A geochemical study of Lewisian metasedimentary granulites and gneisses in the Scourie-Laxford area of the north-west Scotland

1983 ◽  
Vol 47 (342) ◽  
pp. 1-9 ◽  
Author(s):  
P. O. Okeke ◽  
G. D. Borley ◽  
J. Watson
Keyword(s):  
Trace Element ◽  
Igneous Rocks ◽  
Source Rocks ◽  
North West ◽  
Metasedimentary Rocks ◽  
The North ◽  
Granulite Metamorphism ◽  
Geochemical Study ◽  
High Pressure Granulite ◽  
Parent Rocks

AbstractMajor element, trace element, and REE data for metasedimentary granulites and their retrogressed derivatives formed from Archaean parent-rocks at two localities in the Lewisian complex of north-west Scotland are presented.The metasedimentary rocks are enclosed in and intruded by metatonalites and related calc-alkaline rocks and have been highly deformed and metamorphosed along with these rocks. They are geochemically distinct from this meta-igneous suite and range from highly aluminous to highly siliceous types. Comparisons of major and trace element data with those for unmetamorphosed Archaean and post-Archaean sediments suggest that they are derived from a detrital shale-greywacke assemblage, which may have included a volcaniclastic component. High ΣREE and ΣLREE suggest that the source-rocks included fractionated felsic igneous rocks.Evidence that depletion in the large ion lithophile elements K, Rb, Th accompanied high-pressure granulite metamorphism supports the view, based on data derived from the associated meta-igneous rocks, that depletion was effected by active fluids rather than by abstraction of a partial melt and suggests that removal of K and Th began only when a considerable reduction of Rb had taken place.

VI.—The Salt Deposits of Dax and the Pyrenees

1904 ◽  
Vol 1 (6) ◽  
pp. 265-272
Author(s):  
P. W. Stuart-Menteath
Keyword(s):  
Rock Salt ◽  
Mineral Water ◽  
Igneous Rocks ◽  
Thermal Springs ◽  
Salt Formation ◽  
The South ◽  
North West ◽  
The North ◽  
South West ◽  
Salt Deposits

On the rail to Biarritz the roots of the Pyrenees first appear at Dax, and are accompanied by those ophites and thermal springs which are special features of the entire chain. Vast deposits of salt, to whose first development I contributed, have added an important industry to the resources of this ancient capital of Aquœ Tarbelliœ, where the exact harness depicted on Roman medals is still characteristic of every cart. Beneath the existing ditch of the Roman fortifications rock-salt was accidentally discovered by a boring for mineral water, and the salt is now worked at three miles to the south-east, and is indicated by springs for a distance of seven miles. The deposit is known to be about 100 feet in thickness, but is of unknown depth beneath the existing borings.Along the entire outskirts of both sides of the Pyrenees similar salt deposits abound, and they are often similarly accompanied by igneous rocks.The salt formation of Dax is distinctly limited by the valley of the Adour, which here ceases to wander among the sands of the plain, and is suddenly and sharply diverted along a tectonic depression, running towards the Pyrenees in a south-west direction. Precisely parallel to this course, in the Cretaceous and Tertiary rocks of the Pyrenees, there runs, at a dozen miles to the north-west, the most remarkable example known of a tectonic valley sunk beneath the ocean. The Gouf de Capbreton, sinking with steep sides to over 3,000 feet beneath the even bottom of the Atlantic skirt, and affording evidence of igneous rocks in its surroundings and in the irregularities of its floor, is a perfect analogue of the neighbouring tectonic portion of the Adour.

ACCURATE RECOGNITION OF SOURCE ROCK CHARACTER IN THE JURASSIC OF THE NORTH WEST SHELF, WESTERN AUSTRALIA

1992 ◽  
Vol 32 (1) ◽  
pp. 289 ◽  
Author(s):  
John Scott
Keyword(s):  
Source Rock ◽  
Organic Material ◽  
Source Rocks ◽  
Higher Plant ◽  
Pyrolysis Gas ◽  
Screening Analysis ◽  
North West ◽  
The North ◽  
Potential Source Rock ◽  
Rock Eval

The main potential source rock intervals are generally well defined on the North West Shelf by screening analysis such as Rock-Eval. The type of product from the source rocks is not well defined, owing to inadequacies in current screening analysis techniques. The implications of poor definition of source type in acreage assessment are obvious. The type of product is dependent on the level of organic maturity of the source rock, the ability of products to migrate out of the source rock and on the type of organic material present. The type of kerogen present is frequently determined by Rock-Eval pyrolysis. However, Rock-Eval has severe limitations in defining product type when there is a significant input of terrestrial organic material. This problem has been recognised in Australian terrestrial/continental sequences but also occurs where marine source rock facies contain terrestrially-derived higher plant material. Pyrolysis-gas chromatography as applied to source rock analysis provides, by molecular typing, a better method of estimating the type of products of the kerogen breakdown than bulk chemical analysis such as Rock-Eval pyrolysis.

Observations on the Lower Triassic petroleum prospectivity of the offshore Carnarvon and Roebuck basins

2016 ◽  
Vol 56 (1) ◽  
pp. 173 ◽  
Author(s):  
Stephen Molyneux ◽  
Jeff Goodall ◽  
Roisin McGee ◽  
George Mills ◽  
Birgitta Hartung-Kagi
Keyword(s):  
Regional Analysis ◽  
Lower Triassic ◽  
Source Rocks ◽  
Upper Permian ◽  
Regional Study ◽  
North West ◽  
Petroleum Systems ◽  
The North ◽  
Depositional Processes ◽  
Water Margin

Why are the only commercial hydrocarbon discoveries in Lower Triassic and Permian sediments of the western margin of Australia restricted to the Perth Basin and the Petrel Sub-basin? Recent regional analysis by Carnarvon Petroleum has sought to address some key questions about the Lower Triassic Locker Shale and Upper Permian Chinty and Kennedy formations petroleum systems along the shallow water margin of the Carnarvon and offshore Canning (Roebuck/Bedout) basins. This paper aims to address the following questions:Source: Is there evidence in the wells drilled to date of a working petroleum system tied to the Locker Shale or other pre-Jurassic source rocks? Reservoir: What is the palaeogeography and sedimentology of the stratigraphic units and what are the implications for the petroleum systems?The authors believed that a fresh look at the Lower Triassic to Upper Permian petroleum prospectivity of the North West Shelf would be beneficial, and key observations arising from the regional study undertaken are highlighted:Few wells along a 2,000 km area have drilled into Lower Triassic Locker Shale or older stratigraphy. Several of these wells have been geochemically and isotopically typed to potentially non Jurassic source rocks. The basal Triassic Hovea Member of the Kockatea Shale in the Perth Basin is a proven commercial oil source rock and a Hovea Member Equivalent has been identified through palynology and a distinctive sapropelic/algal kerogen facies in nearly 16 wells that penetrate the full Lower Triassic interval on the North West Shelf. Samples from the Upper Permian, the Hovea Member Equivalent and the Locker Shale have been analysed isotopically indicating –28, –34 and –30 delta C13 averages, respectively. Lower Triassic and Upper Permian reservoirs are often high net to gross sands with up to 1,000 mD permeability and around 20% porosity. Depositional processes are varied, from Locker Shale submarine canyon systems to a mixed carbonate clastic marine coastline/shelf of the Upper Permian Chinty and Kennedy formations.

Recent exploration results in the Lower Triassic, Bedout Sub-basin: Australia's next petroleum province?

2018 ◽  
Vol 58 (2) ◽  
pp. 871 ◽  
Author(s):  
Melissa Thompson ◽  
Fred Wehr ◽  
Jack Woodward ◽  
Jon Minken ◽  
Gino D'Orazio ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Lower Triassic ◽  
Effective Porosity ◽  
Petroleum System ◽  
Source Rocks ◽  
Commercial Development ◽  
North West ◽  
The North ◽  
Productive Potential ◽  
Detailed Interpretation

Commencing in 2014, Quadrant Energy and partners have undertaken an active exploration program in the Bedout Sub-basin with a 100% success rate, discovering four hydrocarbon accumulations with four wells. The primary exploration target in the basin, the Middle Triassic Lower Keraudren Formation, encompasses the reservoirs, source rocks and seals that have trapped hydrocarbons in a self-contained petroleum system. This petroleum system is older than the traditional plays on the North-West Shelf and before recent activity was very poorly understood and easily overlooked. Key reservoirs occur at burial depths of 3500–5500 m, deeper than many of the traditional plays on the North-West Shelf and exhibit variable reservoir quality. Oil and gas-condensate discovered in the first two wells, Phoenix South-1 and Roc-1, raised key questions on the preservation of effective porosity and productivity sufficient to support a commercial development. With the acquisition and detailed interpretation of 119 m of core over the Caley Member reservoir in Roc-2 and a successful drill stem test that was surface equipment constrained to 55 MMscf/d, the productive potential of this reservoir interval has been confirmed. The results of the exploration program to date, combined with acquisition of new 3D/2D seismic data, have enabled a deeper understanding of the potential of the Bedout Sub-basin. A detailed basin model has been developed and a large suite of prospects and leads are recognised across a family of hydrocarbon plays. Two key wells currently scheduled for 2018 (Phoenix South-3 and Dorado-1) will provide critical information about the scale of this opportunity.

scholarly journals Identification of Buried "Archeological" Objects in the Area around Kedulan Temple using Geomagnetic Methods

2021 ◽  
Vol 1 (1) ◽  
pp. 597-602
Author(s):  
Firdaus Maskuri ◽  
Wrego Seno Giamboro ◽  
Wahyu Hidayat
Keyword(s):  
Magnetic Anomaly ◽  
Igneous Rocks ◽  
Black Line ◽  
North West ◽  
Volcanic Material ◽  
The North ◽  
The Temple ◽  
Archaeological Objects ◽  
Geophysical Measurements ◽  
Special Region

Temple is a religion place for ancient culture, Yogyakarta have many incridible temples one of the biggest is Prambanan temple. 2 Km to the north west direction from Perambanan temple located the Kedulans temple who still on renovation projects. Kedulan Temple is located in Tirtomartani Village, Kalasan District, Sleman, Yogyakarta Special Region, at coordinates 7° 44' 28" South Latitude and 110° 28' 5" East Longitude, with an altitude of 168, 45 meters above sea level. Kedulan Temple was found in a collapsed state and buried volcanic material from Mount Merapi. Based on the results of a stratigraphic study conducted by Pramumijoyo, et al., (2005) this temple is covered by 8 meters thick lava which is composed of 14 layers of sediment. To obtain information on the existence of archaeological objects that are still buried around the temple in this study, geophysical measurements were carried out using the geomagnetic method which aims to determine the potential for buried archaeological objects in this case assumed to be igneous rocks that have contrasting susceptibility. Based on the geomagnetic signal analytic map obtained, there is a magnetic anomaly which is suspected to be a hidden temple object which is bordered by a black line which is about 50 meters to the east of Kedulan Temple. This assumption is based on a high magnetic anomaly value >480 nT which is thought to originate from the temple rock object in the form of andesite rock.

scholarly journals Content of radionuclides (226Ra, 232Th, 40K, 137Cs) in soils of the North-West region of Russia formed on three types of soil forming rocks

2020 ◽  
Vol 175 ◽  
pp. 09018
Author(s):  
Elena Mingareeva ◽  
Boris Aparin ◽  
Elena Sukhacheva ◽  
Natalia Sanzharova ◽  
Evgeny Shevchuk ◽  
...  
Keyword(s):  
Specific Activity ◽  
Natural Radionuclides ◽  
Parent Rock ◽  
Glacial Deposits ◽  
Physical Clay ◽  
North West ◽  
The North ◽  
West Region ◽  
Significant Difference ◽  
Parent Rocks

The results of a study of the content of natural radionuclides (NR) (226Ra, 232Th, 40K) and technogenic 137Cs in soil samples formed on the most common types of soil-forming rocks of the North-West: lakeglacial (non-boulder and tape clay), glacial and water-glacial deposits are presented. Soil sections laid in the Pskov, Novgorod and Leningrad regions. The granulometric composition in the upper part of the soil profile is lighter than in the parent rock. This is reflected in the NR content in the profile of these soils: with a decrease in the fractions of physical clay and silt, the content of 226Ra, 232Th and 40K decreases. This is due to the fixation of natural radionuclides by secondary clay minerals. According to the increase in the average specific activity of all NRs, the soils form the following sequence: soils on water-glacial deposits soils on moraines - soils on lake-glacial deposits. A comparison of the average specific activity of natural radionuclides and their ranges in the upper part of the soil (0-5, 5-10 and 10-20 cm) and in the parent rock (90-100 cm) revealed a higher content of radionuclides in parent rocks (lake-glacial and moraine deposits). In the soils on water-glacial deposits, no significant difference was found.

THE EFFECT OF INERTINITE ON KEROGEN APPRAISAL BY PROGRAMMED PYROLYSIS, NORTH WEST SHELF, AUSTRALIA

1994 ◽  
Vol 34 (1) ◽  
pp. 297
Author(s):  
E.L. Horstman
Keyword(s):  
Organic Carbon ◽  
Oil And Gas ◽  
Hydrogen Index ◽  
Source Rocks ◽  
Gas Generation ◽  
North West ◽  
The North ◽  
Measured Amount

The oil potential of rocks containing inertinite is systematically underestimated by chemical or programmed pyrolysis techniques. Inertinite is measured as organic carbon, but does not contribute to the hydrocarbons produced during pyrolysis. When maceral data is available the measured amount of organic carbon can be recalculated to establish an Hydrogen Index based only on the kerogen which might contribute to oil and gas generation. Inertiniterich rocks that were previously discounted as being only gas prone should be reviewed.Recalculated HI:OI plots prepared from samples from the North West Shelf of Australia indicate the presence of significant amounts of oil-prone kerogen in source rocks previously evaluated as being predominantly gas-prone, upgrading the oil potential of the area.

Geochemistry and provenance of metasedimentary rocks from the Archean Golden Pond sequence (Casa Berardi mining district, Abitibi subprovince)

1996 ◽  
Vol 33 (5) ◽  
pp. 676-690 ◽  
Author(s):  
M. R. Flèche ◽  
G. Camiré
Keyword(s):  
Chemical Weathering ◽  
Volcanic Rocks ◽  
Source Area ◽  
Source Rocks ◽  
Iron Formation ◽  
Mining District ◽  
Metasedimentary Rocks ◽  
Clastic Rocks ◽  
The North ◽  
Volcanic Source

The Archean Golden Pond sequence is made up of deformed and metamorphosed conglomerates, greywackes, and mafic volcanic rocks, and is overlain by ferrugineous metasedimentary rocks of the North iron formation. The clastic rocks were derived mainly from a volcanic source that had undergone weak chemical weathering. Their source area was dominated by the presence of 60–80% high-Al2O3 felsic volcanics having strongly fractionated [La/Sm]N (= 3.7 ± 0.3) and very low Ta/Th ratios (= 0.09 ± 0.02), with lesser proportions of basaltic (10–30%) and ultramafic volcanic rocks (1–10%). The ferrugineous metasedimentary rocks can be modelled by mixing 20–40% siliciclastic material, of the composition of the average Golden Pond greywacke, with an Fe- and Si-rich precipitate (molecular Fe/Si = 0.6 ± 0.2). The high-Al2O3 felsic source rocks were most likely produced by subduction processes within an oceanic arc environment, but the mafic and ultramafic volcanic rocks were derived by different processes from an asthenospheric mantle source, possibly in an oceanic rift environment. Therefore, it is suggested that the ultramafic, mafic, and felsic volcanic rocks were brought to the same erosional level by dissection of the arc system and rapid exhumation of the felsic arc lithologies and the deeper ocean floor. Intrabasinal hydrothermal activity associated with contemporaneous mafic volcanism and (or) graben development may have also been responsible for the local production of the Fe-rich precipitates of the North iron formation.

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