Geochemical and isotopic evidence for Carboniferous rifting : mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

In this paper, we present detailed field observations, chronological, geochemical and SrNd isotopic data and discuss the petrogenetic aspects of two types of mafic dykes, of alkaline to subalkaline nature. The alkaline mafic dykes exhibit a cumulate to foliated texture and strike NWSE, parallel to the main trend of the region. The 40Ar/39Ar amphibole age of 321.32 0.55 Ma from an alkaline mafic dyke is interpreted as an indication of Carboniferous cooling through ca. 550 C after intrusion of the dyke into the granitic Galeh-Doz orthogneiss and Amphibolite-Metagabbro units, the latter with Early Carboniferous amphibolite facies grade metamorphism and containing the Dare-Hedavand metagabbro with a similar Carboniferous age. The alkaline and subalkaline mafic dykes can be geochemically categorized into those with light REE-enriched patterns [(La/Yb)N = 8.329.28] and others with a rather flat REE pattern [(La/Yb)N = 1.16] and with a negative Nb anomaly. Together, the mafic dykes show oceanic island basalt to MORB geochemical signature, respectively. This is consistent, as well, with the (Tb/Yb)PM ratios. The alkaline mafic dykes were formed within an enriched mantle source at depths of 90 km, generating a suite of alkaline basalts. In comparison, the subalkaline mafic dykes were formed within more depleted mantle source at depths of 90 km. The subalkaline mafic dyke is characterized by 87Sr/86Sr ratio of 0.706 and positive Nd(t) value of + 0.77, whereas 87Sr/86Sr ratio of 0.708 and Nd(t) value of + 1.65 of the alkaline mafic dyke, consistent with the derivation from an enriched mantle source. There is no evidence that the mafic dykes were affected by significant crustal contamination during emplacement. Because of the similar age, the generation of magmas of alkaline mafic dykes and of the Dare-Hedavand metagabbro are assumed to reflect the same process of lithospheric or asthenospheric melting. Carboniferous back-arc rifting is the likely geodynamic setting of mafic dyke generation and emplacement. In contrast, the subalkaline mafic sill is likely related to the emplacement of the Jurassic Darijune gabbro.(VLID)223441

The Sanandaj–Sirjan Zone in the Neo-Tethyan suture, western Iran: Zircon U–Pb evidence of late Palaeozoic rifting of northern Gondwana and mid-Jurassic orogenesis

The Zagros Orogen, marking the closure of the Neo-Tethyan Ocean, formed by continental collision beginning in the late Eocene to early Miocene. Collision was preceded by a complicated tectonic history involving Pan-African orogenesis, Late Palaeozoic rifting forming Neo-Tethys, followed by Mesozoic convergence on the ocean\u27s northern margin and ophiolite obduction on its southern margin. The Sanandaj-Sirjan Zone is a metamorphic belt in the Zagros Orogen of Gondwanan provenance. Zircon ages have established Pan-African basement igneous and metamorphic complexes in addition to uncommon late Palaeozoic plutons and abundant Jurassic plutonic rocks. We have determined zircon ages from units in the northwestern Sanandaj-Sirjan Zone (Golpaygan region). A sample of quartzite from the June Complex has detrital zircons with U-Pb ages mainly in 800-1050 Ma with a maximum depositional age of 547 ± 32 Ma (latest Neoproterozoic¿earliest Cambrian). A SHRIMP U-Pb zircon age of 336 ± 9 Ma from gabbro in the June Complex indicates a Carboniferous plutonic event that is also recorded in the far northwestern Sanandaj-Sirjan Zone. Together with the Permian Hasanrobat Granite near Golpaygan, they all are considered related to rifting marking formation of Neo-Tethys. Scarce detrital zircons from an extensive package of metasedimentary rocks (Hamadan Phyllite) have ages consistent with the Triassic to Early Jurassic age previously determined from fossils. These ages confirm that an orogenic episode affected the Sanandaj-Sirjan Zone in the Early to Middle Jurassic (Cimmerian Orogeny). Although the Cimmerian Orogeny in northern Iran reflects late Triassic to Jurassic collision of the Turan platform (southern Eurasia) and the Cimmerian microcontinent, we consider that in the Sanandaj-Sirjan Zone a tectonothermal event coeval with the Cimmerian Orogeny resulted from initiation of subduction and closure of rift basins along the northern margin of Neo-Tethys

On Net Load and Invisible Solar Power Generation Estimation In Modern Power Systems

Integration of wind and solar power generation into power systems has grown significantly over the past decade. While system operators have managed the variable and non-dispatchable nature of these resources at current levels, their large-scale integration would pose new challenges in power systems operation procedures. In particular, net load, which is the conventional load minus the non-dispatchable generation, would significantly deviate from load as the penetration level increases. The main non-dispatchable sources of electricity generation are utility-scale and small- scale behind-the-meter wind and solar power. This thesis focuses on characteristics of the net load in power systems when a large amount of wind and solar power generation is integrated into the grid. Historical and simulated net load scenarios are analyzed from a variety of perspectives. It also evaluates the effect of wind integration level on the net load forecasting accuracy. Additionally, the thesis proposes two methodologies to estimate invisible solar power generation using the data from a limited number of sites. The first approach uses data mining tools to identify the critical sites for continuous monitoring. The second approach models the uncertainties of the invisible solar power production using fuzzy arithmetic applied to publicly available production data. This is the first study using public data in the field. Numerical simulations are provided based on California, Alberta, and Ireland power systems. The results show the importance of understanding the changes related to significant wind and solar power generation. New morning downward and an increased level of afternoon upward net load ramps were found compared to the conventional load. The net load was also found to be more volatile compared to the load. In addition, numerical results prove the efficiency and accuracy of the proposed methodologies for the invisible solar power generation estimation. The results showed that continuous monitoring of a small number of sites is enough for accurate estimations. Moreover, the fuzzy model is capable of producing accurate estimations by using public data of only 20 sites per subregion

Swiss Journal of Geosciences / Tectonic significance of Triassic mafic rocks in the June Complex, Sanandaj-Sirjan zone, Iran

This study concentrates on the petrological and geochemical investigation of mafic rocks embedded within the voluminous Triassic June Complex of the central Sanandaj-Sirjan zone (Iran), which are crucial to reconstruct the geodynamics of the Neotethyan passive margin. The Triassic mafic rocks are alkaline to sub-alkaline basalts, containing 43.3649.09 wt% SiO2, 5.1920.61 wt% MgO and 0.664.59 wt% total alkalis. Based on MgO concentrations, the mafic rocks fall into two groups: cumulates (Mg# = 51.6158.94) and isotropic basaltic liquids (Mg# = 24.5442.66). In all samples, the chondrite-normalized REE patterns show enrichment of light REEs with variable (La/Yb)N ratios ranging from 2.48 to 9.00, which confirm their amalgamated OIB-like and E-MORB-like signatures. Enrichment in large-ion lithophile elements and depletion in high field strength elements (HFSE) relative to the primitive mantle further support this interpretation. No samples point to crustal contamination, all having undergone fractionation of olivine + clinopyroxene + plagioclase. Nevertheless, elemental data suggest that the substantial variations in (La/Sm)PM and Zr/Nb ratios can be explained by variable degrees of partial melting rather than fractional crystallization from a common parental magma. The high (Nb/Yb)PM ratio in the alkaline mafic rocks points to the mixing of magmas from enriched and depleted mantle sources. Abundant OIB alkaline basalts and rare E-MORB appear to be linked to the drifting stage on the northern passive margin of the Neotethys Ocean.(VLID)231624

Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

In this paper, we present detailed field observations, chronological, geochemical and Sr–Nd isotopic data and discuss the petrogenetic aspects of two types of mafic dykes, of alkaline to subalkaline nature. The alkaline mafic dykes exhibit a cumulate to foliated texture and strike NW–SE, parallel to the main trend of the region. The 40Ar/39Ar amphibole age of 321.32 ± 0.55 Ma from an alkaline mafic dyke is interpreted as an indication of Carboniferous cooling through ca. 550 °C after intrusion of the dyke into the granitic Galeh-Doz orthogneiss and Amphibolite-Metagabbro units, the latter with Early Carboniferous amphibolite facies grade metamorphism and containing the Dare-Hedavand metagabbro with a similar Carboniferous age. The alkaline and subalkaline mafic dykes can be geochemically categorized into those with light REE-enriched patterns [(La/Yb)N = 8.32–9.28] and others with a rather flat REE pattern [(La/Yb)N = 1.16] and with a negative Nb anomaly. Together, the mafic dykes show oceanic island basalt to MORB geochemical signature, respectively. This is consistent, as well, with the (Tb/Yb)PM ratios. The alkaline mafic dykes were formed within an enriched mantle source at depths of ˃ 90 km, generating a suite of alkaline basalts. In comparison, the subalkaline mafic dykes were formed within more depleted mantle source at depths of ˂ 90 km. The subalkaline mafic dyke is characterized by 87Sr/86Sr ratio of 0.706 and positive ɛNd(t) value of + 0.77, whereas 87Sr/86Sr ratio of 0.708 and ɛNd(t) value of + 1.65 of the alkaline mafic dyke, consistent with the derivation from an enriched mantle source. There is no evidence that the mafic dykes were affected by significant crustal contamination during emplacement. Because of the similar age, the generation of magmas of alkaline mafic dykes and of the Dare-Hedavand metagabbro are assumed to reflect the same process of lithospheric or asthenospheric melting. Carboniferous back-arc rifting is the likely geodynamic setting of mafic dyke generation and emplacement. In contrast, the subalkaline mafic sill is likely related to the emplacement of the Jurassic Darijune gabbro