HR: 0800h
AN: GP41A-0817    [Abstracts]
TI: GIS Analysis of Spatial Distribution of Granitoid and Au-Quartz Deposits in the Metaturbidite Terranes of the Northeastern Asia
AU: * Voroshin, S V
EM: sv@magis.ru
AF: North-East Interdisciplinary Research Institute FEB RAS, 16, Portovaya St., Magadan, 685000 Russian Federation
AU: Zinkevich, A S
EM: vich@magis.ru
AF: North-East Interdisciplinary Research Institute FEB RAS, 16, Portovaya St., Magadan, 685000 Russian Federation
AB: Au-quartz deposits of the Northeastern Asia metaturbidite terranes have close spatial and temporal relations with granitoid intrusions. This was the basis for many years discussion about the ore genesis. Multi-variant calculations by the GIS tools on the area bounded by the North-Asian Craton Margin (Verkhoyansk fold belt), the Kular-Nera turbidite terrane, the Polousno-Debin terrane of accretionary wedge, the Nagondzha turbidite terrane, and the Viliga turbidite terrane were carried out in order to examine the possible dependence of coefficient of the host rocks saturation by granitoid (relatively area of granitoids on the modern surface) from the intensity of the gold-quartz mineralization (the amount of lodes per unit of the area). The terrane boundaries were taken from the GIS Compilation of Geophysical, Geologic, and Tectonic Data for Circum-North Pacific (ed. W. Nokleberg and M. Digges, 1999); the granitoid boundaries were digitized from the geological map of the USSR North-East , the scale of 1:1500000 (ed. M. Gorodinsky, 1980). The terranes area was gradually filled with the regular net of similar clipping cells (circles with the overlapping). Thus, the crossing of the neighbouring circles has formed the hexagon. The circle radius varied from 20 to 40 km for the different series of calculations. Calculation of the ratio of granitoid and metaturbidite was done in every cell. The obtained values were given to the cell centers. Isolines were built from the regular point's distribution coverage. After that, statistic parameters of the gold-quartz deposits distribution within the fields bounded by isolines, were analyzed. The maximum amount of deposits is within the interval of 0 to 15% of granitoid, with the average value 7,7% with the circle of 20 km in radius, and the value of 8.8% with the circle of 40 km in radius. At the cell of 40 km in radius, the distribution is the more close to the normal one. Thus, the granitoid saturation zone from 5 to 10% is the most favorable to locate of the gold-quartz deposits. The obtained values are lower than those obtained during the analysis of the gold-bearing province in general which is 12-14%. An interpretation of gold-quartz deposits maximum location in the zone of 5-10% of saturation by granitoid is possible on the basis of the metamorphic model, that supposes the mobilization of fluids and metals at the boundary of greenschist facies and hornfels i.e., relatively high temperature metamorphism with the low pressure. The obtained in the isolines picture of the granitoid spatial distribution reflects the superposition of collision and subduction belts, and also the intensity of these tectonic events, the data may be used at the paleotectonic reconstruction.
DE: 8194 Instruments and techniques
DE: 9320 Asia
DE: 9820 Techniques applicable in three or more fields
DE: 8115 Core processes (1507)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting