Eruptive fluid fracture formations of Nakyn diamondiferous field of Yakutia

2018 ◽  
pp. 37-44
Author(s):  
P. A. Ignatov ◽  
K. V. Novikov ◽  
N. R. Zaripov ◽  
M. S. Khodnia ◽  
A. A. Burmistrov ◽  
...  
Keyword(s):  
Sedimentary Cover ◽  
Lower Paleozoic ◽  
Tectonic Control ◽  
Different Ages

In Nakyn diamondiferous field of West-Yakutian province various fluid fracture rocks determined, including kimberlites, eruptive breccias of basites, fluid fracture carbonate breccias and accompanying fluidizite streaks. Shown their characteristic petrographic features and regularity of distribution in the rocks of the lower Paleozoic sedimentary cover. Revealed a predominant tectonic control of fluid fracture formations with bi — and confocal distribution. Suggested the formation of these fluid fracture rocks as a result of different ages directed at faults phreatic explosions.

Age of xenocrystic zircon from diatremes of western Canada

1991 ◽  
Vol 28 (8) ◽  
pp. 1232-1238 ◽  
Author(s):  
R. R. Parrish ◽  
I. Reichenbach
Keyword(s):  
Sedimentary Cover ◽  
Crystalline Basement ◽  
Late Paleozoic ◽  
Western Canada ◽  
Magmatic Activity ◽  
Early Paleozoic ◽  
Lower Paleozoic ◽  
Single Zircon ◽  
Crustal Xenoliths ◽  
Middle Proterozoic

Numerous diatremes of middle and late Paleozoic age intrude miogeoclinal middle and lower Paleozoic strata in the Canadian Cordillera. In addition to abundant crustal xenoliths and conspicuous mantle-derived mineral xenocrysts, rare zircon grains are present. U–Pb dating of single zircon crystals from many of these diatremes has failed to identify the presence of cogenetic (magmatic) zircons. All dated zircon grains are interpreted as xenocrysts derived from the crust. Their morphologies range from euhedral to very rounded, and their ages range from early Paleozoic to Archean. Most ages fall between 1.8 and 2.1 Ga, with subordinate age groupings in the late Archean (ca. 2.6 Ga), Middle Proterozoic (1.0–1.1 Ga), and early Paleozoic (ca. 470 Ma, 530 Ma). The Proterozoic and Archean zircons could have been derived from either the crystalline basement or its overlying sedimentary cover of Late Proterozoic to early Paleozoic age. Paleozoic zircons were probably derived from either intrusions within the basement or sills that intrude the early Paleozoic sedimentary cover, and they signify magmatic activity possibly related to rifting of the continental margin.

scholarly journals ANALYSIS OF FRACTION CONTENTS IN ROCK SCRATCH TESTS FOR ESTIMATING THE ANGLE OF INTERNAL FRICTION FOR THE SEDIMENTARY COVER OF THE KOVYKTA FIELD

2021 ◽  
Vol 12 (3S) ◽  
pp. 748-753
Author(s):  
K. V. Toropetsky ◽  
G. A. Borisov ◽  
A. S. Smirnov ◽  
A. V. Nosikov
Keyword(s):  
Internal Friction ◽  
Sedimentary Cover ◽  
Geological Structure ◽  
Seismic Survey ◽  
Southeastern Part ◽  
Lower Paleozoic ◽  
Angle Of Internal Friction ◽  
Granulometric Analysis ◽  
Complex Geological Structure ◽  
Scratch Tests

The article describes the possibility of using the granulometric analysis of rock cuttings formed in controlled core scratching tests to estimate the angle of internal friction.The study object is the Kovykta gas-condensate field (GCF) that occupies a wide area in the southeastern part of the Irkutsk amphitheater of the Siberian platform. This uniquely complex geological structure holds significant reserves of hydrocarbons. Its sedimentary cover is composed of the Vendian – lower Paleozoic and partly Riphean formations. Their total thickness exceeds 6000 m, as estimated from the new seismic survey data [Vakhromeev et al., 2019].The sedimentary cover of the Kovykta GCF has been studied by surface and borehole geophysical techniques, remote sensing and geostructural methods, in combination with the tectonophysical approach [Seminsky et al., 2018] based on drilling data, including standard and special core sampling data.

Middle Paleozoic tear faulting, basin development, and basement uplift, central Canadian Arctic

1993 ◽  
Vol 30 (3) ◽  
pp. 603-620 ◽  
Author(s):  
T. A. de Freitas ◽  
U. Mayr
Keyword(s):  
Carbonate Platform ◽  
Sedimentary Cover ◽  
Hanging Wall ◽  
Canadian Arctic ◽  
Lake Basin ◽  
Western Basin ◽  
Lower Paleozoic ◽  
Early Devonian ◽  
Northern Segment ◽  
Basin Fill

The Boothia Uplift of the central Canadian Arctic Islands, located some 1200 km west of the Caledonian collision zone, is a "Laramide-type" basement-cored uplift that affected Precambrian crystalline basement and lower Paleozoic carbonate platform sequence. The two major segments of the Boothia Uplift, separated by the east-trending Barrow Strait, had different deformational histories. In the southern segment, uplift of the basement began in Late Silurian time, while in the northern segment, there was subsidence and platform drowning.In the northern segment, a thick sedimentary succession, containing numerous potential detachment surfaces, was involved in Early Devonian deformation. Folding of the cover along northerly trends resulted in the longitudinal infilling of two small, synclinal basins in the hanging wall of the uplift. The type of basin fill was dependent on source proximity and was influenced by contemporaneous flexure of the sedimentary cover. The western basin, the Grove Lake basin, received predominantly terrestrial sediments, and the eastern one, the Sutherland River basin, received mostly marine sediments, including a thick, possibly submarine, synsedimentary breccia that accumulated in response to tilting of partly lithified, carbonate strata. Southward-transported clastic sediments of the basin-fill sequence and contours showing the amount of pre-Emsian erosion suggest that a high-angle tear fault influenced sedimentation in the Grove Lake basin.The areally restricted and variably transported syntectonic clastics of the northern segment are different from coeval clastics of the southern segment. This is attributed to different deformational histories along the uplift and, in particular, to the deformation of a thick, locally anisotropic sedimentary cover sequence in the northern segment.A thick Emsian to early Eifelian carbonate platform sequence onlapped the eroded Boothia Uplift which had acted as a paleohigh for some 10–15 Ma. Early Devonian basement faults appear to have been reactivated as dextral wrench faults during Tertiary time.

Fracture pattern of the Lower Paleozoic sedimentary cover in the Lublin Basin of southeastern Poland derived from seismic attribute analysis and structural restoration

2018 ◽  
Vol 6 (3) ◽  
pp. SH73-SH89 ◽  
Author(s):  
Mateusz Kufrasa ◽  
Łukasz Słonka ◽  
Piotr Krzywiec ◽  
Krzysztof Dzwinel ◽  
Jarosław Zacharski
Keyword(s):  
Sedimentary Cover ◽  
Fracture Pattern ◽  
Strike Slip ◽  
Normal Faults ◽  
Late Devonian ◽  
Structural Restoration ◽  
Stress Regime ◽  
Lower Paleozoic ◽  
Attribute Analysis ◽  
Fracture Modeling

We have characterized Late Devonian fracture systems in the northeastern part of the Lublin Basin in Poland using two independent approaches: (1) seismic data conditioning and volumetric attribute analysis and (2) structural restoration, geomechanical modeling, and fracture modeling. The study area was subjected to reverse faulting in the basement and fault-related folding at the end of Devonian. These late Devonian structures were not overprinted by later deformation events. We have applied a set of structurally oriented filters and seismic attributes aimed at highlighting discontinuities to reduce the seismic noise and improved the fracture visibility on structural steering volume. The main faults cutting intra-Neoproterozoic and intra-Ordovician horizons are principal east–west-striking reverse faults and minor northwest–southeast-oriented normal faults. Based on analysis of the seismic-scale faults, we have carried out fracture modeling for strike-slip and compressional stress fields, with a northwest–southeast-oriented axis of maximum compression. We have correlated tentative strikes for tensile, shear, and closing-mode fractures for both stress regimes, with fault-likelihood attribute maps. The observed fracture system can have developed in the strike-slip stress regime, although cracks generated due to gas overpressure, or of pre-Devonian age, are not excluded. The final fracture model may be extrapolated into Silurian strata, but the results should be perceived as a general approximation of structural trends due to significant differences in mechanical properties of Silurian shales and underlying Ordovician carbonates. Improved model calibration could be achieved after inspection of scanner image logs. We believe that understanding the fracture distribution within the gas-bearing Silurian strata may contribute to effective planning and performing of hydraulic fracturing because part of these fracture planes may be reopened and provide new conduits for fluid flow.

scholarly journals 60 years of the Serbo-Macedonian Unit concept: From Cadomian towards alpine tectonic frameworks

2020 ◽  
Vol 81 (1) ◽  
pp. 41-66
Author(s):  
Darko Spahic ◽  
Tivadar Gaudenyi
Keyword(s):  
Sedimentary Cover ◽  
High Grade ◽  
Active Margin ◽  
Lower Paleozoic ◽  
Magmatic Arc ◽  
Pan African ◽  
Northern Shore ◽  
North Gondwana

The study represents a summary of the hitherto tectonic concepts revolving around a peri-Gondwanan fragment referred to as the Serbo- Macedonian Unit. The Serbo-Macedonian Unit as a gneiss-dominated basement segment is positioned in the proximity of the Baltican craton (peri-Moesian realm). This area represents a repository of the transferred broadly similar thus highly complex, elongated polycrystalline vestiges of the Pan-African inheritance. This peculiar far-travelled composite crustal fragment of north Gondwana is amalgamated on top of the Supragetic unit during the late Variscan peri-Moesian amalgamation. However, the original early Pa - leozoic tectonostratigraphic configuration of these three intimate green schistand medium- to high-grade gneiss-amphibolite basement vestiges (Serbo-Ma - cedonian/Supragetic and Getic) is further perplexed by the presence of poorly documented pre-Variscan (Ordovician?) lithospheric-scale event. The Pan-African to Lower Paleozoic subduction/magmatic arc stage led to the amalgamation, breakup and dispersal of a cluster of peri-Gondwanan continental and oceanic terranes. Breakup and dispersal from the northern shore of the Gondwanan active margin triggered the development of the Paleozoic deep-marine sedimentary cover (?Kucaj unit? or Getic unit). To make matter more complex, prior the Lower Paleozoic terrane agglomeration and sub - sequent dispersal, it appears that a Lower Paleozoic geodynamic linkage is additionally marked by the poorly investigated cross-lithospheric event. This event connects the outboard oceanic Supragetic/?Kucaj? succession with a segment of the former north Gondwanan protobasin (juvenile Serbo-Ma - cedonian Unit).

Conodonts recovered from the carbonate xenoliths in the kimberlites confirm the Paleozoic cover on the Hall Peninsula, Nunavut

2014 ◽  
Vol 51 (2) ◽  
pp. 142-155 ◽  
Author(s):  
Shunxin Zhang ◽  
Jennifer Pell
Keyword(s):  
Late Jurassic ◽  
Sedimentary Cover ◽  
Late Ordovician ◽  
Baffin Island ◽  
Upper Ordovician ◽  
Lower Paleozoic ◽  
Lower Silurian ◽  
Wide Range ◽  
Erosion History ◽  
Color Alteration

Hall Peninsula, located on southeastern Baffin Island, Nunavut, hosts the newly discovered Chidliak kimberlite province. Presently, this area lacks Phanerozoic sedimentary cover, except for the unconsolidated glacial deposits; however, Late Ordovician and Early Silurian microfossil conodonts have been recovered from carbonate xenoliths preserved in the Late Jurassic – Early Cretaceous kimberlites. Over 1300 conodont specimens were recovered, among which 32 species representing 23 genera are recognized, with four elements indeterminate. The well-preserved conodont faunas provide reliable evidence on the Hall Peninsula for (i) reconstructing the Lower Paleozoic stratigraphic units, including the Upper Ordovician Frobisher Bay, Amadjuak, Akpatok, and Foster Bay formations, and the Lower Silurian Severn River Formation, (ii) estimating a total of 270–305 m in thickness of Lower Paleozoic sedimentary cover prior to the emplacement of the kimberlites, (iii) tracing the erosion history after the emplacement of the kimberlites, and (iv) calculating a minimum erosion rate of 2 m/Ma. The conodonts have a wide range of conodont Color Alteration Index (CAI) values between 1.5 and 8, which is the largest range recorded in any known suite of xenoliths entrained in kimberlites.

scholarly journals Local geochemical features of Lower Paleozoic rocks in the area of Duderhof dislocations (North-West of the Russian plate)

LITOSFERA ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 5-22
Author(s):  
E. N. Terekhov ◽  
S. Yu. Kolodyazhny ◽  
A. S. Baluev ◽  
O. I. Okina
Keyword(s):  
Baltic Shield ◽  
Chemical Elements ◽  
Sedimentary Cover ◽  
Black Shales ◽  
Lower Paleozoic ◽  
Near Surface ◽  
North West ◽  
Geochemical Study ◽  
High Concentrations ◽  
The Baltic

Research subject. A geochemical study of Cambrian-Ordovician deposits was carried out within the area of the Duderhof dislocations of the platform cover of the southern frame of the Baltic shield. Materials and methods. The ICP-MS method was used to study 14 samples of sandstones, limestone, phosphorites and black shales, which comprise both weakly dislocated stratified formations (stratified horizons) and strongly deformed formations, as well as secant dome-like and dike-like bodies. Results. Geochemical studies showed that, in the zones of tectonic disturbances, lower Paleozoic deposits are characterized by high concentrations of a number of trace elements, significantly exceeding the Clark values for sedimentary rocks. This applies to such chemical elements, as Be, Sc, V, Co, Ni, Cu, Mo, Pb, Th and U. At the same time, the concentrations of V and U are higher than those in the developed fields of Estonia and Sweden. An analysis of the cambriansands of the sablin formation showed that the eastern (Archean) part of the Baltic shield could not have been the source of food for their formation. The presence of leucoxene in the sands of the Sablinsky formation, a mineral formed by ilmenite under the influence of high temperatures, and the presence of mechanically unstable minerals in dike-like formations, indicate the influence of deep fluids on the sedimentary cover, whose flows moved along fault zones and carried the above-mentioned chemical elements to the near-surface layers of the earth’s crust. All this points to the endogenous rather than exogenous (glacial) nature of secondary structural-material transformations in the area of the Duderhof dislocations, as well as their genetic relationship with deformations in the Baltic-Mezen shear zone.

Confidence and accuracy of eyewitness memory for target faces at different ages

2013 ◽  
Author(s):  
Christopher D. Kimbrough ◽  
Brian H. Bornstein ◽  
Heather Bryden
Keyword(s):  
Eyewitness Memory ◽  
Different Ages
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