EXPLORATION IN THE CANADIAN ROCKIES AND FOOTHILLS

1966 ◽  
Vol 3 (5) ◽  
pp. 713-723 ◽  
Author(s):  
L. F. Keating

The Canadian Rockies form the most easterly ranges of the Cordilleran system for a distance of more than 1 050 miles, from the Yukon border south into central Montana. They are bounded on the east by the Interior Plains and to the west by the Rocky Mountain Trench. The main deformation occurred during the Eocene, resulting in a system of stacked thrust plates which are restricted to the sedimentary section and do not involve the crystalline basement rocks. More than 100 miles of shortening in the sediments occurred as a result of this deformation.Exploration in this structural belt has resulted in an important oil- and gas- producing province, with the major reserves located in the southern Foothills. The vast amount of information that has been accumulated in the course of this exploration through surface mapping, drilling, and geophysical work has provided excellent structural detail over a large part of the area.Prospective structures are difficult to locate, and they require careful integration of all available geological and geophysical control. Reflection and refraction seismic methods have had considerable success in locating many of the presently producing fields and have provided information that is fundamental to our understanding of this complex structural belt.

Geology ◽  
2021 ◽  
Author(s):  
Jason W. Ricketts ◽  
Jacoup Roiz ◽  
Karl E. Karlstrom ◽  
Matthew T. Heizler ◽  
William R. Guenthner ◽  
...  

The Great Unconformity of the Rocky Mountain region (western North America), where Precambrian crystalline basement is nonconformably overlain by Phanerozoic strata, represents the removal of as much as 1.5 b.y. of rock record during 10-km-scale basement exhumation. We evaluate the timing of exhumation of basement rocks at five locations by combining geologic data with multiple thermochronometers. 40Ar/39Ar K-feldspar multi-diffusion domain (MDD) modeling indicates regional multi-stage basement cooling from 275 to 150 °C occurred at 1250–1100 Ma and/or 1000–700 Ma. Zircon (U-Th)/He (ZHe) dates from the Rocky Mountains range from 20 to 864 Ma, and independent forward modeling of ZHe data is also most consistent with multi-stage cooling. ZHe inverse models at five locations, combined with K-feldspar MDD and sample-specific geochronologic and/or thermochronologic constraints, document multiple pulses of basement cooling from 250 °C to surface temperatures with a major regional basement exhumation event 1300–900 Ma, limited cooling in some samples during the 770–570 Ma breakup of Rodinia and/or the 717–635 Ma snowball Earth, and ca. 300 Ma Ancestral Rocky Mountains cooling. These data argue for a tectonic control on basement exhumation leading up to formation of the Precambrian-Cambrian Great Unconformity and document the formation of composite erosional surfaces developed by faulting and differential uplift.


2021 ◽  
pp. M57-2020-20
Author(s):  
E. Henriksen ◽  
D. Ktenas ◽  
J. K. Nielsen

AbstractThe Finnmark Platform Composite Tectono-Sedimentary Element (CTSE), located in the southern Barents Sea, is a northward-dipping monoclinal structural unit. It covers most of the southern Norwegian Barents Sea where it borders the Norwegian Mainland. Except for the different age of basement, the CTSE extends eastwards into the Kola Monocline on the Russian part of the Barents Sea.The general water depth varies between 200-350 m, and the sea bottom is influenced by Plio-Pleistocene glaciations. A high frequency of scour marks and deposition of moraine materials exists on the platform areas. Successively older strata sub-crop below the Upper Regional Unconformity (URU, which was) formed by several glacial periods.Basement rocks of Neoproterozoic age are heavily affected by the Caledonian Orogeny, and previously by the Timanide tectonic compression in the easternmost part of the Finnmark Platform CTSE.Depth to crystalline basement varies considerably and is estimated to be from 4-5 to 10 km. Following the Caledonian orogenesis, the Finnmark Platform was affected by Lower to Middle Carboniferous rifting, sediment input from the Uralian Orogen in the east, the Upper Jurassic / Lower Cretaceous rift phase and the Late Plio-Pleistocene isostatic uplift.A total of 8 exploration wells drilled different targets on the platform. Two minor discoveries have been made proving presence of both oil and gas and potential sandstone reservoirs of good quality identified in the Visean, Induan, Anisian and Carnian intervals. In addition, thick sequences of Perm-Carboniferous carbonates and spiculitic chert are proven in the eastern Platform area. The deep reservoirs are believed to be charged from Paleozoic sources. A western extension of the Domanik source rocks well documented in the Timan-Pechora Basin may exist towards the eastern part of the Finnmark Platform. In the westernmost part, charge from juxtaposed down-faulted basins may be possible.


Fact Sheet ◽  
2018 ◽  
Author(s):  
Christopher J. Schenk ◽  
Tracey J. Mercier ◽  
Michael E. Brownfield ◽  
Marilyn E. Tennyson ◽  
Cheryl A. Woodall ◽  
...  

1968 ◽  
Vol 5 (3) ◽  
pp. 737-747 ◽  
Author(s):  
J. D. Obradovich ◽  
Z. E. Peterman

This paper presents new radiometric data that permit some qualified statements to be made on the depositional history of the Belt sedimentary rocks. The period of deposition of sedimentary rocks of the Precambrian Belt Series has been placed within a broad time interval, for they rest on metamorphosed basement rock dated at ~ 1800 m.y. and are overlain by the Middle Cambrian Flathead Quartzite (circa 530 m.y.). Prior geochronometric data gathered during the last decade indicate most of the Belt Series to be older than ~ 1100 m.y.K–Ar and Rb–Sr techniques have been applied recently to a variety of samples selected from the whole gamut of the Belt Series. Glauconite from various formations in the sequence McNamara Formation down to the uppermost beds of the Empire Formation in the Sun River area has been dated at 1080 ± 27 m.y. by the K–Ar method and at 1095 ± 22 m.y. by the Rb–Sr mineral isochron method. A Rb–Sr whole-rock isochron based on argillaceous sedimentary rocks from this 5000-ft section gives an age of 1100 ± 53 m.y. The concordance of the preceding results and the K–Ar ages (1075 to 1110 m.y.) on Purcell sills and lava imply that this age represents the time of sedimentation of these units.A Rb–Sr isochron based on whole-rock samples stratigraphically far below the Umpire Formation— the Greyson Shale, Newland Limestone, Chamberlain Shale, and Neihart Quartzite in the Big Belt and Little Beit Mountains—yields an age of 1325 ± 15 m.y. This result is interpreted as indicating a substantial unconformity beneath the Belt Series, at least in central Montana; it also suggests a major hiatus, unsuspected from field evidence, between the uppermost part of the Empire Formation and the Greyson Shale.The results for the youngest of Belt rocks—the Pilcher Quartzite and the Garnet Range Formation, which are exposed in the Alberton region—are equivocal in that there is widespread dispersion. A large component of detrital muscovite in some of the samples could readily account for the magnitude and sense of this dispersion. A maximum age of ~930 m.y. based on an isochron of minimum slope through the various points may be inferred for this sequence. A K–Ar age of 760 m.y. obtained on biotite from a sill in the Garnet Range Formation provides a minimum age for these younger Belt rocks.Three distinct periods of sedimentation for Belt rocks sampled are suggested at ≥ 1300, 1100, and ≤ 900 m.y., with two substantial hiatuses of 200 m.y. or more. In addition the data for the sequence in the Big and Little Belt Mountains suggest that sedimentation may not have commenced for a period of possibly 400 m.y. after the metamorphism that affected basement rocks, while the data for the Garnet Range and Pilcher sequence suggest that sedimentation ceased some 200 to 400 m.y. prior to the deposition of the Middle Cambrian Flathead Quartzite.To suggest that the Belt sediments were deposited continuously over a period of 400 m.y. or more would imply an unusually low average rate of deposition of ≤ 0.1 ft/1000 yr, and this for the thickest part of the Belt Series. As a realistic expression of the depositional history of the Belt Series, both viewpoints are open to question, but the viewpoint that the Belt basin has been characterized by discontinuous sedimentation would be more in keeping with the principle of uniformity.


Author(s):  
N. M. Kutukova ◽  
V. L. Shuster

The paper shows the application of modern methods for studying the structure of combined oil-traps. Methods for determining the conceptual geological model of reservoir rocks are described. The examples of the complex-constructed deposits of the Yurubcheno-Tokhomskoye oilfield (Eastern Siberia) and the deposits in the basement rocks in the fields of Western Siberia and Vietnam are considered in the paper. The creation of a conceptual geological model is also necessary for the successful localization of oil and gas deposits and the identification of promising zones in complex non-traditional traps.


Author(s):  
Richard Potts ◽  
Daniel Cole

A geographic information system is an ideal tool for use in interdisciplinary studies because it provides automated means of linking and relating different spatial databases. In this paper we discuss GIS applications to ongoing archaeological and paleoecological studies at Olorgesailie, an early hominid archaeological locality in the rift valley of southern Kenya and one of the most noted Acheulian handaxe sites worldwide (Isaac 1977). The questions being asked in early hominid archaeology require thinking beyond individual artifacts and site excavations to broader spatial scales within welldefined time intervals (or chronostratigraphic units) (Blumenschine and Masao 1991; Potts 1991). The sedimentary exposures at Olorgesailie permit the smallest spatial scale of individual artifacts and fossils to be integrated with regional-scale studies. Since many of the GIS applications are still in initial form, the purpose here is largely to illustrate the conceptual framework by which GIS integrates the analysis of spatial data at varying geographic scales in the Olorgesailie basin. Covering over 4000 km in length, the African Rift System trends southward from the Afar Triangle in the Red Sea region to south of the Zambezi River in Zambia. The numerous continental rift basins that make up the rift system have a complex structural and volcanic history. For most of its length, the African Rift traverses Ethiopia, Kenya, and Tanzania. The rift is divisible into eastern and western portions, which merge into a broad faulted region in northern Tanzania (Baker et al. 1972). Between the eastern and western rifts, occupying portions of Uganda, Tanzania, and northern Kenya, is an uplifted plateau 1000 to 1200 m in elevation. Uplifted, elongated domal structures located in Ethiopia and Kenya form the structural base from which the East African Rift System has developed. The rocks that make up this shield complex are Precambrian gneisses, quartzites, and schists. In addition to intrusions by dikes and plutons, these basement rocks have been altered by partial melting and metamorphism. Significant though episodic uplift of the Kenyan dome and its flanks during the late Cretaceous and middle and late Tertiary contributed to the development of a graben structure (Baker 1986; Baker et al. 1972).


1982 ◽  
Vol 22 (1) ◽  
pp. 213 ◽  
Author(s):  
B. M. Thomas ◽  
D. G. Osborne ◽  
A. J. Wright

Ever since the early discoveries at Cabawin (1960) and Moonie (1961), the origin of oil and gas in the Surat/Bowen Basin has been a subject of speculation. Hydrocarbons have been found in reservoirs ranging in age from Permian to Early Jurassic; even fractured pre-Permian 'basement' rocks have occasionally recorded shows.Recent geochemical studies have identified rich source rocks within the Jurassic, Triassic and Permian sequences. The Middle Jurassic Walloon Coal Measures are thermally immature throughout the Surat Basin and are unlikely to have generated significant amounts of hydrocarbons. Lower Jurassic Evergreen Formation source rocks have reached 'nominal early maturity' (VR = 0.6) in parts of the basin. The Middle Triassic Moolayember Formation lies within the oil generation zone in the northern Taroom Trough. However, no oil has yet been confidently correlated with either a Jurassic or a Triassic source. On geochemical and geological grounds it is likely that most, if not all, of the hydrocarbons discovered to date were generated from Permian source rocks.The probability of finding gas as well as oil in Permian, Triassic or Jurassic reservoirs increases from south to north, in accord with organic maturity trends in the Permian of the Taroom Trough. On the narrow thrust-bounded eastern flank, vertical migration has occurred, resulting in oilfields at Moonie and Bennett. In contrast, extensive lateral migration of hydrocarbons across the gentle western flank of the basin is indicated by numerous small oil and gas fields on the Roma Shelf and Wunger Ridge.


Author(s):  
Rene Nsanzineza ◽  
Jana Milford

Across the U.S., electricity production from coal-fired generation is declining while use of renewables and natural gas is increasing. This trend is expected to continue in the future. In the Rocky Mountain region, this shift is expected to reduce emissions from electricity production while increasing emissions from the production and processing of oil and gas, with significant implications for the level, location, and timing of the air pollution emissions that are associated with these activities. In turn, these emissions changes will affect air quality in the region, with impacts on ground-level ozone of particular concern. This study aims to evaluate the tradeoffs in emissions from both power plants and oil and gas basins resulting from contrasting scenarios for shifts in electricity and oil and gas production through the year 2030. The study also incorporates federal and state-level regulations for CH4, NOx, and VOC emissions sources. These regulations are expected to produce significant emissions reductions relative to baseline projections, especially in the oil and gas production sector. Annual emissions from electricity production are estimated to decrease in all scenarios, due to a combination of using more natural gas power plants, renewables, emissions regulations, and retiring old inefficient coal power plants. However, reductions are larger in fall, winter, and spring than in summer, when ozone pollution is of greatest concern. Emissions from oil and gas production are estimated to either increase or decrease depending on the location, scenario, and the number of sources affected by regulations. The net change in emissions thus depends on pollutant, location, and time of year.


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