Armandita et al. Origin, structural geometry, and development of a giant coherent slide: The South Makassar Strait mass transport complex Cipi Armandita1,2,3,*, Chris K. Morley3,4, and Philip Rowell2,† 1SKK Migas, Gedung Wisma Mulia Building, Lantai 35, JI Jend, Gatot Subroto No. 42, 12710, Jakarta, Indonesia 2Petroleum Geoscience Program, Chulalongkorn University, 254 Phayathai, Pathumwan, Bangkok, 10330, Thailand 3PTTEP (PTT Exploration and Production Public Company Limited), Soi 11, Vibhavadi-Rangsit Road, Chatuchak, 10900, Bangkok, Thailand 4Petroleum Geophysics Program, Department of Geological Sciences, Chiang Mai University, 239 Huay Kaew Road, Chiang Mai, 50200, Thailand ABSTRACT cene. Variable uplift promoted sliding domi- when the MTC was deposited in the early Plio- nantly from the eastern and western margins cene (Fig. 1). The South Makassar Strait mass transport of the headwall. The internal fault patterns Mass transport complex (MTC) is a general complex (MTC) covers an area of at least of the MTC show that extension in the upper term used for an underwater landslide deposit 9000 km2 and has a total volume of 2438 km3. slope to lower slope in the core area changes that undergoes some combination of creeping, It is composed of a shale-dominated sedimen- downslope to compressional structures in the sliding, slumping, and/or plastic fl ow in a marine tary unit with high water content. Seismic toe domain and apron. Later extensional col- or freshwater lacustrine environment (e.g., Dott, refl ection data across the South Makassar lapse of parts of the compressional toe area 1963; Nardin et al., 1979; Moscardelli and Strait MTC show that it displays relatively occurred with negative inversion on some Wood, 2008). Underwater landslides in a marine coherent internal sedimentary stratigraphy faults. The coherent internal stratigraphy, environment commonly occur around the slope that in the toe region is deformed into well- and evidence for multiphase extension in area, in the transition zone between the shelf defi ned thrust-related structures (imbricates, the eastern headwall area, suggests that the and deep-water areas. In recent years 2D, and ramps and fl ats, fault bend folds). It is one ~6–7 km of shortening in the toe region of the particularly 3D, seismic data have enabled large of the largest known coherent MTCs. The MTC occurred at a slow strain rate. There- MTCs to be described in considerable detail. bowl-shaped central core region is as much fore, this type of MTC does not have the Numerous kinematic indicators internal to large as 1.7 km thick, and is confi ned to the west potential to generate tsunamis. slides can be identifi ed from seismic data (e.g., and east by 355° and 325° trending (respec- Bull et al., 2009) and can be seen in parts of tively) lateral ramps in the upper slope area INTRODUCTION the slide described here. The traditional clas- that pass via oblique ramps into a northeast- sifi cation systems for describing MTCs focus southwest–trending frontal ramp area. The Since the Indonesian government conducted on sedimentary processes (e.g., Nardin et al., core area passes via the lateral, oblique, and speculative two-dimensional (2D) seismic 1979). More recent classifi cations have defi ned frontal ramps into an extensive, thin (tens of surveys in the eastern part of the deep-water the geological context of the slides by divid- meters thick) region of the MTC (the lateral Makassar Strait basin from 2001 to 2004, ing them into shelf attached, slope attached, and frontal apron areas) that are internally several oil and gas companies signed explora- and detached systems (Moscardelli and Wood, deformed by thrusts, normal faults, and tion contracts in 11 working areas. Signifi cant 2008), or focus on the magnitude of translation thrust faults reactivated as normal faults. activities include acquisition of more than (Frey-Martinez et al., 2006). Two end members The MTC anatomy can be divided into exten- 13,000 km of 2D, 12,000 km2 of 3D seismic of MTC translation were identifi ed by Frey- sion headwall, translational, toe, fl ank, lateral surveys, and 15 exploration wells. Data from Martinez et al. (2006) as (1) frontally restricted apron, and frontal apron domains. The head- the southern part of the Makassar Strait basin MTCs where translation is limited and the slide wall region is located in the upper slope area revealed a very extensive mass transport com- does not overrun the undeformed downslope of the Paternoster platform; the main body plex (MTC) in the upper part of the basin fi ll strata, and (2) frontally emergent, where the of the slide is in the deep-water region of the that covers an area of ~8985 km2. Here we slide ramps up from its basal shear surface and Makassar Strait. The complex is interpreted focus on describing the morphology of this overruns the seafl oor in an unconfi ned fashion. to be triggered by uplift of the platform area giant relatively coherent MTC, and try to The South Makassar Strait MTC discussed (accompanied by inversion), and/or basin explain why it is characterized by large-scale herein is in the slope-attached category of Mos- subsidence, which caused seaward rotation internal deformation rather than disintegrating cardelli and Wood (2008), and is closer to the of ~2° of the Paternoster platform in the Plio- into smaller, more chaotic blocks. Water depths frontally restricted than the frontally emergent in which the MTC is found range from 1000 end member of Frey-Martinez et al. (2006). *Formerly at Chulalongkorn University. to 2000 m. The MTC covers the slope to basin In a deep-water environment, MTCs, products †Present address: 1107 Green Valley Drive, Hous- fl oor area and the current seafl oor morphology of mass transportation processes, often domi- ton, Texas 77055, USA. is probably similar to the paleomorphology nate the basin stratigraphy, and are intercalated Geosphere; April 2015; v. 11; no. 2; p. 376–403; doi:10.1130/GES01077.1; 27 fi gures; 1 table. Received 9 May 2014 ♦ Revision received 26 November 2014 ♦ Accepted 8 January 2015 ♦ Published online 17 February 2015 376 For permissionGeosphere, to copy, contact April [email protected] 2015 © 2015 Geological Society of America Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/11/2/376/3335682/376.pdf by guest on 23 September 2021 South Makassar Strait mass transport complex with turbidite deposits (Dykstra et al., 2011). REGIONAL GEOLOGY The younger basins initiated during the middle MTCs are commonly large enough to be geo- Eocene are exposed onshore (Bachtiar et al., hazards, and the largest can be tsunami genic The study area is in the southern Makas- 2013). The majority of the deep-water rift sub- (e.g., Watts, 1998, 2003; Wright and Rathje, sar Strait between the Paternoster platform on basins in the Makassar Strait are sealed by early 2003; Mosher et al., 2010; Yamada et al., 2011). the eastern margin of Borneo to the west and Oligocene postrift sediments. However, on the MTCs became of interest to oil and gas explora- the West Sulawesi fold belt to the east (Figs. western margin of the deep-water area on the tion and development when wells and facilities 1–3). It is generally accepted that the Makassar Paternoster platform, extension appears to have were placed in deep-water environments (Shipp Strait basins were formed as result of a broad continued on some faults into the Oligocene, et al., 2004; Mosher et al., 2010; Yamada et al., zone of extension that continues onshore in the and possibly into the late Oligocene–early Mio- 2011). On a worldwide basis, 90% of MTC’s are Kalimantan region of Borneo and in western cene (Kupecz et al., 2013). Despite this local mud prone (Meckel, 2011), but a few provide Sulawesi (e.g., Cloke et al., 1997, 1999; Calvert evidence for relatively late extensional activ- commercial reservoirs for hydrocarbons. As an and Hall, 2003). The onset of rifting was pre– ity, much of the Makassar Strait area has been example, the reservoir in the nearby Ruby Field 45 Ma in the North Makassar Strait basin, and undergoing postrift thermal subsidence since the (Fig. 1) in the Makassar Strait (Tanos et al., possibly slightly younger in the South Makas- Oligocene. The postrift subsidence may have 2012; Pireno and Darussalam, 2010) is an MTC sar Strait basin around the early-middle Eocene been enhanced by fl exural subsidence related to deposit with a predominantly carbonate facies. (Bachtiar et al., 2013; Kupecz et al., 2013). thrusting and inversion in the East Kalimantan 3800 m 116°E 118°E 120°E 0 0° Borneo (Kalimantan) –5000 m Northern Makassar Straits 2° Paternoster Sulawesi Platform 100 km Ruby Field 4° Well X Southern Makassar Straits Figure 1. The South Makassar Strait mass transport complex. Geosphere, April 2015 377 Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/11/2/376/3335682/376.pdf by guest on 23 September 2021 Armandita et al. Western lateral Eastern frontal A W apron Core area apron E 1.5 2.0 2.5 Seafloor 3.0 3.5 4.0 1.5 km 4.5 Two way travel time (s) travel way Two 5.0 5.5 Pre-rift 6.0 basement 6.5 XYToe and frontal W Lateral apron domain Transpressional region within translational domain apron domains E B 2.5 3.0 3.5 Two way travel time (s) travel way Two 4.0 4.5 Top mass transport complex Western lateral rampCoherent Eastern lateral ramp 5 km central block Base mass transport complex Figure 2. (A) East-west seismic line through the South Makassar Strait showing an oblique section through the mass transport complex (MTC) that is more oriented in the strike-direction than the dip direction.