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首页> 外文期刊>Marine Geology >Magnetostratigraphy and tephrochronology of the Upper Quaternary sediments in the Okhotsk Sea: implication of terrigenous, volcanogenic and biogenic matter supply
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Magnetostratigraphy and tephrochronology of the Upper Quaternary sediments in the Okhotsk Sea: implication of terrigenous, volcanogenic and biogenic matter supply

机译：鄂霍次克海上第四纪沉积物的磁地层学和年代学：陆源，火山成因和生物成因供应的含义

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Seven lithological units, alternating between horizons enriched in biogenic opal (diatoms) and carbonate (foraminifera) and units composed largely of terrigenous sediment with very low biogenic admixture, were distinguished in a series of Late Quaternary sediment cores from the Sea of Okhotsk. Sediments were characterised using on-board visual description, smear-slides analyses, grain-size composition and magnetic susceptibility (MS) records. Five tephra marker layers, identified as Ko, TR, K2, K3 and K4, were distinguished using petrological, mineralogical and geochemical analyses. Age models were developed by comparing lithological units, tephra stratigraphy and MS records with oxygen isotope curves and with records of biogenic CaCO_3, opal content, and sediment grain-size composition in three AMS radiocarbon dated Okhotsk cores. This chronological framework allowed us to investigate climate control over the sedimentation regime and productivity, and to clarify the formation times of the lithological and tephra units.The data show that sediment MS variations in the south-eastern area of the glacial Okhotsk Sea arose primarily from volcanic material input. The sedimentation in all other parts of the sea was mainly controlled by the supply of terrigenous material. The cores show a tight correlation between MS, sediment grain size and climate change in the Okhotsk Sea: coarse sediments with a high MS were accumulated during the cold period-oxygen isotope stages (MIS) 2, 4, 6; fine sediments with a low ice-rafted debris (IRD) content and MS were formed in the warm isotope stages.According to the oxygen isotope stratigraphy and radiocarbon data, the Ko, TR, K2, K3 and K4 tephra were deposited at 7.7, 8.0, 26.0 kyr BP, in MIS 4 about 60-70 kyr ago, and near MIS 5.4, respectively. Comparison of tephra mineralogy, petrology, spatial distributions and ages with the history of Kurile-Kamchatka volcanism allows us to identify likely candidates for the tephra source eruptions. The combined use of MS records, tephrochronology and lithological unit sequences provides a detailed basis for Okhotsk Sea sediment stratigraphy.
机译：在鄂霍次克海的一系列晚第四纪沉积岩心中，区分了七个岩性单元，它们在富含生物蛋白石（硅藻）和碳酸盐（有孔虫）的地层之间交替，并且主要由陆源沉积物组成，具有很低的生物成因混合物。使用机载视觉描述，涂片滑动分析，粒度组成和磁化率（MS）记录对沉积物进行表征。通过岩石学，矿物学和地球化学分析，将特菲拉的五个标记层识别为Ko，TR，K2，K3和K4。年龄模型是通过比较三个AMS放射性碳年代为鄂霍次克岩芯的岩性单位，特菲拉地层学和MS记录与氧同位素曲线以及生物成因CaCO_3，蛋白石含量和沉积物粒度组成的记录而建立的。这个年代学框架使我们能够研究气候对沉积机制和生产力的控制，并弄清岩性和特非拉单元的形成时间。数据表明，鄂霍次克海东南部地区的沉积物MS变化主要来自于火山物质输入。海洋其他所有部分的沉积主要受陆源物质的供应控制。核心显示鄂霍次克海的MS，沉积物粒径与气候变化之间密切相关：在寒冷时期-氧同位素阶段（MIS）2、4、6积累了具有高MS的粗沉积物。在暖同位素阶段形成了低浮冰碎片（IRD）和MS的细小沉积物，根据氧同位素地层和放射性碳数据，分别在7.7、8.0和7.7 8.0沉积了特弗拉的Ko，TR，K2，K3和K4等，大约在60-70年前的MIS 4中达到了26.0 yr BP，并且接近5.4。将特非拉的矿物学，岩石学，空间分布和年龄与千岛-堪察加火山的历史进行比较，使我们能够确定特非拉火山喷发的可能候选者。 MS记录，年代学和岩性单元序列的结合使用为鄂霍次克海沉积物地层学提供了详细的基础。

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