Continental shelves host 90% of modern Organic Carbon (OC) burial and play a key role in the sequestration of terrigenous OC over geological timescales. The efficiency of OC burial in these systems, however, varies greatly depending on the duration of exposure to oxic-suboxic conditions during sediment transport. In this study, we use observations across a wide range of stratigraphic and sedimentological scales coupled with geochemistry data from muddy shelf deposits along the western Adriatic to investigate the relation between sediment transport and burial of terrigenous (land-derived) fraction of OC (OC_Terr). Our analysis focused on the Little Ice Age (LIA, 1500–1850 CE) interval, which was characterized by wet, cold, and stormy weather conditions, before the time of widespread regulation and damming of rivers. On the Adriatic shelf, LIA deposits are organized as clinothem: strata that dip gently seawards. The LIA clinothem becomes progressively steeper and deeper from north to south. Basin-scale seismic-stratigraphic analysis and biogeochemical data show evidence of elongated stratal units associated with low OC_Terr content in the northern sector of the LIA clinothem, whereas farther south, where clinoforms are steeper, the LIA clinothem exhibits wavy stratal units with limited cross-shelf continuity and high OC_Terr concentrations. Based on these data we infer two contrasting scenarios for OC_Terr deposition during the LIA: 1) protracted sediment redistribution under the influence of coastal currents with efficient OC_Terr degradation prior to final burial in the northern sector; and (2) rapid deposition of OC_Terr-rich event beds as a result of flood-driven hyperpycnal flows with limited dispersion across the shelf in the southern sector. The latter scenario of deposition resulted in scattered hot spots of OC_Terr burial along the apparently homogeneous western Adriatic shelf deposit. Our work documents significant lateral variability of a fine-grained system in which hot spots of OC_Terr can be preserved in scattered prodelta bedsets (<1 km in across-shelf lateral continuity) over a 600 km long shelf. Shelfal clinothems worldwide should not be considered as homogeneous pools of OC_Terr because of the influence of river, storm, and oceanic currents.

大陆架拥有 90% 的现代有机碳 (OC) 掩埋，并在地质时间尺度上陆源 OC 的封存中发挥关键作用。然而，这些系统中 OC 掩埋的效率根据沉积物运输过程中暴露于有氧 - 无氧条件的持续时间而有很大差异。在这项研究中，我们使用广泛的地层和沉积学尺度的观测结果，结合亚得里亚海西部泥质陆架沉积物的地球化学数据，研究沉积物迁移与 OC 的陆源（陆源）部分（OC _Terr）埋藏之间的关系。）。我们的分析集中在小冰河时代（LIA，公元 1500 年至 1850 年）区间，其特征是在广泛调节河流和筑坝之前的潮湿、寒冷和暴风雨天气条件。在亚得里亚海陆架上，LIA 矿床被组织成斜面：向海轻轻倾斜的地层。LIA 斜面从北向南逐渐变陡和变深。盆地尺度的地震地层分析和生物地球化学数据显示，在 LIA 斜面北段，拉长的地层单元与低 OC _Terr含量相关，而在更远的南部，斜面更陡，LIA 斜面表现出波浪状地层单元，交叉有限-货架连续性和高 OC _Terr浓度。根据这些数据，我们推断出LIA 期间OC _Terr沉积的两种截然不同的情景：1）在沿海流的影响下，长期的沉积物重新分布与北部地区最终埋藏之前的OC _Terr有效降解；(2)_富含OC _{Terr 的}事件床迅速沉积，这是洪水驱动的超重流的结果，在南部陆架上的扩散有限。后一种沉积情况导致沿明显均质的亚得里亚海西部陆架沉积物散布着 OC _Terr埋藏的热点。我们的工作记录了细粒度系统的显着横向变化，其中 OC _{Terr 的}热点可以保存在 600 公里长的陆架上分散的前三角洲床层（跨陆架横向连续性小于 1 公里）。由于河流、风暴和洋流的影响，世界范围内的陆架倾斜不应被视为 OC _{Terr 的}同质池。