STUDY ON THE STRUCTURES OF THE ZONGSHUBAN AREA, CHENXIAN,HUNAN PROVINCE AND ORE CONTROLLING CONDITIONS

Zongshuban Pb-Zn deposit occurs in the eastern part of Chenxian where the E-W-trending Shanhe anticlinorium meets with the S-N-trending Xishan anticlinorium.The country rocks of the deposit is Sinian epimetamorphic detrital rocks.The NE-trending compresso-shear faults are the important ore-controlling structures.There develop some ore shoots in the strong kataclastic rocks in the fault zone.Individual ore shoot is lenticular,with the major/minor axis ratio of 2 to 1,and the major axis pitching to southwest at an angle of 50°-60°.Ore shoots are often en echelon arranged,one overlapping the other in longitudinal section from northeast to southwest along the mineralization zone.The metallogenic elements are derived mainly from the Mosozonic Qianlishan granite as indicated by the data of REE,microelements,sulfur isotope and lead isotope.The metallogenic temperature is determined as 168-224℃ and metallogenic period as 155-170 Ma.It is therefore a postmagmatic meso and epithermal deposit,one of the magmatic metallogenic sequence of the Qianlishan granite (Dongpo polymetallic orefield).The granite porphyry emplaced into the NE-trending faults is younger than the Pb-Zn metallogenesis and was found to cut and disrupt the ore veins.Thus the area around the early Yanshanian granite stock (or a buried granite at a depth of 3-5km) is most favorable for further exploration.