我国东海陆架区新生代地层岩石生热率研究

Heat Generation of the Cenozoic Layer of East China Sea Shelf

岩石生热率是描述地球内热的一个重要的热物理参数。通过测定岩石样品的密度、放射性元素U、Th、K的含量可以定量计算地壳岩石的生热率。根据东海陆架多口钻井新生代地层样品、东海陆架表层样品和冲绳海槽柱状样品的密度、放射性元素U、Th、K含量对岩石生热率进行了计算。发现东海陆架地区地层岩石的生热率介于 0 .4～1.7μW /m3 之间 ,落于正常沉积岩生热率范围 ,比火成岩的生热率要高。同时 ,岩性对生热率起明显的控制作用 ,岩性不同 ,生热率不同。其中 ,泥岩的生热率最高 ,而粉沙岩、砂岩的生热率次之。东海区新生代地层的生热率由新到老生热率呈下降的趋势 ,但 ,其中玉泉组、龙井组和花港组地层生热率几乎一致。这和该地层的波速特征非常吻合。关系式lnA =1.0 4 - 0 .2 915vp 能够较好地描述东海陆架区新生代地层波速和生热率之间的关系。在已知地层层速度的情况下 。

Heat generation is an important thermal parameter used to describe the thermal status of the Earth.Only the rock sample density data,the abundance data of the radioative elements U,Th,K are used to calculate the heat generation of the rock sample. Drilling well sample and sea floor sample from East China Sea Shelf and core sample from Okinawa Trough were collected, and the heat generation of each sample was calculated based on the abundance of the radio elements of each samples. The results show that all the heat generation data of the Cenozoic layer of the East China Shelf are between 0.4～1.7μW/m 3,which is in the sediment heat generation data range and a little bit higher than that of igneous rock. We find that the lithology control's the heat generation, different rocks have different heat generation. Mudstone has highest heat generation comparing with siltstone and sandstone. The heat generation of the Cenozoic layer of East China Sea shelf is decreasing as the layer age become old. But the heat generation of the Yuquan group, Longjing group and Huagang group is almost the same that tallies with velocity rule of the three groups. The equation ln A =1.04-0.2915 v p, which is given by this paper, can describe the relationship between the heat generation and velocity well and can be used to calculate the heat generation on the Cenozoic Layer of the East China Sea Shelf when there is velocity data available.