Geochemistry of the Zargoli granite: Implications for development of the Sistan Suture Zone, southeastern Iran

Abstract

The Zargoli granite, which extends in a northeast-southwest direction, intrudes into the Eocene-Oligocene regional metamorphic flysch-type sediments in the northwest of Zahedan. This pluton, based on modal and geochemical classification, is composed of biotite granite and biotite granodiorite, was contaminated by country rocks during its emplacement, and is slightly changed to more aluminous. The SiO 2 content of these rocks range from 62.4 to 66 wt% with an alumina saturation index of Shand [molar Al 2 O 3 / (CaO + Na 2 O + K 2 O)]~1.1. Most of its chemical variations could be explained by fractionation or heterogeneous distribution of biotite. The features of the rocks resemble those which are typical to post-collisional granitoids. Chondrite-normalized rare-earth element patterns of these rocks are fractionated at (La/Lu) N = 2.25-11.82 with a pronounced negative Eu anomaly (Eu/Eu* = 3.25-5.26). Zircon saturation thermometry provides a good estimation of magma temperatures (767.4-789.3°C) for zircon crystallization. These characteristics together with the moderate Mg# [100Mg/(Mg + Fe)] values (44-55), Fe + Mg + Ti (millications) = 130-175, and Al-(Na + K + 2Ca) (millications) = 5-50 may suggest that these rocks have been derived from the dehydration partial melting of quartzfeldspathic meta-igneous lower crust.

Tectonic interactions between India and Arabia since the Jurassic reconstructed from marine geophysics, ophiolite geology, and seismic tomography

“…Biostratigraphic data suggest that the Sistan oceanic basin formed in Early Cretaceous time [ Babazadeh and De Wever , ]. Ages of high‐pressure rocks of ~89–78 Ma suggest that subduction of the Sistan Ocean occurred in Late Cretaceous time [ Bröcker et al ., ], but collision‐related granitoids as young as late Oligocene are interpreted to result from collision‐related lithosphere removal [ Rezaei‐Khakhaei et al ., ] and may indicate that shortening continued well into the Cenozoic. Middle Miocene volcanics (14–11 Ma) are only weakly deformed and postdate significant E‐W shortening [ Pang et al ., ].…”

Restoration of Cenozoic deformation in Asia and the size of Greater India

“…We do not reconstruct the western margin of the collision zone in Afghanistan and Pakistan because there is a general absence of kinematic data. We note, however, that there is evidence for Cenozoic extrusion of the Afghan Block westward along the conjugate Helmand and Chaman strike‐slip faults [ Tapponnier et al , 1981], and E‐W closure of the Sistan ocean between the Afghan Block and the Lut Block in eastern Iran, which perhaps continued until Oligocene‐Miocene times [ Rezaei‐Kahkhaei et al , 2010] (Figure 2). Given the kinematics of the known major faults and the E‐W compression in eastern Iran, restoring this region would probably indicate some westward lateral escape of the Afghan Block.…”

Geochemistry, petrogenesis and tectonic implications of granitic plutons at the Liziyuan orogenic goldfield in the Western Qinling Orogen, central China

“…It has been suggested that during the initial collision of an orogenic wedge with a continent, major compressional stresses can be transmitted into the continent as a consequence of subduction resistance, giving rise to large-scale intraplate deformations and strike-slip shear zones (Ziegler, van Wees & Cloetingh, 1998; Rezaei-Kahkhaei et al . 2010). Similarly, Triassic collisional orogenesis of the Qinling Orogen produced intensive brittle-ductile shearing deformation and greenschist-facies metamorphism in the WQO (Zhang et al .…”