Shao Yongjun

Rock-forming mechanism of Fenghuangshan rockbody in Tongling area

Based on the detailed geological investigation and record of galleries and drill holes, a new idea has been advanced that granodiorite is earlier than quartz monzodiorite porphyry. Both of them are products of two different magmatic intrusive activities. The analysis results of trace elements show that the Sr content is beyond any other crustal rock and the Th content is beyond that of Ta. The whole-rock analysis indicates that rockbody is rich in CaO and poor in K2O. In the composition of Pb istope of rockbody, the ratio of 207Pb to 204Pb is less than 15.60. All these show that the magma mainly comes from the upper mantle. Ti,Zr,Cr,Nb trace elements and the relation between the Gardini index(τ) and the Rittmann index(σ) indicate that the rockbodies are formed in the orogenic belt and island arc tectonic setting. The summation (ΣREE) and the characteristic value (m(La)/m(Yb)) of the rare earth elements show that the original rock is alkalic basalt. The analysis of the characteristic values of REE and the quantitative modeling calculation indicate that the rock-forming process is dominated by mixed crystallization. According to the analysis on the rock-forming order, magmatic source, tectonic setting and rock-forming process, combined with the achievements of regional rock-controlling structures and division of sublayer of crust, it is believed that Fenghuangshan rock body derives from the deep-seated alkalic basalt magma. The rock-forming process has undertaken sialic and calcareous assimilation and contamination of two different degrees. The rock-forming model belongs to the typical assimilation and fractional cryatalization mechanism.

Approaches to location prognosis of concealed ore deposits (bodies) of productive mines

This paper demonstrates the channels and methods for location prognosis of concealed ore deposits (bodies) in the deep-seated and surrounding districts of productive mines in accordance with their special features. The system frame map is built, from quick exploration in the field to the rapid building of a model indoors. The main research points of location prognosis are also discussed in the paper, which include: 1) integrating the location with the surrounding geological areas, microscopic with macroscopic; 2) analyzing and synthesizing all geological information of different levels, depths and aspects; 3) laying stress on mineralization series; 4) paying attention to the study of the distribution law of ore bodies; 5) introducing the theory of nonlinear dynamics of ore forming processes to ordinary static prognosis; 6) the necessity of the geophysical method in recovering information of concealed ore bodies; 7) the combination of all kinds of geology, geophysics, geochemistry and remote -sensing methods.

New evidences for the formation of granitic rocks by remelting of the sial crust in Southern Hunan

Comparatively analyzing 47 REE distribution data of the Southern Hunan geosynclinal arkose-silicarenite and various period granitic rocks and the results of their partially melting experiment series in company with the occurence and petrogeochemical features of various period granitic rocks, the authors suggest that all of the above-mentioned salic rocks can be partially melt to produce granitic magma.Comparatively analyzing 47 REE distribution data of the Southern Hunan geosynclinal arkose-silicarenite and various period granitic rocks and the results of their partially melting experiment series in company with the occurence and petrogeochemical features of various period granitic rocks, the authors suggest that all of the above-mentioned salic rocks can be partially melt to produce granitic magma.