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Ichnofabric analysis as a tool for characterization and differentiation between calcareous contourites and calciturbidites
Journal of Sedimentary Research ( IF 2.0 ) Pub Date : 2021-11-30 , DOI: 10.2110/jsr.2020.147
Olmo Miguez-Salas 1 , Francisco J. RodrÍguez-Tovar 1
Affiliation  

The Eocene–Miocene Cyprus paleoslope system records complex deep-marine sedimentation comprising background vertical settling of autochthonous pelagic–hemipelagic particles (chalks) which were punctuated by calcareous bottom currents (contourites) and gravity flows (calciturbidites). The Eocene Lefkara Formation at the Petra Tou Romiou beach section (Cyprus) shows the incidence of deep-marine bottom currents and distal turbiditic episodes in a context of pelagic–hemipelagic sedimentation. Trace-fossil analysis of this section, using an ichnofabric approach (i.e., ichnodiversity, Bioturbation Index, Bedding Plane Horizontal Index and crosscutting relationships), was conducted to precisely describe the paleoenvironmental conditions of this complex setting. Ichnofabric analysis allow the characterization and differentiation of sporadic turbiditic events that disrupted both pelagic–hemipelagic and contourite deposition. Calciturbidite intervals show ichnofabrics consisting of postdepositional U-shaped traces (i.e., Arenicolites isp., ?Diplocraterion isp.,) and vertical borings typical of consolidated substrates. High-energy sandy contourite deposits are dominated by horizontal deposit-feeder traces and the development of ichnofabrics with Planolites isp., and Thalassinoides isp. The record of ichnofabrics with slightly deformed Planolites in the interbeds of sandy contourites or in the transition between the facies reveals variations in sedimentation in the bi-gradational contourite succession, and can potentially act as an indicator of depositional hiatus.

中文翻译:

Ichnofabric 分析作为表征和区分钙质等高岩和钙质浊积岩的工具

始新世-中新世塞浦路斯古斜坡系统记录了复杂的深海沉积,包括原生远洋-半远洋颗粒(白垩)的背景垂直沉降,这些颗粒被钙质底流(轮廓)和重力流(方解石)打断。Petra Tou Romiou 海滩部分(塞浦路斯)的始新世 Lefkara 组显示了在远洋-半远洋沉积背景下深海底部洋流和远端浊流事件的发生。对该部分的痕量化石分析,使用 ichnofabric 方法(即,ichnodiversity、Bioturbation Index、Bedding Plane Horizo​​ntal Index 和 crosscutting 关系)来精确描述这个复杂环境的古环境条件。Ichnofabric 分析允许对破坏远洋-半远洋和等高岩沉积的零星浊流事件进行表征和区分。方解石层段显示由沉积后 U 形迹线(即,砭石石,?Diplocraterion isp.,)和固结基质典型的垂直钻孔组成的石质织物。高能砂质等高岩矿床以水平沉积-馈线痕迹为主,并发育具有 Planolites isp. 和 Thalassinoides isp. 的地层织物。在砂质等高岩的夹层或相之间的过渡中具有轻微变形的平纹岩的地层织物的记录揭示了双梯度等高岩序列中沉积的变化,并可能作为沉积中断的指标。
更新日期:2021-11-12
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