Palaeontology, sedimentology, and biostratigraphy of a fossiliferous outcrop of the Early Miocene Querales Formation, Falcón Basin, Venezuela

Abstract

The top of the Querales Formation is well exposed at the Quebrada Corralito section, 17 m thick, in northern Venezuela. The section, dominated by siliciclastic accumulations of fine-grained sediments, preserves one cycle of transgressive-regressive phases of the deltaic environments facing the marine platform. An X-ray analysis revealed kaolinite as the main clay mineral. The age ranges from late Early Miocene to early Middle Miocenezones N8 to N9, Late Burdigalian to Langhian. The section shows low biodiversity, including eleven macroinvertebrate taxa and two ichnotaxa; at its base, it contains mostly plant debris and amber from the continent, thus revealing a continental source near the littoral zone. Its middle portion preserves macroinvertebrates from the littoral zone, but also including the cephalopod Aturia sp., transported by a hydraulic flow to an area of greater depth; these macroinvertebrates are absent from overlying sections, at a time in which the basin was flooded most. The X-ray diffraction on six rock samples revealed mainly the presence of quartz with calcite, subordinated plagioclase and traces of potassium feldspar. Other minerals that compose this stratigraphic section are pyrite, dolomite and siderite, but they are disseminated in a siltstone. The section is dominated by mudstone sediments. The succession is kaolinite in the most pure fraction, and in lesser proportion smectite and illite; the stratified illite-smectite, chlorite and chlorite-smectite are present in low quantity. The mineralogical components of a molluscan valve were also examined, showing abundant pyrite, and moderate amounts of siderite and dolomite. In a part of the section, we recorded a rich assemblage of calcareous microfossils with foraminifers, nannofossils and marine ostracods. In the

The Neogene Record of Northern South American Native Ungulates

“…For a detailed description of the key studies, see appendix 2 in supplementary materials (Carrillo et al, 2018b). The age of the Querales Formation is further supported by nannoplankton (Pérez et al, 2016). The foraminiferal ages of the Urumaco Formation are also supported by vertebrates (Linares, 2004;Sánchez-Villagra, 2006;Sánchez-Villagra and Aguilera, 2006).…”

“…We provide a detailed description of each section, including its geographic position, in appendix 1 of the supplementary materials (Carrillo et al, 2018b). The biostratigraphic record of foraminifera in the Urumaco region (both western and eastern) has been extensively studied, and correlated to Bolli's biostratigraphic schemes from Trinidad (Renz, 1948;Bermudez and Bolli, 1969;Blow, 1969;Díaz de Gamero 1977a,b, 1985a,b, 1989, 1996Díaz de Gamero et al, 1988;Díaz de Gamero and Linares, 1989;Wozniak and Wozniak, 1987;Guerra and Mederos, 1988;Rey, 1990;Hambalek, 1993;Bolli et al, 1994;Pérez et al, 2016). For a detailed description of the key studies, see appendix 2 in supplementary materials (Carrillo et al, 2018b).…”

“…1). The ages (mya) are derived from multiple foraminiferal, nannoplankton, and magnetic stratigraphic studies (Renz, 1948;Bermudez and Bolli, 1969;Blow, 1969;Díaz de Gamero 1977a,b, 1985a,b, 1989, 1996Díaz de Gamero et al, 1988;Díaz de Gamero and Linares, 1989;Wozniak and Wozniak, 1987;Guerra and Mederos, 1988;Rey, 1990;Hambalek, 1993;Bolli et al, 1994;Pérez et al, 2016). here will serve as a basis to compare the postcranial morphology of uruguaytheriine and non-uruguaytheriine astrapotheres in order to assess possible paleobiological differences or phylogenetically informative characters.…”

“…The mammalian fauna of the Ware Formation is characterized by a high diversity of herbivores (Figures 34, 35), which includes at least five different taxa of sloths (Amson et al, 2016), as well as cingulates, caviomorph rodents (Moreno et al, 2015;Pérez et al, 2016), a toxodont, a proterotheriid, and a camelid ( Table 1). The diversity and wide body mass range of herbivores from the Ware Formation suggest that they occupied different ecological niches, and that there was enough vegetation cover to sustain a complex herbivorous community.…”

The chemistry of American and African amber, copal, and resin from the genus Hymenaea

“…In addition to the localities above we have also analysed samples from a recently discovered site in Venezuela which is of late Early Miocene to early Middle Miocene (Pérez et al, 2016) in age. The botanic origin of this amber has never been studied.…”