Petrography, geochemistry, and tectonics of a rifted fragment of Mainland Asia: evidence from the Lasala Formation, Mindoro Island, Philippines

Abstract

Petrological and geochemical investigations of the sedimentary Lasala formation in northwest Mindoro, Philippines, offer new insights into the origin of this geologically contentious region. Mindoro island's position at the boundary between Sundaland and the Philippine Mobile Belt has led to variable suggestions as to how much of it is continent derived or not. The Eocene Lasala formation overlies the Jurassic Halcon metamorphics, a regionally metamorphosed suite generally thought to have formed as a result of arc-continent collision processes. The sedimentary formation consists mainly of sandstones and shales interbedded with mudstones, basalt flows, and subordinate limestones and conglomerates. Petrographic information on the Lasala clastic rocks demonstrates a uniform framework composition that is predominantly quartzose. Major oxide, trace element abundances, and various elemental ratios similarly impart a strongly felsic signature. These characteristics are taken to indicate a chiefly continental, passive margin derivation and deposition of the Lasala sediments during the Eocene. The weak indication of active margin influence is suggested to be an inherited signature, supported by paleogeographic models of the southeastern Asian margin area during the preCenozoic.

Geochemistry of Cretaceous Mudrocks and Sandstones from Douala Sub-Basin, Kumba Area, South West Cameroon: Constraints on Provenance, Source Rock Weathering, Paleo-Oxidation Conditions and Tectonic Environment

“…Particularly, the geochemical signature, comprising of major, trace and rare earth elements (REEs) geochemistry, of siliciclastic sediments is indicative of several interacting variables such as provenance, weathering, transportation and diagenesis [10] [11] [12] [13]. A number of recent geochemical studies on ancient and modern clastic sediments from different parts of the world have been carried out and provided some valuable information on the source rock composition [14]- [20], climate, mode of transportation, depositional environment, degree of source rock weathering [21] [22] [23], tectonic setting and post depositional processes such as diagenesis and metasomatism [24] [25] [26] [27] [28].…”

Provenance, depositional setting, and crustal evolution of the Cathaysia Block, South China: Insights from detrital zircon U–Pb geochronology and geochemistry of clastic rocks

“…This discrepancy of using trace elements in this study may reflect inherited signatures of the clastic sediments from old provenance terranes (e.g., ancient basement of active continental margins) rather than its depositional environment (e.g., Bai, Zhou, Wang, Zhang, & Ma, ; Concepcion et al, ; Savoy, Stevenson, & Mountjoy, ). The U–Pb detrital zircon dating of the sandstone samples is dominated in Neoproterozoic to Mesoarchean, much older than their depositional age (Sinian–Cambrian) confirms this hypothesis.…”

Stratigraphic units overlying the Zambales Ophiolite Complex (ZOC) in Luzon, (Philippines): Tectonostratigraphic significance and regional implications

“…Integrating geological, biostratigraphic and geophysical data, recent models of Dimalanta et al (2009) andConcepcion et al (2012) place the collision boundary east of the Mindoro island and the Romblon Group of Islands, and southward across the Panay island. The presence of Upper Palaeozoic and Mesozoic sequences in the Central Philippines, particularly in the islands of Panay and Mindoro as well as in Busuanga island in northern Palawan, provided principal evidence to distinguish terranes of PCB affinity from those of the PMB affinity.…”