In the Iberian Peninsula, Alpine tectonics built several Cenozoic basins that were mainly filled with continental deposits. The Guadiana Basin is located halfway between two of the most important Cenozoic basins of the SW of Spain, the Tajo and the Guadalquivir basins. In this paper, both geophysical and mineralogical studies have been carried out in order to establish the lithostratigraphy of the Guadiana basin. A combination of electric resistivity properties and variations in clay mineral assemblage content of the basin infill was used to identify several depositional sequences within the Cenozoic deposits of the basin. Three depositional sequences, DS1, DS2 and DS3 characterized by differentiated clay content and mineral assemblages were distinguished. The lower depositional sequence, DS1, consists of reddish siltstones and clays that scarcely crop out in the basin. Clay content of the <2 μm fraction is dominated by illite averaging 60% of the total clay content, with kaolinite and a few amount of smectite. DS2 deposits lie unconformably over DS1 and the Variscan basement and consist of a siliciclastic succession where carbonate units occur at bottom and at the top of the depositional sequence. Smectite dominates throughout the entire succession except in the basal carbonate unit where up to 70% of palygorskite is found. In the younger sequence DS3, kaolinite is the dominant clay mineral. Electrical resistivity imaging helped in the physical characterization and horizontal and vertical distribution of each unit and provided good insight on the structure of the Guadiana Basin, allowing to infer the basin structure due to high resistivity contrast between the basement and the sedimentary rocks. In addition, in areas where the lower sedimentary units do not crop out, and borehole information is not available, the geophysical response of the resistivity units imaged can be used to infer the corresponding depositional sequence.

The joint interpretation of the clay mineral assemblages and geophysical properties of the sedimentary units showed to be a useful tool to gather a reliable identification of depositional sequences in basins characterized by scarcity of good outcrops, lack of borehole information and similarity of sedimentary rocks. This is very important to properly correlate the different sedimentary units mapped as well as to infer the basin structure and its evolution through time.

在伊比利亚半岛，高山构造构造了几个新生代盆地，这些盆地主要是大陆性沉积物。瓜迪亚纳盆地位于西班牙西南部两个最重要的新生代盆地之间，即塔霍（Tajo）盆地和瓜达尔基维尔盆地（Guadalquivir）之间。为了建立瓜迪亚纳盆地的岩石地层学，本文进行了地球物理和矿物学研究。结合电阻率特性和盆地填充物粘土矿物组合含量的变化来确定盆地新生代沉积物中的几种沉积层序。区分了三个沉积序列，分别为DS1，DS2和DS3，其特征在于粘土含量和矿物组合的差异。较低的沉积序列DS1 由淡红的粉砂岩和粘土组成，几乎没有在盆地中种植。小于2μm的粘土含量以伊利石为主，平均占总粘土含量的60％，其中包括高岭石和少量蒙脱石。DS2沉积物不一致地分布在DS1和Variscan基底之上，由硅质碎屑演替组成，其中碳酸盐单元位于沉积序列的底部和顶部。蒙脱石在整个演替过程中均占主导地位，除了在底部碳酸盐岩单元中发现了高达70％的坡缕石。在较年轻的序列DS3中，高岭石是主要的粘土矿物。电阻率成像有助于每个单元的物理特征以及水平和垂直分布，并有助于深入了解瓜迪亚纳盆地的结构，由于基底和沉积岩之间的高电阻率差异，可以推断盆地结构。此外，在较低的沉积单元没有播出并且没有井眼信息的区域，可以使用成像的电阻率单元的地球物理响应来推断相应的沉积序列。

对粘土矿物组合和沉积单元的地球物理性质的联合解释显示是有用的工具，可用来收集以可靠的露头，缺乏井眼信息和沉积岩的相似性为特征的盆地中沉积序列的可靠识别。这对于正确关联绘制的不同沉积单元以及推断盆地结构及其随时间的演变非常重要。