Age–depth model of the past 630 kyr for Lake Ohrid (FYROM/Albania) based on cyclostratigraphic analysis of downhole gamma ray data
Age–depth model of the past 630 kyr for Lake Ohrid (FYROM/Albania) based on cyclostratigraphic analysis of downhole gamma ray data
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DOI：
10.5194/bg-12-7453-2015
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发表时间：
2015-12
期刊：
影响因子：
4.9
通讯作者：
H. Baumgarten;T. Wonik;D. Tanner;A. Francke;B. Wagner;G. Zanchetta;R. Sulpizio;B. Giaccio;S. Nomade
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文献类型：
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作者：
H. Baumgarten;T. Wonik;D. Tanner;A. Francke;B. Wagner;G. Zanchetta;R. Sulpizio;B. Giaccio;S. Nomade
抽象的。从奥赫里德湖湖底（b.l.f）以下0至240 m的沉积物中获得的井下测井数据的伽马射线（GR）波动和钾（K）值。与全球海底同位素堆LR 04中δ 18 O值的波动相关（Lisiecki和Raymo，2005年）。GR和K值被认为是一个可靠的代理描绘冰川间冰期循环，高碎屑输入在寒冷和/或干燥的时期和高碳酸盐沉淀在温暖和/或潮湿的时期在奥赫里德湖。频谱分析被用来调查气候信号和演变的长度钻孔。将井下测井数据与轨道周期联系起来，用于估算沉积速率，并补偿压实的影响。沉积层解压缩后，沉积速率平均增加14%，平均沉积速率从0 - 110 m之间的45 cm kyr−1变为110 - 240 m b.l.f.之间的30 cm kyr−1。调整的最小值和最大值的伽马射线和钾值与LR 04极值，结合8个独立的灰岩地层的连接点，允许建立一个强大的年龄模型的井下测井数据在过去的630 kyr。
Abstract. Gamma ray (GR) fluctuations and potassium (K) values from downhole logging data obtained in the sediments of Lake Ohrid from 0 to 240 m below lake floor (b.l.f). correlate with fluctuations in δ18O values from the global benthic isotope stack LR04 (Lisiecki and Raymo, 2005). GR and K values are considered a reliable proxy to depict glacial–interglacial cycles, with high clastic input during cold and/or drier periods and high carbonate precipitation during warm and/or humid periods at Lake Ohrid. Spectral analysis was applied to investigate the climate signal and evolution over the length of the borehole. Linking downhole logging data with orbital cycles was used to estimate sedimentation rates and the effect of compaction was compensated for. Sedimentation rates increase on average by 14 % after decompaction of the sediment layers and the mean sedimentation rates shift from 45 cm kyr−1 between 0 and 110 m to 30 cm kyr−1 from 110 to 240 m b.l.f. Tuning of minima and maxima of gamma ray and potassium values versus LR04 extrema, in combination with eight independent tephrostratigraphical tie points, allows establishing of a robust age model for the downhole logging data over the past 630 kyr.