Application of multi-source data synthetic analysis to Uranium exploration in Northern Hebei and Langshan area, inner Mongolia
By synthetic analysis it is known that they are crust-cutting faults formed in accompany with inner Mongolia axis, having long and complex active history and controlling geological and mineral developing history from Lower Proterozoic era to Mesozoic-Cenozoic era. During Lower Proterozoic in the north margin of Inner Mongolia axis they restrict accretion of the platform, to set apart from Inner Mongolia geosyncline with a fault zone. The eruptive zones in volcanic rock extending in EW direction was controlled by late Jurassic epoch to be closed and opened for many times. From late Yanshanian period to Himalayan period, reactivation of EW and NS striking faults and stretching to cover volcanics caused fracturing and hydrothermal alternation in volcanic rock strata, to bring about multiple mineralization of polymetals, precious metals and metallic uranium, therefore, fault structures can be interpreted from images, and become regional structural indications for uranium and gold exploration. Now, lead, zinc, copper, gold and uranium deposits and occurrences discovered almost occur in alternation zones in EW and NS striking fault structures and their vicinity, so it is verified that distribution of end genetic metal minerals coincide with regional EW and NS striking fault structures.
Prospecting for uranium and gold deposits arranging in the developed portion of EW and NS striking deep faults by following synthetic interpretation has received primary effect. One uranium prospect, two surface exposed points of uranium and two points of gold mineralization have been discovered. Among them, one gold mineralized structure zone with a length of over 3,000m and a mineralization range of 200m are considered to be promising areas to search for altered rock of gold deposit.
The satellite image can clearly reflect altered structure zone, which has been mutually proved by synthetic interpretation and has been confirmed that it is an or-controlling structure. This obvious effect of ore prospecting by remote sensing is certainly is certainly a rare example.
Establishment of volcanic appratus type of image model
Upper Jurassic volcanic rocks are widely distributed in northern Hebei, in which numerous mineral deposits are located. By synthetic interpretation of remote sensing geology, it has been discovered that the known large type lead-zinc deposit occurs in central edifice at the intersection of EW and NS deep faults. A large type type of uranium-molybdenum deposit and several occurrences are related with volcanic apparatus compounded with deep faulting, and mineralization is present in sub volcanic rock body and contact zone controlled by volcanic apparatus. Therefore, they will cause great interest in remote sensing geological interpretation, if in the interpretation of volcanic apparatus, a great attention is paid to the difference between types, and their spatial and genetic relation with mineral deposits.
A perfectly developed volcanic appratus is a volcanic appratus regularly consisting of multiple structural elements as a whole. Because of different modes of volcanism, Corresponding characteristic types of volcanic appratus are produced, providing marks for the interpretation of remote sensing image. Many circular patterns are interpretated by carefully contrasting and analysing and based on similarity of image structure feature, five types of image models of volcanic appratus have been established and determined by field verification.
- Image Model of Volcanic Domal Structure
The patterns of volcanic activity never only are strongly explosive or effusive. If the upwelling strength of volcanic matter is no enough, then it may produce sub volcano or cryptovolcano which overlie the wall rock to form as modal. This is just the formation mechanism of volcanic modal structure. In general, the principal features of modal structure image behave as the multilayer ring structural imagery units. The center of dome is generally negative landform, and ring mountain bodies and ring valleys intermitting with multilayers are alternately around the center, some-times associated with radiated valleys. The slopes of the ring mountain bodies are long and gentle or short and steep for backing or facing to the center respectively, that is the reflection of landform of volcanic rock strata inclined from domal center outward.
