Formation of Arcs and Backarc Basins Inferred from the Tectonic Evolution of Southeast Asia Since the Late Cretaceous
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Tectonophysics 384 (2004) 23–53 www.elsevier.com/locate/tecto Formation of arcs and backarc basins inferred from the tectonic evolution of Southeast Asia since the Late Cretaceous E. Honzaa,*, K. Fujiokab a Graduate School of Science and Technology, Kumamoto University, Kurokami, Kumamoto 860-8555, Japan b Japan Marine Science and Technology Center, Natsushima, Yokosuka 237-0061, Japan Received 23 July 2002; accepted 10 February 2004 Available online 10 June 2004 Abstract Results of the geological and geophysical surveys in the Daito ridges and basin in the northern West Philippine Basin suggest that the Daito Ridge was an arc facing toward the south from the Late Cretaceous to the Early Tertiary. The Late Cretaceous and Tertiary history of Southeast Asia is evaluated based on these data in the Daito ridges and basins and reconstructed based on overall plate kinematics that have operated in this area. During the Late Cretaceous, the Daito Ridge and the East Philippine Islands were positioned along the boundary between the Indian and Pacific Plates. The western half of the Philippines setting on the Indian Plate approached from the south and collided with the East Philippine–Daito Arc either during the latest Paleocene or the earliest Eocene. It is inferred that the bulk of the Philippine archipelago rotated clockwise and Borneo spun counterclockwise during the Tertiary. From the reconstruction, the formation of backarc basins and their spreading direction are assessed. As a result, some primary causes and significant characteristics are suggested for the opening of backarc basins in Southeast Asia. First, opening of some backarc basins commenced with or was triggered by collisions. Second, backarc basins opened approximately parallel to oceanic plate motion. Third, the formation of some backarc basins was triggered by the approach of a hot spreading center. Fourth, the spreading mode or direction of backarc basins was greatly affected by the configuration of the surrounding continent and was also rearranged to spread approximately parallel to oceanic plate motion. The formation of backarc basins and their spreading direction can be reasonably explained by plate kinematics. However, the generative force responsible for their formation is possibly within the subduction system, particularly to form horizontal tensional force in backarc side. D 2004 Elsevier B.V. All rights reserved. Keywords: Daito ridges and basins; Arc and backarc basin formation; SE Asia; Reconstruction 1. Introduction Plates, forming an area of enigmatic plate boundaries with collision and subduction zones (Fig. 1).Its Southeast Asia is composed of many small plates modern configuration, with complicated sutures, and strewn between the Pacific and the India–Australia arc–backarc basin formations was initiated by the northward movement of India in the Late Cretaceous * Corresponding author. Tel.: +81-96-342-3415; fax: +81-96- and by the northward translation of Australia since the 342-3411. Eocene (e.g. Norton and Sclater, 1979; Mutter et al., E-mail address: [email protected] (E. Honza). 1985; Powell et al., 1988; Royer and Sandwell, 1989). 0040-1951/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.tecto.2004.02.006 24 E. Honza, K. Fujioka / Tectonophysics 384 (2004) 23–53 E. Honza, K. Fujioka / Tectonophysics 384 (2004) 23–53 25 There already are a number of regional reconstruc- Paleomagnetic work in Southeast Asia suggests tion models for Southeast Asia based on geological that the West Philippine Basin has rotated clockwise evidence, magnetic anomaly identification in marginal by approximately 80j since the earliest Tertiary basins and paleomagnetic analyses. These varied (Louden, 1977; Kinoshita, 1980; Haston and Fuller, models have some very basic difference. For example, 1991). From the work in Halmahera, Hall et al. (1995) one of their distinct disagreements is in the recon- suggested approximately 90j clockwise rotation of struction of the Philippine Plate, which is a conse- the Philippine Plate since the Eocene. This result is quence of how they isolate that from the surrounding based on an assumption that Halmahera is a part of the major plates. Some authors propose counterclockwise Philippine Plate since the Early Tertiary. The Celebes rotation (Holloway, 1982; Karig, 1983; Stephan et al., Basin is considered to have rotated counterclockwise 1986; Longley, 1997) while others suggest clockwise approximately 60j (Shibuya et al., 1991). Counter- rotation (Daly et al., 1987; McCabe and Cole, 1987; clockwise rotation of approximately 90j is postulated Hall et al., 1995). Despite some differences, a few for Borneo since the latest Cretaceous (Haile et al., elements are common among the models. Most of 1977; Haile, 1978; Sasajima et al., 1980; McCabe and them suggest that Philippine islands were initially on Cole, 1987; Schmidke et al., 1990; Fuller et al., 1991, the Pacific Plate located approximately to the north of 1999). Other paleomagnetic work suggests that there Australia. Formation of the West Philippine Basin is was no rotation of western Kalimantan during the also widely interpreted to have been associated with Tertiary (Lumadyo et al., 1993). Borneo is considered northwestward movement of the Philippines along to be a part of Sundaland behaved as a single tectonic sinistral strike slip faults (Seno and Maruyama, unit with no rotation observed in western Sundaland 1984; Sarewitz and Karig, 1986; Jolivet et al., 1989; (e.g. Hamilton, 1979; Hutchison, 1996). From the 20j Rangin et al., 1990; Honza, 1991). to 33j counterclockwise rotation of Malay Peninsula Some marginal basins age-formation was estab- during the Tertiary, possible rotation of Sundaland lished by magnetic anomaly identifications and by was suggested (Richter et al., 1999). Sundaland itself DSDP and ODP drillings. Results suggest that most does not appear to behave as a single block based on marginal basins in Southeast Asia were formed in paleomagnetic studies. It seems more logical to divide the Cenozoic and appear to have an intimate rela- that region into at least two parts: the northern Indo- tionship with subduction events that also corresponds China and southern Sundaland blocks. in duration to the formation of the marginal basin The Daito ridges and basins in the northern margin (Tamaki and Honza, 1991). This relationship is also of the West Philippine Basin are in the NWW–SEE well demonstrated in the backarc basins of the trend, approximately parallel to the magnetic character Tertiary arc chain along the central and southwestern of the basin but different from the surrounding trends of rim of the Pacific Plate (Honza, 1991). From these the Ryukyu Trench and Kyushu-Palau Ridge. This reconstructions and models for backarc basin forma- suggests that the Daito ridges and basins were formed tion, it is inferred that during the Cenozoic, some arc at a much earlier stage than the formation of the West regions in Southeast Asia were under tensional Philippine Basin. They are postulated to have formed in forces that led to backarc basin formation. This the Late Cretaceous and Early Tertiary (e.g. Uyeda and contrasts with Mesozoic arcs that were dominantly Ben-Avraham, 1972; Mizuno et al., 1978; Klein and formed under compression. Kobayashi, 1980; Shiki et al., 1985; Tokuyama, 1995). Fig. 1. Tectonic setting of Southeast Asia. Thick lines with closed triangles are modern active trenches and those with open triangles are inactive. Thick arrows show the direction of plate movement in a fixed hotspot reference frame after Engebretson et al. (1985) and Royer and Sandwell (1989). Length of bar is motion for 10 Ma. Spreading centers are shown in double lines. Thin lines are active structural boundaries and thin broken lines are traces of offshore or buried structural boundaries. Abbreviation: T: Trench or Trough, JB: Japan Basin, NA: Nankai Trough, OT: Okinawa Trough, DRB: Daito ridges and basins, SB: Shikoku Basin, OD: Ogasawara Depression, MA: Mariana Trough, PB: Parece Vela Basin, WPB: West Philippine Basin, SCB: South China Basin, AB: Andaman Basin, PA: Palawan Trough, NE: Negros Trench, SU: Sulu Basin, CO: Cotobato Trench, CB: Celebes Basin, NS: North Sulawesi Trench, MB: Makassar Basin, BB: Banda Basin, MO: Molucca Collision, SO: Sorong Fault, CE: Ceram Trough, CAB: Caroline Basin, NG: New Guinea Trench, WE: West Melanesia Trench, NB: New Britain Trench and TR: Trobriand Trench, RF: Red River Fault, SF: Seribu Fault. 26 E. Honza, K. Fujioka / Tectonophysics 384 (2004) 23–53 These data and some unpublished data are assessed lites and asterocyclina studies (Mizuno et al., 1975). to establish a possible formation history of the ridges Layer N in the basin is intercalated by basalt lavas and and basins. In this study, the tectonic evolution of the diabase sills and reworked Paleocene foraminifera Philippines and SE Asia is deciphered from the suggesting an age that is a little older than that from evaluation of the Daito ridges and basins, and the the ridges (Shipboard Scientific Party Leg 31, 1975; possible mechanism to form backarc basins is dis- Shipboard Scientific Party Leg 58, 1980; Shiki et al., cussed based on these results. 1985). Draped on Layer N and abutting the foot of the ridges is the Oligocene to Miocene Layer J whose age was determined using its nannofossil and radiolarian 2. Results of the geological and geophysical contents. Layer J exhibits a distinct alternation pattern surveys in the Daito ridges and basins in the and is intercalated by turbidites in basins and in northern Philippine Sea benches on slopes. The topmost Layer O is pelagic clay similarly distributed in the basins and on the The Daito ridges and basins in the northern margin ridges and ranges from the Middle Miocene to Qua- of the West Philippine Basin consist of the Amami ternary (Figs. 3 and 4). Basin, the Amami Plateau, the Kita-Daito Basin, the Most ridge and basin areas, Layer N in the basin is Daito Ridge, the Minami-Daito Basin and the Oki- traced to abut the foot of some highs, suggesting Daito Ridge.