DOI: 10.1016/j.quascirev.2014.03.016
Scopus记录号: 2-s2.0-84909585607
论文题名: Facies characterization based on physical properties from downhole logging for the sediment record of Lake Van, Turkey
作者: Baumgarten H. ; Wonik T. ; Kwiecien O.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2014
卷: 104 起始页码: 85
结束页码: 96
语种: 英语
英文关键词: Cluster analysis
; Downhole logging
; ICDP
; Lake sediments
; Paleoclimate
; PALEOVAN
; Physical properties
; Quaternary
; Tephra
Scopus关键词: Physical properties
; Downholes
; ICDP
; Lake sediments
; Paleoclimates
; PALEOVAN
; Quaternary
; Tephra
; Cluster analysis
; basalt
; chemical composition
; clay
; cluster analysis
; depositional environment
; facies
; lacustrine deposit
; paleoclimate
; paleolimnology
; physical property
; Pleistocene
; sediment core
; sedimentation
; silt
; tephra
; volcanic eruption
; volcanogenic deposit
; well logging
; Lake Van
; Turkey
; Turkey
英文摘要: Lake Van (Turkey) is the 4th largest terminal lake in the world and is located at a key position for climatic reconstruction. The ICDP project 'PALEOVAN' is a deep-drilling campaign initiated in the summer of 2010 to enhance the understanding of paleoclimatic and paleoenvironmental conditions in the Middle East for a period of 550,000 years. Multiple coring of two sites (Northern Basin and Ahlat Ridge) at a water depth of up to 360m has been performed. The sedimentary record is mainly composed of clayey silts and tephra deposits that were supplied by four volcanic sources: 1) the Süphan volcano, located on the northern shore, 2) the Nemrut volcano, 15km west of the westernshore, 3) the Incekaya volcano, on the southwestern shore and 4) intralake eruptive centers. The dominant chemical composition of the volcanic sources is known from studies of land deposits.High-quality downhole logs have been acquired from both sites. To construct a continuous lithological profile, 180m of downhole logging data from the Ahlat Ridge have been analyzed by cluster analysis. To improve the differentiation of the sediments, two elemental intensity profiles from x-ray fluorescence core-scanning (calcium and zirconium) performed on the composite profile core material were added to the cluster analysis. Five cluster units were derived and transformed into three tephra and two clayey silt units. To compare the two clayey silt units with the composite profile from the visual core description (VCD) that showed 15 lithological units, the composite profile was classified into two major groups of lacustrine sediments: banded clayey silts (interpreted as glacial deposits) and laminated clayey silts (interpreted as interglacial deposits). Despite this simplification, no correlation between the two clayey silt units derived from cluster analysis and the banded and laminated clayey silts could be found. The following reasons are proposed: (a) the comparability of the datasets was limited by significant depth shifts of up to 2.5m between the composite profile based on the VCD and the downhole measurements in hole 2D of the Ahlat Ridge, (b) a correlation was difficult to ascertain from the vertical resolution of the downhole logging data and the extremely detailed core description in mm-scale, (c) mixed signals were obtained because of prevailing thin layers and intercalations of different lithotypes and (d) cluster analysis was difficult to perform because the contrast within the input data is too low (possibly background sedimentation) to distinguish between glacial and interglacial deposits. Tephra units are characterized by contrasting properties and differ mainly in their magnetic susceptibility, spectral gamma ray components (uranium, thorium and potassium) and XRF-intensities of calcium and zirconium. Tephra units have been linked to the dominant volcanic composition of the deposited tephra layers and partly to the volcanic sources. Depth trends are derived with prevailing basaltic deposits in the bottom part (128m-210m below lake floor) and are gradually outweighed by the highly differentiated (dacitic and rhyolitic/trachytic) products towards the top of the record. © 2014 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/60129
Appears in Collections: 过去全球变化的重建
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作者单位: Leibniz Institute for Applied Geophysics (LIAG), Rock Physics and Borehole Geophysics, Stilleweg 2, Hannover, Germany
Recommended Citation:
Baumgarten H.,Wonik T.,Kwiecien O.. Facies characterization based on physical properties from downhole logging for the sediment record of Lake Van, Turkey[J]. Quaternary Science Reviews,2014-01-01,104