A study of the carbonaceous matter in carbonaceous chondrites for evaluating the degree of alteration/thermal metamorphism in meteorite parent bodies.

1.硫K边XAFS分析结果表明：（1）CM球粒陨石的典型XAFS谱显示了无机硫化物、硫酸盐和噻吩类（有机硫）杂质的富集;（2）CV（阿连德）和CO（奥尔南斯）的吸收光谱缺少硫酸根和噻吩的吸收，说明母体与CM的吸收光谱不同。（3）未加热或弱加热的碳酸盐的光谱显示出较强的噻吩吸收。（4）根据噻吩吸收的强度，可将样品分为以下几类：Ⅰ弱吸收，对应于强加热的碳酸盐; Ⅱ与硫化物吸收相当，对应于未加热或仅弱加热的碳酸盐;（5）塔吉什湖显示出相对较强的噻吩吸收，相对较弱的硫酸盐吸收是该样品的另一个特征。（6）实验室加热的Muchison样品的XAFS谱中缺少硫酸盐和噻吩类的结构，说明这些结构在加热过程中已经丢失。（7）对XAFS谱的定量处理表明，未加热或弱加热的玄武岩可分为两个亚类。2.利用同步辐射X射线衍射技术，确定了狭山中的矿物和筑波玄武岩中的CI样碎屑。筑波球粒陨石中的碎屑未被加热超过500℃，而狭山的氧同位素分析表明其在蚀变过程中经历了比Murchison等其他CM球粒陨石更高的温度（超过120℃）。

1.Sulfur K-edge XAFS analysis of the chondrites shows the following results :(1)A typical XAFS spectrum of a CM chondrite shows the absorptions of inorganic sulfide, sulfate, and thiophenic (organic sulfur) absorptions.(2)The spectra of the CV (Allende) and CO (Ornans) chondrites lack in the sulfate and thiophenic absorptions, indicating the difference of parenrt bodies from the CM chondrites.(3)The spectra of unheated or weakly heated chondrites show relatively strong thiophenic absorption.(4)Based on the intensity of thiophenic absorption, the samples can be classified into the following groups : I Weak, corrssponds to strongly heated chondrites, II Comparable to the sulfidic absorption, corresponds to unheated or only weakly heated chondrites, III CV and CO chondrites.(5)Tagish Lake shows relatively strong thiophenic absorption, and relatively weak sulfate absorption is another characteristic of this sample.(6)The XAFS spectrum of the Muchison sample heated in laboratory lacks in the sulfate and thiophenic absorptions, suggesting such partial structure have been lost during heating.(7)Quantitative treatment of the XAFS spectra suggests that the unheated or weakly heated chondrites can be classified into two subgroups.2.Minerals in the Sayama and the CI-ike clast in the Tsukuba chondrites were determined by X-ray diffraction using synchrotron irradiation. The clast in Tsukuba chondrite have not been heated more than 500℃, and Oxygen isotope analysis of Sayama shows that it have experienced higher temperature (more than 120℃) than the other CM chondrites such as Murchison during its alteration.3.The laboratory simulation of aqueous alteration using Ningqiang shows that Q-gas have not been lost during alteration, but Ar-rich gas have been lost.