新元古代“雪球”事件对海水碳、硫同位素组成的影响  

The Effects of the Neoproterozoic Snowball Earth on Carbon and Sulfur Isotopic Compositions in Seawater

作　　者：张同钢[1] 储雪蕾[1] 冯连君[1] 张启锐[1] 郭建平[2] 

机构地区：[1]中国科学院地质与地球物理研究所,国矿物资源研究重点实验室,北京100029 [2]中国地质大学,北京100083

出　　处：《地球学报》2003年第6期487-493,共7页Acta Geoscientica Sinica

基　　金：国家自然科学基金项目 ( 4 9973 0 0 8;40 172 0 15 );中国科学院创新工程项目资助

摘　　要：在新元古代晚期地球上曾发生过全球性的冰川作用 ,一些学者称之为“雪球”事件。在新元古代“雪球”事件前后 ,古海水的C、S同位素组成都出现了非常大的变化 ,在“雪球”之前海水中的碳酸盐非常富集13 C ,在“雪球”期间和紧随其之后贫13 C ,然后δ13 C值出现了高达 10‰的正漂移 ;在“雪球”开始之前古海水硫酸盐的δ3 4 S值呈逐渐降低的变化特征 ,紧随“雪球”之后古海水硫酸盐的δ3 4 S值出现了超过 2 0‰的正漂移 ,达到地质史上的最高值 ,同期形成的硫化物具有异常高的δ3 4 S值。“雪球”事件前后古海水C、S同位素组成的大幅度变化 ,是由“雪球”前后全球环境的剧烈变化引起的。“雪球”前后海水C、S同位素的大幅度变化是与“雪球”有关的特殊环境条件作用的结果 ,也是“雪球”Global glaciations took place in the earth in Neoproterozoic, which are called the “Snowball Earth” event by some scho-lars. Seawater carbon and sulfur isotopic compositions experienced considerable variations near the Snowball Earth event. The carbo-nate in seawater was remarkably enriched in 13C before the Snowball Earth and was subjected to 13C depletion during and after the Snowball Earth event. Then,δ 34S values of carbonates underwent an obvious positive drift to +10‰. The δ 34S values of seawater sulfate got gradually lower before the Snowball Earth event. There was large positive drift of δ 34S values which exceeded +20‰ and reached the climax as soon as the snowball Earth was over. The synchronous sulfides had ultra-high δ 34S values. These striking variations of carbon and sulfur isotopic compositions in seawater were caused by the drastic change of the environment near the Snowball Earth. These variations of seawater carbon and sulfur isotopes resulted from the effect of the Snowball Earth, which can be regarded as the evidence of the existence of the Snowball Earth event.

关 键 词：元古代 “雪球”事件 海水 碳 硫 同位素 

分 类 号：P734.24[天文地球—海洋化学]