本文選題：紗帽組 + 斑脫巖��； 參考：《地質(zhì)科技情報(bào)》2017年04期

【摘要】：揚(yáng)子地臺(tái)紗帽組的地質(zhì)年代歸屬一直存在爭(zhēng)議。鄂西地區(qū)紗帽組主體由砂泥巖組成,但在頂部出現(xiàn)一套夾生物屑灰?guī)r透鏡體的碎屑巖。在恩施地區(qū)紗帽組灰?guī)r段之下發(fā)現(xiàn)了一套斑脫巖,通過(guò)對(duì)斑脫巖的鋯石U-Pb測(cè)年,得到加權(quán)平均年齡為(424.5±6.4)Ma,由此認(rèn)為紗帽組頂部的沉積時(shí)限為文洛克世�？紤]到紗帽組下部為早志留世,綜合分析認(rèn)為紗帽組是一跨時(shí)代的地層單元。該層斑脫巖產(chǎn)于含生物屑灰?guī)r團(tuán)塊或條帶的巖性段的下部,因此認(rèn)為以灰?guī)r的出現(xiàn)作為文洛克統(tǒng)沉積的開(kāi)始;同時(shí),認(rèn)為該層斑脫巖為加里東運(yùn)動(dòng)在華南活動(dòng)的產(chǎn)物。
[Abstract]:The geochronology of the Yangzi floor yarn cap formation has always been controversial. The main body of the Shimao formation in western Hubei is composed of sand and mudstone, but there is a set of clastic rocks with bioclastic limestone lens on the top. A set of porphyry deformations was found under the limestone member of the Shimao formation in Enshi area. By zircon U-Pb dating of the porphyry, the weighted average age is (424.5 鹵6.4) Ma. it is considered that the deposition time at the top of the Shimao formation is Wenloch. Considering that the lower part of the Yarn formation is early Silurian, it is considered that the Yarn formation is an intergenerational stratigraphic unit. The porphyry occurs in the lower part of the lithologic segment of the bioclastic limestone mass or belt, so the occurrence of limestone is considered as the beginning of the Wenloc sedimentary system, and it is considered that the porphyry is the product of the Caledonian movement in South China.
【作者單位】： 湖北省地質(zhì)調(diào)查院;
【基金】：中國(guó)地質(zhì)調(diào)查局地質(zhì)大調(diào)查項(xiàng)目(12120114066101);中國(guó)地質(zhì)調(diào)查局“揚(yáng)子工程湘西-鄂西成礦帶神農(nóng)架-花垣地區(qū)地質(zhì)礦產(chǎn)調(diào)查”二級(jí)項(xiàng)目(DD20160029)
【分類號(hào)】：P534.43;P597.3

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