Petrology
hojjat hajhassani; Jalil Ghalamghash; Mansour Vousoughi Abedini; Rahim Dabiri; Hamideh Rashid
Abstract
The leucocratic granite emplaced as small masses and dykes in the Alvand batholith. The leucocratic granite consists of tourmaline alkali granite, biotite alkali granite, arfvedsonite alkali granite, rutil alkali granite, and biotite- muscovite granites with alkaline and peraluminous affinities. They ...
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The leucocratic granite emplaced as small masses and dykes in the Alvand batholith. The leucocratic granite consists of tourmaline alkali granite, biotite alkali granite, arfvedsonite alkali granite, rutil alkali granite, and biotite- muscovite granites with alkaline and peraluminous affinities. They show enrichments of LREEs relative to HREEs and LILE relative to HFSE with negative anomalies in Nb, Ta and Ti, in normalized trace element diagrams. The leucocratic granite of the Alvand batholith resemble A-type and can be further classified in two of A and A' types granite. The trace elements content of A-type is much higher than A'-type granite. Based on geochemical data, it seems that A- and A'-type granites were generated from partial melting of mantle source. As mantle magma ascends, fractionate and empalce into the crust, A-type leucocratic are formed with minimal contamination and A'-type leucocratic with significant contaminant with continent crust are formed. Field and geochronology data suggest that the leucocratic granite were generated in the late Jurassic, which is contemporaneous with the subduction of the Neo-Tethys oceanic crust beneath the central Iran. It seems that the leucocratic granites were emplaced during a local extensional phase as dykes and small bodies in the Alvand batholith.
Petrology
J. Ghalamghash; Sara Houshmand; Sayad Jamal Shaikhzakariaee; Hamideh Rashid
Abstract
The Kharsare intrusive mass (South of Ghorveh) is located in the middle part of the Sanandaj–Sirjan zone. The batholith comprises three plutonic units including gabbro- diorite, granite and syenite. In addition, the hybrid rocks with a lot of mixing and minling evidences (including lobate or/and ...
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The Kharsare intrusive mass (South of Ghorveh) is located in the middle part of the Sanandaj–Sirjan zone. The batholith comprises three plutonic units including gabbro- diorite, granite and syenite. In addition, the hybrid rocks with a lot of mixing and minling evidences (including lobate or/and ellipsoidal micro granular mafic enclaves sometimes with chilled margins in granite or in hybrid rocks; net-veining granite; and synplutonic brecciated mafic dikes) crop out in interaction zone between granites and gabbros. The calc-alkaline and metaluminous gabbro-diorite and High-K calc-alkaline and peraluminous granites emplaced in Late Jurassic, simultaneously. The peraluminous A-type syenite formed later and intrude two above mentioned plutonic rocks. Geochemical features suggest that gabbro-diorites and granites formed in an active continental margins. It seems the pioneer mafic magma formed in a subduction setting by partial melting of metasomatized mantle. It ascent and emplace in lower crust to produce the granitic melt. The mingling and mixing evidences that may support local crustal contamination of the mafic melt. The younger syenite is resulted from heating by intrusion of the mafic magma in the end phase of continental arc magmatism.
