Ore Study On The Proterozoic Boron Deposits In The East Liaoning Province

The boron deposits in the east Liaoning Province are typical endogenous borate beds, in which there is alone development and characteristics. Depending on the areal geology and the geological characters of these deposits, we have generalized and analyzed the regularties of boron deposit distribution and the controlling factors of boron mineralization. By means of manifold morden testing methods, we have mainly studied the constitutions and structures, mineral compositions and chemical compositions of the ores, and have put forward reliable information and indicators for the cause of the deposits formation and the exploration.We have concluded a suit of methods of systematacially investigating deposit in metamorphic rock area through the study. With the aid of three typical boron deposits, we have obtained progresses as follows:1. Systematacially investigated basal geological materials: detailedly analyzed and digested the strata, lithology, tectonic background, magama activity, sedimentation, metamorphism, geomorphy of the mine fields, realised that the deposits are controlled by the magnesium-rich carbonate rocks in the proterozoic Kuandian group ,that the sedimentation setting of the boracic series rocks was localized in rift geosyncline and that the rocks in place of the metamorphites are a suit of marine volcanic sedimentary rocks and marine carbonate rocks;2. Identified the polished section and slice of the ore samples and confirmed the constitutions and structures of the ores, the mineral formation sequence and the mineral intergrowth and association;divided nature types,industrial tyeps and industrial grades of the ores;3. Systematacially tested the petrochemistry, trace elements, rare-earth element and isotopes of specific rock samples, analyzed the test results and enduced that the cause of the boron ores formation contacts with that of the dolomite and the magnenium-bearing poridotite , that the boron originates from the deep part of the crust and the boron deposits are related with boron-rich volcanic-hot water activity;4. Investigate the metallization of the boron deposits,established the metallogenic model of Liaodong boron deposits , reduce that the boron metallization went through two phases -the phase of the sedimentation and metamorphose and the phase of the hydrothermal alteration and pointed out that the ancient geologic structure of the granite floor is the space condition of controlling the boron deposits, that boron, magnesium, potassium, sodium-rich and calcium-poor hot brine is the geochmistry condition of controlling thedeposits, that the physical chemistry condition of the metamorphose phase is the condition of boron deposit preservation, that the synform structure and the hook folds controlled the re-perch of the boron ore bodies and that the boron deposits formed between 1900 million and 2000 million years ago;5. Integrated the field investigation and the indoor study and established the practicable exploration mode. The mode of finding the surface deposits is that boracic series rocks in both sides of "Liaoji granite" —?magnesium-rich carbonate—^boron ore body;The mode of finding blind deposits is that boracic series rocks in both sides of "Liaoji granite"—? synform structure—*hook fold—?blind ore body.