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扬子克拉通地壳的生成始于太古宙，但依据目前的研究成果，其主体形成于元古宙，对位于扬子克拉通北缘，分布在碑坝地区重要的基底岩系之一的火地垭群铁船山组火山岩进行了Ｓｍ－Ｎｄ和Ｒｂ－Ｓｒ同位素地球化学研究．同位素年代学数据表明，铁船山组岩系形成于约（１６６８５）Ｍａ的中元古代，并源于高亏损的地幔岩浆库（ｄ（ｔ）７．５３．１０），且其亏损地幔模式年龄ＴＤＭ（（１．６８±０．１０）Ｇａ）与Ｓｍ－Ｎｄ等时年龄是一致的．Ｒｂ－Ｓｒ同位素年代学揭示出在新元古代早期（约（８６０±１２）Ｍａ的晋宁期）铁船山组岩系受到了构造热事件的改造．该事件与区内大规模的基性－超基性和碱性、中－酸性岩浆活动的同时出现在时间上是一致的．这些晋宁期岩浆作用有着以下共同特征：（１）岩浆源于亏损程度大为降低的岩浆库；（２）模式年龄ＴＤＭ与铁船山组火山岩的形成时代相近．在本区的西乡地区，同为中元古代形成的西乡群底部的白勉峡组火山岩与其周围的晋宁期基性－超基性和碱性、中－酸性岩浆岩在年代学特征、岩浆库性质和亏损地幔模式年龄等多方面与碑坝地区铁船山组火山岩及其周围晋宁期岩浆岩的特征是类似的．这些同位素地球化学特征所揭示的区内地壳增生和晋宁期构造历史进一
The formation of the Yangtze cratonic crust began in the Archean. However, according to the present research results, its main body was formed in the Proterozoic. For the Hudian Project located in the northern margin of the Yangtze craton and located in one of the important basement rock series in the Tiaba area Sm-Nd and Rb-Sr isotopic geochemistry of the Tieshanshan Formation volcanic rocks. Isotopic chronological data indicate that the Tie Chuanshan formation was formed in the Mesoproterozoic of about 16685 Ma and originated from a high depleted mantle magma reservoir (d (t) 7.53.10), and its depleted mantle mode age TDM ((1.68 ± 0.10) Ga) is consistent with Sm-Nd isochron age. The Rb-Sr isotope chronology revealed that the Tiefushan Formation in the early Neoproterozoic (Jinning period of (860 ± 12) Ma) was altered by tectonic thermal events. This event coincides with the simultaneous appearance of large-scale mafic-ultramafic and alkaline and intermediate-acidic magmatic events in the region in time. These magmatic processes of Jinning Period have the following common features: (1) Magma originated from magma reservoirs with a great loss reduction; (2) TDM of the model age is similar to that of the Tiechuanshan Formation volcanic rocks. In the Xixiang area in this area, the Baimianxia volcanic rocks at the bottom of the Xixiang Group formed in the Neoproterozoic and the Jinningian basic-ultrabasic and alkaline-acidic magmatic rocks at the bottom of the Xixiang Group are characterized by chronological characteristics , The nature of magma reservoirs and the age of depleted mantle model are all similar to those of the Tiechuanshan Formation volcanic rocks and the Jinning Period magmatic rocks in the Shiba area. These isotopic geochemical features reveal the regional crustal proliferation and Jinning period tectonic history into a