Bed-scale characteristics and microfacies of Eocene-Miocene bottom-current deposits on Cyprus: Diagnostic criteria for contourite identification and drift-related spatial facies trends

在许多现代大陆边缘，沿斜坡和向下的海洋沉积流动过程的相互作用，导致互层等深岩、浊积岩和与之伴生的深水相的聚集，已经被很好地记录下来。然而，尽管经过几十年的研究，这种相互作用的性质，特别是不同相类型之间的区别仍然知之甚少。事实上，对于等高岩，特别是较粗(砂质)等深岩与浊积岩的识别和区分标准，仍然存在很大的争议。该项目旨在研究塞浦路斯始新世-中新世陆坡序列中的钙质等深岩及其伴生的深海相。由于其良好且易于获取的暴露，以及沿斜坡底部洋流沉积的明确证据，Circum Troodos沉积记录是陆地上暴露的古代等深线的原型例子。在第一步中，我们评估了漂移类型和三维几何形状，并建立了塞浦路斯碳酸盐等深岩沉积体系的区域相模型。这项大规模的几何评估将基于陆上数字地形和露头模型以及近海地震数据。在第二步中，我们对现有的碳酸盐等深岩和底流改造碳酸盐浊积岩的相模式进行了严格的评价和改进。这些在床尺度上的研究将集中在等高线沉积体系的不同亚环境中的相序及其横向变化。此外，我们还将在微观层面上包括碳酸盐微相，以便更准确地区分等深岩、浊积岩和长白岩，它们都在不同程度上对等深岩沉积体系的聚集做出了贡献。特别是，我们将研究(I)典型的双级配等深岩序列及其内部细分(层理、层理和层理)的可变性，(Ii)牵引构造的类型和保存，以及(Iii)生物扰动的临时性和影响。由此得到的微相和床尺度诊断标准可望适用于世界范围内的斜坡沉积，从大尺度和小尺度角度获得的结果将加深我们对等深岩沉积体系相互关联的亚环境内的变化和控制的理解，并将用于建立区域相模式。该模型将汇编所有已记录的等深岩沉积和底流改造的浊积岩沉积的分层类型，以便在空间上将床层尺度的沉积特征和微相与漂移尺度的结构联系起来。

The interaction of along-slope and down-slope marine sedimentary flow processes, resulting in the accumulation of interbedded contourites, turbidites and associated deep-water facies, has been well documented on many modern continental margins. However, despite many decades of research, the nature of this interaction and, in particular, the distinction between different facies types remains poorly understood. In fact, there is still much controversy over the criteria by which contourites, especially coarser (sandy) contourites, can be identified and distinguished from turbidites.This project aims to investigate calcareous contourites and associated deep-marine facies from an Eocene-Miocene continental slope succession on Cyprus. Because of its excellent and easily accessible exposure, as well as the clear evidence for deposition by along-slope bottom currents, the Circum Troodos sedimentary record is a prototype example of ancient contourites exposed on land. In a first step, we assess the drift type and the 3D geometry and establish a regional facies model of the carbonate contourite depositional system on Cyprus. This large-scale geometric assessment will be based on onshore digital terrain and outcrop models as well as offshore seismic data. In a second step, we critically evaluate and improve existing facies models for carbonate contourites and bottom-current reworked carbonate turbidites. These investigations at the bed-scale will focus on facies sequences and their lateral variation within the different sub-environments of the contourite depositional system. In addition, we will include carbonate microfacies at the microscopic level for a more accurate differentiation between contourites, turbidites and pelagites, which all contribute, to various degrees, to the accumulation of contourite depositional systems. In particular, we will examine (i) the variability of archetypical bi-gradational contourite sequences and their internal subdivision (bedding, layering, and lamination), and (ii) the type and preservation of traction structures, and (iii) the temporality and impact of bioturbation. The resulting microfacies and bed-scale diagnostic criteria are expected to be applicable to slope deposits worldwide.The results obtained from the large-scale and the small-scale perspective will increase our understanding of the variations and controls within the interconnected sub-environments of the contourite depositional system and will be used to establish a regional facies model. The model will include a compilation of stratification types for all documented contourite deposits and bottom-current reworked turbidite deposits, in order to spatially relate the bed-scale sediment characteristics and microfacies with the drift-scale architecture.