Abstract Diverse freshwater green algal microfossils and dispersed fungal spores among rich terrestrial palynofloras were recovered from the upper part of the Quebrada de los Fósiles Formation, Puesto Viejo Group, cropping-out in the fault-bounded San Rafael Basin, Mendoza Province, Argentina. Sedimentological data suggest that the vegetation recorded from this unit grew in floodplains of high-sinuosity fluvial systems when intense episodic volcanic activity provided great quantities of ash deposits to the sites. Small and temporary shallow lake deposits and thin peat ponds were recorded at two sections, yielding palynofloras composed of variable contents of spores, pollen, freshwater algae and fungal associations. The taxa described and illustrated herein consist of representatives of colonial Chlorophyta algae (Botryococcus), a diverse group of Zygnematales zygospores represented by the genera Lecaniella, Maculatasporites, Mehlisphaeridium, Ovoidites and the incertae sedis algae Leiosphaeridia and Retirotundia as well as representatives of fungi assigned to Microsporonites and Portalites. Two new species of Ovoidites are described herein, Ovoidites tripartitus and Ovoidites circumplicatus, and the new combination Ovoidites scissus is also presented. The terrestrial and aquatic vegetation grew associated with shallow water bodies in floodplain environments developed under warm temperate, strongly seasonal climatic conditions. The environment was stressed by volcanism that probably restricted the colonization and development of the ecosystem. The occurrence of algal microfossils in the Quebrada de los Fósiles Formation suggest shallow and episodic locally restricted aquatic environments inhabited by autochthonous freshwater green algae consistent with the sedimentological evidence. A Middle Triassic age is inferred from recent radiometric dating obtained from the basal and upper ignimbrite beds of the Quebrada de los Fósiles Formation indicate an age of 243.9 ± 2.0 Ma and 235.8 ± 2.0 Ma, respectively, thus mostly constrained to the Ladinian age. The composition of the fossil flora (palynoflora and macroflora) also indicates Middle Triassic age. Ana M. Zavattieri [amz@mendoza-conicet.gob.ar], Unidad de Paleopalinología, Departamento de Paleontología, Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CCT-CONICET-Mendoza, Av. A. Ruíz Leal s/n, Parque General San Martín, M5502IRA Mendoza, Argentina; Pedro Raúl Gutiérrez [pedroraulgutierrez@gmail.com], Museo Argentino de Ciencias Naturales “B. Rivadavia”, CONICET, Sección Paleopalinología, Área Paleontología. Buenos Aires, Argentina, Av. Ángel Gallardo 470, C1405DJR Buenos Aires, Argentina; Mariana Monti [mariana.monti@ypftecnologia.com.ar], YPF Tecnología S.A. (Y-TEC), Avenida del Petróleo s/n, entre 129 y 143, B1924CKU Berisso, Argentina.

中文翻译：

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阿根廷中西部 Puesto Viejo 盆地的中三叠世淡水绿藻和真菌：古环境影响

摘要 在阿根廷门多萨省圣拉斐尔盆地断层边界的 Puesto Viejo Group 的 Quebrada de los Fósiles 组上部发现了丰富的陆生孢粉植物群中的多种淡水绿藻微化石和分散的真菌孢子。沉积学数据表明，当强烈的间歇性火山活动为这些地点提供大量灰烬沉积物时，从该单元记录的植被生长在高曲折河流系统的漫滩中。在两个部分记录了小型和临时浅湖沉积物和薄泥炭池，产生由孢子、花粉、淡水藻类和真菌组合的不同含量组成的孢粉菌群。此处描述和说明的分类群由群落绿藻（葡萄球菌）的代表组成，由 Lecaniella、Maculatasporites、Mehlisphaeridium、Ovoidites 和 incertae sedis 藻类 Leiosphaeridia 和 Retirotundia 代表的一组多样化的 Zygnematales zygospores 以及分配给 Microsporonites 和 Portalites 的真菌代表。本文描述了两种新的卵形石种，即三方卵形石和环绕型卵形石，还介绍了新的剪形卵形石组合。在暖温带、强烈季节性气候条件下形成的漫滩环境中，陆地和水生植被与浅水体相关。火山活动对环境造成了压力，这可能限制了生态系统的殖民和发展。Quebrada de los Fósiles Formation 中藻类微化石的出现表明浅层和偶发性的局部限制水生环境由本土淡水绿藻栖息，与沉积学证据一致。从最近从 Quebrada de los Fósiles 组的基底和上部熔凝岩层获得的辐射测年推断出中三叠世时代，表明年龄分别为 243.9 ± 2.0 Ma 和 235.8 ± 2.0 Ma，因此主要限于拉迪尼阶。化石植物群（孢粉植物群和大型植物群）的组成也表明中三叠世时代。Ana M. Zavattieri [amz@mendoza-conicet.gob.ar], Unidad de Paleopalinología, Departamento de Paleontología, Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), Avidad de Paleopalinología, Departamento de Paleontología A. Ruíz Leal s/n, Parque General San Martín，M5502IRA 门多萨，阿根廷；Pedro Raúl Gutiérrez [pedroraulgutierrez@gmail.com]，阿根廷自然博物馆“B. Rivadavia”，CONICET，Sección Paleopalinología，Área Paleontología。布宜诺斯艾利斯，阿根廷，Av。Ángel Gallardo 470, C1405DJR 布宜诺斯艾利斯，阿根廷；Mariana Monti [mariana.monti@ypftecnologia.com.ar], YPF Tecnología SA (Y-TEC), Avenida del Petroleo s/n, entre 129 y 143, B1924CKU Berisso, Argentina。