Metallogenic Regularities In Middle-northern Daxinganling, Inner Mongolia

The metallogenic geological conditions in the northern section of Daxinganling are excellent, with good exploration prospects. On the basis of the research of typical deposits and metallogenic geological backgrounds, summarizing metallogenic regularity in this area, can not only deepen the understanding of metallogenic characteristics in this area, but also contribute to the further work deployment in this region and promote the development of prospecting exploration.The northern section of Daxinganling stretch across Siberian Plate and North China Plate, the regional tectonic evolution experienced the Paleo-Asian Ocean tectonic domain evolution of pre-Mesozoic and the circum-Pacific strong Superimposition and reformation of tectonism-magmatism of Meso-Cenozoic, forming a highly complex structural scene. The regional tectonic evolution has undergone three phases, which are the formation of Precambrian massif(basement), the Paleozoic fold accretion and plate opening and closing as well as the Mesozoic intraplate tectonic activities. Mesozoic tectonism-magmatism that has a close relationship with the metal mineralization is highly intense.The types of metal deposits that have been found in the region mainly are skarn, porphyry and hydrothermal types, followed by marine sedimentary, alkaline granite, magmatic rock and greisen types. Among them, the porphyry, skarn and epithermal-mesothermal deposits types in the region are the main deposit types. Most metal deposits were formed between 250 Ma to 120 Ma, 87% of which were formed between Middle Jurassic to Early Cretaceous(170Ma ~ 120Ma). The age of different types of deposits are also different, porphyry-type deposits were formed from the early Paleozoic to late Mesozoic, but nearly 41 percent of them were formed between 150 Ma to 120 Ma, and almost 67% of the skarn deposits were formed between 150 Ma to 120 Ma, as well as the continental volcanic deposits were all formed between 150 Ma to 110 Ma. Generally, the ore-forming geological backgrounds of different types of deposits are different, and the skarn type deposits are mainly distributed in the uplifting-depression structure transition zone since Middle Jurassic, and the continental volcanic deposits are located in volcanic basin edge of Mesozoic, while the porphyry type deposits may be formed in various types of tectonic units.The formation and distribution of metallic ore deposits as well as the deposits type in the study area are controlled by tectonic backgrounds. The uplifting-depression structure pattern is the most important controlling factor to the Late Mesozoic deposits, and the deposits are mainly distributed near the uplifting-depression structure transition zone; the deposits development is significantly controlled by NE and NW fracture structural system, and its distribution characteristics are to be lines in north-east direction and to be rows in the north-west direction. The magmatic rocks related to mineralization are mainly superhypabyssal-hypabyssal, high, intermediate-felsic, acidic dykes or small stocks, and the volcanic structure or the ring structure is the significant structural environment of controlling the deposits or ore fields. Besides, some massive sulfide deposits and skarn type deposits are controlled by some certain lithostratigraphy.