發(fā)布時間：2018-02-27 09:40

  本文關(guān)鍵詞： 印度與歐亞大陸初始碰撞時間 判別標(biāo)志 轉(zhuǎn)換斷層 板塊俯沖帶 巖漿作用 構(gòu)造變形　出處：《中國科學(xué):地球科學(xué)》2017年03期 　論文類型：期刊論文

【摘要】：關(guān)于印度與亞洲大陸初始碰撞時間,目前存在3種主流認識,即(65±5)、(45±5)和(30±5)Ma.文中厘定了5種碰撞判別標(biāo)志,包括板塊運動速率的突然衰減、俯沖型巖漿作用的停止、大陸之間的物質(zhì)交換、海洋的消亡和構(gòu)造變形.通過綜合分析認為,在上述3種認識中,(65±5)Ma構(gòu)造事件符合一個判別標(biāo)志,即物質(zhì)交換——岡底斯碎屑物質(zhì)在此時出現(xiàn)在印度板塊北緣,不過,在此時岡底斯再次發(fā)生大規(guī)模的巖漿活動,反映出俯沖作用發(fā)生活化,意味著兩大陸仍未碰撞.俯沖成因的岡底斯巖漿作用在白堊紀(jì)末-第三紀(jì)初(72~65Ma)間斷了約7Myr,文中提出這可能與構(gòu)造轉(zhuǎn)換有關(guān),即特提斯俯沖消減帶被轉(zhuǎn)換斷層置換,亞洲與印度大陸由此呈水平走滑匯聚,到了約65Ma,隨著新俯沖帶的形成,巖漿作用重新開始,直到約45Ma結(jié)束.(45±5)Ma的構(gòu)造事件導(dǎo)致海相沉積和俯沖型巖漿作用的停止,符合大部分大陸碰撞判別標(biāo)志,文中定義為初始碰撞時間.(30±5)Ma的構(gòu)造事件與上述判別標(biāo)準(zhǔn)多不符合,反映的是印度和亞洲大陸大規(guī)模陸內(nèi)匯聚作用,即硬碰撞,由此形成青藏高原現(xiàn)今的地質(zhì)、地貌格局.文中得出的結(jié)論是:印度與歐亞大陸的匯聚并非僅僅是受新特提斯海的俯沖消減協(xié)調(diào),兩者在足夠接近時經(jīng)歷了3個階段,即早期的水平走滑匯聚(72~65Ma)、初始碰撞((45±5)Ma)和晚期的陸內(nèi)匯聚((30±5)Ma).
[Abstract]:As to the initial collision time between India and the Asian continent, there are three kinds of mainstream cognition, namely, 65 鹵5 + 45 鹵5) and 30 鹵5 Ma. Five kinds of discriminant markers of collision are determined in this paper, including the sudden attenuation of the velocity of plate movement and the cessation of subduction magmatism. The material exchange between continents, the extinction of the ocean and the tectonic deformation. Through the comprehensive analysis, it is concluded that the tectonic event of 65 鹵5 Ma accords with a discriminant marker in the above three kinds of cognition. That is, mass exchange-Gangdis clastic material appeared in the northern margin of the Indian plate at this time, but at this time Gangdis again occurred large-scale magmatism, reflecting the activation of subduction, This means that the two continents have not collided. The Gangdis magmatism of subduction origin interrupted about 7Myr during the late Cretaceous to the early Tertiary. It is suggested in this paper that this may be related to tectonic transformation, that is, the replacement of converted faults in the Tethys subduction zone. This resulted in horizontal strike-slip convergence between Asia and the Indian continent, and at about 65 Ma, magmatism resumed with the formation of the new subduction zone until the end of about 45 Ma and the tectonic event of 45 鹵5 Ma resulted in the cessation of marine sedimentary and subductive magmatism. The tectonic events defined in this paper as the initial collision time of 30 鹵5 Ma do not accord with the above criteria, reflecting the large-scale continental convergence between India and Asia, that is, the hard collision. It is concluded that the convergence of India and Eurasia is not only coordinated by the subduction of the New Tethys Sea, but also goes through three stages when they are close enough. That is, the early horizontal strike-slip convergence is 72n 65 Ma, the initial collision is 45 鹵5 Ma) and the late continental convergence is 30 鹵5 Ma.
【作者單位】： 巖石圈演化國家重點實驗室中國科學(xué)院地質(zhì)與地球物理研究所;中國科學(xué)院青藏高原地球科學(xué)卓越創(chuàng)新中心;
【基金】：中國科學(xué)院戰(zhàn)略性先導(dǎo)科技專項(B類)項目(編號:XDB03010500) 國家自然科學(xué)基金項目(批準(zhǔn)號:41672220,41130312)資助
【分類號】：P542

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