四川地质学报

为研究汉中天坑群集中分布区二叠系、三叠系灰岩岩石特征及沉积环境，对区内二叠系阳新组、吴家坪组灰岩段及三叠系大冶组进行了详细的野外调查；利用电感耦合等离子体质谱仪以及工业分析等方法对该区各组岩石的微量元素地球化学特征进行分析。研究结果显示：汉中天坑群集中分布区阳新组及吴家坪灰岩段整体处于还原环境，仅在少部分时期处于贫氧环境；大冶组整体处于贫氧-缺氧环境。阳新组、吴家坪灰岩段及大冶组沉积时期均为干燥炎热气候。通过天坑四个集中分布区Sr/Ba、U/Th及Sr/Cu值的对比，得出阳新组沉积时期古盐度及受海水影响程度：西乡地区>南郑地区>宁强地区>镇巴地区；宁强及西乡地区处于还原环境，且还原性较南郑及镇巴地区略强；南郑及西乡地区气温相近，宁强及镇巴地区气温较前者有所降低。吴家坪灰岩段沉积时期，古盐度及受海水影响程度:南郑地区>宁强地区>西乡地区>镇巴地区；宁强及西乡地区该时期处于还原环境，且还原性较南郑及镇巴地区略强；南郑地区气温大于西乡地区，宁强及镇巴地区气温较前者有所降低。大冶组沉积时期，大冶组下段古盐度及受海水影响程度大于上段；大冶组下段还原性大于上段；大冶组下段至上段气温有所下降。

To study the rock characteristics and sedimentary environment of the Permian and Triassic limestones in the concentrated distribution area of the Hanzhong sinkhole group, a detailed field investigation was conducted on the Permian Yangxin Formation, Wujiaping Formation Limestone Member, and Triassic Daye Formation. The geochemical characteristics of trace elements in each group of rocks in this area were analyzed by means of Inductively Coupled Plasma Mass Spectrometry(ICP-MS) and industrial analysis. The research results show that the Yangxin Formation and Wujiaping limestone section in the concentrated distribution area of the Hanzhong sinkhole group are generally in a reducing environment, and only in a few periods are they in an oxygen-poor environment; while the Daye Formation as a whole was in an oxygen-poor to anoxic environment. The sedimentary periods of the Yangxin Formation, the Wujiaping limestone section and the Daye Formation were all dry and hot climates. By comparing the Sr/Ba, U/Th and Sr/Cu values in the four concentrated distribution areas of the sinkhole, the paleosalinity and the degree of marine influence during the sedimentary period of the Yangxin Formation were determined as follows: Xixiang Area > Nanzheng Area > Ningqiang Area > Zhenba Area. The Ningqiang and Xixiang areas were in a reducing environment, and their reducibility was slightly stronger than that of the Nanzheng and Zhenba areas. The temperatures in Nanzheng and Xixiang areas are similar, while those in Ningqiang and Zhenba areas are slightly lower than the former. During the sedimentary period of the Wujiaping Formation Limestone Member, the paleosalinity and the degree of marine influence were in the order of: Nanzheng Area > Ningqiang Area > Xixiang Area > Zhenba Area; the Ningqiang and Xixiang areas were in a reducing environment during this period, and their reducibility was slightly stronger than that of the Nanzheng and Zhenba areas; the temperature in Nanzheng Area was higher than that in Xixiang Area, while the temperatures in Ningqiang and Zhenba areas were lower than the former two areas. During the sedimentary period of the Daye Formation, the paleosalinity and the degree of marine influence in the lower section were greater than those in the upper section; the reducibility of the lower section of the Daye Formation was stronger than that of the upper section; temperatures decreased from the lower to the upper section of the Daye Formation.