海洋地壳辉长岩层中晶体颗粒大小随深度分布的初步探讨

A PRELIMINARY STUDY OF DEPTH DISTRIBUTION OF CRYSTAL SIZES WITHIN THE GABBRO LAYER OF THE OCEANIC CRUST

通过海洋地壳生成模型得到的典型快速扩张的太平洋中脊处海洋地壳内的热结构和速度场 ,推算出海洋地壳内的辉长岩层上、下组的成岩时间存在大于一个数量级的差异 (成岩时间是指岩浆降温到某一指定温度时所经历的时间 ) .并试图用这个结果来解释在Oman蛇绿岩套辉长岩层野外实际观测得到的结论 :海洋岩石圈底部的辉长岩的结晶颗粒大小的平均值要比浅部辉长岩结晶颗粒大小的平均值高出一个数量级 .

The present crustal accretion model at a fast spreading ridge predicts at least an order of magnitude difference on average in the crystallization time, the time for a crystal to cool itself to a given temperature, between the upper gabbros and lower gabbros. As a consequence, lower gabbros of the oceanic crust could have a larger crystal grain size on average than that of the upper gabbros as seen from the filed observations at the Oman ophiolite.