Petrological Characteristics of Radiolarian Silicalite and Its Geological Significance of Lower Silurian in the Hanzhong Region
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摘要: 汉中梁山地区的放射虫硅质岩成层性好，层次多，厚度较大，分布面积较广，主要同充填石英的放射虫铸型与隐晶质、微晶质的玉髓、石英及少量伊利石泥质基质构成。岩石中ＳｉＯ２的平均含量在９０%以上。从岩石学碱性条件下转变和分解，析出ＳｉＯ２，造成有利于硅质生物大量繁殖的条件。本区下志留统龙马溪组的放射虫硅质岩形成在水深相对较浅的深水陆棚与大陆坡过渡带上，水深约在２００ｍ左右。Abstract: The well stratificatied and widespread radiolarian silicalite with a fairly great thickness in the Liang- shan region, Hanzhong, is mainly composed. of quartz filling radiolarian cast, aphanitic or microcrystalline chert and quartz as well as a little illite matrix. The average content of SiO 2 in the rock is above 90 %. By analysis of petrological characteristics, the origin of radiolarian silicalite in this region is explained that the distal volcanic product provided SiO , for volcanic product changes, dissolved and released out SiO 2 into sea water where formed a favorable environment for the growth of siliceous organism. The radiolari- an silicalite of the Lower Silurian Longmaxi Formation in this region was formed in the transitive zone between the deepwater continental shelf where the water depth is relatively shallow and the continental slope,in which the sea-water depth is about 200 m.
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Key words:
- rediolarian silicalite /
- Lower Silurian /
- Hanzhong
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[1] 杨万蓉,江纳言.浙江长兴组火山岩和放射虫的发现.地层学杂志, 1980, 4( 1): 67 ～ 69. [2] 黄志诚,黄钟瑾,陈智娜.下扬子区五峰组火山碎屑岩与放射虫硅质岩.沉积学报, 1991, 9( 2): 1 ～ 15. [3] Jones D L. and Murchey B., Geologic sig nificance of Paleozoicand M eso zoic radiolarian chert. Ann. Rev. Earth Planet Sci.,1986, 14: 455 ～ 492. [4] 吴浩若.放射虫岩及其地质意义.国外地质, 1986, ( 7): 1 ～ 4. [5] 西北大学地质系.梁山地质,西安: 西北大学出版社, 1992, 14 ～52. [6] 李耀西,宋礼生,周志强等编著.大巴山西段早古生代地层志.北京: 地质出版社, 1975, 62 ～ 101. [7] 孔庆玉,龚与觐.苏皖地区下二叠统放射虫硅质岩形成环境探讨.石油与天然气地质, 1987, 8( 1): 86 ～ 89. [8] 童玉明,周祖勋.鄂东南下二叠统茅口组放射虫硅质岩的成因初探.沉积学报, 1985, 3( 2): 67 ～ 74. -
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