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，海相沿坡流和下坡流的相互作用导致了互层的等高岩、浊积岩和伴生的深水相的聚集。然而，尽管经过了几十年的研究，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，对于轮廓岩，特别是粗质（砂质）轮廓岩与浊积岩的识别和区分标准仍存在很大争议。本项目旨在研究塞浦路斯始新世-中新世大陆斜坡演替中的钙质等高岩和相关的深海相。由于其极好且容易接近的暴露，以及沿坡底流沉积的明确证据，环特罗多斯沉积记录是古代陆地上暴露的轮廓岩的原型。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轮廓岩沉积体系的区域相模型。这种大规模的几何评估将基于陆上数字地形和露头模型以及海上地震数据。在第二步中，我们批判性地评估和改进现有的碳酸盐岩轮廓岩和底流改造碳酸盐岩浊积岩相模型。这些床级尺度的研究将集中在沉积体系不同亚环境中的相层序及其横向变化。此外，我们将在微观水平上包括碳酸盐微相，以便更准确地区分轮廓岩、浊积岩和长泥岩，它们都在不同程度上有助于轮廓岩沉积体系的聚集。特别是，我们将研究(i)典型双层序轮廓岩序列的可变性及其内部细分（层理，分层和层压），（ii）牵引构造的类型和保存，以及（iii）生物扰动的时间性和影响。所得的微相和床层尺度诊断标准有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增加我们对等长岩沉积体系相互连接的亚环境内的变化和控制的理解，并将用于建立区域相模型。该模型将包括所有已记录的等高岩矿床和底流改造浊积岩矿床的分层类型汇编，以便在空间上将床尺度沉积物特征和微相与漂流尺度结构联系起来。

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.