【摘要】 CCSD流体中He、N2、Ar是记录地震的敏感载体,可能记录了本地一些中小地震及远强震的异常信息。与远强震对应的流体异常幅度大,一般始于远强震前数天,且He、He／Ar、N2／Ar多为负异常,Ar多为正异常;而本地中小地震大多造成主孔流体组分的小幅度波动变化。远强震可能改变了CCSD钻探区的地下流体循环,地震期间监测到泥浆中相对富Ar贫N2和He的地下流体贡献增加,震后,地震引起的附加流体贡献逐渐消失。CCSD的流体组分和比值可能记录了区内地壳应力变化,反映了远强震期间区域构造活动乃至地球深部构造活动产生的场兆、源兆信息,地壳屈曲的假设可以加深CCSD流体作为远强震敏感载体的理解。远强震期间CCSD流体异常也可能是记录了震前长周期波传播至CCSD主孔时激发的流体变化,反映了震源区的应力变化。更多还原

【Abstract】 The concentration time series and first order differential curves of He, Ar, He/Ar and N2/Ar in the mud of the Chinese Continental Scientific Drilling Hole ( CCSD) show that all the earthquakes larger than 7. 5 around Asia and larger than 7. 0 up to 3000km away correspond to the fluid anomalies. The composition variations of gases seem to be correspondent to the occurrences of distant strong earthquakes. The He concentration, and the He/Ar and N2/Ar ratios showed obviously negative anomalies, however, the Ar concentration positive anomalies, several days before the distant larger earthquake occurred. Gaseous geochemical anomalies caused by the local moderate or small earthquakes didnt show obviously. The extraordinary Ar-rich or He-poor fluids may bring into the drilling mud before and during the occurrences of large earthquakes, but gradually disappear after the earthquakes. The gas geochemical anomalies might be a sensitive indicator for regional strain variations in crust related to regional or deep tectonic activities during the earthquake generations. The changes can be understood by the crustal buckling hypothesis. On the other hand, the variations of the concentrations and ratios of gas compositions might be triggered by the transmission of long period wave produced by the events.更多还原