In the northwest Himalaya of Pakistan, the panjal volcanics of the Kahuta, Muzaffarabad and Kaghan areas form an elongate exposure of the Permian to Triassic basalts. The Panjal volcanics wrap around the apex of the Hazara-Kashmir syntaxis. The basaltic exposure runs northwest-southeast and dips to the northeast.
The panjal volcanics structurally lie between the Panjal Thrust and the Main Boundary Thrust at the upper and lower structural levels, respectively. The Agglomeratic slates and the Panjal volcanics were formed in two phases In the first phase Agglomeratic slates were deposited in Late Carboniferous and were followed by the second phase eruptions of basaltic lavas that. took place during Permian to Triassic. The feeders to basaltic lavas in the northwest Himalaya of Pakistan have been dated at 284± to 262± 1 Ma by previous workers.
The volcanics are characterized by massive lava flows and pillow lavas with intercalations of limestone and bedded chert. The volcanics are metamorphosed to lower greenschist facies during Himalayan orogeny. The Panjal volcanics are variably vesicular and altered to chlorite, epidote, Fe-oxides, sodic plagioclase, actinolite and calcite. Petrographic and chemical data of the less altered volcanics indicate that they were originally pyroxene and plagioclase phyric tholeiites.
The Panjal volcanics were analysed for major, minor and trace elements to investigate their nature, origin and tectonic setting. Whole rock analyses (120) of the Panjal volcanics from the Kahuta, Muzaffarabad and Kaghan areas were plotted ill various discrimination diagrams. The geochemical data indicate that the Panjal volcanics are dominantly tholeiitic to mildly alkalic hasalts.
REE (La, Sm and Yb), Ti%, Zr and Y data suggest that the source rocks (Garnet lherzolite and lherzolite) for the Panjal volcanics have undergone variable degrees (13 to 28%) of partial melting. Geochemical variations in the Panjal volcanics indicate that these rocks have been effected by fractional crystallization, mantle heterogeneity and with some degrees of crustal contamination. The Panjal volcanic rocks are characterized by their higher Zr/Y (3.8 to 4.12) and Ti/Y (331 to 352) ratios than the N-MORB. In contrast, the trace elements (Zr/Nb = 2.6 to 33, Zr/Y = 3.8 to 4.12 and Ti/Y = 331 to 352) and chondrite normalized light rare earth elements (La/Yh)= 3.29 to 11.16, (Ce/Yb )= 2.83 to 8.62 and (La/Sm )= 1.96 to 41 data indicate within-plate to P-type mid ocean ridge basalts. The geochemical data plotted in tectono-magmatic discriminant diagrams also suggest a within plate to P-type mid ocean ridge environment.
The geology, geochemistry and tectonics of the Panjal volcanics show that the lava flows were erupted during the Permian-Triassic rifting and initiation of incipient ocean along the northern margin of India.