Emplacement time of the Loe–Shilman carbonatite from NW Pakistan: Constraints from fission-track dating

• Published in: Radiation measurements Vol. 43; pp. S313 - S318
• Main Authors: Khattak, N.U., Akram, M., Khan, M.A., Khan, H.A.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2008; Elsevier
• Subjects: Age standard approach; Crystalline rocks; Durango apatite; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fission-track dating; Formation age; Geochronology; Igneous and metamorphic rocks petrology, volcanic processes, magmas; Isotope geochemistry. Geochronology; Loe–Shilman carbonatite; Afghanistan; Pakistan; Asia; Indian Peninsula; Loe–Shilman carbonatite; Age standard approach; Formation age; Fission-track dating; Durango apatite; emplacement; crystals; Loe-Shilman carbonatite; igneous rocks; low temperature; metamorphic rocks; Precambrian; apatite; fission-track dating; Paleozoic; carbonatites; phosphates; standard samples; plutonic rocks; sills; fault zones; metasedimentary rocks; methodology; retention
• ISSN: 1350-4487; 1879-0925
• DOI: 10.1016/j.radmeas.2008.03.038

The Loe–Shilman carbonatite complex is situated in the extreme west of the Peshawar Plain Alkaline Igneous Province (PAIP), near the Pakistan–Afghanistan border. It comprises sill-form bodies emplaced along an E–W trending and N dipping fault zone in Paleozoic to Precambrian metasedimentary rocks of Khyber Agency. Fission-track dating studies on the apatite crystals using the external detector method and age standard approach (the ζ method) yielded an age of 30.0 ± 1.5 Ma for the Loe–Shilman carbonatite. Close agreement between the previously determined radiometric ages from the same as well as the neighboring carbonatite complexes of the PAIP and the fission-track apatite age of this study indicates that the Loe–Shilman carbonatite was emplaced at relatively shallow crustal level and quickly cooled to low temperatures ( < 60 ∘ C ) required for the complete retention of fission tracks in apatite and that the fission-track age of this study is the emplacement age of the Loe–Shilman carbonatite.