北秦岭富水基性杂岩体岩石谱系单位划分及演化

DETERMINATION OF THE GLACIAL STAGE AND EPIGLACIAL STAGE AND ESTABLISHMENT OF THE TALAHULUN FORMATION IN NORTHWESTERN HEBEI

北秦岭富水基性杂岩体位于商丹断裂带北侧，为新元古代深成杂岩体。通过１∶５万地质填图将该杂岩体划分为５个岩石谱系单位：金盆中细粒变辉石岩单元、黑潭沟细粒暗色变辉长岩单元、马槽沟中粒变辉长岩单元、丁家沟中粒变辉长闪长岩单元和八里湾变角闪石黑云母二长岩、正长岩单元，合并为一个序列———富水序列。依据接触关系、包体特征确定了其侵入序次，构成了比较完整的岩浆演化序列，在岩石矿物组成、岩石化学成分、微量元素及稀土元素组成上具有明显的同源岩浆演化特征，形成于北秦岭新元古代活动大陆边缘的岛弧构造环境。

This paper describes glacial remains and the epiglacial phenomenon found for the first time in the Bashang area of northwestern Hebei. The glacial stage and epiglacial stage since the Middle Pleistocene have been determined and named the Talahulun glacial stage and Liujiaying epiglacial stage. The former may be correlated with the Lushan glacial stage, while the latter is equivalent to the late Dali'an glacial substage. The traditional view advocates that in the late Late Pleistocene, the climate in northern China was dry and cold, but a study of the epiglacial phenomenon indicates that there appeared a very humid cold stage in the late Late Pleistocene. The author has established a new lithostratigraphic unit—the Talahulun Formation, which is located above the Chicheng Formation and below the Malan Formation and whose age is late Middle Pleistocene.