摘要
THE parallel strike of geochemical steep zones and geophysical gradient zones represent geochemicalboundaries with tectonic hiding and almost no magmatism, but there existed great variation of lithosphereor crustal thickness. Tectonically, these areas were located in the foreland basins of craton margin. Thesegeochemical boundaries were usually associated with the low-temperature mineralization and petroleumgeneration. The Nd, Sr and Pb isotopic evidence indicated that there still existed strong crustal-mantle interaction through fluid activation along deep-seated faults at the craton margin. Fig. 1 is the <sup>207</sup>Pb/<sup>204</sup> Pb-<sup>208</sup>Pb/<sup>204</sup> Pb diagram, which shows the evident crust-mantle mixing for crude oil, chloroform bitumen-A,
