This paper reviews the tectonic and paleoceanographic events based on the investigation of ODP Legs 115 to 123 in the Indian Ocean, and discusses the interaction between events which occurred in the Indian Ocean and in the Himalayan Range. ODP Leg 122 and 123 revealed that the incipient Indian Ocean formed at Argi Abyssal Plain, off the northwest Australia after the late Jurassic breakup of eastern Gondwana. Purely pelagic sediments began to be deposited after the Cenomanian/Turonian anoxic event. The terminal events of the Cretaceous/Paleogene and Palaeocene/Eocene boundaries were recovered in some cores of Legs 119 to 122. The study of Cenozoic magnetic anomalies in the Indian Ocean confirms that the collision between India and Eurasia began between 53 to 55 Ma (the middle Eocene) and coincides with the initiaton of global oceanographic cooling based on paleontological and geochemical data. Sedimentation in the Ganges-Indus submarine fan complexes is controlled by uplift and denudation of the Himalayan Range. The analysis of detrital heavy minerals in the cores of ODP Leg 116 indicates two-phase episodic uplift of the Higher Himalayas, dated at 10.9-7.5 Ma and after 0.9 Ma. Monsoonal upwelling in the Indian Ocean started at about 10 Ma, and may represent the appearance of extensive high mountains and plateau. In the Quaternary, the upwelling records of the western Arabian Sea suggest that southwest summer monsoon became strong during interglacial times, and weak during glacial times.
|ジャーナル||Journal - Geological Society of Japan|
|出版ステータス||Published - 1997 12月 1|
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