Abstract Our current knowledge of deep-water depositional systems is mainly built of extensive achievements obtained from marine basins. Although lacustrine basins are important oil & gas productive areas of the world, gravity-induced deposits in these basins are poorly understood in the literature when compared with those documented in marine basins. Based on new insights from 3D seismic data, this paper attempts to investigate the effect of the interaction between gravity-induced flows and lake-floor topography on the resulting external geometry of gravity-induced deposits in the Cretaceous Qingshankou and Nenjiang formations of the Songliao Basin (SLB). Eight different shapes of gravity-induced deposits were identified in the SLB, and which were in turn grouped into four distinct categories according to external shape, internal architecture and spatial assembly: (1) Channel-fan complexes; (2) Fan-form complexes; (3) Strip-form complexes; and (4) Pond-form complexes. Furthermore, fan-form complexes can be subdivided into four subcategories (isolated fan with compressional ridges, isolated fan without compressional ridges, mother-son fans and stacked fans). Strip-form complexes can be subdivided into two subcategories, including strip-form controlled by gully system and strip-form controlled by growth faults. Sediment transport mechanism (density flows or mass transport flows) and lake-floor topography together influence the pathways, runout distances, discharge places and internal characteristics of gravity induced deposits, which could ultimately influence external geometries of gravity-induced deposits in the SLB. Consequently, sublacustrine gravity-induced deposits does not exhibit classic fan-like geometry. Frequent and powerful hyperpycnal flows associated with flood events are fairly common, and develop channel-distal fan complexes. MTDs exhibit various external geometries, which are significantly affected by growth faults, slope gullies, gradient, and basin-floor irregularities. The new depositional model built from the SLB is vital to understanding the distribution of gravity-flow deposits in a sublacustrine slope.

中文翻译：

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湖底重力诱发沉积物：外部几何形状和成因的多样性

摘要 我们目前对深水沉积系统的了解主要建立在从海盆中获得的广泛成果之上。尽管湖泊盆地是世界上重要的石油和天然气生产区，但与海洋盆地中记录的沉积物相比，这些盆地中的重力诱发沉积物在文献中知之甚少。基于 3D 地震数据的新见解，本文试图研究重力诱发流和湖底地形之间的相互作用对松辽盆地白垩纪青山口组和嫩江组重力诱发沉积物外部几何形状的影响。 (SLB)。在 SLB 中发现了八种不同形状的重力诱发沉积物，并根据外部形状将其分为四个不同的类别，内部建筑和空间组合：（1）通道-扇复合体；(2) 扇形配合物；(3) 条状复合体；(4) 池状复合体。此外，扇形复合体可细分为四个子类（带压脊的孤立扇、无压脊的孤立扇、母子扇和叠扇）。条状杂岩体又可细分为两大类，包括沟壑系统控制的条状和生长断层控制的条状。沉积物输运机制（密度流或质量输运流）和湖底地形共同影响重力诱发沉积物的路径、跳动距离、排放位置和内部特征，最终可能影响 SLB 中重力诱发沉积物的外部几何形状。最后，湖底重力诱发的沉积物不表现出经典的扇状几何形状。与洪水事件相关的频繁而强大的超重流相当普遍，并形成了河道-远端扇复合体。MTD 具有各种外部几何形状，受生长断层、斜坡沟壑、坡度和盆底不规则性的显着影响。根据 SLB 建立的新沉积模型对于了解湖底斜坡中重力流沉积物的分布至关重要。