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1
Edgett, Kenneth S., e Ranjan Sarkar. "Recognition of Sedimentary Rock Occurrences in Satellite and Aerial Images of Other Worlds—Insights from Mars". Remote Sensing 13, n. 21 (26 ottobre 2021): 4296. http://dx.doi.org/10.3390/rs13214296.
Testo completoAbstract (sommario):
Sedimentary rocks provide records of past surface and subsurface processes and environments. The first step in the study of the sedimentary rock record of another world is to learn to recognize their occurrences in images from instruments aboard orbiting, flyby, or aerial platforms. For two decades, Mars has been known to have sedimentary rocks; however, planet-wide identification is incomplete. Global coverage at 0.25–6 m/pixel, and observations from the Curiosity rover in Gale crater, expand the ability to recognize Martian sedimentary rocks. No longer limited to cases that are light-toned, lightly cratered, and stratified—or mimic original depositional setting (e.g., lithified deltas)—Martian sedimentary rocks include dark-toned examples, as well as rocks that are erosion-resistant enough to retain small craters as well as do lava flows. Breakdown of conglomerates, breccias, and even some mudstones, can produce a pebbly regolith that imparts a “smooth” appearance in satellite and aerial images. Context is important; sedimentary rocks remain challenging to distinguish from primary igneous rocks in some cases. Detection of ultramafic, mafic, or andesitic compositions do not dictate that a rock is igneous, and clast genesis should be considered separately from the depositional record. Mars likely has much more sedimentary rock than previously recognized.
2
Lyu, Qiqi, Shunshe Luo, Yulong Guan, Jinhua Fu, Xiaobing Niu, Liming Xu, Shengbin Feng e Shixiang Li. "A new method of lithologic identification and distribution characteristics of fine - grained sediments: A case study in southwest of Ordos Basin, China". Open Geosciences 11, n. 1 (26 febbraio 2019): 17–28. http://dx.doi.org/10.1515/geo-2019-0002.
Testo completoAbstract (sommario):
Abstract Lithologic identification is critical for studying fine - grained sediments, which further elucidates sedimentary environment, and formation. The oil - bearing Chang 7 Section of the Yanchang Formation in Ordos Basin contains thick dark mudstone with a wide distribution, interbedded by siltstone and fine sandstone. The lacustrine fine - grained sedimentary rocks constitute the chief source rock of the Yanchang Formation. On the grounds of fine core description, thin rock slice identification and X - ray diffraction analysis, we proposed a new method based on conventional logging data. This method is using density (DEN) and natural gamma (GR) logging curve intersection and multivariate linear regression analysis of logging curve value and measured mineral content value which is carried out by SPSS software to identify the lithology and the vertical distribution characteristics of fine - grained sedimentary rock of Chang 7 formation in the study area. This method is mainly suitable for lithologic identification of fine - grained sedimentary rocks in lake basin. It not only quantitatively analyses the contents of main minerals and organic matter in fine - grained sedimentary rocks, but also greatly improved the accuracy and universality of using conventional logging data to identify the lithology of fine - grained sedimentary rocks, which provides a reference for the exploration of tight oil.
3
Zhao, Ranlei, Xiao Xu, Wentao Ma, Cunlei Li, Qiushi Zhang e Qingyou Yue. "Reservoir Characteristics and Controlling Factors of Sedimentary Pyroclastic Rocks in Deep-Buried Basins: A Case Study of Yingtai Fault Depression, Southern Songliao Basin". Energies 15, n. 18 (9 settembre 2022): 6594. http://dx.doi.org/10.3390/en15186594.
Testo completoAbstract (sommario):
In this article, based on core description, thin section, scanning electron microscope (SEM), well logging and reservoir physical properties, the reservoir controlling factors of sedimentary pyroclastic rocks in deep-buried basins are assessed via the relation between reservoirs and defining factors, including lithological characteristics, sedimentary microfacies and diagenesis. In addition, the contributing factors of anomalously high-porosity and high-permeability zone are analyzed. The lithological characteristics and diagenesis of the sedimentary pyroclastic rocks are closely related to reservoirs. The reservoir porosity–permeability of sedimentary pyroclastic rocks with large volcanic clastic particles is better than in those with small volcanic clastic particles. Sedimentary pyroclastic rocks with high content of unstable clastic particles, such as feldspar and rock debris, are easier to form the high-quality reservoirs than those with high content of quartz. The dissolution is the most important and direct reason to form the anomalously high-porosity and high-permeability zones of the sedimentary pyroclastic rocks in deep-buried basins. It is concluded that the size and composition of the clastic particles in the sedimentary pyroclastic rocks are the internal-controlling factors of the effective reservoirs, while the diagenetic fluid and the burial process are the external-controlling factors which form the effective reservoirs.
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DA SILVA, JOSÉ LUIZ SILVÉRIO, e EGYDIO MENEGOTTO. "Aspectos Geoquímicos de Silicificações em Rochas Sedimentares no Rio Grande do Sul, Brasil". Pesquisas em Geociências 32, n. 2 (31 dicembre 2005): 29. http://dx.doi.org/10.22456/1807-9806.19543.
Testo completoAbstract (sommario):
Some exposures of silicified sedimentary rocks and duricrusts occur in the central Depressão Periférica along the edge of the Paraná Basin in Rio Grande do Sul State, in southern part of Brazil. These silicified materials were firstly studied in the petrographic aspects by Silvério da Silva & Menegotto (2002). This paper presents geochemical results of the analysis on samples of sedimentary rocks and silica duricrusts collected in two profiles (Santa Maria and Cachoeira do Sul). The relationships between the sedimentary rocks and the duricrusts, as well their probable provenance and genesis, are discussed. Silicification occurs as lenses, concretions, nodules and pedotubules, in the Mesozoic sedimentary rocks of these profiles. Micro quartz predominates and forms the most part of the matrix. Fibrous chalcedony and mega quartz were present in minor amounts filling vughs. Three types of silicification were recognized: silcretes (SiO2>87%), silica rich concretions (SiO2 from 76.10 % to 86.76% SiO2) and sedimentary rocks with few silica cement. Gresen′s mass balance is presented to point out the gain of SiO2. The silica source is related to weathering processes of the minerals of the sedimentary rock and added to the groundwater.
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LINDSTRÖM, SOFIE. "Palynology of Permian shale, clay and sandstone clasts from the Basen till in northern Vestfjella, Dronning Maud Land". Antarctic Science 17, n. 1 (28 febbraio 2005): 87–96. http://dx.doi.org/10.1017/s0954102005002476.
Testo completoAbstract (sommario):
The palynological content of randomly collected sedimentary rock clasts from the till on the south-east slope of the Basen nunatak in northern Vestfjella in western Dronning Maud Land indicate that these sedimentary rocks were derived from strata of Middle Permian age. The palynological content and preservation is similar to palynofloras described from the sedimentary rocks that crop out at the Fossilryggen nunatak to the south-east, therefore, it seems likely that the Fossilryggen area represents the source of the sedimentary rock samples in the Basen till. This is further supported by known ice flow directions obtained from striations and clast fabric measurements in the area.
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Bilić, Šime, e Vesnica Garašić. "PETROLOGICAL CHARACTERISTICS OF CLASTIC SEDIMENTARY ROCKS FROM THE ST. BARBARA ORE MINE IN RUDE NEAR SAMOBOR". Rudarsko-geološko-naftni zbornik 36, n. 1 (2021): 121–35. http://dx.doi.org/10.17794/rgn.2021.1.10.
Testo completoAbstract (sommario):
In the scope of this research, the petrographic and geochemical analyses of clastic sedimentary rocks from the St. Barbara, copper and iron ore mine in Rude near Samobor, have been made, aiming to classify and determine the provenance and environment of formation of clastic sedimentary rocks, as well as the influence of hydrothermal fluids on their properties. Eight samples were collected in total from different locations in the mine. Six of those samples have been studied in detail. The results showed structural and geochemical variability and uneven hydrothermal alteration intensity in the samples. Based on petrographic analyses, three rocks are classified as sublithoarenite, quartz arenite and quartz greywacke. Three of the samples are classified as ore breccia, ore sandstone, and ore silt-sandstone due to the pronounced hydrothermal alterations and ore mineralisation. Comprehensively, petrographic and geochemical analyses indicate that the source rocks of the investigated clastic sedimentary rocks were felsic (La/Sc = 0.9-6.2; Th/Sc = 1.3-2.4), most probably sedimentary, possibly resedimented rocks. The extent of source rock weathering was very high (Chemical Index of Alteration CIA = 52.1 - 81.3 %) and the geotectonic position of the sedimentary basin was very likely to be at the passive continental margin.
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Pujar, Anant G., A. Sreenivasa e Ajaykumar N. Asode. "Petrography and Provenance Study of South-Central Part of Kaladgi Basin, Belgaum, Karnataka, India". International Journal of Economic and Environmental Geology 11, n. 1 (7 luglio 2020): 108–12. http://dx.doi.org/10.46660/ijeeg.vol11.iss1.2020.421.
Testo completoAbstract (sommario):
The area under investigation covers the south-central part of Kaladgi series comprising of sedimentary rocks, mainly quartzarenites. From the geological point of view the study area comprises southcentral part of Kaladgi basin covering around 54 km2 which encompasses rocky hills of moderate height, showing three types of facies i.e., argillaceous, arenaceous and rudaceous. Among these three, arenaceous facies is more prominent in the area. These sedimentary rocks rest unconformably over gneisses. Detailed study of the rocks exposed are done by studying the petrological aspects of the rock samples which were subjected to microscopic studies, bifurcating different minerals and counting each parameter of the minerals which is plotted in the QFR ternary diagram and further illustrating the tectonic provenance of the area. Present work mainly focuses on the studies related to petrological, diagenesis and provenance of the study area where the rocks exposed in the vicinity are quartz arenites indicating that these sediments were deposited in a riverine condition.
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Pujar, Anant G., A. Sreenivasa e Ajaykumar N. Asode. "Petrography and Provenance Study of South-Central Part of Kaladgi Basin, Belgaum, Karnataka, India". International Journal of Economic and Environmental Geology 11, n. 1 (7 luglio 2020): 108–12. http://dx.doi.org/10.46660/ojs.v11i1.421.
Testo completoAbstract (sommario):
The area under investigation covers the south-central part of Kaladgi series comprising of sedimentary rocks, mainly quartzarenites. From the geological point of view the study area comprises southcentral part of Kaladgi basin covering around 54 km2 which encompasses rocky hills of moderate height, showing three types of facies i.e., argillaceous, arenaceous and rudaceous. Among these three, arenaceous facies is more prominent in the area. These sedimentary rocks rest unconformably over gneisses. Detailed study of the rocks exposed are done by studying the petrological aspects of the rock samples which were subjected to microscopic studies, bifurcating different minerals and counting each parameter of the minerals which is plotted in the QFR ternary diagram and further illustrating the tectonic provenance of the area. Present work mainly focuses on the studies related to petrological, diagenesis and provenance of the study area where the rocks exposed in the vicinity are quartz arenites indicating that these sediments were deposited in a riverine condition.
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Hu, Zeng, Fang, Qi, Yin, Chen, Li e Zhu. "Geochemical Study of Detrital Apatite in Sediment from the Southern Okinawa Trough: New Insights into Sediment Provenance". Minerals 9, n. 10 (8 ottobre 2019): 619. http://dx.doi.org/10.3390/min9100619.
Testo completoAbstract (sommario):
Detrital apatite is a promising accessory mineral for reliable fingerprinting of the protolith composition of detrital sediment. Here, we present the geochemical compositions of detrital apatites from four sections of a high-resolution (~140 cm/kyr) sedimentary archive from the southern Okinawa Trough (SOT) for constraining sediment source rock types and establishing changes in provenance. A series of diagrams based on the geochemical data show that apatites in Section 1 derived mainly from mafic/intermediate rocks, while apatites in the three younger sections largely originated from mafic/intermediate rocks and acid rocks. Further, the four sections included a few contributions of apatites from alkaline rocks and metamorphic rocks. Through a comprehensive analysis of controlling factors and regional stratigraphy in the study area, we concluded that sediments in the SOT are the weathering/erosion products of sedimentary and meta-sedimentary rocks in the western and northeastern Taiwan Island, with ultimate sources containing a wide variety of rock types. The sediment from rivers in eastern Taiwan did not significantly contribute to deposition in the SOT. Apatites in Sections 2–4 showed strong geochemical similarity but differed from those in Section 1, indicating that the types of weathered/eroded sedimentary rocks in the weathering profile of river drainage basins of Taiwan Island changed in Section 2 (2010–1940 cal. yr BP) and have remained stable since then.
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Rasbury, E. Troy, e Jennifer M. Cole. "Directly Dating Sedimentary Rocks". Paleontological Society Papers 12 (ottobre 2006): 77–105. http://dx.doi.org/10.1017/s1089332600001364.
Testo completoAbstract (sommario):
This contribution seeks to provide a summary of radiometric dating techniques that are currently applicable to Phanerozoic sedimentary deposits and therefore relevant to paleontologists. First we overview the assumptions necessary for radiometric dating and introduce isochrons and concordia diagrams as methods for calculating ages and evaluating isotope systematics. We then focus on the four most promising systems: U-Pb dating of carbonates, Re-Os dating of black shales, and U-Pb and Lu-Hf dating of phosphates. We review expected geochemical behavior of daughter and parent isotopes in the context of both marine and terrestrial depositional environments. A critical evaluation of previously published ages and potential directions for future work are provided.
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Marica, F., U. Mayer, B. Balcom e T. Al. "Diffusivity in sedimentary rocks". Magnetic Resonance Imaging 25, n. 4 (maggio 2007): 573. http://dx.doi.org/10.1016/j.mri.2007.01.074.
Testo completo
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Ariansyah, Muhammad Resky, Muhammad Fawzy Ismullah Massinai e Muhammad Altin Massinai. "Rock Types Classification and Distribution on Anabanua Village, Barru Regency, South Sulawesi". Jurnal Geomine 8, n. 1 (27 giugno 2020): 1–8. http://dx.doi.org/10.33536/jg.v8i1.530.
Testo completoAbstract (sommario):
Anabanua Village, Barru Regency is one of the areas in South Sulawesi that has quite unique geological conditions. This condition inseparably comes from the complicated geological process that took place during the formation of the island, Sulawesi. In Anabanua Village, there are many types of rocks such as sedimentary rocks, metamorphic rocks and igneous rocks. This paper aims to map and classify the types of rock by taking samples on different places in the research area. Then we observe the samples physical properties. The results showed, from taking 10 rock samples in different places, they have various characteristics. 8 of them were sedimentary rocks, they are Limestone Quartz, Limestone Sand, Shale, Sandstone, Coal, Limestone Bioturbation, Breccia, and Chert Stone. The other 2 samples were metamorphic rocks, they are Greenschist and Quartzite.
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Sang, Pham Nhu, Nguyen Tien Dung, Phan Thi Thanh Hien e Vo Thi Cong Chinh. "The degree of chemical weathering in the Ba River basin, South Central Vietnam: Major-element geochemistry investigations of morden river sediments and sedimentary rocks". Journal of Mining and Earth Sciences 61, n. 1 (28 febbraio 2020): 82–91. http://dx.doi.org/10.46326/jmes.2020.61(1).09.
Testo completoAbstract (sommario):
Major-element geochemistry of Miocene sedimentary rock and modern river sediment samples in the Ba River basin, South Central Vietnam are utilized to assess the degree of chemical weathering in the Miocene and the present time. Sediment samples were analysed by X-ray fluorescence (XRF) spectrometer show that Miocene sedimentary rocks contain higher SiO2 and K2O, but lower Fe2O3, TiO2, MgO, Na2O, MnO, CaO, P2O5 than modern river sediment. Major-element geochemistry indicates that Miocene sedimentary rocks and modern river sediment are characterized by stronger depliption of Ca, Na and Mg than K and Si during the chemical weathering in this river basin. The similar relative depleption of Na, Ca, Mg, Si and K between modern river sediments and sedimentary rocks indicate not much deffirent the intensity of chemical weathering in the Miocene and the present time. The chemical index of alteration (CIA) alter from 69 to 93 in Miocene sedimentary rocks (average 74) and from 69 to 78 (average 77) in morden river sediments, indicating moderate chemical weathering in the Ba River basin in the Miocene and the present time.
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Liu, Chao, Hai Tao Xue, Shuang Wang e Yu Jiao Sun. "Study on Law of Structural Evolution and Sedimentary Evolution for North Uskyurt Basin". Advanced Materials Research 671-674 (marzo 2013): 302–5. http://dx.doi.org/10.4028/www.scientific.net/amr.671-674.302.
Testo completoAbstract (sommario):
North Uskyurt Basin, located on Turan Plain, northwestern Central Asian, is continental polycyclic cratonic. The structural evolution of the basin underwent six phases: basement formulation, passive edge, rifting, post-rifting, compression, early Neogene depression. Regional structural evolution takes control of complicated transition of North Uskyurt sedimentary structure. In general, basin sedimentary environment underwent basement (granite, metamorphic rocks) passive edge, late Devonian epoch carboniferous period (marine facies) rifting, late Permian epoch-triassic period (continental facies) post-rifting, Jurassic period-Cretaceous period (Marine-continental Transition Facies, marine facies) compression, late Eocene-Miocene epoch (marine-continental facies coexistence) Neogene depression, Pliocene-Holocene (continental facies). Consequently, sedimentary formation in which various sedimentary environment, such as marine facies, continental facies, are coexisted with various rock types, such as clastic rocks, carbonate rocks, is generated.
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Read, D., D. C. Cooper e J. M. McArthur. "The composition and distribution of nodular monazite in the Lower Palaeozoic rocks of Great Britain". Mineralogical Magazine 51, n. 360 (giugno 1987): 271–80. http://dx.doi.org/10.1180/minmag.1987.051.360.09.
Testo completoAbstract (sommario):
AbstractMillimetric, ellipsoidal monazite nodules found within Lower Palaeozoic sedimentary rocks in Wales, south-west England and Brittany are characterised by a pronounced zonation of light and heavy REE, an inclusion fabric of low-grade metamorphic minerals indistinguishable from the host rock and a low Th content. They are interpreted as the product of in situ recrystallization of detrital monazites derived from pegmatitic or granitic source rocks and are potentially useful as indicators of Lower Palaeozoic sedimentary rock provenance.
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Yang, Yepeng, Zaixing Jiang, Jianguo Zhang, Zongxuan Zhang e Chun Yang. "Control Effect of Deposition Processes on Shale Lithofacies and Reservoirs Characteristics in the Eocene Shahejie Formation (Es4s), Dongying Depression, China". Energies 16, n. 5 (24 febbraio 2023): 2200. http://dx.doi.org/10.3390/en16052200.
Testo completoAbstract (sommario):
The lacustrine fine-grained sedimentary rocks in the upper interval of the fourth member of the Eocene Shahejie Formation (Es4s) in the Dongying Depression are important shale oil exploration targets in Bohai Bay Basin. They are widely distributed and rich in organic matter. In this study, samples were observed under the optical microscope and FESEM, combined with geochemical test and physical property analysis to study the sedimentary characteristics and reservoir characteristics of them. Nine lithofacies are recognized based on the mineral composition, the content of organic matter and the beddings. The middle-high organic laminated calcareous fine-grained sedimentary rocks (LF1) and the middle-high organic laminated mixed fine-grained sedimentary rocks (LF2) resulted from seasonal sediment variations and settled by suspension in the deep lake. The middle-high organic flaggy mixed fine-grained sedimentary rocks (LF3), the middle-high organic flaggy calcareous fine-grained sedimentary rocks (LF4), the middle-high organic massive calcareous fine-grained sedimentary rocks (LF5) and the middle organic massive mixed fine-grained sedimentary rocks (LF6) were formed by redeposition. The low organic massive argillaceous fine-grained sedimentary rocks (LF7), the low organic massive felsic fine-grained sedimentary rocks (LF8) and the low organic massive mixed fine-grained sedimentary rocks (LF9) are affected by the terrigenous input events. The pore structures vary in different beddings which are influenced by the kinds and arrangement of minerals and particles. In the laminated lithofacies, the ink-bottle-shaped pores are dominant. In the flaggy and massive lithofacies, the ink-bottle-shaped pores and the slit-shaped pores coexist. LF1 and LF2 are the best target for shale oil exploration and the LF3, LF4, LF5 and LF6 are the second. The deposition processes control the lithofacies and reservoir characteristics of the fined-grained sedimentary rocks.
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Takagi, T., S. M. Koh, M. S. Song, M. Itoh e K. Mogi. "Geology and properties of the Kawasaki and Dobuyama bentonite deposits of Zao region in northeastern Japan". Clay Minerals 40, n. 3 (settembre 2005): 333–50. http://dx.doi.org/10.1180/0009855054030177.
Testo completoAbstract (sommario):
AbstractThe Kawasaki and Dobuyama bentonite deposits in northeastern Japan show contrasting properties even though they are only 5 km apart in a sequence of Neogene sedimentary and pyroclastic rocks. The Kawasaki deposit consists of stratiform bentonite layers up to >50 m thick, and its wall rocks are unaltered shallow marine sedimentary rocks. In contrast, the Dobuyama deposit consists of a funnel-shaped ore body 200 m across, and its wall rocks are hydrothermally altered terrestrial rhyolitic pyroclastic rocks. The Kawasaki and Dobuyama bentonites mainly consist of Na-Ca smectite and Ca smectite, respectively, with subordinate opal-CT, quartz and zeolite. The geological occurrences of the deposits and wall-rock properties suggest that the Kawasaki and Dobuyama deposits were probably formed by diagenesis and low-temperature hydrothermal alteration, respectively. The difference in exchangeable cation ratios of the smectite between the two deposits is attributable to the difference in their sedimentary environments and/or burial depth.
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Bérubé, Charles L., Gema R. Olivo, Michel Chouteau e Stéphane Perrouty. "Mineralogical and textural controls on spectral induced polarization signatures of the Canadian Malartic gold deposit: Applications to mineral exploration". GEOPHYSICS 84, n. 2 (1 marzo 2019): B135—B151. http://dx.doi.org/10.1190/geo2018-0404.1.
Testo completoAbstract (sommario):
Applications of the spectral induced polarization (SIP) method to mineral exploration are limited by our knowledge of the relationships among rock texture, mineral composition, and electrical properties. Laboratory SIP responses were measured on rock samples from the Canadian Malartic gold deposit. Field SIP responses were also measured at the outcrop scale, along a profile that intersects a well-studied mineralized zone. The mineralogy and the texture of sedimentary rocks from this deposit were quantitatively determined with mineral liberation analysis. A systematic decrease (Pearson [Formula: see text]) in total chargeability with increasing fraction of the sulfide mineral interfaces associated with feldspar minerals (namely, K-feldspar and albite) was observed. On the other hand, total chargeability increased with the fraction of sulfide mineral interfaces associated with carbonates and micas (Pearson [Formula: see text]). At Canadian Malartic, proximal alteration in the mineralized zones is marked by rocks that lack a foliation plane and that were subjected to pervasive K-feldspar, albite, and pyrite alteration. In contrast, distal alteration in sedimentary rocks is marked by biotite, albite, carbonate, and pyrite that are oriented along the regional [Formula: see text] foliation. In the least-altered (LA) sedimentary rocks, quartz and biotite are associated with pyrrhotite and ilmenite as the main sulfide and oxide mineral phases, respectively. SIP measurements conducted at district and outcrop scales and along a drill core indicated that proximally altered sedimentary rocks were characterized by low total chargeability values ([Formula: see text] to [Formula: see text] in the laboratory and [Formula: see text] in the field). In contrast, the LA sedimentary rocks were characterized by total chargeability values up to [Formula: see text] in the laboratory and [Formula: see text] in the field. We conclude that mineralized zones associated with this type of ore deposit are characterized by low chargeability anomalies.
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Raven, K. G., K. S. Novakowski, R. M. Yager e R. J. Heystee. "Supernormal fluid pressures in sedimentary rocks of southern Ontario – western New York State". Canadian Geotechnical Journal 29, n. 1 (1 febbraio 1992): 80–93. http://dx.doi.org/10.1139/t92-009.
Testo completoAbstract (sommario):
Fluid pressures up to 1.7 times greater than hydrostatic have been measured in argillaceous Paleozoic rocks of low permeability in southern Ontario and western New York State. These supernormal formation fluid pressures were measured at depths of 50–310 m using submersible pressure transducers with straddle packers and multiple-packer casings isolating the test intervals. Measurements were obtained over periods of 7–46 months following casing installations. The pressure measurements from 11 monitoring wells are compiled and supporting hydrogeologic data for 5 selected wells are used as examples to illustrate the occurrence of supernormal fluid pressures in the Ordovician, Silurian, and Devonian sedimentary sequence of southern Ontario and western New York State. Possible explanations for the occurrence of supernormal fluid pressures in sedimentary rock are evaluated considering the available geologic and hydrogeologic information obtained from the monitoring wells. Based on this review, it is hypothesized that gas migration and accumulation from deeper distant sources via permeable vertical pathways is the most plausible explanation for the observed fluid pressures, although secondary contributions from local neotectonic activity are also possible. The implications of such supernormal fluid pressures on regional groundwater flow in sedimentary rocks and related activities such as waste disposal in sedimentary rock are briefly discussed. Key words : supernormal fluid pressure, sedimentary rocks, gas migration.
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TROLL, VALENTIN R., JANE P. CHADWICK, ROBERT M. ELLAM, SUSAN Mc DONNELL, C. HENRY EMELEUS e IAN G. MEIGHAN. "Sr and Nd isotope evidence for successive crustal contamination of Slieve Gullion ring-dyke magmas, Co. Armagh, Ireland". Geological Magazine 142, n. 6 (novembre 2005): 659–68. http://dx.doi.org/10.1017/s0016756805001068.
Testo completoAbstract (sommario):
The Palaeogene Slieve Gullion Igneous Centre in southern Armagh, Northern Ireland, consists of a layered central intrusive complex surrounded by a prominent and slightly older ring-dyke that intrudes both Lower Palaeozoic sedimentary rocks and the Caledonian Newry Granodiorite pluton (452 Ma). The ring-dyke comprises two major rock types: porphyritic felsite and porphyritic granophyre. We analysed both ring-dyke lithologies, both types of country rock, and a local Palaeogene basalt dyke sample for Sr and Nd isotopes. Trace element and whole rock data for this suite suggest that there are two distinct groups of both felsite and granophyre: one Si-rich and one Si-poor, most likely representing two magmas from a zoned chamber and their mushy chamber wall equivalents (McDonnell et al. 2004). Isotope data show the low-Si rocks to be higher in radiogenic Sr than the high-Si rocks, which is inconsistent with a simple AFC-scenario of increasing sediment assimilation with higher degrees of differentiation. However, using MORB-type basalt as a starting composition, the low-Si ring-dyke rocks can be modelled through AFC with Lower Palaeozoic sedimentary rock as the contaminant. The decreasing 87Sr/86Sr trend from low-Si to high-Si dyke rocks, in turn, represents a second stage of contamination. Selective assimilation of the most fusible portions of Newry Granodiorite, which is lower in radiogenic Sr than the local sedimentary rocks, appears to be the most plausible solution. The Sr and Nd data are consistent with (a) at least a two-stage contamination history during upper crustal residence and storage, whereby fractionating magmas of basaltic and intermediate composition are contaminated by local sedimentary rocks, giving rise to rhyolite magmas that experience additional shallow contamination by Newry Granodiorite, and (b) a zoned rhyolite magma chamber where high-Si magma is stored in the upper part of the chamber where crystallization and crustal contamination are most extensive.
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Otavio, Jonatas Malaquias, Osvaldo Girão, Tiago Fernando de Holanda e Wenderson Sávyo Aguiar Da Silva. "FORMAÇÃO E DIAGÊNESE DE ARENITOS DE PRAIA: Uma Revisão Conceitual". CLIO – Arqueológica 32, n. 3 (5 settembre 2017): 88. http://dx.doi.org/10.20891/clio.v32n3p88-106.
Testo completoAbstract (sommario):
Os arenitos de praia, ou beachrocks, são sedimentos que sofreram um processo de litificação e são encontrados paralelamente à linha de costa na zona intermaré, apresentando uma forma alongada, estreita e cimentados por carbonato de cálcio. O processo de diagênese consiste na formação da rocha sedimentar propriamente dita a partir da compactação, dissolução, cimentação e recristalização. O estudo da formação e diagênese do arenito de praia são relevantes pois possibilita o entendimento de como as rochas sedimentares detríticas são geradas, além de reconhecer como a variação do nível do mar se comportou durante o Holoceno, permitindo a gênese destas feições que se constituem em relevantes elementos de resguardo das linhas de costas em ambientes majoritariamente tropicais. FORMATION AND DIAGENÈSE IN BEACHROCKS:A Conceptual Review ABSTRACTThe beach sandstones, or beachrocks, are sediments that underwent a lithification process and are found parallel to the coastline in the intertidal zone, presenting an elongated, narrow shape and cemented by calcium carbonate. The process of diagenesis consists on the formation of the sedimentary rock itself, following deposition, compaction, dissolution, cementation and recrystallization. The study of the formation and diagenesis of beach sandstone is relevant since it permits the understanding of how clastic sedimentary rocks are formed, besides with recognizing how sea level variation behaved during the Holocene, thus allowing the genesis of these features that constitute relevant elements of shelter along coastlines in most tropical environments. Keywords: Beachrocks, sedimentary rock, cementation.
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Bucholz, Claire E., e Christopher J. Spencer. "Strongly Peraluminous Granites across the Archean–Proterozoic Transition". Journal of Petrology 60, n. 7 (7 giugno 2019): 1299–348. http://dx.doi.org/10.1093/petrology/egz033.
Testo completoAbstract (sommario):
Abstract Strongly peraluminous granites (SPGs) form through the partial melting of metasedimentary rocks and therefore represent archives of the influence of assimilation of sedimentary rocks on the petrology and chemistry of igneous rocks. With the aim of understanding how variations in sedimentary rock characteristics across the Archean–Proterozoic transition might have influenced the igneous rock record, we compiled and compared whole-rock chemistry, mineral chemistry, and isotope data from Archean and Paleo- to Mesoproterozoic SPGs. This time period was chosen as the Archean–Proterozoic transition broadly coincides with the stabilization of continents, the rise of subaerial weathering, and the Great Oxidation Event (GOE), all of which left an imprint on the sedimentary rock record. Our compilation of SPGs is founded on a detailed literature review of the regional geology, geochronology, and inferred origins of the SPGs, which suggest derivation from metasedimentary source material. Although Archean and Proterozoic SPGs are similar in terms of mineralogy or major-element composition owing to their compositions as near-minimum melts in the peraluminous haplogranite system, we discuss several features of their mineral and whole-rock chemistry. First, we review a previous analysis of Archean and Proterozoic SPGs biotite and whole-rock compositions indicating that Archean SPGs, on average, are more reduced than Proterozoic SPGs. This observation suggests that Proterozoic SPGs were derived from metasedimentary sources that on average had more oxidized bulk redox states relative to their Archean counterparts, which could reflect an increase in atmospheric O2 levels and more oxidized sedimentary source rocks after the GOE. Second, based on an analysis of Al2O3/TiO2 whole-rock ratios and zircon saturation temperatures, we conclude that Archean and Proterozoic SPGs formed through partial melting of metasedimentary rocks over a similar range of melting temperatures, with both ‘high-’ and ‘low-’temperature SPGs being observed across all ages. This observation suggests that the thermo-tectonic processes resulting in the heating and melting of metasedimentary rocks (e.g. crustal thickening or underplating of mafic magmas) occurred during generation of both the Archean and Proterozoic SPGs. Third, bulk-rock CaO/Na2O, Rb/Sr, and Rb/Ba ratios indicate that Archean and Proterozoic SPGs were derived from partial melting of both clay-rich (i.e. pelites) and clay-poor (i.e. greywackes) source regions that are locality specific, but not defined by age. This observation, although based on a relatively limited dataset, indicates that the source regions of Archean and Proterozoic SPGs were similar in terms of sediment maturity (i.e. clay component). Last, existing oxygen isotope data for quartz, zircon, and whole-rocks from Proterozoic SPGs show higher values than those of Archean SPGs, suggesting that bulk sedimentary 18O/16O ratios increased across the Archean–Proterozoic boundary. The existing geochemical datasets for Archean and Proterozoic SPGs, however, are limited in size and further work on these rocks is required. Future work must include detailed field studies, petrology, geochronology, and constraints on sedimentary source ages to fully interpret the chemistry of this uniquely useful suite of granites.
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SAEIN, ALI FARZIPOUR, e ZAHRA TAJMIR RIAHI. "Controls on fracture distribution in Cretaceous sedimentary rocks from the Isfahan region, Iran". Geological Magazine 156, n. 06 (25 maggio 2017): 1092–104. http://dx.doi.org/10.1017/s0016756817000346.
Testo completoAbstract (sommario):
AbstractIn this study, relationships between fracture patterns, lithology, thickness, diagenetic processes and grain size are evaluated within Cretaceous sediments in two sections of Dizlu and Kolah Ghazi of Isfahan. This study area was selected based on its outcrops of different rock units and its well-developed tectonic fractures. The fracture patterns within stratigraphic units of these sections are studied using geometrical and statistical analyses. This study finds that variable fracture spacing and fracture spacing ratios can be affected by lithology, thickness, grain size of sediments and diagenetic processes. A study of fracture stratigraphy based on fracture pattern evaluation within different cropped-out sedimentary rocks can be used to improve understanding of the same types of sedimentary rock units below the surface or throughout other sedimentary basins. Consequently, this could improve information regarding storage and fluid flow pattern throughout sedimentary rocks in different regions, even for subsurface purposes.
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Muhammad, W. N., N. I. Setiawan, S. Husein e M. Nukman. "A preliminary study of geology and skarn of Cemorosewu Area, Bayat, Central Java, Indonesia". IOP Conference Series: Earth and Environmental Science 851, n. 1 (1 ottobre 2021): 012045. http://dx.doi.org/10.1088/1755-1315/851/1/012045.
Testo completoAbstract (sommario):
Abstract We present the first finding of skarn rocks in Cemorosewu area of East Jiwo Hill, Bayat, Central Java, Indonesia. The geological conditions of this area which related to the appearance of the skarn is also reported. The methods used in this research are DEM acquisition using drone to generate basemap for geological mapping and thin section petrographic analyses. The geological map shows that Cemorosewu area consists of metamorphic rocks (mica phyllite, graphite phyllite, with quartzite and marble lenses), sedimentary rocks (carbonate breccia and siltstone), and igneous rock (microdiorite). Based on the field observation and geological map, the regional metamorphic rocks are the oldest units in this area followed by sedimentary rocks and igneous rock which intruded both rocks. Skarn rocks were cropped out as a boulder along the Kluwihan creek with the maximum size of 8 m in length. The skarn consists of garnet, clinopyroxene, zoisite, actinolite, and minor quartz. Metasiltstone and skarn rock are suggested formed by contact metamorphism of microdiorite intrusion. The marble, which lenses within the phyllites, is suggested to be the protolith of the skarn formation in this area.
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Malin, M. C. "Sedimentary Rocks of Early Mars". Science 290, n. 5498 (8 dicembre 2000): 1927–37. http://dx.doi.org/10.1126/science.290.5498.1927.
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Baranov, V. A., V. A. Kirichenko e Y. V. Antipovich. "Geological processes in sedimentary rocks". Geo-Technical mechanics, n. 139 (2018): 179–94. http://dx.doi.org/10.15407/geotm2018.02.179.
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Fielding, C. R. "Sedimentary Rocks in the Field". Sedimentary Geology 109, n. 1-2 (marzo 1997): 207–8. http://dx.doi.org/10.1016/s0037-0738(96)00039-5.
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Narr, W., e J. Suppe. "Joint spacing in sedimentary rocks". Journal of Structural Geology 13, n. 9 (1991): 1037–48. http://dx.doi.org/10.1016/0191-8141(91)90055-n.
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McBride, Earle F. "Petrology of the sedimentary rocks". Geomorphology 4, n. 2 (giugno 1991): 156–57. http://dx.doi.org/10.1016/0169-555x(91)90027-8.
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Lesmes, David P., e Frank Dale Morgan. "Dielectric spectroscopy of sedimentary rocks". Journal of Geophysical Research: Solid Earth 106, B7 (10 luglio 2001): 13329–46. http://dx.doi.org/10.1029/2000jb900402.
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McCann, C. "Geophysical properties of sedimentary rocks". Marine and Petroleum Geology 9, n. 2 (aprile 1992): 114. http://dx.doi.org/10.1016/0264-8172(92)90083-q.
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McKinley, MarvinD. "Diffusion coefficients in sedimentary rocks". Journal of Hazardous Materials 28, n. 1-2 (settembre 1991): 207–8. http://dx.doi.org/10.1016/0304-3894(91)87036-2.
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Evans, Diane. "Multisensor classification of sedimentary rocks". Remote Sensing of Environment 25, n. 2 (luglio 1988): 129–44. http://dx.doi.org/10.1016/0034-4257(88)90097-1.
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Li, Yuezhe, Jie Yin e Zhenqi Wang. "Lithofacies Characteristics and Controlling Factors of Fine-Grained Sedimentary Rocks in the Lower First Member of the Shahejie Formation in the Northern Lixian Slope of Raoyang Sag, China". Minerals 12, n. 11 (8 novembre 2022): 1414. http://dx.doi.org/10.3390/min12111414.
Testo completoAbstract (sommario):
In order to further explore the potential of unconventional oil and gas in the northern Lixian Slope of Raoyang Sag, the lithofacies types and their controlling factors of the lower first member of the Shahejie Formation (Es1L) in the Xiliu area were analyzed through the comprehensive application of core log studies, micro-sections and their magnified analyses, mineral suits recognitions with XRD, and major and organic geochemistry. The results show that the lacustrine sedimentary rocks of Es1L in the Xiliu area comprise five lithofacies types: medium organic silty mixed fine-grained rock, medium organic massive clay rock, high organic shale calcareous mixed fine-grained rock, high organic matter shale calcareous clay rock, and high organic matter shale limestone. The vertical variation of the characteristic element reflects that the deposition in Es1L has different stages; that is, the bottom of Es1L is formed with low source influence, high water salinity, and strong reduction conditions, while the upper fine-grained rocks are formed in a sedimentary environment with high source influence, low water salinity, and weak reduction conditions. The change of the sedimentary environment controls the development of lithofacies and the occurrence of organic matter. These results advocate for the basic research of fine-grained sedimentary rocks in the faulted lacustrine basin aid for further unconventional oil and gas exploration.
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Li, Qiang. "Geochemistry and Diagenetic Pattern of Ore-Bearing Rocks about Two Types of Gold Deposit in Fengxian-Taibai Basin, South Qinling". Advanced Materials Research 616-618 (dicembre 2012): 240–45. http://dx.doi.org/10.4028/www.scientific.net/amr.616-618.240.
Testo completoAbstract (sommario):
Baguamiao and Shuangwang gold deposit are two important gold types in Fengxian-Taibai basin. The gold deposits are all located at the bottom of the Upper-Devonian Xing-hongpu Formation. However the ore-bearing rocks are different between them. The ore-bearing rock of Baguamiao gold deposit is ankerite rocks, which is concordant with the strata by bedded or stratoid and assume rhythmic layering form. The ore-bearing rock of Shuangwang gold deposit is albite breccias, which are mostly lens-shaped. The data of petrochemistry show that both of them are poor in Fe2O3 and K2O, which are different from normal sedimentary rocks. The elements contents of Cu, Pb and Zn are close to Clarke value. But the content of dispersed element Ge is rich in rocks, which reflect hydrothermal sedimentary origin. The characteristic of REE are different between them. The REE contents of ankerite rocks are low and elements of Ce and Eu are positive anomaly. The REE contents of albite breccias are close to regional strata and elements of Ce and Eu are middle negative. The chondrite-normalized REE patterns are also alike. It’s shown that the diagenetic fluid are high-density which been mixed by sea water slightly. So the ankerite rocks hold the REE characteristic of thermal fluid. The diagenetic fluid of albite breccias are low-density thermal fluid which been mixed by sea water intensively. It has same REE characteristic to normal sedimentary rocks.
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Zisser, Norbert, Georg Nover, Helmut Dürrast e Siegfried Siegesmund. "Relationship between electrical and hydraulic properties of sedimentary rocks". Zeitschrift der Deutschen Gesellschaft für Geowissenschaften 158, n. 4 (1 dicembre 2007): 883–94. http://dx.doi.org/10.1127/1860-1804/2007/0158-0883.
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Crook, Keith A. W. "Sedimentary geology: An introduction to sedimentary rocks and stratigraphy". Sedimentary Geology 107, n. 3-4 (gennaio 1997): 304–6. http://dx.doi.org/10.1016/s0037-0738(97)84049-3.
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Yan, Fuyong, De-Hua Han, Tongcheng Han e Xue-Lian Chen. "Comparison of seismic anisotropy of sedimentary strata at low- and high-frequency limits". GEOPHYSICS 85, n. 1 (22 novembre 2019): MR1—MR10. http://dx.doi.org/10.1190/geo2018-0677.1.
Testo completoAbstract (sommario):
The layer-induced seismic anisotropy of sedimentary strata is frequency-dependent. At the low-frequency limit, the effective anisotropic properties of the layered media can be estimated by the Backus averaging model. At the high-frequency limit, the apparent anisotropic properties of the layered media can be estimated by ray theory. First, we build a database of laboratory ultrasonic measurement on sedimentary rocks from the literature. The database includes ultrasonic velocity measurements on sandstones and carbonate rocks, and velocity-anisotropy measurements on shales. Then, we simulate the sedimentary strata by randomly selecting a certain number of rock samples and using their laboratory measurement results to parameterize each layer. For each realization of the sedimentary strata, we estimate the effective and apparent seismic anisotropy parameters using the Backus average and ray theory, respectively. We find that, relative to Backus averaging, ray theory usually underestimates the Thomsen parameters [Formula: see text] and [Formula: see text], and overestimates [Formula: see text]. For an effective layered medium consisting of isotropic sedimentary rocks, the differences are significant. These differences decrease when shales with intrinsic seismic anisotropy are included. For the same sedimentary strata, the seismic wave should perceive stronger seismic anisotropy than the ultrasonic wave.
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Bock, B., S. M. McLennan e G. N. Hanson. "The Taconian orogeny in southern New England: Nd-isotope evidence against addition of juvenile components". Canadian Journal of Earth Sciences 33, n. 12 (1 dicembre 1996): 1612–27. http://dx.doi.org/10.1139/e96-122.
Testo completoAbstract (sommario):
Nd-isotope data for pre-Taconian (meta)sedimentary and igneous rocks, syn-Taconian (meta)sedimentary rocks, and Late Ordovician–Silurian plutonic rocks indicate that the Ordovician Taconian orogeny did not add significant amounts of juvenile crust to the Laurentian margin in southern New England. Nd-isotope compositions of Grenvillian crust and Late Proterozoic to Early Cambrian rift sediments range from εNd of −3.1 to −6.6 at 450 Ma. Sedimentary rocks deposited during the Cambrian and the early Middle Ordovician, which represent the drift stage of Laurentia, and earliest Taconian sedimentary rocks show more negative εNd(450 Ma), with a range from −11.7 to −13.3. Sedimentary rocks deposited in response to the Taconian orogeny have uniform εNd(450 Ma) values of about −8. Middle to Late Ordovician and Permian plutonic rocks from southwestern Connecticut have εNd(450 Ma) values of −2 to −5, which indicates that these rocks contain older crustal components. Rocks with juvenile Nd characteristics are the early Paleozoic Maltby Lake Volcanics (εNd(450 Ma) +8) from southwestern Connecticut, and Middle Ordovician igneous samples from the Hawley Formation (εNd(450 Ma) +6 to −0.6) in Massachusetts.
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Marinos, P. V., e G. Tsiambaos. "STRENGTH AND DEFORMABILITY OF SPECIFIC SEDIMENTARY AND OPHIOLITHIC ROCKS". Bulletin of the Geological Society of Greece 43, n. 3 (24 gennaio 2017): 1259. http://dx.doi.org/10.12681/bgsg.11302.
Testo completoAbstract (sommario):
The paper deals with the evaluation of strength and deformability of sedimentary rocks and ophiolites based on the processing of laboratory testing results. Characteristic values and their typical range for the parameters σci, Ei , as well as the Modulus Ratio (MR) are presented. These parameters are significant for the estimation of the strength and deformability of the rock mass since σci is basic component for the solution of Hoek-Brown failure criterion and Ei and MR are important components of the latest rock mass deformability expression (Hoek-Diedrichs, 2006). The recent site investigation and laboratory work undergone for the design of numerous tunnels in the Greek territory provided very good and sufficient data, derived from a specifically established database, for the estimation of strength and deformability of specific rocks. These rocks are sandstones and siltstones of flysch and molassic formations, as well as limestones and ophiolites.
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Abdulsalam, N. N., e O. Ologe. "Measurement of Magnetic Susceptibility on Some Rock Samples in Parts of Kuje Area, Abuja-Nigeria". NIGERIAN ANNALS OF PURE AND APPLIED SCIENCES 1 (13 marzo 2019): 275–80. http://dx.doi.org/10.46912/napas.49.
Testo completoAbstract (sommario):
Magnetic Susceptibility values are important in interpreting regional magnetic anomalies and in crustal modeling. In this study, Magnetic Susceptibility has been measured on rock samples from the sedimentary succession of Kuje Area in FCT. Variation of susceptibility for the different samples has been analyzed and confirm in the study. According to the measured susceptibility values based on the selected samples, the minimum susceptibility value for sedimentary rocks was found to be 0 which was the minimum value obtained for Dolomite and the maximum susceptibility value for sedimentary rocks was found to be 1480cgs which was the maximum value obtained for shales. For metamorphic rock, the minimum susceptibility value was found to be 25cgs which was the minimum value obtained for schists and its maximum susceptibility value was found to be 3,000cgs which was the maximum value obtained for slate. Finally, the minimum susceptibility value for igneous rocks was found to be 20cgs which was the minimum value obtained for rhyolite and its maximum susceptibility value was 14500cgs which was the maximum value obtained for basalts
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Ansdell, Kevin M., Karen A. Connors, Richard A. Stern e Stephen B. Lucas. "Coeval sedimentation, magmatism, and fold-thrust belt development in the Trans-Hudson Orogen: geochronological evidence from the Wekusko Lake area, Manitoba, Canada". Canadian Journal of Earth Sciences 36, n. 2 (1 febbraio 1999): 293–312. http://dx.doi.org/10.1139/e98-082.
Testo completoAbstract (sommario):
Lithological and structural mapping in the east Wekusko Lake area of the Flin Flon Belt, Trans-Hudson Orogen, suggested an intimate relationship between magmatism, fluvial sedimentation, and initiation of fold and thrust belt deformation. Conventional U-Pb geochronology of volcanic rocks in fault-bounded assemblages provides a minimum age of 1876 ± 2 Ma for McCafferty Liftover back-arc basalts, and ages of between 1833 and 1836 Ma for the Herb Lake volcanic rocks. A rhyolite which unconformably overlies Western Missi Group fluvial sedimentary rocks has complex zircon systematics. This rock may be as old as about 1856 Ma or as young as 1830 Ma. The sedimentary rocks overlying this rhyolite are locally intercalated with 1834 Ma felsic volcanic rocks, and yield sensitive high resolution ion microprobe (SHRIMP) U-Pb and Pb-evaporation detrital zircon ages ranging from 1834 to 2004 Ma. The Eastern Missi Group is cut by an 1826 ± 4 Ma felsic dyke, and contains 1832-1911 Ma detrital zircons. The dominant source for detritus in the Missi Group was the Flin Flon accretionary collage and associated successor arc rocks. The fluvial sedimentary rocks and the Herb Lake volcanic rocks were essentially coeval, and were then incorporated into a southwest-directed fold and thrust belt which was initiated at about 1840 Ma and active until at least peak regional metamorphism.
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Nkpadobi, Johnbosco Ikenna, John Kuna Raj e Tham Fatt Ng. "Classification of cut slopes in weathered meta-sedimentary bedrocks". Earth Sciences Research Journal 20, n. 2 (1 luglio 2016): 1. http://dx.doi.org/10.15446/esrj.v20n2.52781.
Testo completoAbstract (sommario):
In order of abundance, the meta-sedimentary rocks along Pos Selim Highway in Perak state Malaysia comprise quartz mica schist, graphitic schist, and quartzite layers. Field investigations revealed that these meta-sedimentary rocks have gradational weathering profile based on differences particularly in textures, hardness, lateral changes in colour, and consistency of material extension. The results from uniaxial compressive strength tests confirmed field observations whereby failure occurred mostly on outcrops having joints almost perpendicular to foliation. From the kinematic analyses, the investigated cut slopes are unstable with possibilities of wedge and planar failures. Application of rock mass classification schemes including Rock Quality Designation (RQD) and Rock Mass Rating (RMR) yielded almost similar poor to good quality ranges for each investigated rock mass. While Slope Mass Rating (SMR) classified the cut slopes from stable to unstable slopes, this study categorized them into one actively unstable, four marginally stable and five stable slopes. ResumenEn orden de abundancia, las rocas metasedimentarias a lo largo de la carretera Pos Selim, en el estado Perak de Malasia, se componen de esquistos de cuarzo mica, esquistos de grafito y capas de cuarzo. Las investigaciones de campo revelan que estas rocas metasedimentarias tienen perfiles de meteorización progresiva basados en diferencias particulares como textura, dureza, cambios laterales de color y consistencia del material de extensión. Los resultados de los ensayos uniaxiales de esfuerzo de compresión confirmaron las observaciones de campo por las cuales se estableció que las fallas ocurrieron mayormente en los afloramientos con coyunturas perpendiculares hacia la foliación. De los análisis cinemáticos se desprende que los taludes de corte investigados son inestables con posibilidades de fallas planas y de cuña. La utilización de esquemas de clasificación rocosa como el índice RQD (del inglés Rock Quality Designation) y la clasificación geomecánica de Bienawski o RMR (del inglés Rock Mass Rating) evidencia rangos similares de baja y buena calidad para cada masa rocosa estudiada. Mientras que el índice de taludes SMR (del inglés Slope Mass Rating) clasificó los taludes de corte de estables a inestables, este estudio los categorizó de uno activamente inestable, cuatro marginalmente estables y cinco estables.
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Wakabayashi, John. "Clastic Sedimentary Rocks and Sedimentary Mélanges: Potential Naturally Occurring Asbestos Occurrences (Amphibole and Serpentine)". Environmental and Engineering Geoscience 26, n. 1 (20 febbraio 2020): 15–19. http://dx.doi.org/10.2113/eeg-2267.
Testo completoAbstract (sommario):
ABSTRACT Petrography of mélange matrix and clastic sedimentary rocks in coastal California reveals the occurrence of detrital serpentine and detrital asbestiform sodic amphibole (glaucophane). Many sandstones of the Franciscan Complex have small amounts of detrital serpentine, with amounts of up to several percent in some cases. Detrital amphibole, including asbestiform glaucophane, is also present in some sandstones. Whereas rare sandstones have so much detrital glaucophane that they appear blue in hand specimen (up to nearly half of the rock volume), most glaucophane-bearing sandstones lack blue color, and the detrital glaucophane is not apparent in hand specimen. Most of the occurrences of detrital glaucophane are in blueschist facies sandstones, some of which also contain neoblastic (grew in place) glaucophane, but a notable exception is a widespread prehnite-pumpellyite facies unit that crops out primarily in Sonoma and Marin Counties. The detrital mineralogy of sandstones mirrors the block and matrix compositions of Franciscan mélanges that can be thought of as scaled-up equivalents of these clastic sedimentary rocks (mega-conglomerates/sedimentary breccias). Franciscan mélanges range from having a detrital siliciclastic to a detrital serpentinite matrix, and interfingering and gradation of the two matrix types is common. These findings suggest that clastic sedimentary rocks associated with current or past active orogenic settings else-where in the world may contain naturally occurring asbestos (NOA) even if the NOA component minerals are not visible in hand specimen.
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Khishigsuren, Sodnom, Nuramkhaan Manchuk, Ser-Od Tseden-Ish e Bayarmaa Batsaikhan. "Petrochemical study of Middle-Late Paleozoic sedimentary and metamorphic rocks near the great meandering of Tuul River, Central Mongolia". Mongolian Geoscientist, n. 48 (4 luglio 2019): 3–16. http://dx.doi.org/10.5564/mgs.v0i48.1144.
Testo completoAbstract (sommario):
The great meandering of Tuul River is located in the Khentii section of the Khangai-Khentii orogenic belt, Central Mongolia. At the study area, dominanty distributed sedimentary and metamorphic roks of venlok-lower Devonian Sugnugur Formation of Asralt Khairkhan terrane and Pensilvanian Altan-Ovoo Formation of Ulaanbaatar terrane. The source of sedimentary rock are important to understand the geology and tectonic evoluation of the region. Whole-rock major elements compositions of 15 sandstone and mudrocks (siltstone and mudstone) and shale from the Sugnugur and Altan-Ovoo Formations were determind by X-ray fluorescence spectrometry at Nagoya University, Japan. Shale protolith of Sugnugur and Altan-Ovoo formations are terrigenous sedimentary rocks. The sandstone and mudstone of Sugnugur and Altan-Ovoo formations are almost similar to petrochemical properties, mostly of greywacke composition. The source of sandstone and mudstone of Altan-Ovoo Formation are the only silicic magmatic rocks, while the rocks of Sugnugur Formation are silicic magmatic rocks, with a mixture of quartz-sedimentary rocks, intermediate to mafic magmatic rocks. Sandstone and mudstone of Altan-Ovoo and Sugnugur formations are deposited in the active continental area by their petrochemical properties. These results support the results of the previous research on the Middle to Upper Paleozoic sedimentary rocks of the previous researcher's Khangai-Khentii orogenic belt. This study curried out funding of “Higher Engineering Education Development (M-JEED ) Project” and Nagoya University of Japan.
Төв Монгол, Туулын их тохойрол орчмын дунд-дээд палеозойн тунамал, хувирмал чулуулгийн петрохими
Хураангуй: Туулын их тохойрол нь Төв Монголын Хангай-Хэнтийн ороген тогтолцооны Хэнтийн хэсэгт байрлана. Судалгааны талбайд Асралт хайрханы террейний венлок-доод девоны Сөгнөгөр ба Улаанбаатар террейний пенсилванийн Алтан-Овоо формацын тунамал, хувирмал чулуулгууд зонхилон тархдаг. Тунамал хурдсын эх үүсвэр, тектоник орчны судалгаа нь уг бүс нутгийн геологи, тектоникийн хөгжлийн түүхийг ойлгоход чухал ач холбогдолтой. Судалгаанд Сөгнөгөр формацын 9 ш, Алтан-Овоо формацын 6 ш алевролит, элсэн, чулуу, занар хамрагдав. Гол элементийн геохимийн шинжилгээг Японы Нагоягийн Их сургуулийн Геохимийн лабораторид рентген флюоресценцийн (XRF) аргаар хийлээ. Сөгнөгөр ба Алтан-Овоо формацын занарын протолит нь терриген тунамал чулуулаг байна. Сөгнөгөр ба Алтан-Овоо формацын алевролит, элсэн чулуу петрохимийн шинжээрээ ойролцоо, голдуу грауваккын найрлагатай байна. Алтан-Овоо формацын аргиллит, элсэн чулууны эх үүсвэр дан ганц хүчиллэг магмын чулуулаг, харин Сөгнөгөр формацынх хүчиллэг магмын чулуулгаас гадна багаар кварцын тунамал чулуулаг, дундлаг ба суурилаг магмын чулуулаг бүхий холимог найрлагатай байна. Сөгнөгөр ба Алтан-Овоо формацын чулуулгууд петрохимийн шинжээрээ эх газрын идэвхтэй захад хуримтлагдсан байна. Эдгээр үр дүн нь өмнөх судлаачдын Хангай-Хэнтийн ороген тогтолцооны дунд-дээд палеозойн тунамал чулуулагт хийсэн судалгааны үр дүнг дэмжиж байна. Судалгааны ажил нь Япон-Монголын хамтарсан M-JEED “1000 инженер” инженер технологийн дээд боловсрол төслийн санхүүжилтээр хийгдэв.
Түлхүүр үг: Төв Азийн ороген бүс, элсэн чулуу, Улаанбаатар террейн, Асралт хайрхан террейн
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Petersen, Nathan T., Paul L. Smith, James K. Mortensen, Robert A. Creaser e Howard W. Tipper. "Provenance of Jurassic sedimentary rocks of south-central Quesnellia, British Columbia: implications for paleogeography". Canadian Journal of Earth Sciences 41, n. 1 (1 gennaio 2004): 103–25. http://dx.doi.org/10.1139/e03-073.
Testo completoAbstract (sommario):
Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, SmNd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and SmNd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.
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Irwan, Andesta Granitio. "Effect of Porosity on Uniaxial Compressive Strength in Sedimentary Rocks". PROMINE 8, n. 2 (4 marzo 2021): 61–64. http://dx.doi.org/10.33019/promine.v8i2.2057.
Testo completoAbstract (sommario):
The rock strength parameter is an important factor used in determining the geotechnical design in determining the stability of the underground slope or mine. One of the rock strength tests in the laboratory (intact rock) is the uniaxial compressive strength test. One of the factors that influence rock strength is the porosity of the rock itself, especially in sedimentary rocks. The rock porosity test is carried out by testing the physical properties of the rock, then a regression analysis is carried out to obtain the correlation of the effect of porosity on rock strength and the correlation between porosity and absorption considered in the analysis. The linear regression results obtained between porosity and saturated water content of rocks showed a positive correlation where the increase in porosity, the saturated water content also increased. The correlation between porosity and uniaxial compressive strength obtained a strong correlation with the power regression model as the best model compared to other regression models because it has the lowest error based on the Root Mean Square Error (RMSE). The final result is obtained by comparing the effect of porosity on rock strength, that is the higher the porosity value have the smaller porosity, so that an increase in rock porosity will reduce the strength of the rock.
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Setiadi, I., Marjiyono e T. B. Nainggolan. "Gravity Data Analysis Based on Optimum Upward Continuation Filter and 3D Inverse Modelling (Case Study at Sedimentary Basin in Volcanic Region Malang and Its Surrounding Area, East Java)". IOP Conference Series: Earth and Environmental Science 873, n. 1 (1 ottobre 2021): 012008. http://dx.doi.org/10.1088/1755-1315/873/1/012008.
Testo completoAbstract (sommario):
Abstract The study on the fore-arc sedimentary basin for hydrocarbon exploration is rare because of the more complicated geological structures, and conventional seismic methods cannot optimally penetrate the rock layers as there are many volcanic and limestone rocks. One of the natural resources potential in the Southern part of the East Java region, especially in Malang and its surrounding areas is the possibility of hydrocarbons in the fore-arc basin, so research is needed to know the existence of these sedimentary basins. The gravity method is one of the geophysical methods used to assess sedimentary basins based on physical parameters of mass density. The aims of this research are to delineate the sedimentary sub-basin, to find out its structure pattern, interpret subsurface geological and basement configuration. The data analysis approach used in this study involves spectral analysis, upward continuation filter, and 3D inverse modeling. The maximum height for the optimum upward continuation filter is 3000 m, which results in regional and residual anomalies. There were five sedimentary sub-basins identified based on residual gravity anomaly, and the gravity anomalies can also detect structure patterns such as basement high, lineament, and fault pattern. The bedrock is supposed as an intermediate igneous rock with a mass density of around 2.7 gr/cc according to the results of 3D inverse modeling. Deposition from bottom to upward is Mandalika, Nampol, and Wonosari Formations and completed by the uppermost are quaternary volcanic rocks. The inversion modeling results show that the Malang and surrounding areas have thick sedimentary rocks covered by volcanic deposits, which is impressive for further investigation to explore the possibility of the hydrocarbon existence in these areas.
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Li, Xiaoshuang, Yingchun Li e Saisai Wu. "Experimental Investigation into the Influences of Weathering on the Mechanical Properties of Sedimentary Rocks". Geofluids 2020 (8 dicembre 2020): 1–12. http://dx.doi.org/10.1155/2020/8893299.
Testo completoAbstract (sommario):
The time-dependent behaviors of the sedimentary rocks which refer to the altering of the mechanical and deformable properties of rock elements in the long-term period are of increasing importance in the investigation of the failure mechanism of the rock strata in underground coal mines. In order to obtain the accurate and reliable mechanical parameters of the sedimentary rocks at different weathering grades, the extensive experimental programs including the Brazilian splitting test, uniaxial compression tests, and direct shear tests have been carried out on the specimens that exposed to the nature environments at different durations. The correlation between the weathering grades and mechanical parameters including uniaxial tensile strength, uniaxial compression strength, elastic modulus, Poisson’s ratio, cohesion, and friction coefficient was proposed. The obtained results suggested that uniaxial tensile strength, uniaxial compressive strength, elastic modulus, and cohesion dramatically decreased with increasing weathering time, characterized as the negative exponential relationship in general. The influences of various weathering grades on fracture behavior of the rock specimens were discussed. The cumulative damage of the rock by the weathering time decreased the friction coefficient of the specimens which led to the initiation and propagation of microcrack within the rock at lower stress conditions. The obtained results improved the understanding of the roles of weathering on the mechanical properties of sedimentary rocks, which is helpful in the design of the underground geotechnical structures.
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Ma, Ke, Anzhou Ma, Guodong Zheng, Ge Ren, Fei Xie, Hanchang Zhou, Jun Yin, Yu Liang, Xuliang Zhuang e Guoqiang Zhuang. "Mineralosphere Microbiome Leading to Changed Geochemical Properties of Sedimentary Rocks from Aiqigou Mud Volcano, Northwest China". Microorganisms 9, n. 3 (9 marzo 2021): 560. http://dx.doi.org/10.3390/microorganisms9030560.
Testo completoAbstract (sommario):
The properties of rocks can be greatly affected by seepage hydrocarbons in petroleum-related mud volcanoes. Among them, the color of sedimentary rocks can reflect the changes of sedimentary environment and weathering history. However, little is known about the microbial communities and their biogeochemical significance in these environments. In this study, contrasting rock samples were collected from the Aiqigou mud volcano on the southern margin of the Junggar Basin in Northwest China as guided by rock colors indicative of redox conditions. The physicochemical properties and mineral composition are similar under the same redox conditions. For example, the content of chlorite, muscovite, quartz, and total carbon were higher, and the total iron was lower under reduced conditions compared with oxidized environments. High-throughput sequencing of 16S rRNA gene amplicons revealed that different functional microorganisms may exist under different redox conditions; microbes in oxidized conditions have higher diversity. Statistical analysis and incubation experiments indicated that the microbial community structure is closely related to the content of iron which may be an important factor for color stratification of continental sedimentary rocks in the Aiqigou mud volcano. The interactions between organics and iron-bearing minerals mediated by microorganisms have also been hypothesized.