Geological Society of Malaysia Annual Geological Conference 2002 May 26 - 27, Kota Bharu, Kelantan, Malaysia Middle Miocene planktonic foraminifera and their implications in the geology of Sabah BASIR JASIN Program Geologi, Pusat Pengajian Sains Sekitaran & Sumber Alam Fakulti Sains & Teknologi, Universiti Kebangsaan Malaysia 43600 Bangi, Selangor D.E., Malaysia Abstract: Planktonic foraminifera flourished during Middle Miocene. They were recorded from the Ayer, Kuamut, Garinono melanges, the Libong Tuffite, Tungku Formation, Tabanak Conglomerate, and Setap Shale Formation. Three assemblages of planktonic foraminifera were identified from the Libong Tuffite, the Garinono melange, and the Setap Shale Formation. The assemblages indicate an age ranging from the early Middle Miocene Globigerinoides sicanus-Globigerinatella insueta Zone (N 8) to the middle Middle Miocene Globorotaliafohsifohsi Zone (NI2). The occurrence of the planktonic foraminifera suggests that a transgressive event caused the influx of the nutrient-rich water mass into the area. This event was probably related to the rifting of the Sulu Sea and the development of the eastern Sabah deep marine environment where the melanges were deposited. The occurrence of tuff and tuffite indicates volcanic activity in the region. The age of the volcanic tuff is middle Middle Miocene as dated by planktonic foraminifera. INTRODUCTION The Libong Tuffite Formation comprises well-bedded tuffaceous conglomerate, sandstone and mudstone. It is Miocene planktonic foraminifera are very widespread very similar to the Tungku Formation except the latter has in Sabah. Their occurrences have been recorded by many carbonaceous sandstone with conglomerate and mudstone geologists especially from the Tanjung, Kapilit and (Haile & Wong, 1965). The Libong Tuffite Formation Kalabakan Formations (Collenette, 1965), the Labang, overlies the Ayer melange. It is overlain by the Sebahat Ayer, Libong Tuffite, Tungku and Sabahat Formations Formation (Wong, 1993). (Haile & Wong, 1965; Basir Jasin & Sanudin Tahir, The Setap Shale consists of predominantly thick dark 1987), the Kuamut and Tabanak formations (Leong, 1974), grey mudstone with minor sandstone intercalations. The the Garinono and Sandakan Formations (Lee, 1970; Basir shale is occasionally calcareous, silty and may contain Jasin et at., 1995) and Setap Shale (Basir Jasin et ai., carbonaceous material. In Labuan Island the Setap Shale 1993). , overlies the Temburung Formation. It is overlain by the Planktonic foraminifera were obtained from three' Belait Formation. localities which represent the Libong Tuffite, Garinono and Setap Shale Formations (Fig. 1). These formations are PLANKTONIC FORAMINIFERA AND AGE partly correlatable to the Kalumpang, Kuamut, Ayer, Labang, Tungku, Tabanak and Sandakan Formations. Most Age determination of the formations is based on the of these formations contain tuff, and tuffaceous material stratigraphic distribution of some selected index forms except the Sandakan Formation. (Fig. 2). Basir Jasin et ai. (1995) recorded two assemblages The aim of this paper is to study the planktonic of planktonic foraminifera from the Garinono Formation foraminifera and their implications to the biostratigraphy, in the Bidu-Bidu area. The first assemblage was retrieved paleooceanography, and depositional environment. from the matrix of melange. The assemblage is composed of Giobigerinoides trilobus (Reuss) Praeorbulina GEOLOGICAL SETTING transitoria (Blow), Giobigerinoides diminutus Bolli, Globigerinoides sicanus De Stefani, Gioboquadrina The Garinono Formation is composed of slump baroemoenensis (LeRoy), Dentogiobigerina aitispira breccia, and mudstone, boulder beds, sandstone, mudstone, altispira (Cushman & Jarvis) and Dentoglobigerina conglomerate, tuff and tuffite (Haile & Wong, 1965; aitispira giobosa (Bolli). The occurrence of Leong, 1974). This formation is similar to the Kuamut Globigerinoides diminutus, Praeorbulina transitoria and and Ayer Formations. The Kuamut, Ayer and Garinono Giobigerinoides sicanus is indicative of the early Middle Formations are chaotic deposits and therefore considered Miocene Giobigerinoides sicanus-Globigerinatella insueta as melange. These formations were partly deposited by Zone (N8). submarine slumping or debris flow (Basir Jasin et at., The second assemblage were retrieved from tuffaceous 1995). In eastern Sabah, the Garinono melange overlies mudstone layer above the melange. Nine species were the Gomantong Limestone. identified; Orbulina universa d'Orbigny, Orbulina 158 BASIR JASIN IIS'E 116'E m'E I18'E I19'E Legend v~ Sample location o 7' 1. Setap Shale 2. Garinono melange N 3. Libong Tuffite t - Road I ~ 6'N II 1I'7'E I19'E Figure 1. Map of Sabah showing the fossillocalities. suturalis Bronnimann, Globigerinoides trilobus (Reuss), Globigerinoides immaturus LeRoy, Globigerina woodi AGE =U STRATIGRAPmC DISTRIBUTION OF SOME 0 SELECTED TAXA Jenkins, Dentiglobigerina altispira altispira (Cushman IN Q.. ~~ M.A. ~ ~N and Jarvis), Globorotalia praescitula Blow, Globorotalia peripheroacuta Blow and Banner and QUAT. N23 Sphaerodenellopsis disjuncta (Finlay). This assemblage N22 W W Z N21 indicates the early Middle Miocene Globorotalia W U ~ N211 peripheroacuta Zone (NlO). ~ N19 9 II:: Sixteen taxa of planktonic foraminmifera were 5 ~ IL i1i N18 retrieved from the tuffaceous shale of the Libong Tuffite N17 Formation exposed at the headwater of Sungai Sabahat, W N18 ~ Dent Peninsula (Basir Jasin & Sanudin Tahir, 1987). The assemblage consists of Globigerinoides immaturus 10 - N15 N14 (LeRoy), Globigerinoides trilobus (Reuss), N13 W N12 Globigerinoides quadrilobatus (d'Orbigny), Orbulina ...J I 0 N 11 I !3 0 bilobata (d'Orbigny), Orbulina suturalis Bronnimann, N10 I '- l w :ii I l ~ ~ Orbulina universa d'Orbigny, Globoratalia praefohsi 15 - i1 Ne I N8 i Blow and Banner, Globorotalia fohsi fohsi Cushman ~ I .!3 I ! ! :IE '" .9 N7 .~ j .S! and Ellisor, Globorotalia fohsi lobata Bermudez, ..~ i ~ ~ Globorotalia mayeri Cushman and Ellisor, Ne i ,g ~ l l ~ .~ 't j ... ... Dentoglobigerina altispira altispira Cushman and .. ~ ~ 20- a: tl ! ·9 oS t:l ii ~ ~ t:l ~ N5 ~.. ~ Jarvish, Globoquadrina baroemoenensis LeRoy, i! .~" ~ Neogloboquadrina dehisens (Chapman, Parr & Collins), ~ 1oS .~ .!!.O Q" N4 .. ... ~ Sphaeroidinellopsis disjuncta (Finlay), ~ ....~ t:J Sphaeroidinellopsis seminulina (Schwager), and 25- ~ t:J Globigerinella obesa (Bolli). The occurrence of w N3 w Globoratalia praefohsi, Globorotalia fohsi fohsi, Z ~ W Globorotalia fohsi lobata, suggests the middle Middle g MioceneBloborotalia fohsi fohsi Zone (N12). 30- CJ N2 Twelve taxa were identified from the Setap Shale ~ ~~ a: exposed at Kampung Sungai Berdaun, Labuan (Basir ~ Jasin et al., 1993). The faunas consists of Figure 2. Stratigraphic distribution of index plantonic foraminifera. Geological Society of Malaysia Annual Geological Conference 2002 MIDDLE MIOCENE PLANKTONIC FORAMINIFERA AND THEIR IMPLICATIONS IN THE GEOLOGY OF S ABAH 159 Globigerinoides iml17 aturus (LeRoy), Globigerinoides DEPOSITIONAL ENVIRONMENT trilobus (Reuss), Globigerinoides quadrilobatus (d'Orbigny), Globigerinoides diminutus Bolli, Planktonic foraminifera are usuall y found living near Globigerinoides sicanus De Stefan i, Praeorbulina the surface of the ocean especially in the top 100 m of the transitoria (B low), Globorotalia bella Jenkins, water column. They are abundant in the open ocean. Most Globoqu'adrina baroemoenensis LeRoy, of the well-preserved planktonic foraminiferal fossils are Neogloboquadrina dehiscens (Chapman, Parr & Collins), commonly found in the deep-sea sediments above the Dentoglobigerina altispira altispira (Cushman & Jarvis), calcite compensation depth. Preservation of the Dentoglobigerina altispira conica (Bronnimann & Resig) foraminiferal tests is very much related to planktonic and Dentoglobigerina altispira globosa. The occurrence of productivity. The productivity is controlled by the nutrient Globigerinoides diminutus, Praeorbulina transitoria and supply and the availability of di ssolved carbonate in the Globigerinoides sicanus is indicative of the early Middle sea-water. Miocene Globigerinoides sicanus-Globigerinatella insueta The occurre nce of abundant Middle Miocene Zone (NS). planktonic foraminifera in the formations indicates that The pl anktonic foraminifera assemblage from the productivity was high and was likely related to the Setap Shale is similar to the assemblage recovered from upwelling of deep nutrient-rich water mass near the the matrix of the Garinono melange. The planktonic continental margin of the western Pacific. All the foraminifera of Sabah ranges from NS (earl y Middle planktonic foraminifera bearing rock formations in Sabah Miocene) to NI2 (middle Middle Miocene). Similar were deposited in a deep water environment. During the planktonic foraminifera assemblage was recorded from Middle Miocene most of the eastern Sabah and Labuan the Ayer melange (Haile & Wong, 1965) and Kuamut Island were deep water environment (Fig. 3). melange (Leong, 1974). Some selected taxa are illustrated in Plate 1 to Plate 3. DEPOSITIONAL HISTORY The Middle Miocene palnktonic foraminifera were also recorded from the Tabanak Conglomerate (Leong, The Garinono me la nge overlies the Gomantong 1974), Sebahat (Haile & Leong, 1965), Tungku (Haile & Limestone, the Kulapis and the Labang Formations. Both Leong, 1965), Tanjung (Collenette, 1965) and Sandakan the Kulapis and the Labang Formations were deposited in Formations (Lee, 1970). deep