The longevity of subcontinental lithospheric mantle beneath Jiangsu-Anhui Region——The Os isotope model age of mantle-derived peridotite xenoliths  

作　　者：支霞臣 彭子成 陈道公 余春江 孙卫东 LaurieReisberg 

出　　处：《Science China Earth Sciences》2001年第12期1110-1118,共9页中国科学（地球科学英文版）

基　　金：the National Natural Science Foundation of China (Grant Nos. 49837005 and 49733110).

摘　　要：The basalt-borne peridotite xenoliths from Jiangsu-Anhui provinces were analyzed for whole rock Os isotopic compositions in two laboratories of USTC, China and CRPG, France, respectively. The ^(187)Os/^(188)Os ratio of the sample set ranges from 0.119 to 0.129 (25 samples, USTC) and from 0.117 to 0.131 (17 samples, CRPG). The Os isotopic compositions of most samples are less than 0.129 and depleted relatively to the primitive mantle, showing a good correlation with the major element compositions. With the ^(187)Os/^(188)Os-AI2O3 alumichron, the samples yield a model age of 2.5±0.1 Ga (data of USTC) and 1.9±0.1 Ga (data of CRPG), late Archean to early Pro-terozoic. The two samples with the lowest ^(187)Os/^(188)Os ratio (0.119 and 0.117) have the T_(RD) (Re depleted age) of 1.1 Ga (USTC) and 1.4 Ga (CRPG), mid-Proterozoic. The Os isotope model age shows that the peridotite xenoliths from Cenozoic alkali basalt in Jiangsu-Anhui provinces have an old formation age (early- to mid- Proterozoic). They are not newly produced mantle after the Phanerozoic replacement of the lithosphere mantle, but residual fractions of Proterozoic mantle.The basalt-borne peridotite xenoliths from Jiangsu-Anhui provinces were analyzed for whole rock Os isotopic compositions in two laboratories of USTC, China and CRPG, France, respectively. The ^(187)Os/^(188)Os ratio of the sample set ranges from 0.119 to 0.129 (25 samples, USTC) and from 0.117 to 0.131 (17 samples, CRPG). The Os isotopic compositions of most samples are less than 0.129 and depleted relatively to the primitive mantle, showing a good correlation with the major element compositions. With the ^(187)Os/^(188)Os-AI2O3 alumichron, the samples yield a model age of 2.5±0.1 Ga (data of USTC) and 1.9±0.1 Ga (data of CRPG), late Archean to early Pro-terozoic. The two samples with the lowest ^(187)Os/^(188)Os ratio (0.119 and 0.117) have the TRD (Re depleted age) of 1.1 Ga (USTC) and 1.4 Ga (CRPG), mid-Proterozoic. The Os isotope model age shows that the peridotite xenoliths from Cenozoic alkali basalt in Jiangsu-Anhui provinces have an old formation age (early- to mid- Proterozoic). They are not

关 键 词：peridotite xenoliths Os isotope model age subcontinental lithospheric mantle Jiangsu-Anhui provinces. 

分 类 号：P597[天文地球—地球化学]