A global increase in the strength of the hydrologic cycle drove an increase in the flux of terrigenous sediments into the ocean during the Cenomanian–Turonian Oceanic Anoxic Event 2 (OAE2) and was an important mechanism driving nutrient enrichment and thus organic carbon burial. This global change is primarily known from isotopic records, but global average data do not tell us anything about changes at any particular location. Reconstructions of local terrigenous flux can help us understand the role of regional shifts in precipitation in driving these global trends. The proto-North Atlantic basin was one of the epicenters of enhanced organic carbon burial during OAE2, so constraining terrigenous flux is particularly important in this region; however, few local records exist. Here, we present two new OAE2 records from the Atlantic Coastal Plain of North Carolina, USA, recognized with calcareous nannoplankton biostratigraphy and organic carbon isotopes. We use carbon $/$ nitrogen ratios to constrain the relative contribution of marine and terrestrial organic matter; in both cores we find an elevated contribution from vascular plants beginning just before OAE2 and continuing through the event, indicating a locally strengthened hydrologic cycle. Terrigenous flux decreased during the brief change in carbon isotope values known as the Plenus carbon isotope excursion; it then increased and remained elevated through the latter part of OAE2. Total organic carbon (TOC) values reveal relatively low organic carbon burial in the inner shelf, in contrast to black shales known from the open ocean. Organic carbon content on the shelf appears to increase in the offshore direction, highlighting the need for cores from the middle and outer shelf.

中文翻译：

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美国北卡罗来纳州沿海平原海洋缺氧事件 2 期间增强的陆地径流

在 Cenomanian-Turonian 海洋缺氧事件 2 (OAE2) 期间，全球水文循环强度的增加推动了陆源沉积物进入海洋的通量增加，并且是推动营养物质富集和有机碳埋藏的重要机制。这种全球变化主要是从同位素记录中得知的，但全球平均数据并没有告诉我们任何特定位置的变化。局部陆源通量的重建可以帮助我们了解区域降水变化在推动这些全球趋势方面的作用。原北大西洋盆地是OAE2期间有机碳埋藏增强的震中之一，因此在该地区限制陆源通量尤为重要；然而，几乎没有地方记录。这里，我们展示了来自美国北卡罗来纳州大西洋沿岸平原的两个新的 OAE2 记录，它们通过钙质微浮游生物生物地层学和有机碳同位素进行识别。我们使用碳 $/$ 限制海洋和陆地有机物质的相对贡献的氮比率；在两个核心中，我们发现维管植物的贡献在 OAE2 之前开始并持续到事件中，表明局部加强了水文循环。在被称为 Plenus 碳同位素偏移的碳同位素值的短暂变化期间，陆源通量下降；然后它增加并在 OAE2 的后期保持升高。总有机碳 (TOC) 值显示内陆架的有机碳埋藏量相对较低，这与公海已知的黑色页岩形成鲜明对比。陆架上的有机碳含量似乎向近海方向增加，突出了对来自中外陆架的岩心的需求。