Chronology of the Early Toarcian environmental crisis in the Lorraine Sub-Basin (NE Paris Basin)
Chronology of the Early Toarcian environmental crisis in the Lorraine Sub-Basin (NE Paris Basin)
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DOI：
10.1016/j.epsl.2014.08.005
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发表时间：
2014-10
影响因子：
5.3
通讯作者：
W. Ruebsam;Petra Münzberger;L. Schwark
中科院分区：
文献类型：
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作者：
W. Ruebsam;Petra Münzberger;L. Schwark
早Toarcian（侏罗纪; 183 Ma）沉积记录了西特提斯陆棚生物大灭绝、全球变暖、海侵以及广泛的底层水缺氧和有机质积累等深刻的环境变化。有机质积累的增强伴随着远洋碳酸盐的正碳同位素漂移（CIE），这标志着Toarcian海洋缺氧事件。这些环境变化伴随着全球碳循环的重大扰动，表现为负CIE，中断了积极的趋势。碳循环扰动的持续时间仍有争议，负CIE的估计范围从200到600 kyr。在这里，我们提出了超高分辨率（<1千年）的磁化率和沉积物颜色的测量，从位于洛林子盆地（NE巴黎盆地）的海洋部分记录米兰科维奇控制的沉积条件的波动，发生叠加到整体海平面的演变。沉积周期波长的差异表明沉积物积累速率的变化，主要是由于海平面的快速波动。最明显的海平面上升，发生在uppermosttenuicostatum带导致在一个强大的凝结的基础上的Atriotes纸箱形成。强凝聚可以解释之前计算的CIE放置在这个地层间隔的持续时间之间的差异。我们的数据分别支持正负CIE的持续时间为900 kyr和600 kyr。基于旋回地层学的时间尺度进一步提出了薄甲带的持续时间>555 kyr和蛇纹带的持续时间为1310 kyr。elegantulum亚带和falciferum亚带的持续时间估计分别为1790 kyr和1520 kyr。在轨道响应的变化，从偏心率，以清晰度强迫，从其他位置明显，是很好地表达在洛林子盆地和CIE间隔内发生。事后沉积物中倾角分量的强烈影响暗示了在高纬度地区最有效的过程，例如极地冰的消长。西特提斯陆棚的古地理特征支持通过维京海盗走廊的水交换将高纬度过程与低纬度过程远程连接。
Early Toarcian (Jurassic; ∼183 Ma) sediments recorded profound environmental changes, including mass extinction, global warming, marine transgression as well as widespread bottom water anoxia and organic matter accumulation on the Western Tethyan shelf. Enhanced organic matter accumulation was accompanied by a positive carbon isotope excursion (CIE) in pelagic carbonate, which marks the Toarcian Oceanic Anoxic Event. These environmental changes were accompanied by a major perturbation of the global carbon cycle, expressed by negative CIE, interrupting the positive trend. The duration of the carbon cycle perturbation is still debated, with estimates for the negative CIE range from ∼200 to ∼600 kyr. Here we present ultra high-resolution (<1 kyr) measurements of magnetic susceptibility and sediment color from a marine section located in the Lorraine Sub-Basin (NE Paris Basin) documenting Milankovitch-controlled fluctuations in depositional conditions that occurred superimposed onto the overall sea level evolution. Differences in the wavelength of the sedimentary cycles indicate variable sediment accumulation rates that mainly resulted from rapid sea level fluctuations. The most pronounced sea level rise that took place within the uppermosttenuicostatum zoneresulted in a strong condensation of the basal Schistes Carton formation. Strong condensation can explain the discrepancy between durations previously calculated for the CIE placed at this stratigraphic interval. Our data support durations of ∼900 kyr and ∼600 kyr for the positive and negative CIE, respectively. The cyclostratigraphy-based timescale further proposes a duration of >555 kyr for thetenuicostatum zoneand 1310 kyr for theserpentinum zone. The durations of theelegantulumandfalciferum subzonescan be estimated to ∼790 kyr and ∼520 kyr, respectively. A change in the orbital response from eccentricity- to obliquity-forcing, evident from other locations, is well-expressed in the Lorraine Sub-Basin and occurred within the CIE interval. The strong impact of the obliquity component in post-event deposits hints to processes most effective at high latitudes, such as the waxing and waning of polar ice. Paleogeographic features of the Western Tethyan shelf supported the tele-connection of higher to lower latitude processes via water exchange through the Viking Corridor.