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A change from warm/humid to cold/dry climate conditions recorded in lower Barremian clay-dominated continental successions from the SE Iberian Chain (NE Spain)
Sedimentary Geology ( IF 2.7 ) Pub Date : 2020-06-01 , DOI: 10.1016/j.sedgeo.2020.105673
Elisa Laita , Blanca Bauluz , Marcos Aurell , Beatriz Bádenas , José Ignacio Canudo , Alfonso Yuste

Abstract A combined facies and clay mineralogy analysis of the continental succession recorded in the lower part of the Blesa Formation (early Barremian, Oliete subbasin, NE Spain) allowed us to specify the palaeoclimatic and palaeoenvironmental conditions under which this sedimentary record originated. Six outcrops including clays, clays/marls and dm-thick interbedded palustrine-lacustrine limestone levels were logged and sampled for X-ray diffraction and optical and electron microscopy analysis. The lower levels consist of red clays with abundant ferruginous pisoids (1–5 mm in size) and macropisoids (>5 mm), whereas the intermediate and upper levels are ochre and violet clays/marls with few or no pisoids. The pisoids normally consist of a nucleus and a cortex made up of several layers. Some pisoids have a fragment of a previous pisoid acting as a nucleus, indicating local re-working processes. Both the nucleus and the cortex are formed by hematite, goethite, variable contents of kaolinite, and minor proportions of ilmenite. Their texture and mineralogy show an in-situ growth. Interbedded limestone beds within the clay- and clay/marl-dominated levels are formed by micrite, microsparite and sparite. These limestones are cemented by kaolinite and they also have pisoids, indicating the occurrence of edaphic processes. The red clays have the lowest calcite content and the highest hematite, anatase, diaspore, goethite and kaolinite content. By contrast, the ochre and violet clays/marls have higher illite content. Smectite is only detected in the ochre clays/marls. This mineral association is characteristic of lateritic palaeosols, formed under warm and humid conditions. Kaolinite and smectite textures indicate that they are authigenic, whereas illite may be of detrital origin. The upward decrease in kaolinite, hematite, anatase, diaspore and goethite content, along with the increase in quartz content and the presence of smectite and illite, reflect a change from warm and humid conditions to drier and colder conditions during the early Barremian in the studied area.

中文翻译:

来自东南伊比利亚链(西班牙东北部)的下巴雷米亚粘土为主的大陆序列中记录的从温暖/潮湿到寒冷/干燥气候条件的变化

摘要 对 Blesa 组下部(早巴雷米亚,Oliete 亚盆地,西班牙东北部)记录的大陆序列进行的相和粘土矿物学组合分析使我们能够详细说明该沉积记录起源的古气候和古环境条件。对包括粘土、粘土/泥灰岩和 dm 厚互层湖湖石灰岩水平的六个露头进行了记录和采样,用于 X 射线衍射和光学和电子显微镜分析。下层由红粘土组成,具有丰富的铁质 pisoids(1-5 毫米大小)和巨粒粒(>5 毫米),而中间和上层是赭石和紫色粘土/泥灰岩,几乎没有或没有 pisoids。pisoids 通常由一个核和一个由多层组成的皮层组成。一些 pisoids 有一个先前 pisoid 的片段作为核,表明局部再加工过程。细胞核和皮质均由赤铁矿、针铁矿、不同含量的高岭石和少量钛铁矿形成。它们的质地和矿物学显示出原位生长。粘土和粘土/泥灰岩主导层内的互层石灰岩床由泥晶、微晶石和亮晶石形成。这些石灰岩由高岭石胶结而成,它们也有 pisoids,表明土壤过程的发生。红粘土的方解石含量最低,赤铁矿、锐钛矿、硬水铝石、针铁矿和高岭石含量最高。相比之下,赭石和紫色粘土/泥灰岩的伊利石含量较高。蒙脱石仅在赭石粘土/泥灰岩中检测到。这种矿物组合是红土古土壤的特征,在温暖潮湿的条件下形成。高岭石和蒙脱石质地表明它们是自生的,而伊利石可能是碎屑来源。高岭石、赤铁矿、锐钛矿、硬铝石和针铁矿含量的上升下降,以及石英含量的增加以及蒙脱石和伊利石的存在,反映了所研究的巴列米亚早期从温暖潮湿的环境转变为干燥寒冷的环境。区域。
更新日期:2020-06-01
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