Tourmaline concentrations in Proterozoic sediments of the southern Cordillera of Canada and their economic significance

1977 ◽  
Vol 14 (10) ◽  
pp. 2348-2363 ◽  
Author(s):  
V. G. Ethier ◽  
F. A. Campbell
Keyword(s):  
Heat Flow ◽  
Sedimentary Rocks ◽  
Local Area ◽  
Economic Importance ◽  
Coarse Grained ◽  
Economic Significance ◽  
Lower Proterozoic ◽  
Lead Zinc ◽  
High Boron ◽  
Boron Level

Local concentrations of tourmaline occur in the lower Proterozoic (Helikian) Aldridge Formation of southeastern British Columbia, in some places in association with stratiform lead–zinc mineralization as at the Sullivan, Stemwinder, and North Star orebodies. The amount of boron in the rock is as much as two orders of magnitude above average levels reported for the Aldridge Formation or other similar types of sedimentary rocks. The concentrations are not detrital, but are caused by an anomalously high boron level, in a local area, at the time of sedimentation. The appearance of tourmaline within rip-up clasts, and in laminae within pebbles, is evidence of syngenetic introduction of boron.Three populations of tourmalines, on the basis of composition as determined by microprobe analyses, are described from the area:(1) A Proterozoic stock intruding the Aldridge Formation contains abundant schorl.(2) A tourmaline intermediate in composition between dravite and schorl is typical of Aldridge metasediments. Texturally this type occurs as (a) fine felted aggregates in the footwall of the Sullivan orebody, (b) disseminated through waste beds, and (c) in local concentrations removed from the Sullivan orebody.(3) Coarse-grained recrystallized tourmaline associated with the Sullivan ore is magnesium-rich. Recrystallization is erratic, and is probably related to uneven heat flow during metamorphism and to differences in bulk composition.The economic importance of tourmaline concentrations in the Aldridge Formation is their association in both space and time with stratiform sulfides.

scholarly journals Sedimentology and Economic Significance of Hangu Formation, Northwest Pakistan

2020 ◽  
Vol 11 (1) ◽  
pp. 48-55
Author(s):  
Kamil Ahmed Qureshi ◽  
Muhammad Raza Shah ◽  
Ishaque Ali Meerani ◽  
Shah Fahad ◽  
Hamid Hussain ◽  
...  
Keyword(s):  
Coal Seam ◽  
Carbon Content ◽  
Calorific Value ◽  
Chemical Study ◽  
Ash Content ◽  
Coarse Grained ◽  
Carbonaceous Shale ◽  
Sedimentary Structures ◽  
Economic Significance ◽  
Quartz Arenite

The Hangu Formation (Paleocene) consists of sandstone, siltstone, carbonaceous shale, coal and laterite. It is well exposed in the Trans Indus Surghar range and the southern Hazara basin. The sandstone is yellowish brown, fine to coarse grained and medium to thick bedded. The sandstone of the Hangu Formation is classified as quartz arenite on the Q-F-L diagram. It is mostly grain supported and are cemented by silica cement. The study of different stratigraphic sections reveal that Hangu Formation can be sub-divided into a number of lithofacies on the basis of sedimentary structures and lithological variations. These include lateritic lithofacies, coal and carbonaceous shale, cross-bedded sandstone, bioclastic limestone and bioturbated sandstone. All these lithofacies are well-developed in the Baroch Nala section of the Surghar range except the lateritic lithofacies which contains a thin bed of ferruginous clay. In the studied sections of the Hazara basin, the lateritic lithofacies is the only well-developed lithofacies present in the area. The coal occurs at two stratigraphic levels in the Baroch Nala section. The lower coal seam is thick and its chemical study indicates higher calorific value and carbon content than the upper coal seam and with low moisture/ash content. On the basis of the calorific value, the coal of the Hangu Formation is characterized as high volatile bituminous. The degree of laterization is strong in the Langrial and Khanpur sections and moderate in Baroch Nala section.

scholarly journals Dominant Weathering Profile Assessment of Kebo-Butak Volcanic Rocks in Gedangsari and Ngawen area, Yogyakarta, Indonesia

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Fathan Hanifi Mada Mahendra ◽  
I Gde Budi Indrawan ◽  
Sugeng Sapto Surjono
Keyword(s):  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Coarse Grained ◽  
Residual Soil ◽  
Geological Condition ◽  
Weathering Profile ◽  
Fine Grained ◽  
Degree Pattern ◽  
Weathering Degree ◽  
East West

The Gedangsari and Ngawen area is predominantly composed of volcanic and volcaniclastic sequencesdistributed east – west direction of the northern parts of Southern Mountain. The massive tectonism as well as tropical climatein this region have been producing weathering profiles in varying thickness which inevitably affects thegeotechnical properties. This study aims to assess the dominant weathering profileof the lower part of Kebo-Butak Formation as well as evaluating the distribution of the discontinuity. In order to know the dominant weathering profile and discontinuity evaluation, this study utilizes a total of  26 panels from five stations investigated through a geotechnical data acquisition including the geological condition, weathering zones, joint distribution, and discontinuity characteristics. The result shows four types of dominant weathering profiles in lower part of Kebo-Butak Formation called as dominant weathering profile A, B, C, and D. Profile A, B, C consisted of a relatively identical weathering degree pattern of fresh, slightly, moderately, completely weathered zone with the variation of thicknesses. However, the weathering degree in profile D reached the residual soil degree controlled by more intensive joints. The fine-grained sedimentary rocks also tends to have smaller spacing, shorter persistence, and higher weathering degree of discontinuities as compared to coarse-grained sedimentary rocks.

Paleomagnetism of the mid-Cretaceous gem-bearing pegmatite dikes of San Diego County, California, USA

2009 ◽  
Vol 46 (9) ◽  
pp. 675-687 ◽  
Author(s):  
D. T.A. Symons ◽  
T. E. Smith ◽  
K. Kawasaki ◽  
M. J. Walawender
Keyword(s):  
Fluid Flow ◽  
Gulf Of California ◽  
Remanent Magnetization ◽  
Sedimentary Rocks ◽  
Economic Importance ◽  
San Diego County ◽  
Magnetization Direction ◽  
Western Zone ◽  
Stable Characteristic ◽  
Tectonic Boundary

Pegmatite dikes in the Peninsular Ranges batholith of southwestern California have produced spectacular crystals of semiprecious and precious minerals for over a century. Aside from their economic importance, these dikes straddle a major tectonic boundary and were used to test hypotheses related to the timing and development of this composite batholith. Paleomagnetic analysis of 252 specimens from 20 sites (12 and 8 sites in the western and eastern zones of the batholith, respectively, from 11 mines in five dike districts) isolated a stable characteristic remanent magnetization direction at 19 sites. The site mean directions for the western and eastern zones are statistically indistinguishable at 95% confidence, supporting petrologic and geochemical arguments that the dikes of the two zones are coeval and cogenetic. After correction for the Neogene opening of the Gulf of California, the paleopole for all 19 site mean directions is indistinguishable from the 94 Ma reference paleopole for North America and supports hypotheses that (1) the dikes are genetically related to intrusion of the La Posta-type plutons; (2) the batholith was already assembled beside the northwestern coastline of Mexico at 94 Ma; (3) ENE-side-up tilting of fault blocks in the batholith’s western zone ended by ∼94 Ma; and (4) the far-sided and clockwise-rotated discordant paleopoles found commonly in Late Cretaceous and younger sedimentary rocks of the batholith’s region are mostly the result of inclination-flattening of the remanence and (or) remagnetization by fluid flow, creating a secondary remanence, excluding Neogene tectonic rotations.

S-type characteristics of the Hercynian granitoids of the Central Palaeozoic Massif, Morocco

1984 ◽  
Vol 121 (4) ◽  
pp. 301-309 ◽  
Author(s):  
A. Mahmood ◽  
A. Bennani
Keyword(s):  
Heat Source ◽  
Sedimentary Rocks ◽  
Chemical Study ◽  
Coarse Grained ◽  
Partial Equilibrium ◽  
Chemical Characteristics ◽  
Mafic Mineral ◽  
Crustal Source ◽  
Zoned Plagioclase

AbstractThis petrographic and chemical study of the Hercynian granitoids of the Central Palaeozoic Massif of Morocco covers the Zaër, Ment, Oulmès, and Moulay Bouazza plutons. These plutons are formed of biotite or two-mica, quartz-rich granodiorites and monzogranites containing reddish-brown, inclusion-rich biotites as the only essential mafic mineral; zoned plagioclase; and perthitic K-feldspar. The modal contents of micas and K-feldspar are highly variable. The granitoids are generally medium to coarse grained, massive; however foliated varieties are also commonly found, particularly at the contact of the' plutons with sedimentary rocks.The strongly peraluminous character of the granitoids is shown by high normative corundum and high molar Al2O3/(CaO + Na2O + K2O) ratio, and is reflected by the occasional presence of aluminosilicates.The mineralogical and chemical characteristics of the granitoids are similar to those of the S-type granites, and were inherited from the crustal source of the granitic magmas which are thought to have been generated by partial equilibrium fusion of the sandy argillaceous sediments of the Massif. The heat source for the fusion might have been provided by intrusion of mantle-derived material.

scholarly journals Unsung Heroes? The Rhodesian Defence Regiment and Counterinsurgency, 1973–80

2019 ◽  
Vol 39 (1) ◽  
pp. 88-120
Author(s):  
Evans B. Tsigo ◽  
Enock Ndawana
Keyword(s):  
Economic Importance ◽  
National Liberation ◽  
Security Forces ◽  
Economic Significance ◽  
The Many

This article examines the Rhodesian Defence Regiment’s role in the Rhodesian Security Forces’ counterinsurgency efforts against the Zimbabwe African National Liberation Army and Zimbabwe People’s Revolutionary Army guerrillas. It argues that the two guerrilla armies successfully used sabotage targeting installations of strategic and economic significance to Rhodesia. This compelled the Rhodesian regime to change its policy of restricting the conscription of Coloured and Asian minorities into the Rhodesian Security Forces to undertake combat duties beyond defensive roles. However, the Rhodesian Defence Regiment largely failed to serve its key duty of countering the guerrilla tactic of sabotage against all major installations and centres of strategic and economic importance. The article concludes that the failure was due to the many challenges the majority members, Coloureds and Asians, that constituted the Rhodesian Defence Regiment faced, including discrimination and mistrust. These challenges derailed the Rhodesian Defence Regiment operations and partly contributed to the overall end of the Ian Smith regime.

scholarly journals Heat flow density estimates in the Upper Rhine Graben using laboratory measurements of thermal conductivity on sedimentary rocks

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Pauline Harlé ◽  
Alexandra R. L. Kushnir ◽  
Coralie Aichholzer ◽  
Michael J. Heap ◽  
Régis Hehn ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Ambient Temperature ◽  
Sedimentary Rocks ◽  
Flow Density ◽  
Upper Rhine Graben ◽  
Heat Flow Density ◽  
Density Estimates ◽  
Wet Rocks ◽  
Upper Rhine

AbstractThe Upper Rhine Graben (URG) has been extensively studied for geothermal exploitation over the past decades. Yet, the thermal conductivity of the sedimentary cover is still poorly constrained, limiting our ability to provide robust heat flow density estimates. To improve our understanding of heat flow density in the URG, we present a new large thermal conductivity database for sedimentary rocks collected at outcrops in the area including measurements on (1) dry rocks at ambient temperature (dry); (2) dry rocks at high temperature (hot) and (3) water-saturated rocks at ambient temperature (wet). These measurements, covering the various lithologies composing the sedimentary sequence, are associated with equilibrium-temperature profiles measured in the Soultz-sous-Forêts wells and in the GRT-1 borehole (Rittershoffen) (all in France). Heat flow density values considering the various experimental thermal conductivity conditions were obtained for different depth intervals in the wells along with average values for the whole boreholes. The results agree with the previous heat flow density estimates based on dry rocks but more importantly highlight that accounting for the effect of temperature and water saturation of the formations is crucial to providing accurate heat flow density estimates in a sedimentary basin. For Soultz-sous-Forêts, we calculate average conductive heat flow density to be 127 mW/m2 when considering hot rocks and 184 mW/m2 for wet rocks. Heat flow density in the GRT-1 well is estimated at 109 and 164 mW/m2 for hot and wet rocks, respectively. Results from the Rittershoffen well suggest that heat flow density is nearly constant with depth, contrary to the observations for the Soultz-sous-Forêts site. Our results show a positive heat flow density anomaly in the Jurassic formations, which could be explained by a combined effect of a higher radiogenic heat production in the Jurassic sediments and thermal disturbance caused by the presence of the major faults close to the Soultz-sous-Forêts geothermal site. Although additional data are required to improve these estimates and our understanding of the thermal processes, we consider the heat flow densities estimated herein as the most reliable currently available for the URG.

Lead–zinc–barite veins of the Dorion Area, Thunder Bay District, Ontario

1977 ◽  
Vol 14 (9) ◽  
pp. 1963-1979 ◽  
Author(s):  
James M. Franklin ◽  
Roger H. Mitchell
Keyword(s):  
Lead Isotopes ◽  
Central Zone ◽  
Chloride Ion ◽  
Coarse Grained ◽  
Vein Wall ◽  
Sulphur Isotope ◽  
Thunder Bay ◽  
Basement Rocks ◽  
Lake Formation ◽  
Lead Zinc

The lead–zinc–barite deposits of the Dorion region are spatially associated with the unconformity between the Sibley Group (Helikian) and Archean and Aphebian basement rocks. The veins are coarse grained, and mineralogically zoned with galena–calcite in the central zone, sphalerite–quartz surrounding the central zone, and barite (±chalcopyrite) in the vein extremities. Veins occur near the pinch-out of the "Pass Lake formation" (basal Sibley Group), within the dolomite of the overlying "Rossport formation", or in nearby basement fractures. Rossport dolomite, where it forms a vein wall, is highly altered to metal-enriched chert and calcite. Archean wall rocks are not altered.Potassium–argon isotopic determinations on mica in Archean pegmatite immediately adjacent to a vein indicate that the transporting solutions were too cool to cause re-equilibration of the Ar within the mica. Sulphur-isotope data indicate equilibrium between galena and sphalerite yielding a depositional temperature range of 35–135 °C, and disequilibrium between sulphide–sulphate pairs. Lead isotopes are highly anomalous, yielding a secondary isochron which indicates either an Archean, or more probably a mixed Archean–Aphebian, source of lead.The deposits formed from metal leached from either basement rocks or breakdown of Sibley sandstone matrix. Metals and sulphate moved through the permeable sandstone, probably as chloride-ion complexes, and precipitated at the sandstone pinch-out. Reduced sulphur, possibly derived from organic decay, and probably held in a gas trap at the sandstone pinch out, caused precipitation of the sulphides by reaction with metal-bearing brines.

Late Jurassic (Kimmeridgian-Tithonian) macrofossil assemblage from Jason Peninsula, Graham Land: evidence for a significant northward extension of the Latady Formation

1997 ◽  
Vol 9 (4) ◽  
pp. 434-442 ◽  
Author(s):  
T.R. Riley ◽  
J.A. Crame ◽  
M.R.A. Thomson ◽  
D.J. Cantrill
Keyword(s):  
Antarctic Peninsula ◽  
Late Jurassic ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Coarse Grained ◽  
Areal Extent ◽  
South Eastern ◽  
Back Arc ◽  
The Antarctic ◽  
Major Sequence

New exposures of fossiliferous sedimentary rocks at Cape Framnes, Jason Peninsula (65°57′S, 60°33′W) are assigned to the Middle–Late Jurassic Latady Formation of the south-eastern Antarctic Peninsula region. A sequence of fine to coarse-grained sandstones of unknown thickness has yielded a molluscan and plant macrofossil assemblage rich in the following elements: perisphinctid ammonites, belemnopseid belemnites, oxytomid, trigoniid and astartid bivalves, and bennettitalean fronds and fructifications. The overwhelming age affinities are with the Kimmeridgian–early Tithonian part of the Latady Formation, as exposed on the Orville and Lassiter coasts. The Cape Framnes sedimentary rocks help to constrain the age of a major sequence of acid volcanic rocks on Jason Peninsula, and show that the Latady Basin was geographically much more extensive than recognized previously. It was the principal depositional centre of Middle–Late Jurassic sedimentation in the Antarctic Peninsula back-arc region and in areal extent may have rivalled the essentially Cretaceous Larsen Basin.

Sedimentology and structure of the trench-slope to forearc basin transition in the Mesozoic of Alexander Island, Antarctica

1993 ◽  
Vol 130 (6) ◽  
pp. 737-754 ◽  
Author(s):  
P. A. Doubleday ◽  
D. I. M. Macdonald ◽  
P. A. R. Nell
Keyword(s):  
Sedimentary Rocks ◽  
Accretionary Prism ◽  
Coarse Grained ◽  
Accretionary Complex ◽  
Forearc Basin ◽  
Marine Transgression ◽  
Tectonic Events ◽  
The World ◽  
Basin Formation ◽  
Trench Slope

AbstractThe Mesozoic forearc of Alexander Island, Antarctica, is one of the few places in the world where the original stratigraphic relationship between a forearc basin and an accretionary complex is exposed. Newlydiscovered sedimentary rocks exposed at the western edge of the forearc basin fill (the Kimmeridgian–Albian Fossil Bluff Group) record the events associated with the basin formation. These strata are assigned to the newly defined Selene Nunatak Formation (?Bathonian) and Atoll Nunataks Formation (?Bathonian-Tithonian) within the Fossil Bluff Group.The Selene Nunatak Formation contains variable thicknesses of conglomeratesand sandstones, predominantly derived from the LeMay Group accretionary complex upon which it is unconformable. The formation marks emergence and subsequent erosion of the inner forearc area. It is conformably overlain by the1 km thick Atoll Nunataks Formation, characterized by thinly-bedded mudstones and silty mudstones representing a marine transgression followed by trench-slope deposition. The Atoll Nunataks Formation marks a phase of subsidence, possibly in response to tectonic events in the accretionary prism that are known to have occurred at about the same time.The Atoll Nunataks Formation is conformably overlain by the Himalia Ridge Formation, a thick sequence of basin-wide arc-derived conglomerates. This transition from fine- to coarse-grained deposition suggests that a well-developed depositional trough (and hence trench-slope break) had formed by that time. The Atoll Nunataks Formation therefore spans the formation of the forearc basin, and marks the transition from trench-slope to forearc basin deposition.

Post Permian tectono-thermal evolution of western Dronning Maud Land, East Antarctica: an apatite fission-track approach

1999 ◽  
Vol 11 (4) ◽  
pp. 451-460 ◽  
Author(s):  
Joachim Jacobs ◽  
Frank Lisker
Keyword(s):  
Fission Track ◽  
Thermal Evolution ◽  
Hot Spot ◽  
Sedimentary Cover ◽  
Sedimentary Rocks ◽  
Coarse Grained ◽  
Reference Plane ◽  
Apatite Fission Track ◽  
Dronning Maud Land ◽  
Lava Pile

New apatite fission-track (AFT) ages from Heimefrontfjella and Mannefallknausane indicate that the Mesoproterozoic basement and Permian sedimentary cover rocks were heated to c. 100°C during the Mesozoic. Heating was due to the burial by up to 2000 m of Jurassic lavas at c. 180 Ma, when the area was affected by the Bouvet/Karoo hot spot. Near the developing coastline, the lava pile was quickly eroded and in part deposited on the continental shelf as pebbly and coarse-grained volcaniclastic sandstones. The AFT data indicate that farther inland the lava pile was not eroded until c. 100 Ma, and the Palaeozoic unconformity between the Mesoproterozoic basement and Permo–Carboniferous sedimentary rocks as a reference plane remained at temperatures of c. 80°C. Formation of an up to 800 m b.s.l. deep graben in from Heimefrontfjella as well as flexural uplift and rapid denudational cooling of the not extended crust from Heimefrontfjella southwards occurred at c. 100 Ma. It is speculated that a period of major plate reorganisation and new rifting at c. 100 Ma is responsible for affecting a much wider continental margin as far inland as Heimefrontfjella and producing a total relief in excess of 3500 m.

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