本文選題：黔東南 + 下江群　； 參考：《地質(zhì)論評(píng)》2017年05期

【摘要】：黔東南下江群是一套具復(fù)理石特征的陸源碎屑巖夾火山碎屑巖建造,由下向上分別為甲路組、烏葉組、番昭組、清水江組、平略組和隆里組。本文研究了該套巖石的主量元素、微量元素和Nd同位素特征。結(jié)果顯示:下江群各個(gè)組樣品均顯示出不同程度的Co、La、Ce、Nd、Y和Lu元素的富集,Ta和Ni元素虧損以及明顯的Eu負(fù)異常,ε_(tái)(Nd)(t)表現(xiàn)出負(fù)異常(ε_(tái)(Nd)(t):-0.35~-3.36)。巖石地球化學(xué)特征顯示源巖以遭受了中等程度化學(xué)風(fēng)化作用(CIA:52~79)的酸性巖為主,并混有適量的基性巖。結(jié)合已有研究成果,判斷物源區(qū)主要以盆地周緣的近源沉積為主,如分布在桂北一帶的花崗質(zhì)巖石和基性巖。構(gòu)造背景判別表明盆地處于與島弧活動(dòng)相關(guān)的活動(dòng)大陸邊緣背景,如此的構(gòu)造背景暗示,江南造山帶西段在下江群沉積期可能仍存在消減作用,揚(yáng)子板塊與華夏板塊此時(shí)還未完全拼合。綜合對(duì)比江南造山帶東、西兩段消減—碰撞的時(shí)間,暗示揚(yáng)子板塊和華夏板塊之間可能具有一個(gè)"東早西晚"的碰撞造山過(guò)程。
[Abstract]:The Lower Yangtze Group in the southeast of Guizhou is a set of continental clastic rocks with the characteristics of clastic rocks and volcanic clastic rocks. The lower ones are respectively Jialu formation, Wuye formation, Fanzhao formation, Qingshuijiang formation, Pinglio formation and Longli formation. In this paper, the main elements, trace elements and ND isotopic characteristics of this set of rocks are studied. The results show that the samples of each group of Xiajiang Group show different degrees of enrichment of elements Coe LaCeCe NdCY and Lu, and the depletion of Ta and Ni elements, as well as the obvious negative EU anomaly, and the negative anomaly of 蔚 _ S _ T _ N _ D _ T _ t (蔚 _ S / N _ D _ T _ T ~ (-1): -0.35 ~ (-3.36) ~ (-1) ~ (-1) ~ (-0.35) ~ (-3.36) ~ (-1)). The petrogeochemical characteristics show that the source rocks are mainly acidic rocks with moderate chemical weathering and mixed with some basic rocks. In combination with the existing research results, the source area is mainly determined by the near-source deposits around the basin, such as granitic rocks and basic rocks distributed in the northern part of Guangxi. Tectonic background discrimination indicates that the basin is in the active continental margin background associated with island arc activity. Such a tectonic setting suggests that the west segment of the Jiangnan orogenic belt may still have subtractive effects during the sedimentary period of the Lower Yangtze Group. Yangtze plate and Huaxia plate at this time has not been fully combined. Comparing the time of subtractive collision between east and west sections of Jiangnan orogenic belt, it is suggested that there may be a collision orogenic process between Yangtze plate and Huaxia plate.
【作者單位】： 中國(guó)地質(zhì)大學(xué)地球科學(xué)學(xué)院;貴州省地質(zhì)礦產(chǎn)勘查開(kāi)發(fā)局;
【基金】：國(guó)家自然科學(xué)基金資助項(xiàng)目(編號(hào):41472086,41772106)的成果~~
【分類(lèi)號(hào)】：P542;P588.21

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