论文部分内容阅读
应用岩石组合及元素地球化学组合特征,已经能够较成熟的研究区域构造—岩浆演化过程,界定区域构造演化的时空界限。双峰式火山岩组合可形成于不同的大地构造背景下,笔者对不同的大地构造背景形成的双峰式火山岩的岩石学和地球化学特征进行了总结,针对在博格达造山带发现的双峰式火山岩,讨论其对构造—岩浆演化指示作用。博格达双峰式火山岩岩石组合及元素地球化学特征表明:裂谷作用始于早石炭世,结束于晚石炭世晚期或早二叠世早期。博格达裂谷作用存在东西时空差异性,根据裂谷演化早期双峰式火山岩的空间及东西天山在石炭纪火山活动的的差异,推断博格达西段裂谷作用稍微早于东段开始,但由于区域构造演化差异,裂谷演化程度东段强于西段,而东段可能早于西段裂谷闭合。
With the combination of rock assemblages and elemental geochemistry, it has been possible to study the regional tectonic-magmatic evolution more maturely and to define the temporal and spatial boundaries of regional tectonic evolution. The bimodal volcanic assemblage can be formed under different tectonic settings. The author summarizes the petrological and geochemical characteristics of bimodal volcanic rocks formed by different tectonic settings. In view of the bimodal found in the Bogda orogen Volcanic rocks, discussing their role in tectono-magmatic evolution. The Bogda bimodal volcanic rock assemblages and elemental geochemical characteristics show that the rifting began in the Early Carboniferous and ended in the Late Carboniferous or early Early Permian. According to the space of the bimodal volcanic rocks in the early rift evolution and the difference of the volcanic activities in East and West Tianshan during the Carboniferous volcanism, it is concluded that the rifting in the western part of Bogda is slightly earlier than the eastern part However, due to the differences in regional tectonic evolution, the extent of rift evolution is stronger in the eastern segment than in the western segment, while the eastern segment may be closed earlier than the western rift.