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Late Cretaceous palynomorphs from the Golfo San Jorge Basin, Argentina
Journal of South American Earth Sciences ( IF 1.7 ) Pub Date : 2021-01-04 , DOI: 10.1016/j.jsames.2020.103151
V.S. Perez Loinaze , S.R. Giordano , C.O. Limarino

A lithofacial and palynological study was carried out on the Cañadón Seco Formation in the La Frieda Oeste x-1 well (Golfo San Jorge Basin). According to sedimentological characteristics of the core four main litofacies lithofacies are defined: 1. Cross-bedded sandstones, 2. Interlaminated fine-grained sandstones and mudstones, 3. Shales, and 4. Muddy tuff. The cross-bedded sandstones correspond to channel deposits, which are interpreted as lateral bars (point bars) or attached bars. The interchannel area is dominated by interlaminated fine-grained sandstones and mudstones, together with shales. The former represents sedimentation occurred in proximal floodplain areas, while shales correspond to deposition in distal floodplains, where thin and scarce muddy tuff intercalations indicate ash fall events. The palynological assemblage here analyzed was recovered from the green shales corresponding to distal floodplains areas, probably surrounding temporary water bodies. The floristic assemblage contains abundant fern spores as a dominant group, followed by angiosperm and gymnosperm pollen grains. Bryophyte and lycophyte spores, along with fungal remains, are also present in lower proportions. Based on the taxonomic content of the palynoflora, a Turonian–Coniacian age is suggested for this assemblage. Additionally, some taxa present in the assemblage allow inferring temperate to warm and humid conditions. This new record represents a period of time little known for the evolution of angiosperms in the southern region of Gondwana.



中文翻译:

来自阿根廷戈尔福圣豪尔赫盆地的晚白垩世晚绿质

在La Frieda Oeste x-1井(Golfo San Jorge盆地)的CañadónSeco地层进行了岩相和孢粉学研究。根据岩心的沉积学特征,确定了四种主要的岩相岩相:1.层状砂岩; 2.层状细粒砂岩和泥岩; 3.页岩;和4.泥泞凝灰岩。跨层砂岩对应于河床沉积物,被解释为侧向钢筋(点状钢筋)或附着的钢筋。通道间区域以层状细粒砂岩和泥岩以及页岩为主。前者代表沉积物发生在近洪泛区,而页岩对应于沉积物在远端泛滥区,那里稀薄的泥泞凝灰岩夹层表明发生了落灰事件。这里分析的孢粉组合是从对应于洪泛平原区(可能围绕临时水体)的绿色页岩中回收的。植物群落包含丰富的蕨类孢子作为主要种群,其次是被子植物和裸子植物的花粉粒。苔藓植物和苔藓植物孢子以及真菌残留物也以较低的比例存在。根据古植物的分类学含量,建议将这种组合命名为Turonian-Coniacian年龄。此外,组件中存在一些分类单元,可以推断温度为温暖和潮湿的条件。这项新记录代表了一段时期,在冈瓦纳南部地区被子植物的进化鲜为人知。植物群落包含丰富的蕨类孢子作为主要种群,其次是被子植物和裸子植物的花粉粒。苔藓植物和苔藓植物孢子以及真菌残留物也以较低的比例存在。根据古植物的分类学含量,建议将这种组合命名为Turonian-Coniacian年龄。此外,组件中存在一些分类单元,可以推断温度为温暖和潮湿的条件。这项新记录代表了一段时期,在冈瓦纳南部地区被子植物的进化鲜为人知。植物群落包含丰富的蕨类孢子作为主要种群,其次是被子植物和裸子植物的花粉粒。苔藓植物和苔藓植物孢子以及真菌残留物也以较低的比例存在。根据古植物的分类学含量,建议将这种组合命名为Turonian-Coniacian年龄。此外,组件中存在一些分类单元,可以推断温度为温暖和潮湿的条件。这项新记录代表了一段时期,在冈瓦纳南部地区被子植物的进化鲜为人知。建议将此年龄段设为Turonian-Coniacian年龄。此外,组件中存在一些分类单元,可以推断温度为温暖和潮湿的条件。这项新记录代表了一段时期,在冈瓦纳南部地区被子植物的进化鲜为人知。建议将此年龄段设为Turonian-Coniacian年龄。此外,组件中存在一些分类单元,可以推断温度为温暖和潮湿的条件。这项新记录代表了一段时期,在冈瓦纳南部地区被子植物的进化鲜为人知。

更新日期:2021-01-10
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