Colin P North

University of Aberdeen | ABDN · Department of Geology and Petroleum Geology

Transient aragonite seas occurred in the early Cambrian but several models suggest the late Cambrian was a time of calcite seas. Here, evidence is presented from the Andam Group, Huqf High, Oman (Gondwana) that suggests a transient Furongian (late Cambrian) aragonite sea, characterized by the precipitation of aragonite and high-Mg calcite ooids and...

Palaeogeographic interpretation of the sedimentary rock record depends on correct recognition from the preserved evidence of the processes responsible for transporting and depositing the sediment. This in turn depends on robust knowledge transfer from previous workers, and the successful exchange of ideas between workers requires consistent use of...

The sedimentary rock-record literature contains many interpretations and predictions for the way that river systems develop and terminate in semi-arid hydrologically-closed basins. Our own experience of such systems, and our analysis of the literature, suggests that the models for these settings are based too heavily on conjecture and too little on...

Facies models for continental rift basins suggest longitudinal (axis-parallel) fluvial activity dominates sediment transport and deposition. In contrast, modern basins in the arid to semi-arid northern Basin and Range Province, USA, show axial drainage development to be characterized by short endorheic systems that contribute little to the basin fi...

A new approach is recommended for estimating the catchment size and paleohydrology of ancient rivers from analysis of their sedimentary record. Estimates of drainage area have significant predictive value across a broad spectrum of geological applications, though attempts to derive them are remarkably uncommon. Previous sedimentological studies hav...

A fractal analysis method (rescaled-range analysis) was applied to wireline logs through the fluvio-deltaic Brent Group (Middle Jurassic) in the Dunlin field, northern North Sea, to test the applicability of fractal analysis in geological interpretation of subsurface data. This analysis reveals that the fractal dimensions of gamma-ray logs range fr...

The application of rigorous criteria for identifying fluvial style from sedimentary deposits is crucial if environmental reconstructions from stratigraphy are to be reliable. From modern observations, it appears that anabranching (anastomosing) rivers can be divided into separate humid and dryland classes. Each class has dissimilar characteristics...

We propose that the so-called "terminal fan" facies model should be abandoned since it is flawed on several counts and it is leading to misunderstanding and poor communication. Rivers in drylands may experience excessive downstream discharge reduction such that they terminate subaerially rather than reach the sea or a lake. The facies model predict...

Whole-rock geochemical analysis can aid the stratigraphic correlation of faunally barren successions. Compared to petrographic techniques or heavy-mineral separations, such analysis is quick and objective, yet rarely has the reliability of the method been tested against unequivocal correlations. We have applied it to the Kenilworth Member of the Up...

LETOURNEAU, P. M. & OLSEN, P. E. (eds) 2003. The Great Rift Valleys of Pangea in Eastern North America. Volume One: Tectonics, Structure, and Volcanism. xi + 214 pp. New York: Columbia University Press. Price US $79.50, £55.00 (hard covers). ISBN 0 231 11162 2 LETOURNEAU, P. M. & OLSEN, P. E. (eds) 2003. The Great Rift Valleys of Pangea in Eastern...

The growth and subsequent dissolution of salts on or within sediment may alter sedimentary structures and textures to such an extent that it is difficult to identify the depositional origin of that sediment and, as a result, the sediment may be misinterpreted. To help to overcome such problems with investigating ancient successions, results are pre...

Accurate assessment of downhole natural gamma-ray logs requires a reference database built up from well-exposed outcrops where the recognition and interpretation of lithofacies is unequivocal. Although only a few cases have been published for spectral gamma-ray logs, some of these show there is a strong correlation to depositional environment. We p...

Ephemeral-fluvial sandstones form the main reservoirs in many oil and gas fields. Production histories and development difficulties suggest these deposits are more complex than is commonly supposed in the petroleum industry. There is inadequate published information to account for this observation. Relevant sedimentological literature on such depos...

This review is an attempt to assess the current 'state-of-the-art' for techniques of subsurface fluvial stratigraphic analysis. It begins with a brief overview of the requirements of subsurface analysis, the limitations of the data available, and the difficulties presented by fluvial deposits in this context, then moves onto an examination of the p...

The Katnook, Haselgrove and Ladbroke Grove Fields of southeastern SA are characterised by a lack of resistivity contrast above and below known gas-water contacts, poor hole conditions, complex mineralogy and fresh formation water. A multi-disciplinary review of all available data to characterise the Pretty Hill Sandstone reservoir by integrating co...

Fractal geostatistics are being applied to subsurface geological data as a way of predicting the spatial distribution of hydrocarbon reservoir properties. The fractal dimension is the controlling parameter in stochastic methods to produce random fields of porosity and permeability. Rescaled range (R/S)analysis has become a popular way of estimating...

Sedimentological research has traditionally produced geological models primarily relevant to hydrocarbon exploration, focusing predominantly on location and external geometry of sediment bodies and underplaying the importance of the internal reservoir framework. This failure inhibits the application of new technologies to improve recovery efficienc...

The standard approach to integration of satellite imagery and sub-surface geological data has been the comparison of a map-view image interpretation with a selection of sub-surface cross-sections. The relationship between surface and subsurface geology can be better understood through quantitative three-dimensional (3D) computer modeling. This stud...

A well-developed orthogonal vein system is located in the autochthonous foreland just beyond the limits of Variscan thrusting in southwestern Wales. The two vein sets trend 200° and 290°, perpendicular and parallel, respectively, to Variscan structures. The veins contain stretched quartz fibers indicating horizontal extensions of between 0.3 and 2....

The study of alluvial fan sequences, the most proximal components of the alluvial spectrum, can be one of the most profitable avenues of research in basin analysis because fans are particularly sensitive to external influences and have a relatively high preservation potential. Tectonism has long been invoked to explain many variations in fan sedime...