Geological Association Research Articles

Collisional melange development: Geologic associations of active melange‐forming processes with exhumed melange facies in the western Banda orogen, Indonesia

Analysis of block assemblages, matrix clay mineral composition and microfauna, and offshore seismic reflection profiles reveal that the Bobonaro melange in the Timor region is sourced from mud‐rich Australian continental margin sequences that are remobilized during accretion and form various facies depending on the structural conditions of emplacement. Melange facies include broken formation, matrix‐rich mud injections, and classic mixed block‐in‐clay facies. Each of these are distinguished by varying degrees of remobilization, mixing, and dispersion at different structural positions across the orogenic wedge. The most important structural control is whether melange was generated beneath or in front of upper plate Banda forearc basement (Banda Terrane). At the present collisional deformation front in the Timor trough, seismic reflection profiles show that melange forms mostly by stratal detachment and fluid‐assisted remobilization above a basal decollement propagating laterally along overpressured Jurassic to Cretaceous clay‐rich sequences of the distal Australian continental margin. The broken, clay‐rich material injects upward through faults to form intrusive bodies at the base of slope cover sediment to form mud ridges at the surface. Similar patterns of stratal disruption are exposed onshore in the Pliocene Kolbano fold and thrust wedge of southern Timor, which is structurally contiguous with the Timor trough deformation front. Melange in the Kolbano Mountains is mostly broken formation and matrix‐rich injections of mud from Jurassic and Cretaceous units. Deformation mechanisms include intense layer‐parallel extension associated with emplacement by mud diapirs that rise from near the decollement upward to the surface along fault conduits. In the hinterland of the orogenic wedge (East Timor and northern West Timor), melange is dominantly of mixed block‐in‐clay facies with large blocks derived from roof thrust sheets of intermixed Banda Terrane and Maubisse Formation units. At the structural base of these thrust sheets is the Sonnebait Disruption Zone (SDZ), which formed the initial suture between the Banda Terrane and structurally underthrust Australian continental margin sequences during the late Miocene to early Pliocene. The thickest accumulations of mixed block‐in‐clay melange in the Timor region are found at the southern edge (outlet) of the SDZ, near the Central and Viqueque synorogenic basins. The extent of block dispersion and mixing in the SDZ is indicative of intense shear strains perhaps induced by an oversupply of accretable material when the suture zone was clogged by underthrusting of the Australian continental margin.

Geological Association of Canada, Newfoundland Section - 1997 Annual Technical Meeting

Geological Association of Canada, Newfoundland Section - 1997 Annual Technical Meeting

The development and use of mineral deposit models in the United States geological survey : D. P. Cox, Geological Association of Canada Special Paper, 40, 1993(1995), pp 15–19

The development and use of mineral deposit models in the United States geological survey : D. P. Cox, Geological Association of Canada Special Paper, 40, 1993(1995), pp 15–19

Development of grade and tonnage models for different deposit types : D. A. Singer, Geological Association of Canada Special Paper, 40, 1993(1995), pp 21–30

Development of grade and tonnage models for different deposit types : D. A. Singer, Geological Association of Canada Special Paper, 40, 1993(1995), pp 21–30

GEOMODEL — an expert system for modeling layered geological sequences applied to the assessment of coalfields : J. D. Hughes, Geological Association of Canada Special Paper, 40, 1993(1995), pp 707–734

GEOMODEL — an expert system for modeling layered geological sequences applied to the assessment of coalfields : J. D. Hughes, Geological Association of Canada Special Paper, 40, 1993(1995), pp 707–734

Problems and opportunities for mineral deposit models : P. B. Barton Jr, Geological Association of Canada Special Paper, 40, 1993(1995), pp 7–13

Problems and opportunities for mineral deposit models : P. B. Barton Jr, Geological Association of Canada Special Paper, 40, 1993(1995), pp 7–13

PROSPECTOR II — an expert system for mineral deposit models : R. B. McCammon, Geological Association of Canada Special Paper, 40, 1993(1995), pp 679–684

PROSPECTOR II — an expert system for mineral deposit models : R. B. McCammon, Geological Association of Canada Special Paper, 40, 1993(1995), pp 679–684

Spatial mineral deposit models and the prediction of undiscovered mineral deposits : J. D. Bliss & W. D. Menzie, Geological Association of Canada Special Paper, 40, 1993(1995), pp 693–706

Spatial mineral deposit models and the prediction of undiscovered mineral deposits : J. D. Bliss & W. D. Menzie, Geological Association of Canada Special Paper, 40, 1993(1995), pp 693–706

Application of deposit models to exploration : J. F. H. Thompson, Geological Association of Canada Special Paper, 40, 1993(1995), pp 51–67

Application of deposit models to exploration : J. F. H. Thompson, Geological Association of Canada Special Paper, 40, 1993(1995), pp 51–67

What is an exploration model anyway? An analysis of the cognitive development and use of models in mineral exploration : R. W. Henley & B. R. Berger, Geological Association of Canada Special Paper, 40, 1993(1995), pp 41–50

What is an exploration model anyway? An analysis of the cognitive development and use of models in mineral exploration : R. W. Henley & B. R. Berger, Geological Association of Canada Special Paper, 40, 1993(1995), pp 41–50

CLAIM: a new personal computer-assisted simulation model for teaching mineral exploration techniques : C. Bauchau, M. Jaboyedoff & M. Vannier, Geological Association of Canada Special Paper, 40, 1993(1995), pp 685–691

CLAIM: a new personal computer-assisted simulation model for teaching mineral exploration techniques : C. Bauchau, M. Jaboyedoff & M. Vannier, Geological Association of Canada Special Paper, 40, 1993(1995), pp 685–691

Geological Association of Canada - Newfoundland Section - 1996 Annual Meeting

Geological Association of Canada - Newfoundland Section - 1996 Annual Meeting

A review of the origins of subparallel ridges and troughs: Generalized morphological predictions from terrestrial models

The morphologies of ridges and troughs on Earth and the processes involved in their formation are reviewed for application to sets of subparallel ridges and troughs on outer planet satellites. We consider tension fracturing, normal faulting, thrust faulting, buckle folding, strike‐slip tectonism, fissure eruption, wall diapirism, surface folding of a flow, and near‐surface (laccolithic) intrusion. The landform characteristics and geologic associations predicted of each process are generalized to be independent of planet‐specific parameters. We find that the combinations of landforms derived from each process are unique, making each distinguishable in the idealized case. Morphological parameters most diagnostic of formational process are ridge and trough cross‐sectional shape, termination style, and incipient character. The characteristics described are useful in constraining the origin of ridge and trough terrains observed in Voyager images and will aid in analysis of high‐resolution images from the Galileo and Cassini spacecraft.

Geological Association of Canada, Newfoundland Section - Annual Technical Meeting

Geological Association of Canada, Newfoundland Section - Annual Technical Meeting

Oil Springs and Flat Top Anticlines, Carbon County, Wyoming: an unusual fold pair : Mountain Geologist, 31(2), 1994, pp 53–60

Oil Springs Anticline, northwest of Medicine Bow, Wyoming, and located at the northeast corner of the Hanna Basin, lies near the junction of the Freezeout Hills Anticline, the Shirley thrust fault and the Flat Top Anticline. The surface fold as defined by the outcrop of the Wall Creek Sandstone Member of the Frontier Formation is disharmonic to deeper structure at the level of the Jurassic Sundance Formation. The fold is wedged between two major folds and is the result of a space problem between larger structural elements. The controlling Flat Top Anticline is an excellent example of a fold controlled by a well constrained fault in the Precambrian crystalline basement. The basement is bowed upward and outward to the northwest in the hanging wall of the Flat Top Anticline. The purpose of this paper is to describe the geologic structure of the Oil Springs and Flat Top anticlines and their relationship to the Freezeout Hills and the Hanna Basin. Commercial production of petroleum and natural gas occurs on the west flank of the Laramie-Cooper Lake Basin as far north as the northeast corner of the Hanna Basin. Stone reviewed the producing formations in the Laramie and eastern Hanna basins andmore » noted that 11 commercial accumulations of petroleum and natural gas are directly related to anticlinal structures. Production derived from the Permian-Pennsylvanian Tensleep Sandstone in this region has a special geologic framework. Fields that produce from the Tensleep Sandstone are well defined anticlines bounded by faults or fault systems, a situation also reported by Biggs and Espach, Blackstone and in the Wyoming Geological Association Symposium. The Tensleep Sandstone reservoirs in these faulted anticlines are in juxtaposition to potential source rocks of either Jurassic or Cretaceous age in the footwalls of the faults. 17 refs., 9 figs., 1 tab.« less

Observations on the Russian Oil Sector in 1992 and 1993

Russia still is one of the world's major petroleum-producing countries, but output declined precipitously from the peak in 1987 of 569.5 million tons to 260.2 million tons for the first nine months of 1993 (projected at 340 million tons for the year). The crisis in the oil sector is due largely to the underlying political, economic, and organizational problems rather than to deficiencies in the oil reserve base or technology. Major oil-producing regions-West Siberia and Volga-Urals provinces—are identified, and within these regions, geology, reserve size, and major production associations are described. Other noteworthy areas covered in greater detail are the oil fields of Komi and Sakhalin. Concluding sections are devoted to a critical assessment of the Russian government's program to arrest the decline in oil output and to projecting output over the near future based largely on production trends that are appparent in November 1993. Estimates indicate that oil output in Russia will continue to decline th...

R. G. Walker & N. P. James (eds) 1992. Facies Models. Response to Sea Level Change. v + 409 pp. Not a third edition of Facies Models; the book has been completely rewritten, hence new title. Order from: Geological Association of Canada, Publications, Department of Earth Sciences, Memorial University of Newfoundland, St John's, Newfoundland A1B 3X5, Canada. Price: in Canada

R. G. Walker & N. P. James (eds) 1992. Facies Models. Response to Sea Level Change. v + 409 pp. Not a third edition of Facies Models; the book has been completely rewritten, hence new title. Order from: Geological Association of Canada, Publications, Department of Earth Sciences, Memorial University of Newfoundland, St John's, Newfoundland A1B 3X5, Canada. Price: in Canada

The Cigar Lake uranium deposit, Saskatchewan, Canada

The Cigar Lake uranium deposit is exceptional in terms of both tonnage and grade. Geological reserves are estimated at 154 600 t of uranium with an average grade of 7.9%. The richest zone, called the pod, contains 113 000 t of uranium at 12.2%. The surface projection of the orebody would cover an area equivalent to the Champs ElysCes. The Cigar Lake uranium deposit was discovered in May 1981 by Cogema Canada Limited, acting as operator of the Waterbury Lake Joint Venture. The discovery hole was the 13th and last hole of the 1981 drilling campaign. It is interesting to note that the first showing of uranium in the Athabasca Basin was discovered about 40 years ago. However, progress in the development of exploration models was slow and it was not until 1968 that a first uranium deposit, Rabbit Lake, was finally located at the eastern margin of the Athabasca Basin. This discovery was followed the same year by the Cluff Lake deposits in the Carswell structure and since then by several other discoveries. Cogema has encouraged the scientific study of the unconformity-type uranium deposits. Initial studies were compiled in the 1985 Geological Association of Canada Special Paper entitled f i e Carswell structure uranium deposits, Saskatchewan. Similar support was given for the study of the Cigar Lake deposit in both France and Canada. We now have eight manuscripts to present dealing with the main petrological, mineralogical, and geochemical aspects of this deposit. We would like to thank H. Baadsgaard, M. Bernat, G.N. Breit, M. Cuney, Ph. Holliger, T.K. Kyser, J. Leventhal, K.R. Ludwig, C. Hallenstein, A. Meunier, V. Ruzicka, J. Smellie, L. Turpin, B. Velde, E. von Pechmann, and I. Wendt for having reviewed these manuscripts. The contribution of John Clague, former Editor of the journal, is also greatly acknowledged. We also thank FrCdCric Tona, Mineral Exploration Manager at Cogema, and Michel Poissonet, President of Cogema Canada, for their encouragement in having these results published, as well as all the geologists (H. Knipping, P. Caumartin, J. Learn, S. Lavoie, M. Fowler, and J.P. Fouques) whose work provided a solid geological framework. Their assistance and guidance in the choice of study sample material are appreciated. Finally, we would like to thank our joint venture partners: Cameco, Idemitsu, and Kepco for supporting the publication of these manuscripts.

The tectonic evolution of the Superior and Slave provinces of the Canadian Shield: introduction

s, 16: AS. Baragar, W. R. A., and McGlynn, J. C. 1976. Early Archean basement in the Canadian Shield: a review of the evidence. Geoloeical Survey of Canada, Paper 76-15, Beaudry, D., Mueller, W., and Daigneault, R. 1991. Structural analysis of the volcano-sedimentary assemblages adjacent the Porcupine-Destor fault zone, Duparquet, Quebec. Geological Association of Canada Mineralogical Association of Canada Society of Economic Geologists, Program with Abstracts, 16: A9. Begin, N. J., and Pattison, D. R. M. 1991. Granulite grade metamorphism in the Minto Subprovince, Leaf River area, northern Quebec. Geological Association of Canada Mineralogical Association of Canada Society of Economic Geologists, Program with Abstracts, 16: A9. Blackburn, C. E. 1980. Toward a mobilist tectonic model for part of the Archean of Northwestern Ontario. Geoscience Canada, 7:

Book Reviews

Book Reviews Greenstone Gold and Crustal Evolution, edited by F. Roberts, P. A. Sheahan and S. B. Green. Geological Association of Canada, 1991. 252 pp. $25 Cdn. J. W. Gaskarth J. W. Gaskarth Search for other works by this author on: Oxford Academic Google Scholar Journal of Petrology, Volume 33, Issue 4, August 1992, Page 964, https://doi.org/10.1093/petrology/33.4.964 Published: 01 August 1992