Economic Geology
Sanaz Ahmadi; Mohammad Ali Salehi; H Jamali
Abstract
The Hassan Abad Zn-Pb deposits is located in the northeast of Isfahan, Central Iran zone. The host rock of this mineralization is the dolomite of Middle Triassic Shotori Formation. Mineralization included galena, sphalerite, sulfosalts, pyrite and barite which associated with dolomitization. Based on ...
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The Hassan Abad Zn-Pb deposits is located in the northeast of Isfahan, Central Iran zone. The host rock of this mineralization is the dolomite of Middle Triassic Shotori Formation. Mineralization included galena, sphalerite, sulfosalts, pyrite and barite which associated with dolomitization. Based on petrographic studies six types of dolomites (in terms of shape and size of the crystals, the distribution of crystal size and shape of the border crystal) has been identified, that including very fine, medium, coarsely crystalline dolomite, Saddle dolomites and filling pore spaces and veins. The first and second type of dolomites were formed as synsedimentary or diagenetic dolomite with sabkha origin. The third type of dolomite in the late stages of diagenesis was formed in shallow burial conditions due to recrystallization of small crystalline dolomite. Coarse-grained and saddle dolomites have been created under the conditions of deep burial and as hydrothermal dolomites and are related to mineralization. Move over, the origin of magnesium for fine crystalline dolomites were seawater, and for coarse crystalline dolomites are probably the brine fluids of the compacted Sorkh Shale Formation and hydrothermal fluid.
Sedimentology
S. A. Moallemi; M. A. Salehi; A. Zohdi
Abstract
In this study, the sandstones of the Razak Formation at the Finu and Hanudun outcrops and at Sarkhun Field north of Bandar-Abbas have been investigated by petrography and geochemistry analyses to discriminate provenance for determination of tectonic setting, parent rock and palaeoweathering and for comparison ...
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In this study, the sandstones of the Razak Formation at the Finu and Hanudun outcrops and at Sarkhun Field north of Bandar-Abbas have been investigated by petrography and geochemistry analyses to discriminate provenance for determination of tectonic setting, parent rock and palaeoweathering and for comparison with the Ahwaz Sandstone of Asmari Formation. The Razak Formation mainly consists of marl, sandstone, conglomerate and sandy limestone. The results of geochemical investigation of major and trace elements indicated that the sedimentation of the Razak Formation took place in an active continental margin. Provenance analysis shows that the siliciclastic sediments of the Razak Formation were largely derived from mafic and intermediate igneous, low- to high-grade metamorphic and sedimentary rocks. Chemical weathering indices suggested that their source area underwent a moderate degree of chemical weathering in an arid climate. It seems that the sediments of the Razak Formation are results of erosion from a mixture of ophiolitic-igneous rocks belonging to the Neo-Tethys oceanic crust, metamorphic rocks and other sedimentary strata deposited in Zagros sedimentary basin during foreland basin evolution. Wedge thickness of the Razak Formation changes from the hinterland thrust basin towards the Zagros trough and ridge basin and finally disappears in the coastal Fars region. The presence of polymictic conglomerate and coarse-grained sandstone with abundant rock fragments could be considered as additional evidence for the source of Razak Formation from the Zagros imbricated zone.
