Petrology and geochemistry of dolerite and lamprophyre sills in Mesozoic successions of Khanozai–Muslim Bagh area, northwestern Pakistan
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In Khanozai–Muslim Bagh area, NW Pakistan, the sills are intruded into mainly Triassic–Jurassic successions of Indian platform sediments. They are petrographically identified as dolerite and lamprophyre. The dolerite is a normal dolerite and olivine dolerite and is altered compared with lamprophyre. Lamprophyre is classified as sannaite, camptonite, minette, and damtjernite. The geochemical signature of dolerite, olivine dolerite, and lamprophyre suggests that these rocks belong to alkali series by classification and may be alkaline in nature. Normal mid-oceanic ridge basalts (NMORB)–normalized plots of dolerite, olivine dolerite, and lamprophyre show higher enrichment of large ion lithophile elements (LILEs) relative to high field strength elements (HFSEs) and marked positive anomalies on Nb which confirm their origin from an enriched mantle source. The ocean island basalt (OIB)–normalized plots of these rocks exhibit patterns almost alike to those of OIB suggesting a source similar to OIB. The tectono-magmatic discrimination plots of dolerite, olivine dolerite, and lamprophyres plot them in the OIB field and indicate that they are alkaline rocks in nature. The petrogenesis and tectonic setting of these rocks suggest that they are OIB in nature and may represent a Late Cretaceous magmatic activity that erupted as hotspot fluid through the crust of Indian Plate during the Late Cretaceous. It is much similar to the other hotspot-related rocks that intruded into the Parh Group and Bela ophiolite mélange. Much like the magmatism of Deccan Traps and the Chagos-Laccadive Ridge, these rocks may be the melt of a hotspot possibly Réunion that intruded into the Indian Plate margin when it had passed over it during the Late Cretaceous.
KeywordsDolerite Lamprophyre Sills Alkaline Petrogenesis Tectonic setting
Constructive comments from the Claude Moussounda Kounga and other anonymous reviewer are highly acknowledged which certainly improved the manuscript. M Qasim Jan is thanked for editing the manuscript.
This research was funded by the Higher Education Commission, Pakistan, under its NRPU Project No. 3593.
- Aitchison JC, Ali JR, Davis AM (2007) When and where did India and Asia collide? J Geophys Res Solid Earth 112Google Scholar
- Bukhari SWH, Mohibullah, M Khan Kasi A, Iqbal H (2016) Biostratigraphy of the Eocene Nisai Formation in Pishin belt, Western Pakistan. JHES 49(1):17Google Scholar
- Jones AG (1961) Reconnaissance geology of part of West Pakistan. A Colombo plan cooperative project, Government of Canada, Toronto: 550pGoogle Scholar
- Kasi AK, Kassi AM, Umar M, Manan RA, Kakar MI (2012) Revised lithostratigraphy of the Pishin Belt northwestern Pakistan. JHES 45(1):53–65Google Scholar
- Le Maitre RW, Streckeisen A, Zanettin B, Le Bas MJ, Bonin B, Bateman P, Lameyre J (2005) Igneous rocks: a classification and glossary of terms; recommendations of the International Union of Geological Sciences. In Subcommission on the systematics of igneous rocks. Cambridge University Press, CambridgeGoogle Scholar
- Mengal JM, Kimura K, Siddiqui MRH, Kojima S, Naka T, Bakht MS, Kamada K (1994) The lithology and structure of a Mesozoic sedimentary-igneous assemblage beneath the Muslim Bagh ophiolite, Northern Balochistan, Pakistan. Bull Geol Surv Jpn 45:51–61Google Scholar
- Naka T, Kimura K, Mengal JM, Siddiqui RH, Kojima S, Sawada Y (1996) Mesozoic sedimentary-igneous complex, Bagh complex, in the Muslim Bagh area, Pakistan. Opening and closing ages of the Ceno-Tethyan branch. In: Yajima J, Siddiqui RH (eds) Proceedings of geoscience colloquium, geoscience laboratory. Geological Survey of Pakistan, Islamabad 16: 47–94Google Scholar
- Pearce JA (1982) Trace elements characteristics of lavas from destructive plate boundaries. In: Throp RS (ed) Andesites: orogenic andesites and related rocks. John Wiley and Sons, New York, pp 525–548Google Scholar
- Pearce JA (1996) A user’s guide to basalt discrimination diagrams. In: Bailes AH, Christiansen EH, Galley AG, Jenner GA, Keith, Jeffrey D, Kerrich R, Lentz, David R, Lesher CM, Lucas, Stephen B, Ludden JN, Pearce JA, Peloquin SA, Stern RA, Stone WE, Syme EC, Swinden HS, Wyman DA (eds) Trace element geochemistry of volcanic rocks; applications for massive sulphide exploration, short course notes. Geological Association of Canada 12: 79–113Google Scholar
- Searle M, Corfield RI, Stephenson B, McCarron J (1997) Structure of the north Indian continental margin in the Ladakh-Zanskar Himalayas: implications for the timing of obduction of the Spontang ophiolite, India-Asia collision and deformation events in the Himalaya. Geol Mag 134:297–316CrossRefGoogle Scholar
- Sheth HC (2005) From Deccan to Réunion: no trace of a mantle plume. Special Papers-Geological Society of America 388:477–501Google Scholar
- Sun S-S, McDonough WF (1989) Chemical and isotopic systematics in ocean basalt: implication for mantle composition and processes. In: Saunders A D, Norry M J (eds) Magmatism in the ocean basins. Geol Soc Spec Publ 42: 313–345Google Scholar
- Warraich MY, Ali M, Ahmed MN, Siddiqui MRH (1995) Geology and structure of the calcareous zone in the Muslim Bagh in the Killa Saifullah area, Balochistan. Geologica 1:61–75Google Scholar