"THE AGE OF THE HAWASINA AND OTHER PROBLEMS OF OMAN MOUNTAINS GEOLOGY"

by H. Hugh Wilson

DISCUSSION
K.W. Glennie*

*Dept of Geology and Petroleum Geology, University of Aberdeen, Aberdeen AB24 3UE.

email: glennie_ken@hotmail.com

In 1973 and 1974, Glennie and his colleagues presented evidence from the Oman Mountains for the existence of a Permian to Early Cretaceous ocean basin whose sedimentary sequence (Hawasina) and an ophiolite nappe (Semail) were emplaced tectonically over the Arabian continental margin in the Late Cretaceous. This interpretation was questioned by Wilson in 1973 and replied to by Glennie and Hughes Clarke (1973). More than twenty-five years later, Wilson (2000) is still dissatisfied with both our data and our interpretations. He implies that the hundreds of geologists who have extended and modified our model over the intervening years cannot appreciate the correctness of his own earlier paper (1969), in which he advocated that all the rocks of these mountains are essentially autochthonous (see his Fig. 1), and that the Hawasina comprises sedimentary sequences that were redeposited into a tectonically active Late Cretaceous abyssal trench. Wilson wrote very persuasively, but to illustrate his ideas on Oman Mountains development he had the misfortune to use the geosynclinal model that had been in general use for most of the previous century. Our understanding of the geology seemed to fit a new but growing general knowledge of the distribution and development of continents, oceans and spreading oceanic ridges. Had we been mapping in Oman five years earlier, who knows what our interpretations may have been like.

With the hindsight of another 25 years of geological research by geologists of varying backgrounds, our differences would be considerably reduced if Wilsonís abyssal trench is assumed to be of the subduction variety, the Semail ophiolite being generated in a tensional back-arc environment in response to subduction. But the most fundamental difference between us involves the provenance of the Hawasina; we interpret the transport direction of Hawasina turbidites to be from about SW to NE, whereas Wilson believes the opposite direction to apply.


JPG Home