地球化学省与地球化学边界

根据中国大陆各种类型壳，幔源岩石和矿石的大量铅－锶－钕同位素资料，及全球特别是东亚大陆块体广泛的同位素与元素体系对比，发展了地球化学块体划分的同位素地球化学指标和填图方法，在此基础上开展了中国大陆的大尺度铅同位素矢量填图，确定了中国大陆主要地球化学省和地球化学急变带（边界），地球化学边界的形成与板块的斜结合以及结合以后岩石圈结构调整产生的克拉通边界密切相关，地球化学边界与重力正异常梯度带，莫霍面梯度带以及正负磁异常转换带存在平行和交错两种关系，研究表明地球化学急变带控制了中国大陆90％以上的超大型金，铜，锡，银，镍，铅－锌，铀，钾盐，硼镁，磷等（33个）和10个以上的大型矿集区。地球化学省划分制约着全球油气资源分布，而地球化学边界则具体控制着克拉通边缘前陆盆地中产油气位置，陆内六级以上强破坏性的浅源地震与克拉通边界－地球化学边界关系十分密切，喀斯特溶洞奇观的出现与地球化学边界关系同样相当密切，根据铅同位素地球化学填图确定的区域背景值可以对铅污染作出快速的定量评价。

GEOCHEMICAL PROVINCES AND THEIR BOUNDARIES

Based on great quantity of Pb-Sr-Nd isotopic data from variousmantle and crust-derived rocks and ores in Continental China, and globa l comparison of isotopic and element systematics, especially for the blocks in t he eastern Asia, we developed the indexes and mapping methods of isotopic geoche mistry for the division of geochemical provinces. The major geochemical province s in Continental China and their geochemical steep zones, i.e. boundaries, have been established through large scale mapping of Pb isotopic vectors(the values i n three dimensions space of 206Pb/204Pb,207Pb/204Pb and 208Pb/204Pb).The generation of geochemical boundaries was tightly related to inclined combination of plates, as well as craton boundar ies resulted in adjustment of lithosphere structure after plate collision. There are parallel or cross relationships between geochemical boundaries and gravity, Moho and magnet gradisnts. The division of geochemical provinces and establishm e nt of their boundaries not only provide important basis for the paleo-continent reconstruction and ascertaining plate boundaries, but also can be widely applie d to exploration and evaluation of resources, establishment of environment backg round and pollution sources, as well as calamity forecasting. It is indicated fr om our study that the giant Au, Cu,Mo,Sn,Ag,Ni,Pb-Zn,U,K salt,B,Mg and P deposi ts of about 90%, and more than 10 large concentrated mineralization districts i n Continental China was controlled by the geochemical steep zones. The geochemic al provinces constrained on distribution of global oil-gas resources, whereas g eochemical boundaries particularly controlled the sites of oil-gas fields at th e craton margins. There are tight relationships between strong destroying earth quakes with shallow sources and craton-geochemical boundaries. The occurrence o f karst caves and collapses is also closely related to the geochemical boundarie s. As background values of Pb isotopes within a geochemical province is quite st able, based on the background values established by geochemical mapping, fast qu antitative evaluation for Pb pollution level can be made.