对《西藏高原雅鲁藏布江北岸蛇绿岩带的发现及其地质意义》一文的商榷

综合1：5万区调成果，系统阐述了赣西北地区双桥山群的沉积学特征，认为是一套形成于滨海－半深海环境的重力流沉积体系，基本发育－系列重力流沉积相单元，即块状混杂砾岩相，正递变砾岩相，经典浊积岩相等，对各单元基本层序特征进行了总结论述，并结合地球化学特征及粒度分析成果探讨了沉积环境。

Surface microscopic characteristics of quartz sand grains in the Paleogene Baoxiangsi Formation of Lijiang-Jianchuan area, northwestern Yunnan

Quartz sand grains have a variety of surface characteristics, which could be used as the main indicators of their depositional environment. In the present study, the surface characteristics of quartz sand grains were systematically analyzed on the basis of the samples from varying levels of the Baoxiangsi Formation (E2b) in Lijiang-Jianchuan area, Yunnan Province, by using electronic scan microscope. The results show that the grain surfaces of the samples from the lower part of the Baoxiangsi Formation have aqueous characteristics, those from the middle part have eolian characteristics, and those from the upper part have reworked eolian characteristics. It is thus concluded that the lower part is a proximal diluvial environment, the middle part is an eolian dune environment, and the upper part is a lake environment. Moreover, the quartz sand grains of the samples from the middle part are well sorted and rounded, and commonly have standard dish-shaped impact scars, crescent-shaped impact scars and frosted surface, suggesting typical desert sand sediments.