Geology and petrography of the Nagar Parkar Igneous Complex, southeastern Sindh: the Wadhrai body
Keywords:
Nagar Parkar igneous complex, Wadhrai body, Sindh, Pakistan.Abstract
The Wadhrai igneous body occurs to the north of the Nagar Parkar town. This and other bodies constituting the Nagar Parkar Igneous Complex are an extension of the Malani Igneous Suite of western Rajasthan. The body is occupied by petrographically uniform granite composed of perthite, albitic plagioclase, quartz, and small quantities of biotite, opaque oxide and titanite. The rocks are sparingly porphyritic and contain dykes and veins of microgranite, aplite and quartz; pegmatites are rare and simple. In the southeastern part, the granite is invaded by parallel sheets and swarms of many mafic dykes, and rhyolite sheets. The mafic dykes are porphyritic to aphyric and consist of calcic plagioclase, hornblendic amphibole or clinopyroxene +/- olivine, ilmenite, titanite and a range of secondary minerals. Many of the mafic dykes are strongly altered, some totally, and a few beyond recognition. The rhyolite sheets are sparsely porphyritic, at places banded, and composed of perthite, quartz, albite, sodic amphibole, aegirine-augite, opaque oxide and titanite. The main rhyolite sheet extends for more than 2 km and attains a thickness of 30 m. While the felsic dykes are apparently related to the granite, the mutual relations between the granite, mafic and rhyolite sheets are yet to be deciphered, but the rhyolites may represent melts derived from the crust through underplating by mafic magma. This paper gives detailed petrography of the rocks, together with newly prepared geological maps.
References
Ahmad, S. A., Chaudhry, M. N., 2008. A-type granites from the Nagarparkar complex, Pakistan: Geochemistry and origin. Geological Bulletin, Punjab University,
, 69-81.
Ashwal, L. D., Solanki, A. M., Pandit, M. K., Corfu, F., Hendriks, B. W., Burke, K., Torswik, T. H., 2013. Geochronology and geochemistry of the Neoproterozoic Mt. Abu granitoids, NW India: Regional correlation and implications for Rodinia paleogeography. Precambrian Research,
, 265-281.
Bhushan, S. K., 2000. Malani rhyolite – a review. Gondwana Research, 3 (1), 65-77.
Butt, K. A., Jan, M. Q., Karim, A., 1994. Late Proterozoic rocks of Nagar Parkar, southeastern Pakistan: A preliminary petrologic account, In: Ahmed, R. and Sheikh, A. M. (eds.) Geology in South Asia-1. Hydrocarbon Development Institute of Pakistan, Islamabad, 106-109.
De la Roche, H., Leterrier, J., Grandle Claude, P., Marchal., M., 1980. A classification of volcanic and plutonic rocks using R1-R2 diagrams and major element analysis-its relationships and current nomenclature. Chemical Geology, 29, 193-210.
Gregory, L. C., Meert, J. G., Bingen, B., Pandit, M. K., Torsvik, T. H., 2009. Paleomagnetism and geochronology of the Ma1ani Igneous Suite, Northwest India: Implications for the configuration of Rodinia and the assembly of Gondwana. Precambrian Research, 170, 13-26.
Jan, M.Q., Agheem, M. H., Laghari, A., Anjum, S. 2016. Geology and petrography of the Nagar Parkar igneous complex, southeastern Sindh, Pakistan: the Kharsar body. Journal of the Geological Society of India (in press).
Jan, M. Q., Laghari, A., Agheem, M. H., Anjum, S., 2014. Geology and petrography of the Nagar Parkar igneous complex, southeastern Sindh: the Dinsi body. Journal of Himalayan Earth Sciences, 47,
-14.
Jan, M. Q., Lagbari, A., Khan, M. A., 1997. Petrography of the Nagar Parkar igneous complex, Tharparkar, Southeastern Sindh, Pakistan. Geological Bulletin, University of Peshawar, 30, 227-259.
Kazmi, A. H., Jan, M. Q., 1997. Geology and Tectonics of Pakistan. Graphic publishers, Karachi.
Kazmi, A. H., Khan, R. A., 1973. The report on the geology, minerals and water resources of Nagar Parkar, Pakistan, Geological Survey of Pakistan, Information Release, 64,1-32.
Khan, T., Murata, M., Rehman, H. U., Zafar, M., Ozawa, H., 2012. Nagar parker granites showing Rodinia remnants in the southeastern part of Pakistan. Journal of Asian Earth Sciences, 59, 39-51.
Kochhar, N., 2004. Geological evolution of the Trans-Aravalli Block (TAB) of the NW Indian Shield and Seychelles connection in the Late Proterozoic: evidence from plume related A-type Malani magmatism. Geological Survey of India, Special Publication, 84, 247-264.
Kochhar, N., Dhar, S., Sharma, R., 1995.Geochemistry and tectonic significance of acid and basic dykes associated with Ja1or magmatism, west Rajasthan. Memoir, Geological Society of India, 33, 375-389.
Laghari, A., 2004. Petrology of the Nagar Parkar granites and associated basic rocks, Thar District, Sindh, Pakistan. Unpublished Ph.D. thesis, University of Peshawar.
Lagbari, A., Jan, M. Q., Khan, M.A., Agheem, M. H., Sohito, A. G., 2013. Petrogrsphy and major element chemistry of mafic dykes in the Nagar Parkar Igneous Complex, Tharparkar, Sindh. Journal of Himalayan Earth Sciences, 46, 1-11.
Middlemost, E. A. K., 1994. Naming materials in the magma igneous rock system. Earth Science Reviews, 37, 215-224.
Muslim, M., Akhtar, T., Khan, Z. M., Khan, T., 1997. Geology of the Nagar Parkar area, Tharparkar district, Sindh, Pakistan. Geological Survey of Pakistan, Information Release, 605.
O'Connor, J.T., 1965. A classification for quartz-rich igneous rocks based on feldspar ratios. United States Geological Survey, Professional Paper, 525B, B79- B84.
Rizvi, Y., Tagar, M. A., Alizai, A., 2006. Geological map of the Nagar Parkar. Geological Survey of Pakistan, Information Release, 872.
Winter, J.D., 2010. Principals ofigneous and Metamorphic Petrology (2nd Ed). Pearson Education Inc., New Jersey, 07458, USA.
