80年代中期以来,地质学家在地球上一些被称做“造山带”的地方发现,一些典型的地壳岩石含有一种密度很大的矿物——柯石英。这一发现使得地球科学家们大感意外。因为以往只在一些由深部岩浆携带上来的“地慢碎块”中有柯石英的记录,人们认为在构成地壳的其他岩石中不可能出现柯石英。柯石英和石英的化学组成都是二氧化硅,但是前者的密度比后者大将近10％。要使地壳岩石中常见的石英转变为柯石英,需要很高的压力。这样的压力只有在地幔内大约一百公里以下才会普遍存在。正常地壳只有几十公里厚,除了巨型陨石撞击,一般不能产生这样大的压力。有关 Since the mid-1980s, geologists have discovered on some of the Earth’s so-called “orogenic belts” that some of the typical crustal rocks contain a dense mineral called coesite. This discovery made the earth scientists surprised. Because in the past only some of the “slow fragments” carried by deep magmas contain coesite records, it is believed that coesite could not be found in other rocks that make up the crust. The chemical composition of coesite and quartz is silica, but the density of the former is nearly 10% larger than the latter. It takes a lot of pressure to convert the quartz that is common in crustal rocks to coesite. Such pressure will prevail only about a hundred kilometers below the mantle. Normal crust is only tens of kilometers thick, in addition to meteorite impact, generally can not produce such a big pressure. related