西班牙南部Subbetic中带Río Fardes剖面Turonian-Coniacian大洋红层(英文)

TURONIAN-CONIACION OCEANIC RED BEDS IN THE RíO FARDES SECTION, MIDDLE SUBBETIC, SOUTHERN SPAIN

Río Fardes剖面位于西班牙南部Granada东北,构造上属于深水环境的Subbetic中带。该剖面主要由白垩纪Fardes组第Ⅱ段和第Ⅲ段(半)远洋沉积构成,并出现浊流沉积和混杂沉积。本次研究在Fardes组浊流层序内首次发现两段红色沉积。钙质超微化石表明红层的时间从Turonian早期(UC7 带)到Coniacian中期—晚期界线(UC10/?UC11带)。红层由mm级红色泥岩夹灰色、杂色、偶尔黑色泥岩和钙质泥岩组成。沉积学研究表明新发现的Turonian Coniacian远洋红色泥岩沉积形成于CCD面之下深水盆地环境,浊流和碎屑流沉积强烈地影响着(半)远洋环境的背景泥岩相,并成为红色沉积结束的原因。

The Río Fardes section NE of Granada, belongs to the deep basinal Middle Subbetic domain. This section is composed mainly of Cretaceous(hemi) pelagic sediments which appear together with turbidites and olistostromes together forming the Fardes Formation. Two types of red beds are present within the turbidite succession of the Fardes Formation. Nannofossil assemblages show that the age of the red beds is the uppermost part of Lower Turonian (Zone UC 7) to Middle-Upper Coniacian boundary (Zone UC10/?UC11). The red beds sequence consists of mm-thick reddish clays alternating with gray, variegated, locally black clays and calcareous clays. It is concluded that the newly discovered Turonian-Coniacian pelagic red clays were deposited in the deepest basin below the carbonate compensation depth(CCD), where turbiditic and debris flow sediments are diluted and strongly affect the background pelagic/hemipelagic facies. This results in the termination of sedimentation of the red clay facies.