Isotopic signals from late Jurassic–early Cretaceous (Volgian–Valanginian) sub-Arctic belemnites, Yatria River, Western Siberia
Isotopic signals from late Jurassic–early Cretaceous (Volgian–Valanginian) sub-Arctic belemnites, Yatria River, Western Siberia
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来自西西伯利亚亚特里亚河晚侏罗世 - 早白垩世（伏尔加期 - 瓦兰吉期）亚北极箭石的同位素信号
DOI：
10.1144/0016-764903-169
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发表时间：
2004
影响因子：
2.7
通讯作者：
Jörg Mutterlose
中科院分区：
文献类型：
--
作者：
G. Price;Jörg Mutterlose
本文首次详细记录了西伯利亚乌拉尔亚极地亚特里亚河晚侏罗世-早白垩世的氧碳同位素。同位素组成已被确定保存完好的箭石样品从属Lagonibelus，Acroteuthis和Acroteuthis。这些新的数据表明，从晚期Volgian到晚期Valanginian的温度较低，在梁赞和最早的Valanginian中发现了一些温暖的阶段。最低温度的晚Valanginian，与冰点以下的极地温度一致，是一致的推断海平面下降。瓦兰吉尼晚期碳同位素正移与特提斯层序记录的碳同位素偏移相关。最正的碳同位素值对应于最正的氧同位素值（因此是最低的古温度）。在没有广泛的Valanginian有机丰富的黑色页岩沉积，碳同位素漂移可能指向增加存储的有机碳在沿海地区和/或加强保护分层沃茨在高纬度盆地。在这些高纬度地区，由于普遍的寒冷气候，风化率可能要低得多，同位素数据可能指向生产力的脉冲，这是由于河流营养物质转移的增加以及冰融化释放的营养物质。正碳同位素和凉爽气候之间的相关性可能表明这些高纬度碳汇的有效性及其减少大气中二氧化碳的能力，从而导致“逆温室效应”。
This contribution presents the first detailed oxygen and carbon isotope record from the latest Jurassic–early Cretaceous interval of the Yatria River, subpolar Urals, Siberia. Isotopic compositions have been determined on well-preserved belemnite samples from the genera Lagonibelus, Cylindroteuthis and Acroteuthis. These new data indicate a shift to lower temperatures from the late Volgian into the late Valanginian, with some warmer phases recognized within the Ryazanian and earliest Valanginian. The lowest temperatures of the late Valanginian, consistent with subfreezing polar temperatures, are coincident with an inferred eustatic sea-level fall. A late Valanginian positive shift in carbon isotopes correlates with the carbon isotope excursion recorded from Tethyan successions. The most positive carbon isotope values correspond to the most positive oxygen isotope values (and hence lowest palaeotemperatures). In the absence of widespread Valanginian organic-rich black shale deposition, the carbon isotope excursion may point to increased storage of organic carbon in coastal areas and/or enhanced preservation within stratified waters in high-latitude basins. At these higher latitudes, where rates of weathering were presumably much lower because of the prevalent cold climate, the isotopic data may point to pulses of productivity being brought about by increased riverine nutrient transfer and also by nutrients being released by the melting of ice. The correlation between positive carbon isotopes and cool climates may indicate the effectiveness of these high-latitude carbon sinks and their ability to draw down atmospheric CO2, resulting in an ‘inverse greenhouse’ effect.