發(fā)布時(shí)間：2018-10-15 12:07

【摘要】：滇西昌寧更戛鄉(xiāng)下泥盆統(tǒng)向陽(yáng)寺組位于岡瓦納大陸與泛華夏大陸間昌寧—孟連結(jié)合帶北段西側(cè)。文章首次發(fā)現(xiàn)向陽(yáng)寺組中存在硅質(zhì)巖,并對(duì)其硅質(zhì)巖的地球化學(xué)特征等進(jìn)行了深入研究。硅質(zhì)巖中發(fā)育海百合莖、放射蟲(chóng)及硅藻。地球化學(xué)分析表明,向陽(yáng)寺組硅質(zhì)巖Si O2質(zhì)量分?jǐn)?shù)為85.43%~93.50%,Al/(Al+Fe+Mn)平均值為0.77,處于生物成因范疇;硅質(zhì)巖稀土元素分析結(jié)果為其REE總量平均值為53.208×10-6,稀土元素北美頁(yè)巖標(biāo)準(zhǔn)化配分曲線相對(duì)平坦,δCe平均值為1.02,δEu平均值為1.01,LaN/CeN平均值為0.99,LaN/YbN平均值為0.84,表明硅質(zhì)巖形成于近大陸邊緣的深海沉積環(huán)境。隨著早泥盆世昌寧—孟連洋的快速擴(kuò)張,保山地塊邊緣區(qū)域性同沉積斷裂發(fā)育,造成了更戛鄉(xiāng)向陽(yáng)寺組大面積的硅質(zhì)巖沉積。結(jié)合硅質(zhì)巖地球化學(xué)特征的分析與古生物研究,認(rèn)為更戛鄉(xiāng)向陽(yáng)寺組硅質(zhì)巖屬岡瓦納大陸保山地塊邊緣親昌寧—孟連古特提斯洋的深海沉積的產(chǎn)物。
[Abstract]:The Xiangyangsi formation of Lower Devonian system is located on the west side of Changning-Menglian combination belt between Gondwana continent and pan-China continent. In this paper, siliceous rocks are found in Xiangyangsi formation for the first time, and the geochemical characteristics of siliceous rocks are studied. The stem of sea lily, radiolaria and diatom are developed in siliceous rock. Geochemical analysis shows that the mass fraction of Si O 2 in siliceous rocks of Xiangyangsi formation is 85.43% and 93.50% Al / (Al Fe Mn) average is 0.77, which is within the scope of biogenesis. The results of REE analysis of siliceous rocks show that the average value of total REE is 53.208 脳 10-6, the normalized partition curve of REE North American shale is relatively flat, 未 Ce average is 1.02and 未 Eu average is 1.01L LaN / CeN mean value is 0.84, indicating that siliceous rocks were formed in near. The deep-sea sedimentary environment on the continental margin. With the rapid expansion of the early Devonian Shichang Ning- Menglian Ocean, the regional synsedimentary faults on the margin of Baoshan block developed, resulting in a large area of siliceous deposits in Xiangyangsi formation in the town of Gansa. Based on the analysis of geochemical characteristics of siliceous rocks and paleontological study, it is considered that the siliceous rocks of Xiangyangsi formation in Gangwang are the product of deep-sea deposits in the margin of the Baoshan block in Gondwana continent, from the Pro-Changning and Menglian paleoTethys oceans.
【作者單位】： 成都理工大學(xué)地球科學(xué)學(xué)院;四川省地礦局區(qū)域地質(zhì)調(diào)查隊(duì);
【基金】：四川省教育廳項(xiàng)目(80303-KZY006) 中國(guó)地質(zhì)調(diào)查局地質(zhì)調(diào)查工作項(xiàng)目(12120113048700) 成都理工大學(xué)國(guó)土資源部構(gòu)造成礦成藏重點(diǎn)實(shí)驗(yàn)室及成都理工大學(xué)礦物學(xué)、巖石學(xué)、礦床學(xué)國(guó)家重點(diǎn)(培育)學(xué)科聯(lián)合資助~~
【分類號(hào)】：P588.244

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