论文部分内容阅读
太古代地质研究中争论很大的问题之一是有否板块构造作用.Bickle(1978)提出,由太古代变质岩得到的相对冷平衡热梯度,要求太古代时因快速的板块构造作用引起大量的热损耗.但是,相反,因为比较热而薄的、年青的洋壳板块难以俯冲.所以板块的迅速产生和俯冲受到了限制.已经有人论证太古代洋壳的主要组分很可能是科马提岩,和绿岩带有相似性.这意味着幔源熔岩的喷发温度约1650℃,它要求较流圈顶部温度约1700℃,可与根据Gorgona岛的科马提岩推测的约1350—1400℃的现值进行对比.另一方面,Davies(1979)已有力地论证了晚太古代地幔温度仅比现值高150℃左右.不论哪一种情况(Tast=1700℃或Tast=1500℃),
One of the most controversial issues in Archean geology is whether there is tectonic plate tectonics.Bickle (1978) suggested that the relative cold balance thermal gradients obtained from Archean metamorphic rocks require a large amount of However, on the contrary, due to the relatively hot and thin, young oceanic plate is difficult to subduction, so the rapid plate production and subduction has been restricted.It has been argued that the main component of the Pacific Ocean is likely to Cooma There are similarities between the rock and the greenstone, which means that the mantle source lava has an eruptive temperature of about 1650 ° C, which requires about 1700 ° C at the top of the sag, and can be compared with the estimated ca. 1350- On the other hand, Davies (1979) has strongly argued that the temperature of the late Archean mantle is only about 150 ° C higher than the present value. In either case (Tast = 1700 ° C or Tast = 1500 ° C ),