Skip to Main Content
Book Chapter

Late Cretaceous Conglomerates of the Qahlah Formation, north Oman

By
Iftikhar A. Abbasi
Iftikhar A. Abbasi
1
Department of Earth Sciences, Sultan Qaboos University, Al-Khod, Muscat, Oman
Search for other works by this author on:
O. Salad Hersi
O. Salad Hersi
1
Department of Earth Sciences, Sultan Qaboos University, Al-Khod, Muscat, Oman
2
Geology Department, University of Regina, Regina, Saskatchewan, Canada
Search for other works by this author on:
A. Al-Harthy
A. Al-Harthy
1
Department of Earth Sciences, Sultan Qaboos University, Al-Khod, Muscat, Oman
3
Sedimentology Consultant, Geo-Consultancy Center, Al-Khod, Oman
Search for other works by this author on:
Published:
January 01, 2014

Abstract

Conglomerate sequences over 700 m thick were deposited subsequent to ophiolite emplacement during Late Cretaceous time in north Oman. The conglomerates were deposited by streams draining the allochthonous ophiolite and Hawasina complex after their obduction onto autochthonous Mesozoic and older Oman shelf sequences and subsequent uplift. The conglomerates belong to the Qahlah Formation of Late Cretaceous age, which is sandwiched between the Semail Ophiolite/Hawasina complex and Maastrichtian–Palaeogene carbonate rocks. The siliciclastics of the Qahlah Formation are the first sediments deposited over the obducted oceanic crust sequence of ophiolite and Hawasina lithologies. In five locations studied in north Oman, the thickness of the formation varies from 140 m to over 700 m and comprises interbedded conglomerate, sandstone and siltstone. The sediments were deposited in isolated segmented depressions each characterized by its source terrain depending on lithologies exposed in the source area. Lithofacies associations, clast sorting and grain roundness suggest deposition in stream-dominated alluvial fans. Clasts in the conglomerates range from subangular to subrounded pebbles to boulders with both grain and matrix (sandstone) support. Cross-bedded fining-upwards sequences in channelized conglomerate and sandstone suggest deposition by high-energy flows in the proximal to distal reaches of alluvial fans. High proportions of chert and ophiolite fragments in the conglomerates suggest rapid erosion of obducted oceanic crust. The presence of Loftusia-bearing carbonate beds and bivalve-bearing conglomerate beds in different sections indicates occasional interruption of alluvial deposition by marine transgressions.

You do not currently have access to this article.

Figures & Tables

Contents

Geological Society, London, Special Publications

Tectonic Evolution of the Oman Mountains

H. R. Rollinson
H. R. Rollinson
University of Derby, UK
Search for other works by this author on:
M. P. Searle
M. P. Searle
Oxford University, UK
Search for other works by this author on:
I. A. Abbasi
I. A. Abbasi
Sultan Qaboos University, Muscat, Oman
Search for other works by this author on:
A. I. Al-Lazki
A. I. Al-Lazki
Petroleum Development Oman, Oman
Search for other works by this author on:
M. H. Al Kindi
M. H. Al Kindi
Petroleum Development Oman, Oman
Search for other works by this author on:
Geological Society of London
Volume
392
ISBN electronic:
9781862396685
Publication date:
January 01, 2014

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal