Abstract:A study of macro and microfacies, palynoflora and palynofacies of the nonmarine Cerro Negro Formation at President Head Peninsula, Snow Island, northwest of the Antarctic Peninsula, was developed. Two assemblages were recognized: Palynofacies assemblage 1 (P1) at the base of the section with a dominance of fern spores and conifer pollen grains, and facies association consisting of a clastic layer, with the predominance of mudstones; and Palynofacies assemblage 2 (P2) at the top of the section, with remarkable … Show more
“…Mesozoic rock outcrops occur on the President Head Peninsula, 27,28 which is a small promontory (2.6 km in length) comprising sedimentary and igneous rocks of the Byers Group 29 . At the base of the Byers Group occur marine strata (Chester Cone Formation) separated from the Aptian nonmarine volcaniclastic rocks of the Cerro Negro Formation 25,29 . This group includes fossiliferous rocks, ranging from Late Jurassic to Early Cretaceous, 28 with green sandstones, gray siltstones, dark mudstones, and rare thin conglomerates 28,29 .…”
Section: Methodsmentioning
confidence: 99%
“…Intrusive body (basalt/andesite); Cerro Negro Formation (siltstones, sandstones, conglomerates, and andesites); sedimentary marine deposit (mudstones). Source: Adapted from Omerovic and Allamand 24 and Santos et al 25 …”
Section: Methodsmentioning
confidence: 99%
“…Intrusive body (basalt/andesite); Cerro Negro Formation (siltstones, sandstones, conglomerates, and andesites); sedimentary marine deposit (mudstones). Source: Adapted from Omerovic and Allamand 24 and Santos et al 25 T A B L E 1 General characterization (altitude, lithology, landform, horizons, soil depth, depth to permafrost, and soil classes) of the soils from the President Head Peninsula. andesitic basalt, and tuffs (intrusive bodies), 24,28 belonging to the Antarctic Peninsula Magmatic Arc.…”
Section: Study Areamentioning
confidence: 99%
“…29 At the base of the Byers Group occur marine strata (Chester Cone Formation) separated from the Aptian nonmarine volcaniclastic rocks of the Cerro Negro Formation. 25,29 This group includes fossiliferous rocks, ranging from Late Jurassic to Early Cretaceous, 28 with green sandstones, gray siltstones, dark mudstones, and rare thin conglomerates. 28,29 The eastern part of the President Head Peninsula is formed by basalt, F I G U R E 1 (A) Maritime Antarctica; (B) location of Snow Island, South Shetlands Archipelago; (C) President Head Peninsula, Snow Island; and (D) geological map of President Head Peninsula, with the location of the sampled soil profiles.…”
Soil–parent material is a critical controlling factor of soil properties in the Antarctic region due to a limited degree of soil development. However, the degree to which soil–parent material can be considered the major controlling factor in pedogenesis and subsequent soil physical and chemical properties in Antarctica should be better understood to improve soil mapping and interpretations. The present study aims to analyze the soil properties of different lithological groups on the President Head Peninsula on Snow Island, Maritime Antarctica. Thirty soil profiles across the major lithological groupings on Snow Island (beach deposits, andesites, basalts/andesites, conglomerate, sandstones, siltstones, and mudstones) were described, and the morphological, physical, and chemical properties of samples from sampled genetic horizons were characterized. Beach deposits were most clearly differentiated from other lithological groups, whereas most other groups overlapped strongly in observed properties. Whereas some lithological groups (e.g., sedimentary rock groups) were characterized largely by immature soils with little degree of pedogenesis, other sampled soils exhibited more development. The soil–parent material relationships of Snow Island revealed a unique setting of a complex heterogeneous landscape and show that the area has a great pedological complexity induced by phosphatization, melanization, and cryoturbation processes that preclude placing primary importance on parent material and lithology as the major controlling factor in Antarctic soils.
“…Mesozoic rock outcrops occur on the President Head Peninsula, 27,28 which is a small promontory (2.6 km in length) comprising sedimentary and igneous rocks of the Byers Group 29 . At the base of the Byers Group occur marine strata (Chester Cone Formation) separated from the Aptian nonmarine volcaniclastic rocks of the Cerro Negro Formation 25,29 . This group includes fossiliferous rocks, ranging from Late Jurassic to Early Cretaceous, 28 with green sandstones, gray siltstones, dark mudstones, and rare thin conglomerates 28,29 .…”
Section: Methodsmentioning
confidence: 99%
“…Intrusive body (basalt/andesite); Cerro Negro Formation (siltstones, sandstones, conglomerates, and andesites); sedimentary marine deposit (mudstones). Source: Adapted from Omerovic and Allamand 24 and Santos et al 25 …”
Section: Methodsmentioning
confidence: 99%
“…Intrusive body (basalt/andesite); Cerro Negro Formation (siltstones, sandstones, conglomerates, and andesites); sedimentary marine deposit (mudstones). Source: Adapted from Omerovic and Allamand 24 and Santos et al 25 T A B L E 1 General characterization (altitude, lithology, landform, horizons, soil depth, depth to permafrost, and soil classes) of the soils from the President Head Peninsula. andesitic basalt, and tuffs (intrusive bodies), 24,28 belonging to the Antarctic Peninsula Magmatic Arc.…”
Section: Study Areamentioning
confidence: 99%
“…29 At the base of the Byers Group occur marine strata (Chester Cone Formation) separated from the Aptian nonmarine volcaniclastic rocks of the Cerro Negro Formation. 25,29 This group includes fossiliferous rocks, ranging from Late Jurassic to Early Cretaceous, 28 with green sandstones, gray siltstones, dark mudstones, and rare thin conglomerates. 28,29 The eastern part of the President Head Peninsula is formed by basalt, F I G U R E 1 (A) Maritime Antarctica; (B) location of Snow Island, South Shetlands Archipelago; (C) President Head Peninsula, Snow Island; and (D) geological map of President Head Peninsula, with the location of the sampled soil profiles.…”
Soil–parent material is a critical controlling factor of soil properties in the Antarctic region due to a limited degree of soil development. However, the degree to which soil–parent material can be considered the major controlling factor in pedogenesis and subsequent soil physical and chemical properties in Antarctica should be better understood to improve soil mapping and interpretations. The present study aims to analyze the soil properties of different lithological groups on the President Head Peninsula on Snow Island, Maritime Antarctica. Thirty soil profiles across the major lithological groupings on Snow Island (beach deposits, andesites, basalts/andesites, conglomerate, sandstones, siltstones, and mudstones) were described, and the morphological, physical, and chemical properties of samples from sampled genetic horizons were characterized. Beach deposits were most clearly differentiated from other lithological groups, whereas most other groups overlapped strongly in observed properties. Whereas some lithological groups (e.g., sedimentary rock groups) were characterized largely by immature soils with little degree of pedogenesis, other sampled soils exhibited more development. The soil–parent material relationships of Snow Island revealed a unique setting of a complex heterogeneous landscape and show that the area has a great pedological complexity induced by phosphatization, melanization, and cryoturbation processes that preclude placing primary importance on parent material and lithology as the major controlling factor in Antarctic soils.
“…Since 2007, the project PALEOANTAR (organized by the Museu Nacional/Universidade Federal do Rio de Janeiro, Brazil) has been working in the Antarctic Peninsula to shed light on the diversification and evolutionary history of Antarctic ecosystems in the deep past (Lima et al 2021; Kellner 2022; Santos et al 2022), including studies on Mesozoic vertebrates (e.g., Kellner et al 2011, 2019; Brum et al 2022) and invertebrates (e.g., Pinheiro et al 2020; Videira-Santos 2020; Piovesan et al 2021). Here, we report on new ankylosaurian materials recovered from Antarctica during the PALEOANTAR expedition in 2015.…”
The body armor of ankylosaurians is a unique morphological feature among dinosaurs. While ankylosaurian body armor has been studied for decades, paleohistological analyses have only started to uncover the details of its function. Yet there has been an overall bias toward sampling ankylosaurian remains from the Northern Hemisphere, with limited quantitative studies on the morphological and functional evolution of the osteoderms composing their body armor. Here, we describe new ankylosaurian materials recovered from the Late Cretaceous of Antarctica that, in combination with data compiled from the literature, reveal new insights into the evolution of the ankylosaurian body armor. Based on histological microstructure and phylogenetic results, the new Antarctic material can be assigned to Nodosauridae. This group shares the absence/poor development of their osteodermal basal cortex and highly ordered sets of orthogonal structural fibers in the superficial cortex. Our morphospace analyses indicate that large morphological diversity is observed among both nodosaurids and ankylosaurids, but osteoderms became more functionally specialized in late-diverging nodosaurids. Besides acting as effective protection against predation, osteoderms also exhibit highly ordered structural fibers in nodosaurids, enabling a decrease in cortical bone thickness (as in titanosaurs), which could have been co-opted for secondary functions, such as calcium remobilization for physiological balance. The latter may have played a key role in nodosaurid colonization of high-latitude environments, such as Antarctica and the Arctic Circle.
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