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根据近年考察结果,我们认为北喜马拉雅褶皱带在中生代时期为优地槽。它的范围在喜马拉雅山北坡,从低分水岭至雅鲁藏布江沿岸宽约150公里左右的区域内(图1)。优地槽的洋壳沉积从晚三叠世开始出现,历经侏罗纪、白垩纪,直至晚白垩世末,早第三纪始新世时开始海退,沿板块缝合带附近出现残留海盆,形成海陆交互相浅海—滨海相沉积。洋壳岩石组合包括有海底喷发的中基性火山岩、辉长辉绿岩、基性岩、超基性岩、深海相含放射虫硅质岩、深海相复理石建造,以及由于板块俯冲和碰撞造成的混杂堆积。
According to the findings of recent years, we believe that the North Himalayan fold belt was the best groove during the Mesozoic. It ranges from the low watershed to the northern slopes of the Himalayas to a zone about 150 km wide along the Brahmaputra coast (Figure 1). It is suggested that the oceanic crustal deposition of the trough occurred from the Late Triassic to Jurassic and Cretaceous and did not reach the end of the Late Cretaceous. The Early Tertiary began to recede from the Eocene, and the residual sea basin appeared along the plate suture zone. The formation of sea and land interaction phase shallow sea - coastal deposition. The oceanic crustal assemblages include subbasid volcanic rocks, gabbro, mafic rocks, ultrabasic rocks, radiolarian-bearing phyllites from deep-sea facies, and deep-ocean flysch formation from submarine eruptions, Collision caused by the accumulation of mixed.