湘西南震旦地层的微量元素地球化学特征及其地质含义

湘西南震旦系是在“江口裂谷”作用下形成的一套特殊地层。长安组 (长安冰期 )、富禄组 (富禄间冰期 )和洪江组 (洪江冰期 )具有相同或相似的元素组合 (Cu、Pb、Zn、Co、Ni、V、Ti等元素组合正相关 )。他们的微量元素含量和主要组合特征对基底岩石 (高涧群 )具有继承性。从晚震旦世至早寒武世 ,元素Ag、As的相关模式基本相同 ,并且与元素Ba的相关模式曲线相似。还反映了大离子半径元素的热沉积的信息。V/Ni比值升高 ,Au、Ag趋向富集。说明晚震旦世晚期至早寒武世沉积盆地水体较深

REE GEOCHEMICAL CHARACTRISTICS OF SINIAN STRATA IN SOUTHWESTERN HUNAN AND THEIR GEOLOGICAL IMPLICATIONS

Rare-earth elements and depositional environments of the Sinian system in southwestern Hunan are discussed. The Sinian system is a unique sequence formed under the action of the "Jiangkou" rift. Identical or similar element assemblages (Cu, Pb, Zn, Co, Ni, V, Ti) are recognized in the Chang'an, Fulu and Hongjiang formations. The contents and assemblages of rare-earth elements have inherited from the basement rocks (Gaojian Formation).; From Late Sinian to Early Cambrian, Ag and As have the same correlation patterns, similar to Ba. There is developed thermo-deposition information about the "big ionic radius"elements. Au and Ag tend to enrich with V/Ni ratio, indicating a deeper water column during the Late Sinian-Early Cambrian.