Petrology
Nasim Askari; reza Zarei Sahamieh; Jafar Omrani; Mohamad Heshem Emami; C., Vaccaro; J. F. Santos
Abstract
Zarrin Mafic dikes, which outcrop in the Western Yazd block, Central Iran, trending NW–SE, emplaced into the Zarrin granitoid. They are sub-alkaline gabbro; characterized by intergranular and mylonitic foliated texture. Geochemical data reveal the Zarrin mafic dikes are from the partial melting ...
Read More
Zarrin Mafic dikes, which outcrop in the Western Yazd block, Central Iran, trending NW–SE, emplaced into the Zarrin granitoid. They are sub-alkaline gabbro; characterized by intergranular and mylonitic foliated texture. Geochemical data reveal the Zarrin mafic dikes are from the partial melting lithospheric mantle, a spinel-peridotitic source. Furthermore, they are characterized by 87Sr/86Sr ratio of (0.7044-0.7028) and 144Nd/143Nd ratio of (0.5123- 0.5122), that consistent with the derivation from a lithospheric mantle. Their primitive mantle normalized trace elemental patterns display enrichment in LILEs compared to HFSEs, and positive Rb, Ba, and U but negative Ta, Nb, Th, and Zr anomalies, carrying characteristics subduction-related magmatism and metasomatism by subduction-related fluids. The petrogenesis of the Zarrin mafic dikes are related to melting of the lithospheric mantle, and upwelling asthenospheric mantle in the extensional basin which was associated with the subduction.
S Ghaderi; E Rastad; N Rashidnezhad-Omran
Abstract
Tungsten (Cu-Au) mineralization of Southern Chah Palang (SCP) deposit, located in middle part of the Yazd block, occurred as vein-veinlet in normal fault zones, which cut the sandstones and shales of Early-Middle Jurassic Shemshak formation. Based on the mineral paragenesis and quartz type, color and ...
Read More
Tungsten (Cu-Au) mineralization of Southern Chah Palang (SCP) deposit, located in middle part of the Yazd block, occurred as vein-veinlet in normal fault zones, which cut the sandstones and shales of Early-Middle Jurassic Shemshak formation. Based on the mineral paragenesis and quartz type, color and texture, ore-bearing veins can be divided into 1) k-feldspar, apatite (I) bearing milky-white quartz veins, 2) white quartz veins contain apatite (II), 3) hematite- white quartz veins and 4) late carbonate veins. Wolframite is the main tungsten ore mineral in the SCP deposit, which occurred in type 1 vein. Wolframite crystals are riched in Fe and have ferberite composition. Scheelite, as next tungsten ore mineral in SCP deposit, formed in 2nd generation and show significant enrichment in As. Scheelite (I) coexist with Wolframite in type 1 veins, and Scheelite (II) replace wolframite in its fractures and rims, also with arsenic-bearing phases occurred in type 2 veins. Gold in SCP deposit occurred as coexist with and/or fine inclusions in Scheelite (II). Other ore minerals that formed in type 2 veins include base metals and Fe sulfides, cobaltite, niccolite, Cu-Ni-Fe sulfides and native bismuth. Type 3 and 4 veins are white quartz-hematite and barren carbonate veins.
δ18 O of ore-forming fluids, which milky-white and white quartz and wolframite formed from them are 7.91-8.61‰, 5.86-6.76‰ and 3.44-6.94‰ respectively. Based on the oxygen isotope studies, progressive mixing of original magmatic fluids with meteoric waters cause precipitation of metals in veins.
