Hybrid event beds (HEBs) are tiered deep-water deposits that can include significant intervals of organic-rich muddy sandstone and sandy mudstone. They are emplaced by decelerating sediment gravity flows in which turbulence becomes extinguished due to increasing cohesion. Whilst several studies have addressed the distribution of organic matter (OM) in turbidites, the extent to which OM is segregated between the component HEB divisions has yet to be quantitatively addressed for clastic systems. Here we document bed scale fractionation of terrestrial OM in HEBs drawn from a range of deep-water sub-environments (basin floor sheets, outer fan fringes and mid-fan lobes) preserved in the Ross Sandstone Formation, western Ireland, a tropical Pennsylvanian deep-water fan complex. A suite of bulk geochemical techniques (TOC, Rock-Eval pyrolysis, δ¹³C isotopes, and XRF scanning) and petrographic analyses were applied to HEB-dominated core intervals retrieved from four behind-outcrop boreholes. Results shows that muddy sandstones (H3 divisions) of the HEBs have significantly higher OM (average TOC = 1.2 wt% and up to 2.7 wt%) and mud contents than co-genetic cleaner sandstones (H1 divisions; average TOC = 0.2 wt% and up to 0.7 wt%). Muddy caps (H5 divisions) to the event beds have higher mud but relatively low OM contents (average TOC = 0.7 wt% and up to 1 wt%) compared to H3 divisions, implying textural fractionation of OM components, greater burn-down linked to slower suspension settling and/or downward propagation of oxidation fronts. HEBs can dominate distal lobe stratigraphy and are thus an important but under-represented sink for terrestrial carbon with enhanced preservation of OM in H3 divisions on account of rapid en-masse deposition, high mud abundances offering enhanced protection, and where thick, emplacement beyond the reach of oxidation fronts descending from the sea floor. The present study has important implications for understanding how carbon is buried and distributed in deep-water successions.

混合事件床（HEB）是分层的深水沉积物，其中可能包含大量富含有机物的泥质砂岩和砂质泥岩。它们通过降低泥沙重力流而被安置，在泥沙重力流中，由于内聚力的增加，湍流消失了。尽管有几项研究解决了浊质中有机物（OM）的分布问题，但对于碎屑系统，尚未对OM在组分HEB分区之间的隔离程度进行定量分析。在这里，我们记录了从保存在爱尔兰西部罗斯潘斯岩层，宾夕法尼亚州热带深部的一系列深水子环境（盆地地板，外部扇状边缘和中扇状叶）中提取的HEB中地面OM的床尺度分馏。 -水扇综合体。一整套的大块地球化学技术（TOC，Rock-Eval热解，δ¹³C同位素和XRF扫描）以及岩石学分析被应用于从四个露头井眼取回的HEB为主的岩心层段。结果表明，HEB的泥质砂岩（H3分区）的OM（平均TOC = 1.2 wt％，最高可达2.7 wt％）和泥浆含量明显高于共生清洁砂岩（H1分区；平均TOC = 0.2 wt％和高达0.7 wt％）。与H3分区相比，活动床的泥浆帽（H5分区）的泥浆含量较高，但OM含量相对较低（平均TOC = 0.7 wt％，最高为1 wt％），这意味着OM组分的结构性分级，更大的燃尽与较慢的悬浮沉淀和/或氧化前沿的向下传播。HEB可以主导远端肺叶地层，因此是陆地碳的一个重要但代表性不足的接收器，由于快速的大量泥石沉积，高强度的泥浆丰度提供了增强的保护，H3分区中的OM得到了更好的保护，并且厚厚的地块超出了H3地层。从海底下降的氧化前沿的范围。本研究对于理解碳如何在深水演替过程中被掩埋和分布具有重要意义。