The Geology of Sirt Basin, 3 volumes

This three-volume series is a continuation of publication of results of symposia on the geology of Libya held at Al-Fateh University (formerly the University of Tripoli) in Tripoli, Libya. Previous results were published in 1971 (Symposium on the Geology of Libya, 1 vol.; Geology of Libya, vols. I-III, 1980; Geology of Libya, vols. IV-VIII, 1981). The latest symposium was held in 1993 and was organized by the Earth Science Society of Libya and sponsored by the National Oil Corporation (NOC).

This Symposium was focused on the geology of the Sirt (other spellings: Sirte, Surt) Basin, which occupies about one-fourth of the country (about 400,000 square km). This is an area larger than Montana or about three-fourths that of France. Previous symposia were not restricted as to area. This focus is the result of the current importance of the basin in the exploration for oil. Most of the papers reflect the strong interest in oil exploration there ever since the first well was drilled in the late 1950's.

As stated in the Foreword, 70 of about 140 papers presented at the Symposium were chosen for publication. As would be expected, a majority of the authors are with Libyan oil companies; most other contributors were from European countries. Although some papers are multi-disciplinary, they are categorized as follows: General Geology, Biostratigraphy and Paleontology, Sedimentology and Sedimentary Petrology, Petroleum Geology, Structure and Tectonics, Geophysics and Volcanology. A majority of the papers (39) deal with the first three topics and ten deal with petroleum geology. The petroleum geology papers are not confined to specific oil fields, but rather deal with regional stratigraphy/structure, oil generation and migration in the basin.

The editors chose informative papers in the General Geology and Tectonic sections to introduce readers to the geology and structural history of the basin. Most of the stratigraphic, sedimentologic and paleontologic papers are concerned with the Lower Cretaceous through Miocene interval, which contains the most common source and reservoir rock in the basin. The papers also shed light on the mostly clastic, very thick Paleozoic rocks which have been delineated by extensive palynological studies, some of which are included in Volume I. A number of papers also include discussion, dating and significance of the widespread, enigmatic "Nubian" sandstone. Reference or type sections for many stratigraphic units have been established in well sections rather than on the surface because of the lack of good exposures. One has to be impressed with the importance of the seismic techniques used in correlating the sparsely fossiliferous and often thick intervals in the basin.

There is much more agreement on the names and ages of stratigraphic units and events than reported in the literature of 15-20 years ago. This is an indication of the amount of basic geologic work done in the basin and elsewhere in Libya in recent years. Authors concerned with the establishment of the origin of the basin concur on a Late Cretaceous to early Tertiary age for the rifting which led to the development of the horst and graben structures which characterize the basin. Whether the basin was associated with a triple junction, as one author suggests, is perhaps more speculative.

This compilation represents a useful addition to the geologic knowledge of North Africa and likely makes more information available than for any other part of North Africa. The range of information should make the volumes especially useful to those working or consulting in the area. Considering the many authors and diversity of material, the editors have done an excellent job of maintaining a uniform style and consistency of spelling of stratigraphic and place names. The illustrations are clear and usually placed near the appropriate text. The legends/keys for some illustrations could have been expanded for better understanding. The titles and abstracts are written in both Arabic and English. All texts are in English. The volumes are well constructed. The three-volume format makes it easier to handle the volumes. A different aerial illustration is placed on the cover of each volume. The nature of the scene depicted on Volume I had this reviewer guessing.

As brought out in the Preface, a panel discussion after the symposium suggested future trends in exploration of the basin: exploration of the deep troughs, the offshore area, the Paleozoic sequence of eastern Libya as well as the need for better geophysical acquisition and processing methods and fundamental work in basin modeling and sequence stratigraphy. Those not that well acquainted with the area can get a good understanding of the geologic setting and stratigraphic problems of the basin from these papers. This unraveling of the complex history of the basin will be of interest to petroleum geologists as well as others interested in the geology of North Africa. The designation as the First Symposium suggests plans for future volumes.

Unfortunately the hefty price tag for the three-volume set will not put this contribution into too many personal libraries.

A.C. Spreng
Department of Geology and Geophysics
University of Missouri-Rolla
Rolla, MO 65409
U.S.A.

Source

http://archives.datapages.com/data/sepm/journals/v66-67/data/068/068001/0235.HTM