Economic Geology
Ali Rajabzadeh; Hossein Kouhestani; Mir Ali Asghar Mokhtari; Afshin Zohdi
Abstract
In this study, petrography and major and minor elements geochemical data are presented for sandstone layers of the Upper Red Formation (URF) in the Chehrabad Pb-Zn deposit (NW Zanjan) to investigate sandstone composition, tectonic setting and their source rock. In this area, URF has 980 m thickness and ...
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In this study, petrography and major and minor elements geochemical data are presented for sandstone layers of the Upper Red Formation (URF) in the Chehrabad Pb-Zn deposit (NW Zanjan) to investigate sandstone composition, tectonic setting and their source rock. In this area, URF has 980 m thickness and is conformably overlies the Qom Formation limestones. Based on the microscopic studies, these sandstones mainly composed of fine- to coarse-grained clastic fragments including sedimentary and metamorphic rock fragments (45 %), quartz (38 %) and feldspar (17 %). Based on petrographic studies, these sandstones are feldspathic litharenite and litharenite (mainly chertarenite). Based on the main components and major and minor elements geochemical data, the tectonic setting of these sandstones is an active continental margins and foreland basins. These data represent an intermediate to felsic source rock for these sandstones which was affected by the semi-humid to semi-arid climate and a low chemical weathering.
M. Hosseini-Barzi; M. Saeedi
Abstract
The sandstones of Padeha Formation with 390m thickness in section of Samirkooh in Kerman, Zarand have been studied to illuminate their provenance, tectonic provenance, diagenesis by omitting the effect of diagenetic process on sandstone composition. In this direction, petrography of 91 thin sections, ...
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The sandstones of Padeha Formation with 390m thickness in section of Samirkooh in Kerman, Zarand have been studied to illuminate their provenance, tectonic provenance, diagenesis by omitting the effect of diagenetic process on sandstone composition. In this direction, petrography of 91 thin sections, modal analysis of 30 appropriate samples, and use of SEM and EDX analyses of 6 sandstone samples were accomplished .We can point to diagenetic processes including mechanical compaction, coating hematite around the detrial grains (eogenetic stage) and growing up authigenic cholorite and illite, chemical compaction, quartz cementation, dolomite cementation, dedolomitization, albitization of feldspar and corrosion of grains by dolomite cement (mesogenetic stage) and fracturing as well as filling them by calcite, quartz and anhydrite cement (telogenetic stage). We studied tectonic provenance of these sandstones using Qt92 F7 L1, Qm77 F 7 Lt 16, Qp92Lvm4Lsm4, after recognition of diagenetic process and omitting their effect on the results of modal analysis. These results show quartzolithic facies with cratonic, recycled orogen and rifted continental margin tectonic provenance. Using diamond diagram drawn based on particulars quartz grains and also petrographic evidences in these sandstone, we can say that these sandstone derived from multi provenance. The log Qt/F+RF vs. Qt/F+RF climate diagram and QRRF triangle indicate humid climate during deposition of the Padeha Formation.
