Thermal Structure of Archean Cratons

这是一项关于大陆克拉通热结构的研究。这些调查将包括：(1)测量非洲中部和南部克拉通和裂谷地区的地面热流；(2)对非洲、北美洲、澳大利亚和印度克拉通地区及其周围的热流进行比较研究；(3)克拉通结构对区域热传输影响的数值模式研究。非洲热流测量计划以前主要集中在博茨瓦纳和纳米比亚，现在将扩展到津巴布韦、坦桑尼亚和扎伊尔。这些国家共同组成了稳定的太古宙克拉通地体和东非裂谷系统的元古界裂谷活动带。新的测量将提供更多的观测数据，用来检验厚厚的克拉通根部将地幔热量从太古代地体转移到更年轻的周围活动带的假设。来自北美、澳大利亚和印度太古代地形的热流数据也将在克拉通转移模型的背景下进行研究。克拉通和周围地形下面和内部的热传递的数值模型将检查(A)产生与通过温压测量确定的地表热流和地幔温度的观测一致的条件的参数范围，(B)克拉通尺度对转移机制的影响，以及(C)现在的条件与太古宙的条件的比较，当时的产热量比太古宙高2-3倍，但克拉通根部的温度与现在的值相似。

This is a study of the thermal structure of continental crations. The investigations will comprise (i) the measurement of terrestrial heat flow in both cratonic and rifted areas of central and southern Africa, (ii) comparative studies of the heat flow in and around the cratonic regions of Africa, North Amierica, Australia, and India, and (iii) numerical model studies of the effect of cratonic structure on regional heat transfer. African heat flow measurement program, previously focussed in Botswana and Namibia, will be extended into Zimbabwe, Tanzania, and Zaire. These countries collectively comprise both stable Archean cratonic terrains and rifted Proterozoic mobile belts of the East African Rift system. The new measurements will provide additional observations with which to test the hypothesis that thick cratonic roots devert mantle heat away from Archean terrains into younger surrounding mobile belts. Heat flow data from the Archean terrains of North America, Australia, and India will also be examined in the context of the cratonic diversion model. numerical models of heat transfer beneath and within cratonic and surrounding terrains will examine (a) the range of parameters that yield conditions consistent with observations of surface heat flow and mantle temperatures determined from thermobarometry, (b) the effects of cratonic scale on the diversion mechanism, and (c) the comparison of present day conditions to those in the Archean when heat production was 2-3 time greater, but temperatures in the cratonic root were similar to present-day values.