投稿时间：2016-08-30
修订日期：2016-10-27
网络发布日期：2017-01-04
中文摘要:中国大陆是由多个小陆块经多期次离散碰撞拼合而成，而“小陆块是否能成大钾”一直是国内钾盐研究领域关注的科学问题。文章剖析了意大利西西里微陆块的典型海相钾盐矿床形成条件与机理，为中国小陆块成钾研究提供借鉴。在晚中新世墨西拿盐度危机（Messinian Salinity Crisis）最盛期（5.60~5.55 Ma），西西里岛的卡尔塔尼塞塔盆地聚集了高达2亿t的钾盐镁矾矿。通过对卡尔塔尼塞塔盆地钾盐矿的赋存地层格架、矿体特征、成矿模式和机理进行梳理和总结，指出该矿床呈层状赋存于地中海“再沉积下石膏组”的原生石盐岩中，形成于深水、分层的常年性盐湖环境；晚中新世中地中海碰撞挤压的构造活动导致卡尔塔尼塞塔盆地强烈挠曲下凹，形成多个次级成矿凹陷；次级凹陷接受海水的周期性补给；在墨西拿盐度危机最盛期，由于气候变冷变干、直布罗陀海峡关闭、海平面急剧下降，远离补给源的次级凹陷变得更加封闭，从而在5万年的极短时间内经强烈蒸发，聚集为大规模钾盐矿。西西里微陆块尽管陆块小、盆地小，但在满足封闭构造-干旱气候-充足物源三要素耦合的特定时期内，同样形成了大型钾盐矿床。因此，西西里微陆块的钾盐成矿实例证明海相小陆块同样具有形成大型钾矿床的潜力，这对中国海相小陆块汇聚区的找钾工作具有重要的借鉴意义。
Abstract:Potash salt is one of the most required mineral resources in China; nevertheless, China's mainland is mainly composed of several microplates or small blocks which drifted, collided and coalesced together in different periods. Under this tectonic scheme, many scientists in China have doubted that whether large potash salt deposits could be formed in these microplates. During Messinian Salinity Crisis Acme (5.60~5.55 Ma), up to 2×108 t kainite, an available potash salt, was accumulated in the Caltanissetta Basin, the major foreland basin in Sicily, which was a typical marine microplate. In this study, based on exploring stratigraphic framework, orebody characteristics, mineralization pattern and mechanism of kainite in the Caltanissetta Basin, the authors have reached two conclusions. First, kainite was preserved in the primary halite, which was the chief evaporite of ‘Rresedimentary Lower Gypsum’ in the Caltanissetta Basin; kainite crystallized in deep, stratified, perennial saline marine setting, a rather saline pan environment. Second, late Miocene tectonic collision between African and Eurasia plates built flexural Caltanissetta Basin, and many sub-depressions were separated by intra-basinal anticlines, which provided pivotal reservoirs for late potash accumulation. During Messinian Salinity Crisis Acme (5.60~5.55 Ma), global climate became cold, leading to closure of Gibraltar gateway. Consequently, serious sealevel dropdown occurred in the middle Mediterranean Sea as well as in sub-depressions of the Caltanissetta Basin. Due to pulsed transgression and retreat of seawater in these sub-depressions, large quantities of kainite formed only in 50 ka (5.60~5.55 Ma). The potash-forming pattern and mechanism in Sicily suggest that even in small basins in microplate, large potash deposits could form if these basins meet the requirement of restricted setting, arid climate, and sufficient potassium input. The observation and research conducted by the authors shed a great deal of light on exploration and prospecting of potash salt in China.
keywords:geology Sicily microplate Late Miocene Messinian Salinity Crisis mineralization mechanism of potash salt
文章编号：
中图分类号：P619.21+1
文献标志码：
基金项目:本文为国家自然科学基金项目（编号：41302133）和国家重点基础研究发展计划“973”项目（编号：2011CB403007）资助成果
引用文本：
王九一,刘成林,沈立建.2016.典型小陆块海相成钾机理——以西西里微陆块钾盐矿床为例[J].矿床地质,35(6):1269~1280WANG JiuYi,LIU ChengLin,SHEN LiJian.2016.Mineralization mechanism of potash salt in typical marine microplate: An example from the Sicily microplate potash salt deposit[J].Mineral Deposits35(6):1269~1280
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