南华北地区上古生界烃源岩异常热演化因素探讨

南华北地区上古生界分布广泛,烃源岩厚度稳定,有机质丰度高,多为Ⅱ₂—Ⅲ型。经历印支、燕山、喜山等多期差异性构造运动改造,致使烃源岩热演化程度参差不齐,这是南华北地区油气资源评价与勘探选区中至关重要的参数。从南华北地区上古生界烃源岩热演化特征入手,通过对造成上古生界烃源岩热演化异常的因素分析,认为南华北地区上古生界烃源岩异常热演化以深成热变质作用为主,中生代普遍发生的地壳热隆升造成了上古生界烃源岩热演化具有南北分区的特点,中生代以来的岩浆作用是造成局部地区热演化程度较高的根本原因,区域动力变质作用及重力滑动作用对热演化具有一定的促进作用。南华北地区上古生界有效油气资源分布于围绕现今高演化区的边缘带,即洛阳伊川—巨陵襄城—鹿邑—谭庄沈丘—倪丘集—颜集等地区,是南华北地区上古生界油气勘探的有利地区。 

Reasons for abnormal thermal evolution of source rocks in Upper Paleozoic, southern North China

The Upper Paleozoic is widely distributed in southern North China with thick source rock and high organic abundance, mainly Ⅱ₂-Ⅲ type. Multiple stages of deformation during Indosinian, Yan-shanian and Himalayan resulted in the differences in thermal evolution degree between source rocks, which was the key factor for petroleum resource evaluation and exploration target identification in southern North China. Based on thermal evolution characteristics of source rocks in the Upper Paleozoic of the study area, the reasons for abnormal thermal evolution were found out, mainly hypozoic thermal metamorphism. Crust uplift during Mesozoic resulted in the south and north division of thermal evolution of source rocks in the Upper Paleozoic. Magmatism ever since Mesozoic was the root cause for regional high-degree thermal evolution. Regional dynamometamorphism and gravitational sliding also helped thermal evolution. Industrial petroleum resources in the Upper Paleozoic are mainly found around the edge of high thermal evolution zone, such as Yichuan of Luoyang-Xiangcheng of Juling-Luyi-Shenqiu of Tanzhuang-Niqiuji-Yanji. They are the regions favorable for Upper Paleozoic petroleum exploration in southern North China.