论文部分内容阅读
赣东北蛇绿混杂岩带中含晚古生代放射虫硅质岩的ＳｉＯ_２含量变化范围为 ７８．４０％～ ８９．２８％，Ｓｉ／Ａｌ＝ ６．３～２３，Ｓｉ／Ａｌ比和Ａｌ_２Ｏ_３呈很好的负相关关系，表明它们含有 较高比例的陆源泥质沉积物．硅质岩样品的Ａｌ_２Ｏ_３／（Ａｌ_２Ｏ_３＋Ｆｅ_２Ｏ_３）＝０．５１～０．９０，Ｃｅ／Ｃｅ~·＝ ０，９１～１．２２， Ｌａ_ｎ／Ｃｅ_ｎ＝ ０．７６～１．１１， Ｖ＜Ｍ２０μｇ／ｇ，Ｖ／Ｙ＜２．６，Ｔｉ／Ｖ＞４０，一致表明这些硅质 岩形成于与大陆地壳物质输入密切相关的大陆边缘环境，而与大洋盆地、洋中脊环境无 关．因此，这些晚古生代硅质岩既不属于～ １．０Ｇａ蛇绿岩套“三位一体”中的一部分，也 不支持晚古生代扬子和华夏两个块体之间存在深海大洋盆。
The content of SiO_2 in Late Paleozoic radiolarians in the ophiolitic mélange zone in northeastern Jiangxi province ranged from 78.40% to 89.28%, with Si / Al = 6.3 ~ 23, Si / Al ratio and Al 2 O 3 Good negative correlations indicate that they contain a higher proportion of terrigenous muddy sediments. Al 2 O 3 / (Al 2 O 3 + Fe 2 O 3) = 0.51 ~ 0.90, Ce / Ce ~ = 0,91 ~ 1.22, La_n / Ce_n = 0.76 ~ 1.11 and V 40, all of which indicate that these cherts are formed in the continental margin closely related to continental crust material input, but not related to the oceanic basin and mid-ocean ridge environment. Therefore, these Late Paleozoic cherts did not belong to the “Trinity” part of the ~ 1.0Ga ophiolite suite, nor did they support the presence of deep-sea oceanic basins between the Late Paleozoic Yangtze and Huaxia blocks.