|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| Journal of the Geological Society |  |
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Article |
1 School of Geological Sciences, Kingston University, Kingston-upon- Thames, Surrey KT1 2EE, UK
2 British Geological Survey, Murchison House, West Mains Road, Edinburgh EH9 3LA, UK
3 NCE in Geology, University of Peshawar, Peshawar, North West Frontier Province, Pakistan
4 Department of Geology & Geography, Vassar College, Box 255, Raymond Avenue, Poughkeepsie, New York, 12601, USA
New field mapping and structural data, combined with published geochemical data, from the Kohistan arc in the NW Himalaya, enable a re-evaluation of the arc stratigraphy. Key lithological units and their relationships are more clearly defined, permitting the construction of a revised magmatic-tectonic history for the arc. The oldest units are transitional oceanic-type basalts, which form the basement to the subduction related sequence. Arc-type gabbroic sheets and plutons intrude the oceanic basalts: together these form the Kamila Amphibolite Belt. Metasediments and basaltic lavas were deposited, within an extensional basin, onto the Kamila Amphibolite Belt basement. This sequence, exposed across the arc, forms a distinct stratigraphic unit which is formally defined here as the Jaglot Group. Sediment-charged turbidity currents transported material into the basin, whilst submarine eruptions contributed the basaltic component. This period of extension culminated in the eruption of high-Mg boninites of the Chalt Volcanic Group which overlie the rocks of the Jaglot Group. The earliest granitoids of the Kohistan Batholith predate suturing and intrude the Jaglot and Chalt sequences. At c. 100 Ma Kohistan sutured to Asia. suturing being accompanied by thickening of the arc with the development of major intra-arc shear zones and a penetrative, regionally developed steep cleavage. At c. 85 Ma intra-arc rifting permitted the emplacement into the arc of the voluminous gabbronorites of the Chilas Complex which clearly intrudes the Kamila Amphibolite Belt to the south and the Jaglot Group to the north. The Chilas Complex has been regarded as part of the pre-suturing, juvenile arc sequence. Field evidence summarized here show this to be not so. Heat advection associated with emplacement of the Complex caused amphibolite facies regional metamorphism, melting of the lower arc and plutonism. Some of the resultant granitoid plutons were unroofed and eroded during a compressional phase at between 80 and 55 Ma, before emplacement of further plutons and extrusion of basaltic through to rhyolitic volcanic rocks at between 55 and 40 Ma. At least three phases of extension and rifting, each separated by short lived phases of compression, characterized arc evolution. Much of the magmatism is controlled by extensional tectonics within the overriding plate of the kind commonly associated with a retreating subduction zone.
KEYWORDS: Himalaya, Pakistan, Kohistan, island arcs, igneous activity
This article has been cited by other articles:
|
|
 |
|
  B. Dhuime, D. Bosch, C. J. Garrido, J.-L. Bodinier, O. Bruguier, S. S. Hussain, and H. Dawood Geochemical Architecture of the Lower- to Middle-crustal Section of a Paleo-island Arc (Kohistan Complex, Jijal-Kamila Area, Northern Pakistan): Implications for the Evolution of an Oceanic Subduction Zone J. Petrology, March 19, 2009; (2009) egp010v1. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. D. Khan, D. J. Walker, S. A. Hall, K. C. Burke, M. T. Shah, and L. Stockli Did the Kohistan-Ladakh island arc collide first with India? Geological Society of America Bulletin, March 1, 2009; 121(3-4): 366 - 384. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. D. Clift, H. Schouten, and P. Vannucchi Arc-continent collisions, sediment recycling and the maintenance of the continental crust Geological Society, London, Special Publications, January 1, 2009; 318(1): 75 - 103. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. Jagoutz, O. Muntener, P. Ulmer, T. Pettke, J.-P. Burg, H. Dawood, and S. Hussain Petrology and Mineral Chemistry of Lower Crustal Intrusions: the Chilas Complex, Kohistan (NW Pakistan) J. Petrology, October 1, 2007; 48(10): 1895 - 1953. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Rioux, B. Hacker, J. Mattinson, P. Kelemen, J. Blusztajn, and G. Gehrels Magmatic development of an intra-oceanic arc: High-precision U-Pb zircon and whole-rock isotopic analyses from the accreted Talkeetna arc, south-central Alaska Geological Society of America Bulletin, September 1, 2007; 119(9-10): 1168 - 1184. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. J. Garrido, J.-L. Bodinier, B. Dhuime, D. Bosch, I. Chanefo, O. Bruguier, S. S. Hussain, H. Dawood, and J.-P. Burg Origin of the island arc Moho transition zone via melt-rock reaction and its implications for intracrustal differentiation of island arcs: Evidence from the Jijal complex (Kohistan complex, northern Pakistan) Geology, August 1, 2007; 35(8): 683 - 686. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. J. GARRIDO, J.-L. BODINIER, J.-P. BURG, G. ZEILINGER, S. S. HUSSAIN, H. DAWOOD, M. N. CHAUDHRY, and F. GERVILLA Petrogenesis of Mafic Garnet Granulite in the Lower Crust of the Kohistan Paleo-arc Complex (Northern Pakistan): Implications for Intra-crustal Differentiation of Island Arcs and Generation of Continental Crust J. Petrology, October 1, 2006; 47(10): 1873 - 1914. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. D. Clift, A. E. Draut, P. B. Kelemen, J. Blusztajn, and A. Greene Stratigraphic and geochemical evolution of an oceanic arc upper crustal section: The Jurassic Talkeetna Volcanic Formation, south-central Alaska Geological Society of America Bulletin, July 1, 2005; 117(7-8): 902 - 925. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J.-P. Burg, L. Arbaret, N. M. Chaudhry, H. Dawood, S. Hussain, and G. Zeilinger Shear strain localization from the upper mantle to the middle crust of the Kohistan Arc (Pakistan) Geological Society, London, Special Publications, January 1, 2005; 245(1): 25 - 38. [Abstract] [PDF]
|
|
|
|
 |
|
 References Geological Society, London, Memoirs, January 1, 2005; 31(1): 267 - 282. [PDF]
|
|
|
|
|
|
K.-J. Zhang, B.-D. Xia, G.-M. Wang, Y.-T. Li, and H.-F. Ye Early Cretaceous stratigraphy, depositional environments, sandstone provenance, and tectonic setting of central Tibet, western China Geological Society of America Bulletin, September 1, 2004; 116(9-10): 1202 - 1222. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. M. Bignold, S.M. Bignold, and P.J. Treloar Northward subduction of the Indian Plate beneath the Kohistan island arc, Pakistan Himalaya: new evidence from isotopic data Journal of the Geological Society, May 1, 2003; 160(3): 377 - 384. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. V. Hodges Tectonics of the Himalaya and southern Tibet from two perspectives Geological Society of America Bulletin, March 1, 2000; 112(3): 324 - 350. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. D. Clift, P. J. Degnan, R. Hannigan, and J. Blusztajn Sedimentary and geochemical evolution of the Dras forearc basin, Indus suture, Ladakh Himalaya, India Geological Society of America Bulletin, March 1, 2000; 112(3): 450 - 466. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. W. H. Butler Structural evolution of the western margin of the Nanga Parbat massif, Pakistan Himalaya: insights from the Raikhot-Liachar area Geological Society, London, Special Publications, January 1, 2000; 170(1): 51 - 75. [Abstract] [PDF]
|
|
|
|
|
|
R. F. Weinberg, W. J. Dunlap, and M. Whitehouse New field, structural and geochronological data from the Shyok and Nubra valleys, northern Ladakh: linking Kohistan to Tibet Geological Society, London, Special Publications, January 1, 2000; 170(1): 253 - 275. [Abstract] [PDF]
|
|
|
|
|
|
L. Arbaret, J.-P. Burg, G. Zeilinger, N. Chaudhry, S. Hussain, and H. Dawood Pre-collisional anastomosing shear zones in the Kohistan arc, NW Pakistan Geological Society, London, Special Publications, January 1, 2000; 170(1): 295 - 311. [Abstract] [PDF]
|
|
|
|
|
|
R. I. CORFIELD, M. P. SEARLE, and O. R. GREEN Photang thrust sheet: an accretionary complex structurally below the Spontang ophiolite constraining timing and tectonic environment of ophiolite obduction, Ladakh Himalaya, NW India Journal of the Geological Society, October 1, 1999; 156(5): 1031 - 1044. [Abstract] [PDF]
|
|
|
|
|
|
Discussion on geochemical and isotopic constraints on subduction polarity, magma sources and palaeogeography of the Kohistan Arc, northern Pakistan Journal of the Geological Society, October 1, 1998; 155(5): 893 - 895. [Abstract] [PDF]
|
|
|
|
|
|
M. A. KHAN, R. J. STERN, R. F. GRIBBLE, and B. F. WINDLEY Geochemical and isotopic constraints on subduction polarity, magma sources, and palaeogeography of the Kohistan intra-oceanic arc, northern Pakistan Himalaya Journal of the Geological Society, December 1, 1997; 154(6): 935 - 946. [Abstract] [PDF]
|
|
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
