Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Journal of the Geological Society

This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Search for Related Content GeoRef GeoRef Citation

Discussion on the Upper Proterozoic ophiolite mélange zones of the easternmost Arabian Shield

DRS V. E. CAMP, N. J. JACKSON, C. R. RAMSAY, M. J. ROOBOL, D. B. STOESER and D. L. WHITE write: The recent paper by Al-Shanti and Gass (1983) describing ophiolite mélange zones in the eastern Arabian Shield reaches a number of conclusions which we consider do not accord with the evidence.

The oceanic island arc accretion model

The recognition that the Arabian Shield contains island arcs (Jackaman 1972; Greenwood et al. 1976) which have been tectonically juxtaposed (Bakor et al. 1976; Frisch & Al-Shanti 1977; Gass 1977), was a major conceptual breakthrough. However, evidence now indicates that the basic model reiterated by Al-Shanti and Gass (p. 867, ‘accretion of intra-oceanic island arc systems over the period 1100-SO0 Ma’) is an oversimplification. First, part of the eastern Arabian Shield may be underlain by continental sialic crust (e.g. Ramsay et al. 1979; Stacey et al. 1980; Delfour 1980; Stacey & Stoeser 1983). Second, the best estimate for the start of oceanic island arc develop- ment was shortly before about 900 Ma (Marzouki et al. 1982). Third, although the development of oceanic island arc systems was the dominant crustal process from about 900 to about 700 Ma (e.g. Fleck et al. 1980; Jackson & Ramsay 1980; Roobol et al. 1983), most of these arc systems were assembled into a single plate by 670 f 10 Ma ago. Following this suturing, the shield- forming magmatic processes changed from one of lithospheric magma systems dominated by subduction- related procsses, to magma systems dominated by massive

...

This 250-word extract was created in the absence of an abstract.

This article has been cited by other articles:

				P. R. Johnson and B. Woldehaimanot Development of the Arabian-Nubian Shield: perspectives on accretion and deformation in the northern East African Orogen and the assembly of Gondwana Geological Society, London, Special Publications, January 1, 2003; 206(1): 289 - 325. [Abstract] [PDF]