The Geochemistry Characteristics Of Ore-bearing Series In East Liaoning

East Liaoning borate deposits are special matamophic-hydrothermal-metasomatic borate deposits and distributed in"Liaoji paleorift"of Paleoproterozoic of China. Their ore-bearing series are a set of metamorphic assemblages having undergone regional metamorphism of amphibolite facies, occurring in the Liujiahe,Gaoxiaoling,Linjiatai, Laoyinggou and Zhuanmiao formations, and mainly distributed in southern and eastern East Liaoning Peninsula, from Yingkou City in the west to Kuandian in the south. The main ore-bearing series include the Houxianyu,Wengquangou,Ymugan,Zhuanmiao rock series. Their metamorphic rocks are tourmaline leptynites, biotite leptynites and leptites, amphibolite rocks, migmatite and Magnesium marbles. The tourmaline leptynites, biotite leptynites and leptites occurrring distinctly stratiform continuously extend in the region, and are commonly characterized with mutual transitional relationships and with banded and massive structures.The Protolithes of tourmaline leptynites are mainly mudstone, claystone and sandstone; and, some protolithes of positive metamorphic rocks are intermediate- acid tuff. According to the major elements and trace elements, the biotite granulite and granulite show characteristics of positive metamorphic rocks; but as to REE, biotite leptynites, leptites and tourmaline are closely associated mutually, and their REE distribution patterns are fairly similar to those of the clay and clay shale distributed in the continental crust and subcontinent crust geosyncline. The evidence from petrology and geochemistry indicates that protolithes of the leptynites and leptites are equivalent to a set of argillaceous rocks, siltstones and a minor amount of pyroclastic rocks. The amphibolites are stratiform or lentoid structures with gneissic texture and fine-grained granoblastic texture; the major elements, trace elements and REE of the plagioclase amphibolites all indicate that the protolithes of amphibolites are a set of basic igneous rocks with characteristics of continental basalt.The stratiform migmatites are surrended by their country rocks composed of a variety of leptynites and leptites. The migmatites are conformable contact with their country rocks with distint boundaries. There are cross-beddings in the transitional layers and some interbedded amphibolites still remain in the strata so that the relics of leptynites and leptites are commonly discovered. The characteristic of major elements are similar to igneous, but the trace and REEelements are similar to the leptynites and leptites. According to the characteristics, the migmatites were formed by the selected remelting or mix replacement of amphibolites, leptynites and leptites.The stratiform and lenticular Magnesium marbles with intense serpentinization can be traced across the area with discontinuation. Compare to the sedimentary and igneous carbonates , they are higher Mg and lower Ca compare, and the content of TiO2, Al2O3, MnO, K2O, Na2O, P2O5 are similar to carbonates sedimentary in the major elements, and as to trace elements, they are decrement Sr and Ti, especially Ti, which suggests that the carbonates are of originated from crust. Compare to carbonates of sedimentary of Cretaceous and Precambrian in Tibet onion of China, the REE elements are similar, but to the carbonate of igneous, they are different. So, the magnesium marbles of the ore-bearing series are of sedimentary origin.