| 柴达木盆地北缘早奥陶世陆 弧碰撞及弧后前陆盆地——来自碎屑岩地球化学的证据 |
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| 引用本文： | 孙娇鹏,陈世悦,马寅生,彭渊,邵鹏程,马帅,代昆,郑策.柴达木盆地北缘早奥陶世陆 弧碰撞及弧后前陆盆地——来自碎屑岩地球化学的证据[J].地质学报,2016,90(1):80-92. |
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| 作者姓名： | 孙娇鹏 陈世悦 马寅生 彭渊 邵鹏程 马帅 代昆 郑策 |
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| 作者单位： | 中国石油大学(华东)地球科学与技术学院,山东青岛，266580; 2) 中国地质科学院地质力学研究所,北京，100081 |
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| 摘 要： | 奥陶纪是柴达木盆地北缘早古生代碰撞造山演化的重要时期,柴达木地块与滩间山岛弧碰撞起始时限以及欧龙布鲁克海盆盆地类型、构造-古地理格局一直存在争议。本文在对欧龙布鲁克地块早奥陶世碎屑岩沉积野外观测及室内分析的基础上,测试了30个砂泥岩样品的主量元素、微量元素及稀土元素含量。结果表明,石灰沟组碎屑岩建造具有快速堆积、低成分成熟度、低结构成熟度的特征;该套碎屑岩沉积于活动大陆边缘背景下的弧后前陆盆地,碎屑物质来自南部由大陆上地壳与岛弧物质组成的上隆基底;早奥陶世(488~472 Ma)柴达木地块与滩间山岛弧陆-弧碰撞已经开始,但陆-弧碰撞起始时间不会早于493Ma。在此基础上,结合前人研究成果,认为早古生代欧龙布鲁克地块处于滩间山岛弧北部,盆地沉降、沉积演化受柴达木盆地北缘洋盆俯冲及柴达木地块-滩间山岛弧碰撞控制,寒武纪发育弧后伸展盆地,奥陶纪初期转为弧后挤压前陆盆地,弧后伸展与弧后挤压、沉积体系转换发生在490~480Ma之间。该成果从沉积学角度为柴达木盆地北缘陆-弧碰撞起始时限提供了新的制约。
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| 关 键 词： | 柴北缘 早奥陶世 碎屑岩 地球化学 陆-弧碰撞 弧后前陆盆地 |
| 收稿时间： | 2014/9/29 0:00:00 |
| 修稿时间： | 8/1/2015 12:00:00 AM |
Early Ordovician Continental Arc Collision and Retroarc Foreland Basin on the Northern Margin of Qaidam Basin: Geochemical Evidence from Clastic Rocks |
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| SUN Jiaopeng,CHEN Shiyue,MA Yinsheng,PENG Yuan,SHAO Pengcheng,MA Shuai,DAI Kun,ZHENG Ce.Early Ordovician Continental Arc Collision and Retroarc Foreland Basin on the Northern Margin of Qaidam Basin: Geochemical Evidence from Clastic Rocks[J].Acta Geologica Sinica,2016,90(1):80-92. |
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| Authors: | SUN Jiaopeng CHEN Shiyue MA Yinsheng PENG Yuan SHAO Pengcheng MA Shuai DAI Kun ZHENG Ce |
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| Abstract: | Ordovician is an important period of the Early Paleozoic collisional orogenesis in northern margin of Qaidam ba-sin.Arguments on the initial timing of continent-arc collision and the basin type､paleostructure-paleogeographic pattern last-ed till now.In this paper,on basis of the field observations and lab analysises on Early Ordovician clastic deposition in O-ulongbuluke block,combined with major elements､trace elements and rare earth elements measurements and analysises on 30 collected cubic samples.Results indicate that,clastic rocks from Shihuigou Formation has sedimentary and petrology cha-racteristics of rapid accumulation and low maturation of texture and component;the series of clastic rocks deposited in retr-oarc foreland under the background of active continental margin,detritus derived from the neighbouring upwelling basement composed by upper continental crust and island arc in the south;continental-arc collison caused by Qaidam block and Ta-njianshan island arc has begun since the Early Ordovician(488-472Ma),but the initial timing of continent-arc collision is no earlier than 493Ma.On the above mentioned basis,combining previous research results,we suppose that the Oulongbuluke block located to the north of Tanjianshan island arc during Early Paleozoic Era,basin subsidence and sedimentary evolution was controlled by oceanic crust subduction and continental-arc collision,retroarc stretch basin developed during Cambrian period,then transferred to retroarc extrusion foreland basin in the Early Ordovician,retroarc stretch turned to retroarc extrus-ion､sedimentary system transformation occurred approximately 490-480Ma.The conclusions presented in this study provide new sedimentary constraints on the initial timing of continent-arc collision. |
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| Keywords: | Northern Qaidam Early Ordovician detrital rock geochemistry continent-arc collision retroarc foreland basin |
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