南海ODP1148站深海相渐新统硅质成岩作用  

SILICA DIAGENESIS OF DEEP-SEA OLIGOCENE AT ODP SITE 1148, THE SOUTH CHINA SEA

作　　者：房殿勇[1] 王汝建[1] 邵磊[1] 祁景玉[1] 汪品先[1] 池树根 

机构地区：[1]同济大学海洋地质教育部重点实验室,上海200092 [2]渤海石油研究院,天津300452

出　　处：《海洋地质与第四纪地质》2002年第2期75-79,共5页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金资助项目 (4 99995 60 );国家重点基础研究专项经费资助项目 (G2 0 0 0 0 785 0 0 )

摘　　要：南海 ODP114 8站分析结果显示 ,井深 4 75～ 6 0 0 m的硅质化石主要表现为蛋白石 - CT。随着深度增加 ,硅质化石破壳率增大 ,蛋白石 - CT的 X射线衍射峰强度减弱 ,自生石英的衍射峰则相应增强 ,反应了蛋白石 - CT向石英的转变。井深 6 2 0 m附近 ,硅质化石完全溶解 ,蛋白石 - CT衍射峰消失 ,蛋白石 - CT全部转变为石英。样品取心率从 4 70 m处的近 10 0 %降到 4 85 m处的 8% ,可能是硅质成岩作用 ,尤其是蛋白石 - A向蛋白石 - CT的转变影响所致。而取心率的降低 ,则是此井未能观察到蛋白石 - A /蛋白石 -X ray diffraction and scanning electron microscopy analyses were performed on 200 samples taken from the deep sea Oligocene sediments between core depth 450 m and 850 m at ODP Site 1148 in the northern South China Sea. The results show that the opal A of siliceous fossils has been transformed into opal CT in the interval between 475 m and 600 m. With the depth increasing, the fragmentation of siliceous fossils increased, the X ray peaks of authigenic quartz became more prominent and the X ray peaks of opal CT reduced in intensity, indicating the occurrence of the opal CT in quartz transformation in this interval. The opal CT intensity peak disappeared in samples below 600 m, suggesting that the opal CT had been completely transformed into quartz. The abrupt decrease in core recovery from near 100% above 470 m to 8 % in the interval of 470～485 m at Site 1148 is likely to be related to the silica diagenesis, particularly to the transformation of opal A to opal CT. The opal A/opal CT boundary, however, has not been determined in this work mainly due to the poor core recovery.

关 键 词：深海相 硅质成岩作用 蛋白石-A 蛋白石-CT 石英 渐新世 南海 

分 类 号：P736.3[天文地球—海洋地质]