南海西部深海平原SA14-34岩心浊流沉积特征
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摘要
本文对位于南海西部深海平原的SA14-34岩心进行详细的沉积物组分研究,结果表明:该岩心岩性复杂多变,沉积了粘土、粉砂质粘土、砂质粘土、粘土质粉砂、砂质粉砂、砂和粉砂质砂等7种沉积物类型。浊流沉积发育,至少已识别出4个特征明显的浊流层。浊流层厚度为18～120 cm,具有粒度较粗呈下粗上细、异地钙质微体生物化石丰富、陆源碎屑矿物含量高、SiO_2/Al_2O_3比值和CaCO_3含量高四大特点。并对浊流沉积的物质来源、成因进行了初步分析,认为浊积物主要来自西部陆架-陆坡区,有利的地形、丰富的物源和频繁的海底火山活动诱发的地震是浊流发生的主要原因。
Results based on visual core description,smear slide,microfossils,grain size, chemical and mineral analyses indicate turbidity current deposits have been developed in Core SA14-34,At least 4 layers of turbidities can be recognized.These layers,each 18～120 cm thick,are characterized by turbidite sequence with graded bedding,abundant allochthonous calcareous microfossils and high SiO_2/Al_2O_3 ratio,high content of CaCO_3 and high contents of terrigenous detrital minerals.In addition,a preliminary analysis is made on the material source and origin of the turbidity current deposits.The authors suggest that the favorable topography, abundant source materials and earthquakes induced by repeatedly occurring submarine volcanic activities are the main causes for the occurrence of turbidity currents.
Results based on visual core description,smear slide,microfossils,grain size, chemical and mineral analyses indicate turbidity current deposits have been developed in Core SA14-34,At least 4 layers of turbidities can be recognized.These layers,each 18～120 cm thick,are characterized by turbidite sequence with graded bedding,abundant allochthonous calcareous microfossils and high SiO_2/Al_2O_3 ratio,high content of CaCO_3 and high contents of terrigenous detrital minerals.In addition,a preliminary analysis is made on the material source and origin of the turbidity current deposits.The authors suggest that the favorable topography, abundant source materials and earthquakes induced by repeatedly occurring submarine volcanic activities are the main causes for the occurrence of turbidity currents.
引文
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[3]王慧中．南海中沙环礁西南缘深部海流的若干沉积学标志．见：业治铮、汪品先主编，南海晚第四纪古海洋学研究，青岛：青岛海洋大学出版社，1992，206～217
[4]陈文斌．南海北部浊流沉积物初步认识．见：南海海洋沉积作用过程与地球化学研究．北京：海洋出版社，1993，124～135
[5]汪品先等．十五万年来的南海[M]，上海：同济大学出版社，1995
[6]钱建兴．晚第四纪以来南海古海洋学研究．北京：科学出版社，1999，1～156
[7]章伟艳，张富元，张霄宇．南海东部海域柱状沉积物浊流沉积探讨．热带海洋学报，2003，22(3)：36～42
[8]陈芳，李学杰，陈超云等．南海西部表层沉积钙质浮游生物分布与碳酸盐溶解．海洋地质与第四纪地质．2003，23 (2)：33～38
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