H. Jamali; A. Yaghubpur; B. Mehrabi
Abstract
Miveh – Rud area is located 50 km north of Tabriz and 65 km west of Ahar at 36ْْ 33′ 02″to 38ْ, 34′ 52″ N and 46 ْْ 12′ 20″ to 46 ْْ 14′ 35″ E. The oldest rock unit in the area includes a thick sequence of Paleocene sedimentary rocks comprising ...
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Miveh – Rud area is located 50 km north of Tabriz and 65 km west of Ahar at 36ْْ 33′ 02″to 38ْ, 34′ 52″ N and 46 ْْ 12′ 20″ to 46 ْْ 14′ 35″ E. The oldest rock unit in the area includes a thick sequence of Paleocene sedimentary rocks comprising of sandstone, shale, siltstone, marl and marly limestone that have been intruded by a porphyritic intrusive body and dykes of granodioritic to diabasic composition (probably Oligocene in age). The intrusive rocks resulted in the formation of hornfels, skarn and alteration in Paleocene rocks. All of the mentioned rock units are unconformably covered by Pliocene age trachyte, trachyandesite. Alteration of potassic, sericitic, argillic, propylithic and silicification types occurred in the subvolcanic and sedimentary rocks, while there is no observed alteration in the volcanic cover. Anomalies of Au, Ag, Sb, Cu, Bi, W and Mo detected by geochemical investigations are confirmed by field evidences.
The anomalies of Sb, Ag, Au and As are located in the northern part, while the Cu, Co, W and Mo anomalies are in the southern part of the area. The degree of the contact metamorphism decreases toward the north and the potassic alteration can be shown mostly in the southern part of the area. This may suggest uplift and erosion of the southern part compared to northern part of the studied area. Composite halos of As, Pb, Ag / Cu, W and Co confirm the results.The mineralization includes formation of skarn, epithermal and sheeted veins. The epithermal veins cut the skarn and other contact metamorphic rocks.
M. Ghasemi; M. Momenzadeh; A. Yaghubpur; A. A. Mirshokraei
Abstract
Mehdiabad Zn-Pb-Ba deposit is located 110 km south-east of Yazd, in the Central Iran structural zone. The stratigraphic succession consists of three sedimentary formations of lower Creataceous age. The Sangestan formation, the lowest unit of shale and siltstone with calcarenitic interbeded layers. This ...
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Mehdiabad Zn-Pb-Ba deposit is located 110 km south-east of Yazd, in the Central Iran structural zone. The stratigraphic succession consists of three sedimentary formations of lower Creataceous age. The Sangestan formation, the lowest unit of shale and siltstone with calcarenitic interbeded layers. This unit is overlain by ankeritic massive dolomite and dolomitic limestone of Taft formation. The Abkouh formation at the top is composed of cherty or clayey limestone with conglomeritic intercalation, lenses of massive reef limestone and calcareous shale. The structure of ore body shows a half-graben with a vast N-S syn form being complicated by the presence of poly phase faults. The main normal fault is Tappeh Siah fault, suggested to be active during and after the period of sedimentation. Major minerals are sphalerite and galena with minor pyrite, chalchopyrite in sulfide zone, smithzonite, hydrozincite, hemimorphite and cerussite in oxide zone. Mineralization occurs in stratiform-lenticular orebodies and concordant with host rocks. Also ore bodies showing laminated, disseminated, open space filling, karst filling, colloform and botryoidal textures.
