安第斯埃达克岩 :三种成因模式   总被引：37，自引：31，他引：37  

Robert W KAY  Suzanne Mahlburg KAY 《岩石学报》2002,18(3):303-311

在安第斯埃达克岩是常见的。由这种岩石的痕量元素特征揭示的高压组成矿物 ,表明其有三种可能的成因。这三种成因按相对重要性依次为 :安第斯地壳的构造加厚 ;弧前壳的俯冲 -侵蚀 ;年轻洋壳的俯冲。在过去 30 Ma,每种成因模式的埃达克岩在智利 -阿根廷安第斯地区均有喷发。它们的产状与智利 -阿根廷边缘快速变化的构造背景中特定构造条件和事件相吻合。埃达克岩在过去安第斯边缘的产状可望成为矿化的优异构造标志 ,也可用于指导找矿  相似文献   

广西、四川等西南地区地面塌陷成因分析     

冯跃封 《城市地质》2011,6(1):37-39,63

我国西南地区频繁发生的＂天坑＂现象,在给当地居民生产生活造成较大损失的同时,引起了人们对重大自然灾害的恐慌。广西、四川等西南地区频繁出现的＂天坑＂确切地说是人为活动引起的地面塌陷地质灾害。  相似文献   

Comparison of taxonomic diversity,strontium isotope and sea-level patterns     

Edward G. Purdy 《International Journal of Earth Sciences》2008,97(3):651-664

Sepkoski’s compendium of 28,730 marine genera was analyzed with a view toward comparing taxonomic diversity, strontium isotope stratigraphy and sea-level changes. The fossil record analyses discriminated between origination, extinction and pass through genera and collectively delineated changes in number of genera with time at the largely stratigraphic stage level. With notable exceptions of the Cretaceous and Tertiary, taxonomic diversity generally paralleled both strontium isotope stratigraphy and sea-level changes. Sampling bias was suggested in the Tertiary where an increase in genera numbers toward the Recent opposed the downward trends of both strontium isotope and sea level curves. The removal of all Recent genera from the Sepkoski database confirmed the bias in producing complimentary downward trends in all curves. Regression analysis of taxonomic diversity with respect to sea level extent and time duration explained 82% of the variability of the remaining data. Sea-level fluctuations are not always accompanied by significant changes in taxonomic diversity but strontium isotope analyses offers the potential of constraining the extent to which the magnitude of changes are associated with time duration.  相似文献