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Isotope dilution with a modified alkali fusion procedure and negative thermal ion mass spectrometry yields highly precise and accurate Re-Os ages for molybdenite from two well-studied molybdenite deposits in the East Qinling molybdenum belt, China. Individual Re-Os ages carry a 2or precision of _+0.40 to 0.57 percent which includes a 0.31 percent uncertainty in the lS7Re decay constant. For the unusual carbonatite-hosted Mo-Pb deposit at Huanglongpu, the weighted average of seven analyses yields an age of 221.5 _+ 0.3 (0.15%) Ma. The weighted average of two analyses of molybdenite from a porphyry Mo deposit at Jinduicheng, about 10 km to the southwest, yields an age of 138.4 _+ 0.5 (0.39%) Ma. These data provide uncertainties an order of magnitude less than previous Re-Os ages. Molybdenite Re-Os ages are slightly older than ages obtained by other isotopic methods for genetically related host-rock and vein material. It appears that the direct dating of sulfide, rather than altered host and vein material, may be critical to acquiring the correct age for mineralization. The East Qinling molybdenum belt is part of a larger east-west-trending zone that marks the suture between two major cratonic blocks. Consequently, the belt was a site for Early-Middle Triassic compression (Indosinian orogeny) followed by Jurassic-Cretaceous extension (Yenshanian orogeny). We suggest that the Huanglongpu and Jinduicheng deposits provide an analogue for processes that may have been important ingenerating major molybdenum deposits in the Colorado mineral belt. In Colorado, Late Cretaceous (Laramide) compression-related, alkalic magmatism was followed by Tertiary (Rio Grande) extension-related, granitic magmatism and the development of major Climax-type porphyry Mo deposits. In particular, the Jinduicheng deposit appears to be a nearly perfect match for Climax-type mineralization in Colorado. In contrast, the older Huanglongpu deposit may record a mechanism whereby molybdenum is concentrated in the lower crust. In both the Qinling molybdenum belt and the Colorado mineral belt, a time gap of about 50 to 80 m.y. separates alkalic magmatism and exceptionally evolved granitic magmatism.

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Thirty-six coal bench samples from Coal Seam 6 and 13 parting samples from 5 parting layers were taken from the Guanbanwusu Coal Mine, Jungar Coalfield, Inner Mongolia, and the samples were analysed by optical microscopy, A scanning electron microscope in conjunction with an energydispersive X-ray spectrometer (SEM-EDX) analysis, X-ray powder diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence spectrometric (XRF) techniques. The results indicate that the average Li content are 264 ppm in coal and 1320 ppm or 0.28% Li 2 O in coal ash, indicating a Li ore deposit in coal. XRD analysis indicates that the minerals are kaolinite, boehmite, chlorite-group mineral, quartz, calcite, pyrite, siderite and amorphous clay material. The absorbed Li phases by kaolinite, boehmite and chlorite could be the most likely host model. Li could also be migrated into the peat by isomorphic impurity in chlorite. However, this migration form should not be the main form because chlorite contents are relative low. The total Li reserves reach to 24288 tons, that is, 52045 ton Li 2 O in this mine. The Yinshan Oldland chould be the most possible source of Li of the coal. The bauxite of the Benxi formation could be another source of Li of the coal in the NE Jungar Coalfield. The bauxite in the NE Jungar Coalfield was originally derived from the Yinshan Oldland.

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Natural gas, in its migration from source rocks to release zones may travel a long distance and change the geochemical characteristics of the rocks which it flowed through. In order to study the geochemical evidence of the natural gas migration, 24 samples were taken from different natural gas migration zones in the Ordos Basin, China. Five samples of them are from natural gas release zones (dark sandstone samples), 17 samples are from bleaching zones (bleaching sandstone samples), and two samples are from non-release zones (background samples). These samples were analyzed by organic and inorganic geochemical methods. The results of GC traces and ICP-MASS indicate that three zones show different organic and inorganic geochemical characteristics. Natural gas migration and releasing may be recognized by the geochemical evidences.

Lithium is an important energy metal. Its concentrations in coals have been studied by many geologists. Its average content is only 14 mg/kg in the coals of the world. Lithium has never been reported as a coal associated deposit before. In order to study the concentrations in Chinese coals, 159 coal and gangue samples were taken from six coal mines and were determined by ICP-MS and the minerals in the samples were identified by X-ray powder diffraction. The results indicate that the Li contents in the coal samples from the Antaibao Coal Mine have reached the industry grade of coal associated deposits. In Tongxing Coal Mine, Li contents in the coal floor rock samples have reached the industry grade of independent lithium deposits. Main minerals are polylithionite, triphylite, zinnwaldite, lithionite and cookeite, which were transported into the peats. Therefore, lithium enriched most likely in the synsedimentary stage in both coal mines. Furthermore, a revised average Li content in Chinese coals was given.

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