Emplacement Depth Of The Linlong Granitic Complex, Ore-forming Depth And Post-ore Change And Preservation Of Gold Deposits In The Northwestern Jiaodong Peninsula, China

The northwestern Jiaodong peninsula is the place where gold ore resources are most concentrated in China, the reserve volume and output accounting for a quarter of the nationalwide, and has many oversize and large-scale deposits. The gold deposit of the northwestern Jiaodong peninsula has close spatial relationship with granide, and their relationship is always the highlight of the research by geologists.The Linglong granitic complex rock and the gold deposit in it is the research target of this paper, the cut-in point is regional scale, and through collect and analyze a great deal of temperature and pressure data of gold mineralizing fluid to quest alteration regular pattern of the gold ore-forming depth of the northwestern Jiaodong peninsula; the main task of the paper is recovering the uplift history of the Linglong granitic complex rock by mineral thermanometer to get the quantitative data of the denudation degree of the rock mass, with the fission track technique as evidence. Through the comparative study of gold ore-forming depth and denudation quantity to analyze the alteration and preservation conditions after gold deposit formed in the region, which could supply theoretical evidence for potential capacity evaluation and deep mineral prospecting of regional ore deposit.According to the lithogenic depth calculated by geological thermanometer of amphibole and biotite (The mean lithogenic depth of Linglong ganite, Luanjiahe ganite, Guojialing ganite, Aishan ganite is 5.86km, 6.83km, 4.52km, 2.37km respectively. The whole mean denudation depth of the Linglong granitic complex rock is 5.32km, and the denudation degree decline from the Bohai Sea to inland in the northwestern Jiaodong peninsula.), it can be seen that the lithogenic denudation rate of Linglong and Luanjiahe ganite to Aishan granite is far larger than that of Aishan ganite to now, which accords with the conclusion of the fission track technique. The denudation rate has direct ratio with elevation, so the regional crust uplift happened from 160 to 110 Ma.The statistics and computation results of ore-forming temperature, pressure and depth of main gold deposits of the northwestern Jiaodong peninsula show that the ore-forming temperature ranges from 145℃to 400℃, concentrating from 240℃to 300℃, and the average is 255.5℃. The main temperature of ore-forming gradually declines from west to east in space; the ore-forming pressure is between 14.5 and 120 MPa, equally 50.4MPa, first ascends and later decrease from west to east in space, and the high values appear in the mid-southern area; the total pressure alteration is not large, the values along the faulted zone become weak from the trunk to lateral parts. Temperature and pressure do not have the same regional alteration trend, temperature has better adaptation with faulted zone, and pressure has weak correlation. The range of ore-forming depth is from 0.548 to 4.532 km, and the average depth is 1.939km.The main age phase of gold deposit is basically in the late period of large crust uplift and denudation of rock mass in the northwestern region, and the ore-forming depth accords with lithogenic depth of Aishan ganite mass, which coincides with the phenomena that gold deposits develop near the contact zone of ganite mass. Because of the difference of denudation, the condition of gold deposit after forming is quite different, but the gold deposit is preserved well relatively. In conclusion, the prospect of ore-forming of this area is great, and the deep has good space for further mineral prospecting.