scholarly journals Holocene Key-Marker Tephra Layers in Kamchatka, Russia

1997 ◽  
Vol 47 (2) ◽  
pp. 125-139 ◽  
Author(s):  
Olga A. Braitseva ◽  
Vera V. Ponomareva ◽  
Leopold D. Sulerzhitsky ◽  
Ivan V. Melekestsev ◽  
John Bailey
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Mineral Composition ◽  
Kamchatka Peninsula ◽  
Explosive Eruptions ◽  
Shiveluch Volcano ◽  
Stratigraphic Position ◽  
Tephra Layers ◽  
Characteristic Features ◽  
Important Marker

Detailed tephrochronological studies in Kamchatka Peninsula, Russia, permitted documentation of 24 Holocene key-marker tephra layers related to the largest explosive eruptions from 11 volcanic centers. Each layer was traced for tens to hundreds of kilometers away from the source volcano; its stratigraphic position, area of dispersal, age, characteristic features of grain-size distribution, and chemical and mineral composition confirmed its identification. The most important marker tephra horizons covering a large part of the peninsula are (from north to south; ages given in14C yr B.P.) SH2(≈1000 yr B.P.) and SH3(≈1400 yr B.P.) from Shiveluch volcano; KZ (≈7500 yr B.P.) from Kizimen volcano; KRM (≈7900 yr B.P.) from Karymsky caldera; KHG (≈7000 yr B.P.) from Khangar volcano; AV1(≈3500 yr B.P.), AV2(≈4000 yr B.P.), AV4(≈5500 yr B.P.), and AV5(≈5600 yr B.P.) from Avachinsky volcano; OP (≈1500 yr B.P.) from the Baraniy Amfiteatr crater at Opala volcano; KHD (≈2800 yr B.P.) from the “maar” at Khodutka volcano; KS1(≈1800 yr B.P.) and KS2(≈6000 yr B.P.) from the Ksudach calderas; KSht3(A.D. 1907) from Shtyubel cone in Ksudach volcanic massif; and KO (≈7700 yr B.P.) from the Kuril Lake-Iliinsky caldera. Tephra layers SH5(≈2600 yr B.P.) from Shiveluch volcano, AV3(≈4500 yr B.P.) from Avachinsky volcano, OPtr(≈4600 yr B.P.) from Opala volcano, KS3(≈6100 yr B.P.) and KS4(≈8800 yr B.P.) from Ksudach calderas, KSht1(≈1100 yr B.P.) from Shtyubel cone, and ZLT (≈4600 yr B.P.) from Iliinsky volcano cover smaller areas and have local stratigraphic value, as do the ash layers from the historically recorded eruptions of Shiveluch (SH1964) and Bezymianny (B1956) volcanoes. The dated tephra layers provide a record of the most voluminous explosive events in Kamchatka during the Holocene and form a tephrochronological timescale for dating and correlating various deposits.

scholarly journals MINERAL COMPOSITION OF SOME LATGALE LAKE SEDIMENTS

2019 ◽  
Vol 1 ◽  
pp. 304
Author(s):  
Rasma Tretjakova ◽  
Andris Karpovičs
Keyword(s):  
Grain Size ◽  
Lake Sediments ◽  
Size Distribution ◽  
Clay Minerals ◽  
Mineral Composition ◽  
Grain Size Distribution ◽  
Sandy Loam ◽  
Clay Fraction ◽  
Fine Grained ◽  
Two Samples

Our research is focused on sedimentological conditions and postdepositional changes of recent fine grained lake sediments. We used bulk sediment mineralogical composition and grain size distribution as indicators to identify sediment source areas and possible changes during Holocene. We analysed fine grained (clayey) sediments from three Latgale lakes - Zeili, Pauguļi and Plusons, situated in Latgale upland. Lake sediments cover Late Pleistocene glacial deposits – loam and sandy loam. Bulk mineral composition of 6 sediment samples was determined by X-ray diffraction (XRD). Sediments contained typical minerals found in surrounding glacial sediments: rock-forming minerals as quartz, plagioclase, albite, enstatite, dolomite, calcite, and clay minerals - illite, kaolinite. To identify postdepositional changes in lake sediments of Holocene age clay minerals in clay fraction (<2 mkm) should be analysed. Particularly illite, smectite mixed layered minerals - illite/smectite (I/Sm) and chlorite. Additionally, grain size distribution of studied lake sediments was analysed. Accordingly, our studied sediments are clays, silty clays and clayey silts with bimodal particle distribution, except two samples from Zeiļi and Plusons with unimodal distribution.

Etude granulometrique et mineralogique de douze echantillons de boue du fond du lac Majeur (Haute Italie)

1961 ◽  
Vol S7-III (4) ◽  
pp. 379-382
Author(s):  
Gian Clemente Parea ◽  
F. C. Wezel
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Mineral Composition ◽  
Grain Size Distribution ◽  
Northern Italy ◽  
Mineral Matter ◽  
Lake Waters

Abstract Twelve samples of muds were collected from the bottom of Maggiore lake (northern Italy), at approximately equal intervals throughout the length of the lake in order to index the grain-size distribution and mineral composition of the muds. Most of the samples are typically lacustrine; some are typically fluviatile. The data indicate the presence of a significant amount of mineral matter in suspension throughout the lake as a result of strong currents generated by winds and by thermal variations in the lake waters.

Mineral Composition and Grain Size Distribution of Fault Rock from Yangbuk-myeon, Gyeongju City, Korea

2012 ◽  
Vol 45 (5) ◽  
pp. 487-502 ◽  
Author(s):  
Su Jeong Song ◽  
Chang Oh Choo ◽  
Chun-Joong Chang ◽  
Tae Woo Chang ◽  
Yun Deuk Jang
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Mineral Composition ◽  
Grain Size Distribution ◽  
Fault Rock

scholarly journals Reconstructing Permafrost Sedimentological Characteristics and Post-depositional Processes of the Yedoma Stratotype Duvanny Yar, Siberia

2021 ◽  
Vol 9 ◽  
Author(s):  
Denis Shmelev ◽  
Maria Cherbunina ◽  
Victor Rogov ◽  
Sophie Opfergelt ◽  
Arthur Monhonval ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Mineral Composition ◽  
Grain Size Distribution ◽  
Late Pleistocene ◽  
Environmental Changes ◽  
Grain Morphology ◽  
Freeze Thaw ◽  
Promising Tool ◽  
Depositional Processes

Cryogenic weathering is a key driver of periglacial sediment composition and properties. Selective mineral-grain weathering caused by freeze-thaw cycles in permafrost environments has the ability to dominate this process, leading to silt-rich grain-size distributions. The cryogenic weathering index (CWI) is a promising tool to quantify cryogenic weathering and freezing conditions. It considers the low resistance of quartz to freeze-thaw cycles compared to feldspars. Using this approach, this study aims to decipher post-depositional weathering by reconstructing cryogenic late Pleistocene Yedoma origins of the Yedoma stratotype exposure Duvanny Yar. To estimate the recent environmental endmember and to determine the initial mineral composition of sediment until freezing, the distribution of CWI in the active layer was studied. In addition to CWI, we studied mineral composition, heavy mineral distribution, grain size distribution and grain morphology. We suggest that cryogenic weathering likely altered polygenetic deposits (fluvial, nival, colluvial, lacustrine, alluvial, and aeolian processes) during sediment and ground ice accumulation. Moreover, we found two CWI distribution peaks in the late Pleistocene - Holocene sediments at the boundaries between glacial and interglacial ages. In conclusion, we see that the Duvanny Yar sediment facies varied by CWI, but also with grain-size distribution, suggesting environmental changes during formation. Nevertheless, post-depositional processes like cryogenic weathering have influenced sediment characteristics and should be considered in paleoenvironmental reconstructions.

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