Research On The Metallogenia Of The Granite Contach-depression Zones In GeJiu Tin-copper Polymetallic Deposit

Gejiu tin ore deposit is an old mine which has been exploited and researched for a long history. Although there had accumulated a lot of geological data, but few concerned with the contact-depression zones of granite and the tin-copper polymetal within them are found. In this paper, based on the volumes data of field investigation and former research information, and guided by the "Diwa" theory and activation tectonic metallogenic theory, the structural features, forming and ore-controlling mechanism of the contact-depression zones and geological characteristics, ore-controlling factors, mineral deposit genesis and metallogenic disciplines of orebodies occurred in them are studied in detail. the main innovation awareness and results are listed as following:1. On the basis of the partition of regional geological, geophysical and geochemical blocks and belts, the tectonic evolution and movement characteristics of Gejiu and its adjacent areas are probed by using the historic-causative analysis method. It is pointed out that the Gejiu tin ore deposit was originally formed in an ancient aulacogen of residual platform region.2. The spatial distribution of the granite contact-depression zones are described systemically. It is proposed that the contact-depression zones were formed and restricted by compound actions of Yanshanian granite intrusion, structure, strata and Indosinian basalt extrusion. Furthermore, their forming and ore controlling mechanisms are discussed ground on particular geological investigation.3. The ore deposits in the granite contact-depression zones are investigated and their multiple ore-controlling factors are studied through both macroscopical and microcosmic aspect. It is concluded that these ore deposit has "selectivity" with Kafang segment in Gejiu formation. 4. Indosinian metamorphic volcanic rocks is found by the author and her partners in 3-9# depression zones that gives great evidence to the polygenetic compound viewpoint.5. After detail study the characteristics of ore forming and post-ore forming, it is put forward that orebodies occurred in the contact-depression zones were developed on the basis of Indonisian marine volcanic activities and hot water deposition mineralization, associated by the induction of former ore deposits and the intensity of overlaying and reconstructing of Yanshanian magma hydrothermal mineralization.6. The regularities of ore deposit's spatial distribution and the evolution are discussed by combining of metallogenesis with tectonic (progressive) evolution-movement so that the characteristics of poly-geotectonic evolution stage, polygenesis, multiple material sources, multiple ore-controlling factors and variety of mineralizations of the deposits occurred in contact-depression zones are summarized.7. On the foundation of concluding the mineralization regularities and ore-controlling factors, the metallogenic prediction model is established by using multiple exploration methods such geology, geophysics, geochemical and remote-sensing. Totally 6 prediction area are pointed out for further exploiting.