Fluids double-fracturing genetic mechanism and mineralization of gold-copper of the breccia pipe at Qibaoshan in Shandong Province |
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| Authors: | XU Xingwang CAI Xinping QIN Dajun WANG Jie LIANG Guanghe Zhang Xiaoyun LIU Lijin |
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| Institution: | 1. Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China
2. Qibaoshan Gold Corporation,Shandong Province,Wuliang 262321,China |
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| Abstract: | After studying the characteristics and special texture of the fluidogenous tectonics, mineral assemblage in the cemented vein
between breccia and their special distribution, and stress analyzing the joint structures in and around the breccia pipe,
it is found that the observed phenomena are caused by a new tectonic dynamic mechanics of fluid—double-fracturing caused by
temperature and pressure of fluids and pulsating expansion. Under the actions of thermal stress and the pressure of fluids,
thermal cracks and joints that developed along parts of the thermal cracks formed systematically in the rocks. Under these
conditions, up-arching fracture zones that pulsatively expanded upward and cylindrical pressing breccia body were formed.
Rocks at the peak of the pyramidal fractures zone break down instantly. Where the difference between pressure of fluids and
the overburden pressure exceeded greatly the competence of the rocks, fluid junctions occurred and the velocity of the fluid
flow increased as a result. Explosive body expanded upward in the shape of an inverse cone, cone-like explosive breccia body
and cover-like shattering breccia body located on the upper part of the breccia pipe were ultimately formed. Gold-rich fluids
were enriched and mineralized near the boiling surface in the lower part of the inverse cone-like explosive breccia body where
temperature and pressure decreased rapidly, while copper-rich fluids were enriched and mineralized in the junction area where
temperature and pressure were relatively high. |
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| Keywords: | breccia pipe double-fracturing of fluids genetic mechanism mineralization of gold-copper deposit Qibaoshan |
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