本文關(guān)鍵詞：表生環(huán)境中鎂同位素的地球化學(xué)循環(huán)　出處：《地球科學(xué)進(jìn)展》2016年01期 　論文類型：期刊論文

  更多相關(guān)文章： 鎂同位素 風(fēng)化作用 碳酸鹽巖沉淀 水巖反應(yīng) 地球化學(xué)循環(huán)

【摘要】：近些年表生環(huán)境中鎂同位素分餾取得了一系列重要研究進(jìn)展,這些新認(rèn)識(shí)為深入理解表生環(huán)境中鎂同位素地球化學(xué)循環(huán)奠定了基礎(chǔ)。表生環(huán)境中鎂同位素的地球化學(xué)循環(huán)主要涉及風(fēng)化、河流搬運(yùn)、碳酸鹽沉淀、水巖反應(yīng)等重要地質(zhì)過程。風(fēng)化過程中鎂同位素發(fā)生顯著分餾,硅酸鹽風(fēng)化產(chǎn)物中富集重的鎂同位素,輕的鎂同位素易進(jìn)入水體。河流搬運(yùn)過程中,鎂同位素不發(fā)生分餾,但外源輸入可能影響水體的鎂同位素組成。河水匯入海洋后,碳酸鹽沉淀過程可導(dǎo)致輕的鎂同位素以碳酸鹽的形式從海水中移出。在海底高溫水巖反應(yīng)過程中,海水中絕大多數(shù)的鎂(80%~87%)都進(jìn)入巖石,循環(huán)后的熱液可能富集輕的鎂同位素。海底低溫水巖反應(yīng)過程中海水的鎂可以進(jìn)入巖石并形成次生礦物,此過程的鎂同位素分餾主要與次生礦物的形成有關(guān)。此外,海水中的鎂易與黏土礦物發(fā)生交換反應(yīng),此過程黏土礦物傾向于吸附輕的鎂同位素�？傊�,在表生環(huán)境中上地殼的鎂(δ26Mg約為-0.22‰)經(jīng)歷風(fēng)化作用、河流搬運(yùn)、海洋貯存,最終以碳酸鹽巖(δ26Mg一般小于-1‰)或與玄武巖發(fā)生反應(yīng)的形式重新回到巖石圈。
[Abstract]:In recent years, a series of important research progresses in magnesium isotope fractionation in epigenetic environments have been made. These new understandings provide a basis for further understanding of the magnesium isotope geochemistry cycle in the epigenetic environment. The geochemical cycles of magnesium isotopes in the epigenetic environment are mainly related to the important geological processes such as weathering, river transport, carbonate precipitation, water rock reaction and so on. During the weathering process, the isotopes of magnesium are fractionated, and the heavy magnesium isotopes are enriched in the weathering products of the silicate, and the light magnesium isotopes are easy to enter the water body. In the process of river transportation, the isotopes of magnesium are not fractionated, but exogenous input may affect the composition of magnesium isotopes. After the river flows into the ocean, the carbonate precipitation process can lead to the removal of light magnesium isotopes from the sea water in the form of carbonate. In the process of high temperature water rock reaction in the sea bottom, most of the magnesium (80%~87%) in the sea water enters the rock, and the circulating hydrothermal solution may enrich the light magnesium isotopes. In the process of submarine low temperature water rock reaction, magnesium in seawater can enter the rock and form secondary minerals. The magnesium isotope fractionation in this process is mainly related to the formation of secondary minerals. In addition, magnesium in seawater is easily exchanged with clay minerals, and clay minerals tend to adsorb light magnesium isotopes. In conclusion, in the epigenetic environment, the upper crust magnesium (delta 26Mg is about -0.22 per thousand) has undergone weathering, river transportation and marine storage, and finally returned to the lithosphere with carbonate (delta 26Mg generally less than -1 per thousand) or basalt reaction.
【作者單位】： 中國地質(zhì)科學(xué)院地質(zhì)研究所國土資源部同位素地質(zhì)重點(diǎn)實(shí)驗(yàn)室/大陸動(dòng)力學(xué)國家重點(diǎn)實(shí)驗(yàn)室;
【基金】：國家自然科學(xué)基金項(xiàng)目“遼東裂谷帶菱鎂礦鎂同位素特征及其對(duì)礦床成因的制約”(編號(hào):41203004) 國土資源部行業(yè)專項(xiàng)基金項(xiàng)目“Fe;Mg同位素在遼東裂谷帶菱鎂礦及硼鎂鐵礦中的應(yīng)用研究“(編號(hào):201211074)資助~~
【分類號(hào)】：P597
【正文快照】： 1引言鎂是主要的造巖元素,也是動(dòng)植物所必需的生命元素,主要富集于地幔中,在地殼、水體和生物體中也廣泛分布。鎂可富集于巖漿過程早期結(jié)晶的礦物中(如橄欖石、輝石等),易在風(fēng)化過程中以鎂離子的形式進(jìn)入水體。經(jīng)水體搬運(yùn)至海洋后,可通過碳酸鹽的形式沉淀或在水巖反應(yīng)過程中從，

本文編號(hào)：1340847