Geology and Petrography of the Nagar Parkar Igneous Complex, Southeastern Sindh, Pakistan: The Kharsar Body

Abstract

Kharsar hill is one of many granitic plutons comprising the Nagar Parkar igneous complex. The eastern part of the hill is occupied by grey-pink granite (earlier) and the western part by pink granite (later). They are composed of perthite, quartz, and plagioclase, with minor opaque oxide, biotite, titanite, local amphibole, and secondary chlorite, epidote, leucoxene/titanite. The pink granite is characterized by the presence of mafic clots. Both the granitoids are intruded by microgranite/aplite, and porphyritic mafic and rhyolite dykes, locally in swarms. These are abundant in a NE trending 200 m wide zone cutting the entire granite hill. The dykes may extend over 1 km in length and >10 m in thickness, but most are < 100 m in length. The felsic dykes are of several generations; some are associated with the two varieties of granite, others are contemporaneous with the rhyolite and mafic dykes. The mafic dykes can be grouped into two types one of which contains hornblende and the other augite as the principal mafic mineral. Major element analyses suggest that the granitic rocks are metaluminous. The Kharsar granites, like the others in Nagar Parkar, may be an extension of the Malani igneous suite of Rajasthan. The occurrence of bimodal mafic-felsic dykes and petrographic variation in the mafic dykes are briefly discussed.

Provenance, tectonic setting, and source area weathering of Middle Jurassic siliciclastic rocks of Chari Formation, Jumara Dome, Kachchh Basin, Western India: Sedimentological, mineralogical, and geochemical constraints

“…The interpreted source rocks for the Jumara Dome sediments are exposed in the Aravalli Craton and Nagar Parkar Massif terrain in east and northeast, and north and northwest directions, respectively (Jan, Agheem, Laghari, & Anjum, 2017). The synthesis of paleocurrent data collected for this study (n = 37, vector mean = 351.694; n = 30, vector mean = 74.995) indicates the contribution from both these terrains (Figure 8).…”

Sedimentological and petrochemical studies of Jurassic clastic rocks, Habo Dome Basin, Kachchh Mainland, Northwest India: Implications for depositional environment, provenance, and tectonic setting

“…The clastic rocks of Dhrang and Jhikadi formations posses Nb/Y ratio less than 0.7 (a feature of sub‐alkaline igneous rocks) whereas a good number of the samples of Rudramata Shales and Lodai Shales posses a high Nb/Y ratio ≥ 0.7 which points the presence of alkaline rocks in the source terranes (Table ). The alkaline rocks have been reported from the Nagarparkar Massif lying to the north and north–northwest of the Habo Dome (S. A. Ahmad, Mateen, & Chaudhry, ; Jan, Agheem, Laghari, & Anjum, ; Jan et al, ) (Figure ). These are represented by mafic dikes (hornblende microdioritc to gabbro and dolerite), some of which contain titanium augite, an indicator of alkaline affinity (Laghari et al, ).…”

“…These are represented by mafic dikes (hornblende microdioritc to gabbro and dolerite), some of which contain titanium augite, an indicator of alkaline affinity (Laghari et al, ). Other plutonic rocks of the Nagar Parkar area contain high concentration of total alkali oxides (Na 2 O + K 2 O) ranging from 8.33 wt% to 10.96 wt% (Jan et al, ) with alkaline to peralkaline character. Although trace element data on the rocks of Nagar Parkar region is not available, none of the lithocomponents of BGC contains Nb/Y ratio > 0.7 (Granite, 0.64, Tonalite–trondhjemite–granodiorite, 0.43, Mafic enclaves, 0.26, T. Ahmad et al, ) or high total alkali oxides (Na 2 O + K 2 O wt%, Granite, 7.62, Tonalite–trondhjemite–granodiorite, 7.86, Mafic enclaves, 2.19; T. Ahmad et al, ) like Nagar Parkar alkalines.…”

Permian felsic magmatism in the Neoproterozoic Nagar Parkar Igneous Complex of the Malani Igneous Suite: Evidence from zircon U–Pb age

“…It comprises a metamorphosed basement of mafic to tonalitic rocks, Neoproterozoic granitoid intrusions in the basement, and a range of younger felsic and mafic dykes. Based on lithological and petrographic similarities with the Neoproterozoic rocks of Erinpura and Malani Igneous Suite (MIS) of the Trans Aravalli mountain belt in India, the NPIC was considered as the western extension of the MIS (Jan, Agheem, Laghari, & Anjum, ; Jan et al, ; Jan, Laghari, Agheem, & Anjum, ; Kaur, Chaudhri, Sekhar, & Yokoyama, ; Khan et al, ; Khan et al, ; Khan, Murata, Zafar, & Rehman, ; Kochhar, ; Meert, Pandit, & Kamenov, ; Muslim et al, ; Pascoe, ; Srivastava, ; Vallinayagam, ; Vallinayagam, ). Several authors have proposed that the basement rocks and the granitoids in this part of the Indian Shield were formed by an earlier Andean‐type subduction, followed by rift‐related extension tectonics in the Rodinia supercontinent (McKenzie, Houghes, Myrow, Xiao, & Sharma, ; Dharma Rao, Santosh, & Kim, ; Ashwal, Solanki, Pandit, Corfu, & Hendriks, et al, 2013; Meert et al, ; Turner, Meert, Pandit, & Kamenov, ; Jan, Laghari, Khan, Agheem, & Khan, ; Wang et al, ; Wang, Pandit, Zhao, Chen, & Zheng, ).…”

“…Several other authors reported K–Ar and U–Pb zircon ages of 745 to 750 Ma from the rhyolites and granites of the MIS, Seychelles, and Madagascar islands (Ashwal et al, , ; Crawford & Compston, ; Dhar, Frei, Kramers, Nagler, & Kochhar, ; Eby & Kochhar, ; Hoshino, ; Meert et al, ; Rathore, Venkatesan, & Srivastava, ; Suwa et al, ; Torsvik et al, , ; Wang et al, ). Based on identical lithological, petrological, mineralogical and geochemical features, and age data, the granites and some of the felsic dykes in the NPIC were related to the same tectonic regime (i.e., rifting) within the Rodinia during the Neoproterozoic (Jan et al, , ; Khan et al, , , ; Rehman et al, ). Details of the individual outcrops exposed in various parts of the NPIC have been presented elsewhere (e.g., Agheem, Jan, Laghari, & Anjum, ; Jan et al, , , ; Khan et al, ; Markhand, Xia, Agheem, & Jia, ).…”