本文選題：海綠石 + 海水氧化還原狀態(tài)��； 參考：《地學(xué)前緣》2016年06期

【摘要】：顯生宙的海綠石主要形成于具低沉積速率的外陸架至上斜坡深水環(huán)境,而前寒武紀(jì)海綠石則多見于具高沉積速率的淺水環(huán)境。為揭示導(dǎo)致這種明顯差別的主要環(huán)境控制因素,本文對華北中元古代鐵嶺組疊層石礁內(nèi)發(fā)育的海綠石進(jìn)行了包括野外觀察、巖相學(xué)和XRD、SEM、EDS、ICP-MS分析在內(nèi)的綜合研究。據(jù)海綠石的分布位置和基質(zhì)孔隙度特征,本文將鐵嶺組自生海綠石分為3種類型:類型Ⅰ產(chǎn)于孔隙最發(fā)育的疊層石柱和微晶基質(zhì)交接帶,類型Ⅱ位于較少孔隙的基質(zhì)中,類型Ⅲ常見于致密的疊層石柱體內(nèi)。這三種類型的海綠石都具有高且穩(wěn)定的K_2O含量(平均8%),指示孔隙水具有高K~+離子濃度。從Ⅲ型至Ⅰ型海綠石,Fe_2O_3含量逐漸升高,而Al_2O_3含量逐漸降低,表明基質(zhì)孔隙度對海綠石演化具有控制作用,海綠石的成熟度演化需要Fe的持續(xù)補(bǔ)充。由于疊層石碳酸鹽巖明顯缺乏陸源碎屑輸入,因此Fe可能主要來自海水,要求存在很淺的Fe氧化還原界面,這也得到了碳酸鹽巖中Ce異常證據(jù)的支持。我們認(rèn)為多孔的基質(zhì)、高K~+濃度以及次氧化海水條件是促進(jìn)中元古代淺水海綠石沉淀和演化的重要環(huán)境因素。
[Abstract]:The Precambrian glauconite is mainly formed in the deep-water environment of the upper slope of the outer shelf with low deposition rate, while the Precambrian sea greenstone is more common in the shallow water environment with high deposition rate.In order to reveal the main environmental control factors leading to this obvious difference, a comprehensive study including field observation, petrography and the analysis of XRDSEMN EDSICP-MS has been carried out on the mesoproterozoic stromatolites in the Middle Proterozoic Tieling formation of North China.According to the distribution location and matrix porosity characteristics of glauconite, this paper classifies Tieling formation as three types of authigenic glauconite: type I occurs in the intersecting zone between the most developed stony column and microcrystalline matrix, and type 鈪，

本文編號：1738028