中国大陆科学钻探主孔揭示的大陆地壳生热模型  

Heating generation model for the continental crust based on the main hole of the Chinese Continental Scientific Drilling Project

作　　者：何丽娟[1] 胡圣标[1] 杨文采[2] 汪集旸[1] 杨树春[1] 袁玉松[1] 程振炎[2] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国地质科学院地质研究所,北京100037

出　　处：《岩石学报》2006年第11期2808-2814,共7页Acta Petrologica Sinica

基　　金：国家重点基础研究发展计划(973)项目(2003CB716505)资助.

摘　　要：本文对大陆科学钻探主孔149块岩心样品进行了系统的岩石放射性生热元素 U、Th 和 K 的含量测试,同时结合该井浅部井段前人的实测数据,揭示了上地壳5km 生热率的垂向分布。结果显示,以1650m 为界,上下两段生热率均随深度呈增加趋势,与正常地壳生热率特征不同,显示出超高压变质带独特的生热率垂向变化特征。结合地壳的岩性分布,建立了苏鲁超高压变质带地壳的生热模型。该模型中,地壳厚32km,其中上地壳0～10km,由超高压变质岩片组成,按岩性又详细分为8层,生热率变化在0.49～1.73μWm^(-3)。中地壳10～20km,由片麻岩组成,生热率为生热率1.51μWm^(-3)。下地壳20～32km为麻粒岩,生热率0.31μWm^(-3)。整个地壳热流约31mw/m^2,其中上地壳12mW/m^2。上地壳厚度和热流分别占整个地壳的31%和39%。与华北和下扬子地壳生热模型相比,上地壳热流整个地壳热流的比例最低。这表明,苏鲁超高压变质带,作为中朝与扬子板块俯冲-碰撞的产物,其地壳生率垂向分布与正常大陆地壳(华北、下扬子)相比,具有显著的不同。Systemic measurements on the concentrations of the radiogenic elements U, Th and K for the 149 core samples obtained from the main drilling hole of the Chinese Continental Scientific Drilling Project （ CCSD ） have been perforoaed. Combined with the previously published data at shallow depth in the same hole, a detailed vertical distribution of heat generation is provided for the uppermost 5km of the crust. Within two depth intervals, above 1650m and 1650 - 5000m, the heat generation increases with depth respectively. It indicates a specific pattern of heat generation distribution that is different from the normal continental crust. Based on the measurements together with the lithological layers of the crust, this paper presents a heat generation model for the crust of the Sulu ultra-high pressure metamorphic belt. In this model, the crust is 32km thick, including three layers. The upper crust （0 - 10km） is composed of ultra-high pressure metamorphic rocks. It is divided into several sub-layers in detail, and the heat generation varies from 0. 49μWm^-3 to 1. 73 μWm^-3 The middle crust （10 -20 km） is comprised mainly of the gneiss with a heat generation of 1.51 μWm^-3 The lower crust （20 -32km） is granulite with a heat generation of 0. 31μWm^-3 The total crust heat flow is 31 mW/m^2, and only 39% comes from the upper crust, which is much lower than the normal continental crust such as the North China craton and the lower Yangtze area. It indicates that the vertical distribution of heat generation in the Sulu ultra-high pressure metamorphic belt, formed by the collision between Sino-Korea and Yangtze cratons, is different from the normal crust such as the North China and Lower Yangtze cratons.

关 键 词：生热率 地壳生热模型 中国大陆科学钻探工程 

分 类 号：P314.3[天文地球—固体地球物理学]