricted to a shallow­

water environment, whereas Discoaster saipanensis is

preserved mainly in deep water or under deep-water

conditions (Shafik,1983).

Those species mentioned above are present in the

Karangsambung Formation, which indicate their environ­

ments of fOlmation.

The Karangsambung Formation was initially deposited

in a deep, marine environment, as indicated by the

appearance of Discoaster saipanensis, Reticulofenestra

umbilica, Ericsonia formosa and Chiasmolithus gigas.

The upper part of the Karangsambung Formation is

considered to have been deposited in shelf conditions, as

indicated by the presence of the nannofossils Daktylethra

punctulata, Ponthosphaera multipora and Zygrhablithus

bijugatus, indicating a shallow, marine environment. The

environmental conditions suggested by the nannofossil

association is supported by layering of quartz sandstone

with plant remains and related current stratification,

indicating channel-fill deposits of a deltaic environment

(Anonim,1991).

Conclusion

The evidence for an olistostrome deposit is not only

indicated by the chaotic mass of sediment but also by the

mixed association of nannofossil assemblages. In the lower

part of the Karangsambung Formation, a mixed association

of upper Cretaceous and Eocene nannofossils occurs. Based

on the calcareous nannoplankton content, the age of the

chaotic formation ranges from the Middle Eocene to

Oligocene.The dominance of Discoaster saipanensis, Reticulofen­

estra umbilica, Helicosphaera lophota and Cribrocentrum

reticulatum should be considered as a local zonal markerfor the Eocene nannofossil zonation in the Karangsambung

area.A change of sedimentation facies from the deep

marine to shallow marine environment upwardly, is

indicated by the presence of Discoaster saipanensis,Reticulofenestra umbilica and Chiasmolithus gigas in the

30 Calcareous Nannnojossils in the Paleogene Karangsambung, Indonesia

lower sequence.

Acknowledgments

The author express his sincerest appreciation to Dr. Ir.

Jan Sopaheluwakan MSc, the Director of LIPI, for the

opportunity to do the fieldwork. Special appreciation is also

extended to DR. Edy Sunardy and Ir. Subagio Supannan

for Editing the manuscript, and to Djulaeha for her support

in preparing the smear slide

References

Anonim (1991) The Geology of Loh Ulo, Karangsambung,

Kebumen, Central Java. Fieldtrip Guide Book of

Symposium on the Dynamic of Subduction and its

products. 19 p.Asikin,S. (1974) Geological Evolution of Central Java: A

New Global Tectonics View, Bandung. Bandung Insti­

tute Technology, 103 p. PhD Dissertation (Unpub­

lished).

Backman,J., and lO.R. Hermelin (1986) Morphometry of

the Eocene Nannofossil Reticulofenestra umbilica

Lineage and its Biochronological consequences.

Palaeogeography, Palaeoclimatology, Palaeoecology,

57,103-106.Beckmann, lP., Bolli,H.M., Perch-Nielsen,K., Proto

Decima,F., Saunders,lB., and Tourmakin,M. (1981)

Major calcareous nannofossil and foraminiferal events

between the Middle Eocene and Early Miocene.

Palaeogeography Palaeoclimatology, Palaeoecology.,

36, 155- 190.

Belon, H., Maury R.C., Polve, M., Pringgoprawiro,H., and

Bambang Priadi (1989) Chronologie K-Ar du

volcanisme Tertiarie de Java Central (Indonesie) mise

en evidence des deux episodes distincts de

magmatisme d'arc. C.R.Acad.Sci. Paris, 1. 309, Serie II,

1971-1977.Baumann, P.,H. Osterle, Suminta and Wibisono (1972) The

Cenozoic of Java and Sumatera. First Annual Conv.,

Proc. Indon. Petrol Assoc., 31- 42.

Bemmelen, R.W. van (1948) The Geology of Indonesia, 1

A, Martinus Nijhoff, The Hague.Berggren, W,A. Kent, D.V. and Flynn,J. (1985) Paleogene

Geochronology and clu·onostratigraphy. In: N.J.

Snelling, The Chronology of the Geological Record. J.

Geo\. Soc. London. 141-195.

Manuscript received September 2. 1999.

Revised manuscript accepted March 6, 2000.

Djoehanah, S1. (1973) Geology and Paleontological study

of First Marl Unit in Karangsambung area.

Unpublished report, 87.

Kadar, D. (1986) Neogene Planktonic Foraminiferal

Biostratigraphy of the South Central Java Area,

Indonesia. Geol Res. and Dev. Center. Spec.

Publication, 82, 10 pI.

Martini, E. (1971) Standard Tertiary and Quaternary

Calcareous Nannoplankton Zonation. In A.

Farinacci (Ed). Proc.2 nd Plank. Conf. Roma, 2, 739­

785.

Monechi, S. (1986) Calcareous Nannofossil Event around

the Eocene - Oligocene Boundary in the Umbrian

Apennines (Italy). Palaeogeography, Palaeoclimatol­

ogy, Palaeoecology, 57,61-69.

Okada, H., and O. Bukry (1980) Supplementary Modifica­

tion and Introduction of Code Numbers to the Low

Latitude Coccolith Biostratigraphic Zonation. Marine

Micropaleontol., 5, 321- 325.

Paltrinieri, F., S. Sayekti and Suminta (1976) Biostratigra­

phy of Jatibungkus section (Luk Ulo area) in Central

Java. Proc. 5 tho Ann. Conv. Proc.Indon. Petrol. Assoc.,

1,195 - 203.

Perch-Nielsen,K. (1985) Cenozoic Calcareous Nannofossils.

In: H.M. Bolli, lB. Saunders, and K.Perch-Nielsen

(eds.), Plankton Stratigraphy, 427-555.

Shafik, S. (1983) Calcareous Nannofossil Biostratigraphy :

An Assesment of Foraminiferal and Sedimentation

Event in the Eocene of the Otway Basin, Southeastern

Australia. BMR Journ. of Australian Geology &

Geophysic, 8, 1-17.

Sunarti, S. (1973) Facies analyses of Jatibungkus limestone,

Karangsambung, Central Java. Thesis ITB.

Unpublished report.

Tjia, H.D. (1966) Structural Analyses of Pre-Tertiary of theLok - Ulo area, Central Java. Contrib. of Institute

Teclmology Bandung.Wakita,K., Munasri, Widoyoko Bamballg (1994)

Cretaceous Radiolarians from the Lok Ulo Melange

Complex in the Karangsarribung area, Central Java,

Indonesia. Journ.Southeast Asian Earth Sciences, 9., 1

/2,29-43.

Wuchang, Wei, and Sherwood, W.Wise, Jr. (1989)Paleogene Calcareous Nannofossil Maglletobiochro­nology : Result from South Atlantic DSDP Site 516.

Marine Micropaleontology, 14,119-152.