Gold Bearing Conglomerates in some Molasse Basins of Iran
Subject Areas : Mineralogy
Elkhan A.
Mamedov
1
(Baku State University.The Scientific-Research Laboratory." Prediction,Search and Economic Estimation of Gold Placer Deposits".
23, Z.Khalilov str, Baku AZ 1148, Azerbaijan.)
Keywords: Iran, Gold ore province, Gold-bearing conglomerates, Gold placer molasse basin, Mountain building activity,
Abstract :
This article lists a number of geological data on the conditions of formation of some major gold deposits in the conglomerates of the Earth\'s crust. We analyze the metallogenic, tectonic, stratigraphic and other factors controlling the formation of gold-bearing conglomerates in certain fields, such as the Witwatersrand (S. Africa) and Darwaz (Tajikistan). The following tectonic factors play the leading role in controlling the formation of deposits of gold-bearing conglomerates in the Earth\'s crust: Epochs of mountain building of different ages in folded belts; Epochs of mountain building in activation of consolidated gold ore provinces in the domed uplifts of ancient shields, median areas and in areas with complete folding; The role of lithogenesis of the molasse cycle, transgressions and angular unconformity in the formation of gold-bearing conglomerates in a large area; Synchroneity with mountain building in gold ore provinces of different, intermountain molasse and marginal basins of various ages; and imposed volcanic and terrigenic conglomeratic molasse basins in activated gold ore provinces Volcanic belts and deep faults. There are three industrial types of gold-bearing conglomerates: ancient Precambrian (indurated) sedimentary-metamorphosed placer, Phanerozoic cemented placer, and younger, weak, friable Pliocene-Pleistocene placers. We give some details about the methods for their exploration and financial costs for the development of selected industrial types of gold-bearing conglomerates. In this article, it is noted that during the Sassanian and the Mongolian Empire a certain amount of native gold was extracted from the Late Alpine molasse conglomerates which formed during the activation of gold ore area of the major Iranian middle massif. By analogy with the geological conditions of formation of deposits of gold-bearing conglomerates in the Earth\'s crust, the geological search criteria for deposits of gold-bearing conglomerates in some orogenic and widespread activated imposed conglomeratic molasse basins of Iran are given. A number of promising molasse conglomeratic basins are indicated: Mashhad intermountain deflection, as well as a number of superimposed molasse basins in the active superimposed volcano- plutonic belt of Iran, in particular Lut Block, middle massif, Tabriz , Ahar , and other superimposed molasse basins in the large Sabalan ring structure. In conclusion, we propose the development of selected areas and the establishment of new major resources of the gold - placer industry of Iran.