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| 菲律宾海沉积物中石英的来源及其搬运方式 |
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朱潇1,2, 蒋富清1,3, 冯旭光1,2, 董江1,2, 刘喜停1, 王红莉1, 李安春1
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1.中国科学院海洋研究所中国科学院海洋地质与环境重点实验室 青岛 266071;2.中国科学院大学 北京 100049;3.中国科学院海洋大科学研究中心 青岛 266071
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| 摘要: |
| 为了识别菲律宾海沉积物中风尘信号和源区，以及沉积物的搬运方式，取菲律宾海沉积物中的石英，系统研究了石英的粒度组成、形貌特征、氧同位素特征和结晶度指数。菲律宾海中远离岛弧和海脊的石英粒度较细，西菲律宾海中石英主要由EM1（众数粒径平均为2.9μm）、EM2（众数粒径平均8.17μm）和EM3（众数粒径平均为21.67μm）三个端元组成，东菲律宾海中主要由EM1和EM2两个端元组成。靠近岛弧和海脊的石英粒度较粗，吕宋岛附近的石英具有众数粒径平均为103μm的EM4端元。EM1端元石英表面有明显的碰撞凹坑，EM2端元石英有溶蚀孔洞，EM3端元石英呈棱角状，表面相对光滑。包含EM1端元的石英的δ18O值和结晶度指数与塔克拉玛干沙漠中相同粒级石英的特征相近，不包含EM1端元的石英的δ18O值和结晶度指数与火山岛弧来源的石英特征相近。综合分析表明，EM1端元的石英为主要来自于塔克拉玛干沙漠的风尘石英，经由盛行西风搬运至太平洋，并由南向或西南向的风搬运，最终在菲律宾海沉积。EM2和EM3端元石英主要来源于太平洋火山岛弧，其中，EM2端元的石英经历了强烈的化学风化，经河流或洋流输送到研究区；EM3端元的石英没有经历长距离运输，可能是附近岩石风化的产物。 |
| 关键词: 菲律宾海 石英 风尘 源区 古气候 |
| DOI：10.11693/hyhz20171200319 |
| 分类号:P67 |
| 基金项目:国家自然科学基金项目，41576050号，41776065号；中国科学院战略性先导科技专项（A类）项目，XDA11030302号；全球变化与海气相互作用专项项目，GASI-GEOGE-02号。 |
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| THE PROVENANCE AND TRANSPORTATION OF QUARTZ IN THE PHILIPPINES SEA |
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ZHU Xiao1,2, JIANG Fu-Qing1,3, FENG Xu-Guang1,2, DONG Jiang1,2, LIU Xi-Ting1, WANG Hong-Li1, LI An-Chun1
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1.Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2.University of Chinese Academy of Sciences, Beijing 100049, China;3.Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
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| Abstract: |
| In order to identify the signal and source of quartz grains and the transport in the sediment of the Philippine Sea, we separated quartz from the bulk sediments and carried out a comprehensive study in grain size, morphology, oxygen isotopic composition, and crystallinity index (CI) of quartz. The results show that the quartz grains in the Philippines Sea away from the arc island and sea rise are fine-grained. In the West Philippines Sea, quartz is mainly composed of three grain-size end-members (EM), including EM1 (average modal grain size:2.9μm), EM2 (average modal grain size:8.17μm), and EM3 (average modal grain size:21.67μm), while in the East Philippine Sea, quartz is mainly composed of EM1 and EM2 endmembers. In contrast, quartz is coarse near the arc island and sea ridge, e.g., quartz near the Luzon Island has a coarser EM4 in a modal grain size of 103 μm. There are obvious collision pits on the surface of the EM1 quartz, and dissolution pits in the EM2 quartz. The EM3 quartz is angular and the surface is relatively smooth. The δ18O value and CI of quartz containing EM1 are close to that of from the Taklimakan Desert. EM2 and EM3 quartzes are similar in a volcanic origin. We thus conclude that the EM1 quartz is eolian quartz from Taklimakan Desert, which is transported by westerly wind to the Pacific Ocean, then transported by south or southwest wind, finally deposited in the Philippine Sea. The EM2 and EM3 quartzes are in volcanic origin that derived from the Pacific volcanic arcs. The EM2 that experienced strong chemical weathering is transported to the study area by ocean currents or fluvial discharge. The volcanic EM3 quartz does not experience long-distance transportation, which might be the weathering product of nearby rocks. |
| Key words: Philippines sea quartz dust sources paleoclimate |