Application of remote sensing to seeking blind ore deposcts in the middle lower reaches of Yangtze River
Chen Yinxiang Xu Yuxian
Center of Remote Sensing in Geology,
Ministry o Geology & Mineral Resources
29 Institute Road, Beijing, China
Abstract
26 remote sensing geological interpretation maps at 1:200,00 scale have been compiled for the ore belt along the Yungtze River in an area of 184,700 km2, and 1:50,000 remote sensing survey has been conducted for the geological structures in nearly 10,000 km2 of the orefiled and mining area in Southeastern Hubei; Ruichang, Jiujiang; Zongyang, Lujiang; Ma'anshan; Ning-Zhen and Suzhou where ore is concentrated. Based on the processing and interpretation of the images of TM, MSS an SPOT as well as the color IR air photos, and the integration of geological factor in ore formation and also,. The structures and textures f the magmatic rocks that control the ore deposit have been made known. In the mean time a series of ore deposit models have been reconstructed; 74 new sites have been predicted as favourable section for ore formation, target areas for ore seeking, and ore deposit surrounding the mining area. In addition, remote sensing geological technique series has been established as an approach looking for blind ore deposits, and the theoretical model of deep source magmatic thermo-dynamics has been developed for ore prediction.
With systematic remote sensing geological studies and geological interpretation of ore deposit, the original geological maps have been revised a complemented. Lots of information has been obtained regarding ore deep-seated magmatic structures, which would hardly have been revealed through ground investigations. Moreover, 3166 ring (arc) - shaped structures have been discovered, and nearly 500 sites have been identified as centers of magmtic activity with metallogenic significance, deep petrogenetic and metallo genetic passageway's mall blind rock bodies (stocks), subsurface volcanic organisation and subsurface pump explosion structures- all useful geological information for finding blind ore deposits. Special attention has been given to the scientific and technological problems a follows :
Fig.1 Cycle structure & ore Deposit Distribution at Tonglin Metallogenic Area
The analysis of upper and lower boundaries of magmatic rocks an deep geological structures leading to understanding of the background for roe formation.
Among the various factors determining the formation of the ore deposit, it is believed that magmatic thermo-dynamic motion s the major one, according to our careful remote sensing geological studies. Traditionally, the srufce shallow hard curst has been considered to be the mainforce layer in geological structure formation by various geological structure specialists who believe its folding, faulting, uplifting, expansion and interformational sliding act as a force and create space for magmatic intrusion. As a matter of fact, however, the magmatic melting mass that accounts for 98% in volume from lithosphere to mantle possesses predominant material and thermal energy. It is the magmatic melting mass that supports the thin and fragile crust and with its rising and local penetrating intensive vortex flows, disturbs the movement of the crystalline basement and consolidated magmatic rocks, governs the subsequent sedimentary volcanic formations and controls the fluctuations of the crust, depressions, fold sand faults. Obviously, magmatic bodies should be the leading active force, the essence, while the surface shallow crust is merely superficial expression, passive, reformed and responsive. This is one of the significant understandings obtained as a result of this research project. Centers of magmatic activity have been identified in southeaster Hubei; Jiujiang; Anqing; Luzong; Tongling; Ma'anshan; Liyang; Jurong; Taihu; suzhou and Shanghai, where regional structures and ore deposits are exactly controlled by these lithospheric ring structure as shown in Fig.1 where the ore deposit and the magmatic rocks in southeastern Hubei distribute in ring-shape as a whole.
Fig.2 Suzhu Cycle STructure and Anshan Subvolcanic Organization
Fig.3 Metallogenic Pattern by Deep Source Thermo-dynamics
On the other hand, several blind magmatic bodies of second, third and fourth classes have been inferred on the basis of surface shallow geological structures, such as Dayehu rock dome, as well as rock base, magmatic flat, magmatic peak and magmatic pillar (pipe) shown in fig. 2. Most of them have already been confirmed by airborne magnetic survey and historical earthquake activity, magmatic bodies of various classes undergo tacking evolution along their own passageways constantly and with specific regulation.
The results of structural interpretation have revealed intensive pneumatic explosion and impact expansion in magmatic intrusion zones. Deep high-energy intrusions and shallow low-temperature low-energy mixed magmatic layers can be clearly distinguished with the characteristics form of the magmatic rock. Deep section analysis, make along the upper boundary of the high energy magmatic rock with remote sensing and geophysical data, has shown that the major ore forming locations coincide with the protruding ends on the magmatic boundary whose structure, in addition, also controls the evolution of the crystalline basement, sedimentary - volcanic basin, magmatic intrusion-volcanic dome and tectonic block for a long period of time, representing the in-depth thermal background for the ore formation.
