Neogene Tectonic Evolution of the Celebes-Sulu Basins: New Insights from Leg 124 Drilling

Abstract

The Neogene tectonic evolution of the Celebes-Sulu basins is discussed on the basis of representative seismic profiles, published industrial wells, and Leg 124 drilling results. The study is also based on geological data collected all around the margins of these basins. A synthetic cross section was built from the South China Sea to Sulawesi, and correlation of the major magmatic and tectonic events was attempted. We suggest that these basins and their margins (Celebes-Sulu block) collided with the rifted margin of China (Reed Bank) around 16 Ma. A main event of submarine pyroclastic emplacement coincided with this collision. The Sulu Basin probably opened in a back-arc position for the Cagayan volcanic arc in early Miocene time. Incipient closing of the Sulu and Celebes basins, still presently active, is documented within their sedimentary cover.

Crust and upper mantle structure and its tectonic implications in the South China Sea and adjacent regions

“…It has been widely documented that there was an oceanic basin named proto-SCS between South China margin and Borneo (e.g., Rangin and Silver, 1991;Hall, 2002;Clift et al, 2008). The proto-SCS subducted mainly southward beneath Borneo from $45 to $16 Ma (Clift et al, 2008;Hall et al, 2008).…”

Updated interpretation of magnetic anomalies and seafloor spreading stages in the south China Sea: Implications for the Tertiary tectonics of Southeast Asia

“…We suggest it is related to the cessation of motion on the Red River Fault, itself inferred to result from the deformation and clockwise rotation of the fault system, and to changes in the stress field as the Indian indenter passes Malaysia and Indochina [e.g., Tapponnier et al, 1986;Peltzer and Tapponnier, 1988]. The middle Miocene is also a time of crustal shortening between Palawan and the Cagayan Ridge to the south [Rangin and Silver, 1991]. This deformation probably attests to more efficient coupling between the Philippine and the Eurasian Plates.…”

Rapid conversion of an oceanic spreading center to a subduction zone inferred from high-precision geochronology

“…The central Palawan ophiolite was trapped in the forearc of the subduction zone that generated the Cagayan arc (18). Subduction began at ∼34 Ma and lasted for ∼20 My before it was terminated by microcontinent-arc collision (18,29,33 and short duration make it an ideal site to study subduction initiation because it was terminated before a potentially complicated history might have ensued.…”

“…The Cagayan Ridge is located to the southeast of, and trends parallel to, Palawan. It is composed of calc-alkaline volcanic rocks (33) and is the volcanic arc associated with the subduction zone whose inception is preserved on Palawan (18,29,33,34). To the northwest of central and southwest Palawan is the Palawan trough (Fig.…”