The andesite clasts were most likely derived from erosion of igneous rock in middle jurassic time , and the limestone clasts were derived from cambrian and ordovician strata . dolomite clasts were derived from the middle proterozoic jixian group 安山岩砾石是中侏罗统髫髻山组火山岩剥蚀的产物，灰岩砾石来自于寒武、奥陶系灰岩，白云岩砾石主要来自于蓟县系白云岩。
2.
During the yanshanian phrase , the area is in the condition of contractional background , with multi - staged tectonic reversion . 5 . through studying the origin of volcanic rocks and the characteristics of magma evolution , it concludes that there exist 3 originated areas of magma - from mantle , crust , and mantle - crust exchange . the basic magma of nandaling volcanic rocks of early jurassic is derived from upper mantle ; the magma of tiaojishan volcanic rocks of mid jurassic is formed in the contractional tectonic setting , and derived from the transition zone of crust and mantle interaction ; the acid magma of l 5 、通过岩石化学、微量元素、稀土元素的研究，探讨了不同级别节律的火山岩成因、岩浆演化等特征，认为本区燕山期火山岩有三个岩浆源区，即地幔源、地壳源和壳幔混源，早侏罗世的南大岭旋回的基性岩浆，起源于上地幔；中侏罗世髫髻山旋回火山岩是在相对挤压环境中，岩浆起源于壳幔过渡带；晚侏罗世无负eu异常的酸性岩浆来源于下地壳的古老结晶基底的局部熔融，有负eu异常的酸性岩浆来源于上地壳的局部熔融；早白垩世火山岩基性岩浆起源于上地幔，中性岩浆起源于下地壳底部的壳幔过渡带。
