Mechanisms of granite alteration into grus, Karkonosze granite, SW Poland

Kajdas, Bartłomiej; Michalík, Marek; Migoń, Piotr

doi:10.1016/j.catena.2016.11.026

Cited by 29 publications

(7 citation statements)

References 46 publications

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“…Rock art of most probably Bronze Age on the walls demonstrates human presence and use of space in the feature. However, in comparison with the sandstone example above (Qyzyljartas), Black cave and other granite rockshelters that we recorded are less likely to disintegrate that easily into loose sediment, such as grus (Kajdas et al, 2017), and as a result less probable to accumulate thick autochthonous deposits. Since the rate of surface erosion cannot be surpassed by the rate of geogenic deposition, any artifacts or features deposited in the grotto are less likely to be captured and preserved.…”

Section: Pseudokarst and Non-karstic Processescontrasting

confidence: 53%

In search of a Paleolithic Silk Road in Kazakhstan

Ioviţă

Varis

Namen

et al. 2020

Quaternary International

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Paleoanthropological data suggest that the Late Pleistocene was a time of population contact and possibly dispersal in Central Asia. Geographic and paleoclimatic data suggest that a natural corridor through Kazakhstan linked areas to the north and east (Siberia, China) to those further to the west and south (Uzbekistan), much akin to a Paleolithic Silk Road. We review the known Pleistocene archaeology and paleoclimatic setting of this region and provide a geoarchaeological framework for contextualizing preliminary survey results of the PALAEOSILKROAD project's first three seasons of fieldwork. We discuss some systematic biases in three geomorphic and sedimentary archives: karst, loess, and spring deposits, specifying ways in which these biases might determine the kinds of data that are extractable by systematic survey. In particular, we caution about the possibility of future systematic biases in chronology that could come about as a result of the type of geomorphic context in which the sites are recovered. We conclude with recommendations for future work in the area.

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Section: Pseudokarst and Non-karstic Processescontrasting

confidence: 53%

In search of a Paleolithic Silk Road in Kazakhstan

Ioviţă

Varis

Namen

et al. 2020

Quaternary International

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“…These two samples present higher KI values, meaning lower temperatures. It can be explained by the presence of I/S and vermiculite, forming at lower temperature than illite and kaolinite [91,92,95]. The samples NH_26, NH_33, and NH_36 present only kaolinite.…”

Section: Thermal Evolution Toward Fracture Zonesmentioning

confidence: 98%

“…The samples NH_24, NH_26, and NH_33 contain a small amount of vermiculite, which can be associated to hydrothermal alteration at low temperature or to weathering. It is commonly thought that most of the vermiculite is formed under supergene conditions [91,92]. In these samples, the amount of vermiculite is low and the weathering contribution already discarded by [19].…”

mentioning

confidence: 99%

Fluid-Rock Interactions in a Paleo-Geothermal Reservoir (Noble Hills Granite, California, USA). Part 2: The Influence of Fracturing on Granite Alteration Processes and Fluid Circulation at Low to Moderate Regional Strain

et al. 2021

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Fracture connectivity within fractured granitic basement geothermal reservoirs is an important factor controlling their permeability. This study aims to improve the understanding of fluid–rock interaction processes at low to moderate regional strain. The Noble Hills range (Death Valley, CA, USA) was chosen as a naturally exhumed paleo geothermal reservoir. A series of petrographic, petrophysical, and geochemical investigations, combined with a fracture distribution analysis, were carried out on samples collected across fracture zones. Our results indicate that several generations of fluids have percolated through the reservoir. An increase of (1) the alteration degree; (2) the porosity values; and (3) the calcite content was observed when approaching fracture zones. No correlation was identified among the alteration degree, the porosity, or the calcite content. At a local scale, samples showed that the degree of alteration does not necessarily depend on the fracture density or on the amount of the strain. It is concluded that the combined influence of strain and coeval fluid–rock interaction processes drastically influence the petrophysical properties of fracture zones, which in turn impact geothermal production potential.

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“…In the Sudetes, deep weathering is particularly evident within granite landscapes, where both very thick clay-rich saprolites and thinner, but still >10-m-thick, mantles of grus have been documented (Franz 1969;Migoń 1996Kajdas et al 2017). In numerous localities, there is a clear separation of the weathered rock mass into almost fresh boulders, known as "corestones", and thoroughly disintegrated granite.…”

Section: Harzmentioning

confidence: 99%

Tors in Central European Mountains – are they indicators of past environments?

Michniewicz

2019

Bulletin of Geography. Physical Geography Series

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Tors represent one of the most characteristic landforms in the uplands and mountains of Central Europe, including the Sudetes, Czech-Moravian Highlands, Šumava/Bayerischer Wald, Fichtelgebirge or Harz. These features occur in a range of lithologies, although granites and gneisses are particularly prone to tor formation. Various models of tor formation and development have been presented, and for each model the tors were thought to have evolved under specific environmental conditions. The two most common theories emphasised their progressive emergence from pre-Quaternary weathering mantles in a two-stage scenario, and their development across slopes under periglacial conditions in a one-stage scenario. More recently, tors have been analysed in relation to ice sheet extent, the selectivity of glacial erosion, and the preservation of landforms under ice. In this paper we describe tor distribution across Central Europe along with hypotheses relating to their formation and development, arguing that specific evolutionary histories are not supported by unequivocal evidence and that the scenarios presented were invariably model-driven. Several examples from the Sudetes are presented to demonstrate that tor morphology is strongly controlled by lithology and structure. The juxtaposition of tors of different types is not necessarily evidence that they differ in their mode of origin or age. Pathways of tor remodelling and degradation under subaerial conditions are identified and it is argued that processes of tor formation and development are ongoing. Thus, tors are not reliable indicators of past environments, because they are considerably influenced by both geological factors, such as lithology and structure, and geomorphological factors such as hillslope setting..

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Mechanisms of granite alteration into grus, Karkonosze granite, SW Poland

Cited by 29 publications

References 46 publications

In search of a Paleolithic Silk Road in Kazakhstan

In search of a Paleolithic Silk Road in Kazakhstan

Fluid-Rock Interactions in a Paleo-Geothermal Reservoir (Noble Hills Granite, California, USA). Part 2: The Influence of Fracturing on Granite Alteration Processes and Fluid Circulation at Low to Moderate Regional Strain

Tors in Central European Mountains – are they indicators of past environments?

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