CEOSEfl '98 ProceedingJ, Ceoi. Soc. ;/111LaY.l11l BuLL. -15, Deall//lI:r 1999,. pp. 51-59

Ninth Regional Congress on Geology, Mineral and GEOSEA '98 Energy Resources of Southeast Asia - GEOSEA '98 17 - 19 August 1998 • Shangri-La Hotel, Kuala Lumpur,

Regional geological correlation of Paleogene sedimentary rocks between Sabah and , Malaysia

F. TONGKUL

Geology Programme School of Science and Technology Universiti Malaysia Sabah Beg Berkunci No. 2073 88999 Kota Kinabalu Sabah, Malaysia

Abstract: Field observations, aided by SAR and satellite images interpretation, have enabled the recognition of at least three groups of Paleogene sedimentary rock units that can be correlated regionally between Sabah and Sarawak. The three informal groups of rock units have been mapped based on similarities in their ages, lithological characteristics and degree of structural deformation. The first unit has been interpreted to range in age from Lower Paleocene to early Eocene. A large part of this unit has been metamorphosed to slate, sub-phyllite and metasandstone. The remaining part of the unit consists mostly of sandstone and shale with minor occurrence of conglomerate and lenses oflimestone. Structurally, this unit has suffered intense deformation, characterised by the presence of folded cleavage, quartz veins and refolded folds. The second unit has been interpreted to range in age from late Lower Eocene to early Upper Eocene. This unit is mainly made up of a thick sequence of sandstone interbedded with shale. Structurally this unit is also characterised by intense deformation, where most of its bed dip steeply due to tight folding and thrust faulting. The thrust faults generally show transport direction to the north and northwest. The development of cleavage is restricted to the core of folds. The minor occurrence of cleavage, lack of refolded fold and lack of quartz veins differentiate this unit from the older unit above. The third unit is interpreted to range in age from early Upper Eocene to late Upper Oligocene. The unit is composed mainly of sandstone and shale, with local occurrence of conglomerate, limestone and marl. A large part of the unit also shows intense deformation, characterised by tight upright folds and thrust faults, similar to Unit 2. The thrust faults also generally show a transport direction to the north or northwest. Regional geological interpretations suggest that the Paleogene sediments were deposited in a large elongated basin along NW Borneo. The deposition and deformation of sediments occurred in successive stages-younger sediments were deposited on top or in front of older accreted sediments, in response to northwest-southeast closure of the elongate basin.

INTRODUCTION 1979; Lee, 1979) has not progressed very much. The existing regional geological correlation has been The understanding of the early geological strongly based on similarities of depositional history and tectonics of Sabah and Sarawak is still environments (e.g. Rajang group flysch sediments), not very clear although many studies have been rather than on the geological history and tectonics carried out since the early 50s. This is partly due of a particular rock unit. This type of correlation to its complex geology and lack of sufficient which attempted to separate shallow water deposits sedimentological and structural data. Many earlier with deep turbidite deposits, has led to Haile's studies have also been confined to a particular geosynclinal hypothesis of northwest Borneo. The geographical area with varied scope of studies. geosyncline hypothesis was subsequently Recent detailed studies tend to focus their attention reinterpreted by Hamilton as the northwest Borneo more to the productive Neogene sedimentary rocks. subduction complex. Thus, the regional geological correlation of older During the past few years, there have been sedimentary rocks between the two states, including numerous good sedimentary rock exposures in both Brunei (Leichti et al., 1960; Haile, 1969; Hamilton, the states of Sabah and Sarawak due to the 32 F. TONGKUL

construction of major road networks. Remotely­ REGIONAL CORRELATION sensed data, of high quality like those ofSAR images has also been available for both states to The existing geological map of Sabah and complement satellite images and conventional aerial Sarawak (Yin, 1985, 1992; Hon, 1992) is mostly photographs. These good rock exposures and newly based on the old regional compilation map ofLeichti acquired SAR images provided an· opportunity to (1960) and Wilford (1967), as most of the re-Iook into the early geological evolution of Sabah stratigraphic relationships between rock units have and Sarawak, together. To do this, regional not been fully resolved yet, due to lack of precise correlation of similar rock units between the two age indicato:r:s. The Tertiary sedimentary rocks are states has to be carried out. basically differentiated based on their age (e.g. Field observations, aerial photographs and Paleogene and Neogene), depositional environments satellite images interpretations, especially in Sabah (marine, continental or mixed) and degree of have been an ongoing activity for the past few regional metamorphism (weak or strong). Based years. Recent fieldwork in Sarawak was carried on these criteria it has been possible to correlate out during supervision of student's mapping projects sedimentary rocks in Sabah and Sarawak in a broad (Freddy, 1995; Lau, 1995; Jaul, 1996; Lim, 1996). manner. Lacking concrete field evidences however Earlier SAR images interpretations was carried the Paleogene sedimentary rocks, up to ~ow, hav~ out in collaboration with PETRONAS exploration been assumed to be conformable with each other, department staffs (Tongkul, 1995). their depositional environments and degree of metamorphism remain unquestioned. During this present study, attempt has been REGIONAL SETIING made to group the numerous existing rock formations based on their broad similarities, using Sabah and Sarawak, occupying the age, lithological characteristics (depositional northwestern part of Borneo lies at the intersection histories) and degree of structural deformation of three major plates, the Eurasian, Indo-Australian (structural styles, regional continuity and and Philippines located to the north, south and metamorphism) as a criteria. east, respectively (Fig. 1). The movement of the Based on different sedimentation histories and three major plates relative to one another in a structural styles, the Paleogene sedimentary rocks complex and poorly understood pattern has resulted of Sabah and Sarawak have been grouped into in accretion of terrain and creation of marginal three informal tectono-stratigraphic units (Figs. 2 basins since early Tertiary times. Sabah and and 3). Except for some changes in geological Sarawak represent part of an accreted terrain, lying boundaries and subdivisions of units, the three adjacent to an extended continental margin to the units proposed generally follows the distribution of north. The continental margin presently occupied Paleogene rock units mapped by the Geological by the Luconia and Dangerous Grounds Platform Survey (Hon, 1992). The three informal units show is believed to have rifted from the southeastern excellent structural lineaments. Groups of margin of the Eurasian Plate or locally called the lineaments can be easily traced for hundreds of Sundaland Craton (Hutchison, 1989; Taylor and kilometres across Sabah and Sarawak, especially Hayes, 1983). where overlying deposits are absent (see Fig. 2). The accreted terrain in Sabah and Sarawak, commonly referred to as the NW Borneo fold-thrust Tectono-stratigraphic Unit 1 belt or NW Borneo subduction complex (Hamilton, This unit is the oldest, ranging in age from 1979) extends over a distance of more than 1,000 Lower Paleocene to early Eocene, based on findings km along strike and reaches a width of over 300 of previous workers (Collenette, 1958, 1965; km. Its northwest margin ends somewhere along Wolfenden, 1960). The Layar, and Metah the NW Borneo trough, whereas its southern margin Members of Belaga Formation, Lupar and Mulu lies near the international border of West Sarawak Formations in Sarawak, and the Trusmadi and and West Kalimantan. The southern margin being probably part of Sapulut Formations in Sabah are marked by the presence of ophiolitic melange (Tan, included here. A large part of this unit has been 1979; Williams et al., 1986). The northeastern metamorphosed to slate, sub-phyllite and margin ends somewhere in the Sulu Sea. The metasandstone. The remaining part of the unit development of the marginal South China Sea and consists mostly of sandstone and shale with minor Sulu Sea basins has exerted a more complex occurrence of conglomerate. Lenses of limestone deformation towards the accreted terrain in Sabah have been reported to be associated with this unit (Rangin, et al., 1990; Tongkul, 1991, 1994). (Collenette, 1958, 1965; Leichti et al., 1960; Haile,

GEOSEA '98 Procet!(Jill.{} •• (GSA! Bull. -15) · ·REGIONAL GEOLOGICAL CORRELATION OF PALEOGENE SEDIMENTARY ROCKS BETWEEN SA BAH AN D SARAWAK, MALAYSIA 33

140

20

PHILIPPINES PLATE

4::l o 0

oI.'_____ -',100 KM

100

Mesozoic and older Active convergent zones continental crust ~ D Oceanic crust Major horizontal faults ITTITITITITI Terrain accreted or Inactive thrust faults ~ formed since Late Cret. Accreted or atten uated Direction of relative continental crust plate movement I77l Lid Marginal oceanic basin Source: Modified from Hamilton, 1979; Holloway, 1981; Taylor & Hayes, 1983; Ru & Piggot, 1986; Hutchison, 1989

Figure 1. Geological and tectonic setting of Sabah and Sarawak. Sabah and Sarawak form part of an accreted terrain since late Cretaceous time.

Decell1ber J999 s Sarawak Sa bah "'0 .c 'c SULUSEA 0 CJ ;:) Ma ·c 0 .!'" a> c.. a> u 1. 6. 5~ a.. w (J) :c 2. 3. 4. 5. a. Southwest West & North Middle & East ...tel West Middle North sou," CHINA ~r;;;:....®::- DI SEA 5 :;:I '\~,;~ '~----~ ...a> - c.. c.. .s: ----..... I'--- ~ z---(JJ --,' CELEBES :::l C(I ""'---'" - I SEA 0 ....--...... ""---"' 10 f-- s:: a> ..::::--:: J a> a> :c ~ ~~: "'0 C c ,,~~I KALIMANTAN ~ 0 0 0 ...... a> GI :i ...... ' By ...... - ., 15 m CJ ...... '" .... o 0 0 0 0 f-- '" .... .,...... , ...... Kp/Sk 0 0 .. , .... 0" o· ·0· 0 •• o· .·0 . " .... .- ...... '0' 0 '0' Lr/Be Be Be . SB a> , ,. • • 0 .. S s~ LITHOLOGY ::a; .. .., ~ ;:io..... z ...... , ...... ,· .. . · ... " .. . Tj GI .... . Ny ...... 20 ;= ...... , ...... ~ ..... MeiSe · .. Kd ESM Mudstone/ 0 PS · ...... MeiSe ...... s5. ...J ..... :/ Se . ... o 0 Conglomerate .. . '" S s..;;:::r; §§ Shale PnL o 0 0 .. 7:2: '::7. .,.., ... · ... KdL ::::.or SsL MnL LkL ~ GtL 25 ~ ~~ ,;..;,I; ~ Sandstone I ...... " ...... a> --- .... ~ BpL a> ..... ,'. .. c.. • 0" ...... Siltstone Limestone c c...... - ...... GI :::l ...... OSe .... OSe . ... • """ = · ..... Tx ...... ~ ~ CJ f-- ...... ~ ~ Argillite I Slate I ...... 7' •• 0 ••••• LsL 30 0 ...... ~ ...... Slump I > ...... ~ m a> , • •.•. o. " WCr Sub-phyllite I 5 5 0::: ;= ...... Bn ...... - · . WCr .. , ...--" Ks/Lb Melange -« - 0 3 ...... , Kb ...... ~ Metasandstone ~ - 0 ...J o· Q. 0 • SrL ...... J- ...... · . o· ...... 35 0::: ApL · ...... YSp li; ...... SI ...... · ...... FORMATION I MEMBER: La-Layar, Tr-Trusmadi, w Do. · ..... PbL LnL TdL J- Do. o· 0 • 0 • Ta MnL .... ~ ...... ,..,1,."...... H!.: "'..' o· . '" , ... Mt-Metah, Ka-Kapit, Lu-Lupar, Mu-Mulu, Pe-Pelagus, f-2...... · ...... ? 40 555 LAM ...... En-, LAM-Lubok Antu Melange, Bw-Bawang, a> ...... · ,-, ...... 0 ••.••• ::::::::::::::: c a> 5 " a> 5 L- ·...... , ...... Ke-Kelalan, OSp·Old Sapulut, Ta·, Kb·Kelabit, a> c :c ss~ ...... ::::::::::::::: m GI "'0 ...... '" SI-Silantek, Bn-Buan, OSe-Old Setap, Ks·Kulapis, 2 En Pe/Bw Ke . .... ECr ...... ~ 45 0 CJ :i s.o;z:: ...... ECr ECr? a> 0 ... , , ...... :::::::;::::::: YSp-Young Sapulut, WCr·West Crocker, Lb-Labang, - w ~.~.~ · ...... · ...... -...... ~ D.'" f--... ~!.S.. EnL Tx-Temburong, ESM~Sabah Melange, PS·Plateau 50 GI ..... F"'- ?J'\. ~?"" "'-"'? "" r"\.A,. ? ;;y; ? ;= ... .. ,...... Sandstone, Se·Setap, Ny-Nyalau, Me·Meligan, 0 - GI c.. Ka/Mt KnL .. c c.. 1 • 0 • :: .... ~ 'W//I LIMESTONE: TgL-Tutoh Gorge, EnL-Engkilili, a> :::l .. RfL Tr CJ ~ ? RfL-Rufoh, MpL·Maput, KnL-Kalampunian, 60 0 I-- La GI ... TgL • RpL-Rompun, ByL-Bayayo, ApL·Arip, SrL-Saparai, - GI ;= //, 65 a..'" 0 MnL·Melinau, PbL·Punbatu, LnL·Lian, TdL-Telupid, ...J I? ? ~ ~ I LsL-Langusan, BpL·Batuputeh, GtL.Gomantong, I? ? Up. Cretaceous - PnL·Pulun, KdL-Kudat, LkL-Lakutan, SsL-Subis Source: Wolfenden, 1960; Halle, 1962; Kirk, 1957; Wilson, 1960; Leicht! et aI., 1960; Collenette, 1965; James, 1984; Leong, 1974; Tan, 1979; Wilson & Wong, 1960; Lau, 1995; Freddy, 1995. • F. TONGKUL, 1998 •

Figure 2. Regional correlation oftectono-stratigraphic units across Sabah and Sarawak. 111 113 115 117 119 TECTONO-STRATIGRAPHIC UNITS GEOLOGICAL AND STRUCTURAL MAP AGE FORMATION :D m OF SABAH AND SARAWAK G> Middle lambir (lr), Belait (Be), 5 T Miooene South Banggi (SB), Kapilit (Kp), z QI and younger » c D SandBkan (Sk), BongaYB (By) SULU .- G> QI LateEarty r:;;-;, SEA m a> East Sabah Melange (ESM) o o Miocena I.!..!.!.I 5 QI G> Z Nyalau (Ny), Meligan (Me), Setap (Se), Early ~ Kudat (Kd), Tanjong (Ti), .­ 1 Miocene () Plateau Sandstone (PS) o SOUTH CHINA :Xl Silantek (SI), Old Setap (OSe), Buan (Bn), :Xl OJigocene- ~ SEA m Upper 3 33 Tatau (Ta), Kelabit (Kb), Temburong (Tx), T Eooene Wast Crocker (WCr), Young Sapulut (YSp), ~ Kulapis (Ks),labang (lb) 5 z o C "Tl QI Middle Engkilili (En), lubok Antu Melange (lAM), a> »"'1J o Eocene W Pelagus (Pe), Bawang (Bw), .- QI Kelalan (Ke), East Crocker (ECr), ~ G> III m Il.. Z m Lower ["'1"111 layer (La), Kapit (Kp), Lupar (Lu), en 1 m Eocene • ~ Matah (Mt), Mulu (Mu), Cl 1 Paleocene Trusmadi (Tr), Old Sepulut (OSp) SULAWESI SEA ~ m Z Upper ~ Cretaceous Basement Rocks :Xl and older (Ophiolites) GEOLOGICAL SYMBOLS -< el Lineaments () Neogene Igneous Rocks @ and younger 1++++1++++ (Volcanic and Plutonic) Horizontal Faults

/" Thrust Faults

r- Rock Unit Boundaries ...... 1

Scale o 50 100Km

Regional correlallon aided by SAR and .ateliHe images Interpretation • F. TONGKUl,I99B •

115 117 119

Figure 3. Geological and structural map of Sabah and Sarawak. 36 F. TONGKUL

1962). comprise mainly of thick shale interbedded with A large part of the unit (e.g. Belaga, Mulu and thin to medium sandstone (Freddy, 1995). Blocks Trusmadi) was deposited in a deep-water submarine oflimestone, dated to be older than Middle Eocene, fan environment, characterised by turbidite and are associated with the deformed sequence. Tan mass flow deposits. The predominance of (1979) referred to this deformed sequence as the argillaceous sequence suggests an open basin plain Lubok Antu Melange. depositional setting. In Sarawak, some of this unit Structurally this unit is also characterised by (e.g. Lupar) commonly shows slump beds, channeled intense deformation, where most of its bedding is pebbly sandstone and vertical burrows suggesting steeply dipping due to tight folding and thrust deposition on slope settings (Freddy, 1995). faulting. Folds with wavelengths between 200-300 Structurally, this unit has suffered intense metres are common. Repetition of sedimentary deformation. The presence of folded cleavage and sequence due to thrust faults is also characteristic numerous quartz veins are characteristics of this of this unit. The thrust faults generally show metamorphosed unit (Cheing, 1994; Lim, 1996). transport direction to the north and northwest Refolded folds are evident in both the (Tongkul, 1990; Lau, 1995). Low-grade metamorphosed and unmetamorphosed part of the metamorphism with the development of cleavage is unit. The Layar and Kapit Members of the Belaga restricted to the core of folds. In Sabah this unit, Formation in Sarawak shows an earlier fold axis represented by the East Crocker Formation, trends trending approximately NW -SE, followed by a NE­ approximately NW-SE, faulted against Unit 1. SW trend (Jaul, 1996; Lim, 1996). In Sabah, the The minor occurrence of cleavage, lack of metamorphosed Trusmadi Formation shows two refolded fold and lack of quartz veins differentiate fold axis trending NW-SE and NE-SW (Tjia, 1974; this unit from the older unit above. These Cheing, 1994). differences suggest an unconformable relationship The relationship of this unit with the older between Unit 2 and Unit 1. In Sarawak., the Rajang rocks in Sabah and Sarawak is uncertain. The River, at least between and Kapit is the site of contrasting lithologies between the Mesozoic a major faulted boundary. ophiolitic rocks and Unit 1 suggests and unconformable relationship. Tectono-stratigraphic Unit 3 This unit range in age from early Upper Eocene Tectono-stratigraphie Unit 2 to late Upper Oligocene (Collenette, 1958;'"1965; This unit is interpreted to range in age from Wilson and Wong, 1960; Wolfenden, 1960; Tan, late Lower Eocene to early Upper Eocene, also based 1979). The Silantek, Tatau, Buan, Kelabit and strongly on earlier findings of previous workers older part of Setap Formations in Sarawak and mentioned above. The Engkilili Formation (Lubok West Crocker, Temburong, Kulapis, Labang and Antu Melange), Pelagus and Bawang Member of younger part of Sapulut Formations in Sabah are Belaga Formation, and Kelalan Formation in included here. The unit is composed mainly of Sarawak and East Crocker Formation in Sabah are sandstone and shale, with local occurrence of included here. This unit is mainly made up of a conglomerate, limestone and marL The unit is thick sequence of sandstone interbedded with shale characterised by a variety of depositional settings, of various thickness. ranging from deep-water submarine fan to In Sabah, the East Crocke! Formation shows a continental environment. typical deep water submarine fan deposits, reaching Except for the Silantek Formation in Sarawak, more than 1 km in thickness (Cheing, 1994; Khor, structurally the rest of the unit also shows intense 1994). Paleocurrent directions suggest the source deformation, characterised by tight upright folds of sediments to the south. Similar depositional and thrust faults, similar to Unit 2. The thrust settings have been observed in most of the units, faults also generally show a transport direction to near in Sarawak (e.g. Lau, 1995). the north or northwest. The Silantek Formation However, near Sibu town, the Pelagus Member is dips moderately to the south, forming a large represented by a thick sequence of dark grey syncline with its axis trending NW-SE. carbonaceous shale interbedded with thin laminated This unit is interpreted to sit on Unit 2~with sandstone. Vertical burrows are commonly seen in marked unconformity. The basal part being some of the shale interbeds, prgbably suggesting represented in Sarawak by the occurrence of the shallow water deposition. Near Sri Arnan, the Melinau Limestone and conglomeratic Tatau Engkilili Formation is characterised by an Formations. Similarly the Punbatu and Lian intercalation ofundeformed and deformed sequence. limestones occurring in the West Crocker and The deformed sequence is associated with primary younger Sapulut Formations represent the basal slump structures, whereas the undeformed sequence part of the unit in Sabah. This unit is overlain CEOSEA '98 Proceeding.l (CSM Bull. 45) REGIONAL GEOLOGICAL CORRELATION OF PALEOG ENE SEDIMENTARY ROCKS BETWEEN SABAH AND SARAWAK, MALAYSIA 37 unconformably by moderately deformed Neogene states (see Fig. 4). Fold belt on Unit 3 also bend sediments, marked by the presence of Subis and sharply near Kota Belud in Sabah, affecting the Melinau limestones in Sarawak, and Lakutan, original orientation of Unit 2 and Unit 1. Kudat and Gomantong limestones i~ Sabah. Although each unit has its own depositional histories and environmental settings, paleocurrent IMPLICATIONS ON REGIONAL directions indicate a common major source of sediments from the south or southwest. GEOLOGY What the Correlation Mean What the Correlation Show The presence of the three informal units The three informal tectono-stratigraphic units indicates that the Paleogene sedimentary rocks have defined in this study show that the huge expanse of undergone several stages of regional deformation. Paleogene sediments in Sabah and Sarawak could The earliest was probably during the late Lower be broadly classified. The three units generally Eocene (5 0-52 Ma), followed by early Upper Eocene occupy its own distinctive fold-thrust belt. In (37-39 Ma), and then by late Upper Oligocene (25- Sarawak, the older unit, Unit 1 dominates the 27 Ma). Structural evidence from Central Sarawak, southern belt and progressively gives way to Unit indicate that the earliest deformation was associated 2 and 3 to the north (Fig. 4). The lateral northward with NE-SW compression, whereas the latter two extension of Unit 2 is punctuated by the lack of was associated with NW-SE compression. information on the Kalimantan side. Unit 2 and The general distribution of the three tectono­ Unit 3 appear to sit on top of Unit 1. While Unit stratigraphic rock units in Sarawak indicates 2 and Unit 3 exhibits a sharp bend in its belt near progressive southeastward accretion of younger Belaga, Unit 1 appears to be not affected very sediments against older accreted sediments. much. Younger sediments were also deposited on top of In Sabah the situation is a bit complex. Unit 3 the accreted sediments in accretionary basins (Fig. appears to sit on both Unit 1 and Unit 2. Whereas 5). Similar process may have also occurred in Unit 1 overrides Unit 2. While Unit 1 is mostly Sabah, but with some variation due to its different found in Sarawak, Unit 3 occurs widely in both tectonic setting. The Middle Miocene (14-18 Ma)

Schematic Regional Geological Cross-sections

Sabah Kola Kinabalu Crocker Lahad Datu e NW Ophiolitic RT Neogene Unit Basement SE I

o 50 100 Km

Sarawak

Binlulu Tatau Sibu Sri Aman N I I I Bukit Sebangkoi I e Neoger Unit ur 3 UT 1 ur 3 ur 2 I ur 1 ur 2 UT3 s

K ~~

Figure 4. Schematic regional geological cross-sections of Sabah and Sarawak.

December J999 38 F. TONGKUL marking a major compression and uplift in Borneo, thank Lau, Freddy, Lim and Jaul for their may have been responsible for the sharp bends and companionship during the Sarawak fieldwork; for tightening of structures on Unit 2 and Unit 3. the Geological Survey of Malaysia in Kota Kinabalu The common source of sediments from the south and for their continued support and access or southwest suggests that a huge elongate basin to secondary information; and for PETRONAS for must have existed along NW Borneo to granting me access to their SAR imagery data. accommodate the deposition of enormous amount of sediments, which was accreted later. REFERENCES

SUGGESTIONS FOR FUTURE WORK CHEI NG, H.N., 1994. Geologi nm knwnsnn Kirokot-Rendngong, Jnlan Tnmbunan-Ranau, Sabah (Generalgeoiogtj ofthe Kirokot­ Due to the huge size of Sabah and Sarawak, Rendagongarea nlongTambunnn-Ranau Rond, Sabah). B.5c. fieldwork coverage is still inadequate. The present Thesis, Universiti Kebangsaan Malaysia (Unpubl.). work still relied heavily on previous works and on COLLENETfE, P., 1958. The geology and mineral resources of remote sensing data in doing the correlation. Much the Jesselton-Kinabalu area, North Borneo. Br. Bomeo information regarding the ages of Paleogene Geol. Surv. Mem. 6. sediments is still lacking. It would be advisable to COLLENElTE, P., 1965. The geology and mineral resources of carry out more paleontological work on these the Pensiangan and Upper Kinabatangan area, North sediments to elucidate its proper stratigraphic Borneo. Br. Borneo Geol. Surv. Mem . 12. FREDDY H. CHTNTA, 1995. Geologi am knwnsan Mnrup hingga positions. Simpang Betong, Lebuhraya Sri Aman-, Sarawak It would be interesting to see whether similar (General geologtj of to Betong Junction area, along Sri tectono-stratigraphic units can be mapped out from Amnn-Snrikei, Sarawnk Highway). B.5c. Thesis, Universiti the Paleogene sediments in Kalimantan, Indonesia. Kebangsaan Malaysia (Unpubl.). If there were such a correlation, then perhaps it HAILE, N.S., 1962. The geology and mineral resources of the would be easier to reconstruct the depositional and Suai-Baram area, North Sarawak. Brit. Bomeo. Geol. tectonic history of Paleogene basins in Borneo. Sum. Mem. 13 . HAILE,N.5., 1969. Geosynclinal theory and the organisational pattern of the NW Borneo Geosyncline. J. Geol. Soc . ACKNOWLEDGEMENTS London,124,171-194. HAMILTON, W., 1979. Tectonics of the Indonesian region. U.S. I would like to thank Universiti Kebangsaan Geol. Surv. Prof Pnper 1078. Malaysia for supporting this research. I wish to HOLLOW AY , N.H., 1981. The North Palawan Block, Philippines:

Older Accreted Younger Accreted Sediments Sediments Younger Sediments Younger Sediments in Accretionary Basin in Accretionary Basin I NORTH

Figure 5. Schematic model to show the progressive southward accretion of younger sediments against older accreted sediments.

GEOSEA '98 Proceedin,rlJ (GSI1! Bull. 45) REGIONAL GEOLOGICAL CORRELATION OF PALEOGENE SEDIMENTARY ROCKS BElWEEN SABAH AND SARAWAK, MALAYSIA 39

its relation to the Asian Mainland and its role in the Ru,KEAND PIGOTT, J.D., 1986. Episodic rifting and subsidence evolution of the South China Sea. GSM Bull. 14,19-58. in the South China Sea. American Association of Petroleum HON, V. (compiler), 1992. Geological map of Sarawak and Geologists Bull. 70, 1136-55. Sabah. Geol. Surv. Malaysia. TAN, D.N.K., 1979. Lupar valley, West Sarawak, Malaysia. HUTCHISON, CS., 1989. Geological evolution of Southeast Asia. Geol. Surv. Malaysia Rep. 13. Oxford Monographs on Geology and Geophysics No. TAYLOR, B. AND HAYES, D.E., 1983. Origin and history of the 13. Clarendon Press, Oxford, 386p. South China Sea Basin. In: Tectonic and geologic JAMES, D.M.D. (ED.), 1984. The geology and hydrocarbon resources evolution of Southeast Asian seas and islands, Part 2. ofNegara Brunei Darussalam. Brunei Museum and Brunei American Geophysical Union Monograph 27, 23-56. Shell Petroleum Co. TJIA, H.D., 1974. Sense of tectonic transport in intensely JAUL I

------.~.-~~•.. ------Manuscript received 18 August 1998

December 1999