THE INFLUENCE OF DEPOSITIONAL ENVIRONMENT AND BASIN HISTORY ON THE TAPHONOMY OF MAMMALIAN ASSEMBLAGES FROM THE BARSTOW FORMATION (MIDDLE MIOCENE), CALIFORNIA

Palaios ◽  
2020 ◽  
Vol 35 (4) ◽  
pp. 175-190
Author(s):  
KATHARINE M. LOUGHNEY ◽  
CATHERINE BADGLEY
Keyword(s):  
Middle Miocene ◽  
Element Composition ◽  
Depositional Environments ◽  
Skeletal Element ◽  
Ephemeral Wetland ◽  
Facies Associations ◽  
History Of ◽  
Fossil Assemblages ◽  
Depositional Setting ◽  
Barstow Formation

ABSTRACT The Barstow Formation in the Mojave region of California was deposited in an extensional-basin setting of the Basin and Range province and preserves diverse middle Miocene mammalian assemblages. Six facies associations represent the dominant depositional environments in the basin, which changed through time from alluvial-fan and playa-dominated settings to floodplains and spring-fed wetlands. The majority of fossil localities and specimens occur in later-forming facies associations. We analyzed the taphonomic characteristics of fossil assemblages to test whether basin-scale facies associations or locality-scale facies exert more control on the preservational features of mammalian assemblages through the formation. We documented the facies settings of 47 vertebrate localities in the field in order to interpret depositional setting and the mode of accumulation for fossil assemblages. We evaluated skeletal material in museum collections for taphonomic indicators, including weathering stage, original bone-damage patterns, hydraulic equivalence, and skeletal-element composition. We evaluated four alternative modes of accumulation, including attritional accumulation on the land surface, accumulation by fluvial processes, carnivore or scavenger accumulations, and mass-death events. The majority of localities represent attritional accumulations at sites of long-term mortality in channel-margin, abandoned-channel, poorly drained floodplain, and ephemeral-wetland settings. Skeletal-element composition and taphonomic characteristics varied among facies, indicating an important role for depositional setting and landscape position on fossil-assemblage preservation. We find that locality-scale facies have a greater influence on the taphonomic characteristics of fossil assemblages; the taphonomy of each facies association is influenced by the facies that compose it. The facies composition and distribution within facies associations change through the formation, with a greater variety of depositional settings forming later in the history of the basin. Heterogeneous landscapes present more settings for fossil accumulation, contributing to the increase in fossil occurrence through the depositional history of the formation.

scholarly journals Taphonomic analysis of saurischian dinosaurs from the Plottier Formation (Upper Cretaceous), Mendoza, Argentina

2019 ◽  
Vol 46 (2) ◽  
pp. 345 ◽  
Author(s):  
Elena Previtera
Keyword(s):  
Upper Cretaceous ◽  
Holistic Approach ◽  
Depositional Environments ◽  
Continental Deposits ◽  
Wide Range ◽  
History Of ◽  
Fossil Assemblages ◽  
Vertebrate Assemblage ◽  
Taphonomic Analysis ◽  
Fluvial Environments

The uppermost Cretaceous continental deposits of the Neuquén Basin (west-central Argentina) have yielded a high diversity vertebrate assemblage, including numerous dinosaur species. The Neuquén Group is the richest unit in remains of dinosaur of the basin and comprises the Río Limay, the Río Neuquén and the Río Colorado subgroups. In this group, there is abundance of isolated, disarticulated or partially articulated sauropods and theropods. However, little is known about the taphonomic history of fossil assemblages. In this study, dinosaur remains from the Plottier Formation (late Coniacian-early Santonian) found in the Cerro Guillermo area in southern Mendoza are examined. The investigation of fossil occurrences within the study area revealed the existence of different taphonomic modes, from isolated bones until partially articulated skeletons preserved in deposits of floodplain and fluvial channel settings. SEM-EDS analysis showed the substitution of hydroxyapatite by francolite in the bone microstructure. The presence of fluorine-in one of the cases-suggested a link between the elemental composition and depositional environments: floodplain and fluvial channel. The survey of the vertebrate accumulation types and their sedimentary context allowed documenting a wide range of processes responsible for their genesis, operating within a meandering fluvial environment. This contribution represents a holistic approach about taphonomic history of Cretaceous dinosaurs for assessing the differential preservation of fossil assemblages in fluvial environments.

scholarly journals The Tumblagooda Sandstone revisited: exceptionally abundant trace fossils and geological outcrop provide a window onto Palaeozoic littoral habitats before invertebrate terrestrialization

2020 ◽  
Vol 157 (12) ◽  
pp. 1939-1970
Author(s):  
Anthony P. Shillito ◽  
Neil S. Davies
Keyword(s):  
Trace Fossil ◽  
Left Behind ◽  
Depositional Settings ◽  
Facies Associations ◽  
History Of ◽  
Lower Palaeozoic ◽  
Marine Influence ◽  
Early Palaeozoic ◽  
Animal Communities ◽  
Depositional Setting

AbstractThe establishment of permanent animal communities on land was a defining event in the history of evolution, and one for which the ichnofauna and facies of the Tumblagooda Sandstone of Western Australia have been considered an archetypal case study. However, terrestrialization can only be understood from the rock record with conclusive sedimentological evidence for non-marine deposition, and original fieldwork on the formation shows that a marine influence was pervasive throughout all trace fossil-bearing strata. Four distinct facies associations are described, deposited in fluvial, tidal and estuarine settings. Here we explain the controversies surrounding the age and depositional environment of the Tumblagooda Sandstone, many of which have arisen due to the challenges in distinguishing marine from non-marine depositional settings in lower Palaeozoic successions. We clarify the terminological inconsistency that has hindered such determination, and demonstrate how palaeoenvironmental explanations can be expanded out from unambiguously indicative sedimentary structures. The Tumblagooda Sandstone provides a unique insight into an early Palaeozoic ichnofauna that was strongly partitioned by patchy resource distribution in a littoral setting. The influence of outcrop style and quality is accounted for to contextualize this ichnofauna, revealing six distinct low-disparity groups of trace fossil associations, each related to a different sub-environment within the high-ichnodisparity broad depositional setting. The formation is compared with contemporaneous ichnofaunas to examine its continued significance to understanding the terrestrialization process. Despite not recording permanent non-marine communities, the Tumblagooda Sandstone provides a detailed picture of the realm left behind by the first invertebrate pioneers of terrestrialization.

scholarly journals Facies Analysis Of The Late Eocene Deep-Marine Middle- To Outer-Fan Sequence Of The Crocker Formation In Tenom District, Sabah, Malaysia

2021 ◽  
Vol 72 ◽  
pp. 47-62
Author(s):  
Muhd Nur Ismail Abdul Rahman ◽  
◽  
Hafeez Jeofry ◽  
Muhammad Abdullah ◽  
Ismail Abd Rahim ◽  
...  
Keyword(s):  
Marine Environment ◽  
Middle Miocene ◽  
Facies Analysis ◽  
Turbidity Current ◽  
Late Eocene ◽  
Depositional Environments ◽  
Facies Associations ◽  
Bed Form ◽  
Distal Lobe

The Crocker Formation, Late Eocene to Middle Miocene in age, was deposited in a deep-marine environment by a turbidity current. Most of the facies identified in the field are related to the sedimentary bed-form structures belonging to Bouma sequences. These prominently include unit divisions such as Ta referring to grading sand, Tb for parallel laminae, Tc for cross laminae, Td for mud laminae, and Te referring to hemipelagic mud. Five facies have adequately been identified using Bouma sequence implications, namely Facies 1 (F1: Ta-Tb layers), Facies 2 (F2: Ta-Te layers), Facies 3 (F3: Tb-Te layers), Facies 4 (F4: Tb / Tc-Te layers), and Facies 5 (F5: Td-Te layers). Based on the Crocker Formation facies analysis, three distinct groups of facies associations were recognised: Deep-Marine Channel-Lobe Association (Type A1), Deep-Marine Channel-Levee Association (Type A2), and Distal Lobe Association. These facies associations precisely revealed that the Crocker Formation's depositional environments were likely deposited in the middle-fan with associated outer-fan settings.

scholarly journals Multilocus phylogeny and historical biogeography of Hypostomus shed light on the processes of fish diversification in La Plata Basin

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yamila P. Cardoso ◽  
Luiz Jardim de Queiroz ◽  
Ilham A. Bahechar ◽  
Paula E. Posadas ◽  
Juan I. Montoya-Burgos
Keyword(s):  
Middle Miocene ◽  
Drainage Pattern ◽  
Ecological Diversification ◽  
La Plata ◽  
La Plata Basin ◽  
History Of ◽  
Dispersal Corridors ◽  
Shed Light ◽  
Strong Barrier ◽  
Multilocus Phylogeny

AbstractDistribution history of the widespread Neotropical genus Hypostomus was studied to shed light on the processes that shaped species diversity. We inferred a calibrated phylogeny, ancestral habitat preference, ancestral areas distribution, and the history of dispersal and vicariance events of this genus. The phylogenetic and distribution analyses indicate that Hypostomus species inhabiting La Plata Basin do not form a monophyletic clade, suggesting that several unrelated ancestral species colonized this basin in the Miocene. Dispersal to other rivers of La Plata Basin started about 8 Mya, followed by habitat shifts and an increased rate of cladogenesis. Amazonian Hypostomus species colonized La Plata Basin several times in the Middle Miocene, probably via the Upper Paraná and the Paraguay rivers that acted as dispersal corridors. During the Miocene, La Plata Basin experienced marine incursions, and geomorphological and climatic changes that reconfigured its drainage pattern, driving dispersal and diversification of Hypostomus. The Miocene marine incursion was a strong barrier and its retraction triggered Hypostomus dispersal, increased speciation rate and ecological diversification. The timing of hydrogeological changes in La Plata Basin coincides well with Hypostomus cladogenetic events, indicating that the history of this basin has acted on the diversification of its biota.

LITHOLOGICAL AND PALEOCOMMUNITY VARIATION ON A MISSISSIPPIAN (TOURNAISIAN) CARBONATE RAMP, MONTANA, USA

Palaios ◽  
2021 ◽  
Vol 36 (3) ◽  
pp. 95-114
Author(s):  
GARETT M. BROWN
Keyword(s):  
Cluster Analysis ◽  
Environmental Gradients ◽  
Depositional Environments ◽  
Third Order ◽  
Depositional Sequence ◽  
Heterogeneous Distribution ◽  
Point Count ◽  
Sediment Types ◽  
Fossil Assemblages ◽  
Replicate Sampling

ABSTRACT The ecological structure of ancient marine communities is impacted by the environmental gradients controlling assemblage compositions and the heterogeneous distribution of sediment types. Closely spaced, replicate sampling of fauna has been suggested to mitigate the effects of such heterogeneity and improve gradient analyses, but this technique has rarely been combined with similar sampling of lithologic data. This study analyses lithological and faunal data to determine the environmental gradients controlling the composition of Mississippian fossil assemblages of the lower Madison Group in Montana. Eighty-one lithological and faunal samples were collected from four stratigraphic columns in Montana, which represent the deep-subtidal, foreshoal, and ooid-shoal depositional environments within one third-order depositional sequence. Cluster analysis identifies three distinct lithological associations across all depositional environments—crinoid-dominated carbonates, peloidal-crinoidal carbonates, and micritic-crinoidal carbonates. Cluster analysis and nonmetric multidimensional scaling (NMS) identifies a highly diverse brachiopod biofacies and a solitary coral-dominated biofacies along an onshore-offshore gradient. Carbonate point count data and orientation of solitary corals indicate that substrate and wave energy are two potential variables that covary with the onshore-offshore gradient. Overlaying lithological information on the NMS indicates a secondary gradient reflecting oxygen that is expressed by increasing bioturbation and gradation from brown to dark gray carbonates to medium-light gray carbonates. Taken together, these findings demonstrates how combining closely spaced, replicate sampling of lithologic and faunal data enhances multivariate analyses by uncovering underlying environmental gradients that control the variation in fossil assemblages.

Structures megametriques et evolution de la mer Tyrrhenienne et des zones perityrrheniennes

1962 ◽  
Vol S7-IV (5) ◽  
pp. 760-773 ◽  
Author(s):  
Claude Grandjacquet
Keyword(s):  
Large Scale ◽  
Middle Miocene ◽  
Southern Italy ◽  
Western Mediterranean ◽  
Tyrrhenian Sea ◽  
African Continent ◽  
Lower Eocene ◽  
Structural History ◽  
History Of

Abstract A large view of the evolution and structural history of the Tyrrhenian sea and bordering areas suggests that towards the end of the Permian distensions occurring in the western Mediterranean resulted in the opening of a passage to the Atlantic. Lower Eocene deformations along the Sicilian-Tunisian front were either due to local marginal disequilibrium or to the northern drift of the African continent. Oligocene emergence is evident in the Apennines and in Calabria through the existence of widespread hiatuses and by bauxitic and ferruginous beds. Large scale Oligocene movements brought the African continent to its maximum proximity with Europe. It was in the same period that the clay scaglia and flysch nappes began sliding in Tuscany although the movement of Calabrian nappes in southern Italy did not occur until the lower and middle Miocene.

The Middle Miocene of the Fore-Carpathian Basin (Poland, Ukraine and Moldova)

2016 ◽  
Vol 66 (3) ◽  
pp. 359-409 ◽  
Author(s):  
Anna Wysocka ◽  
Andrzej Radwański ◽  
Marcin Górka ◽  
Maciej Bąbel ◽  
Urszula Radwańska ◽  
...  
Keyword(s):  
Water Chemistry ◽  
Large Scale ◽  
Middle Miocene ◽  
Carpathian Basin ◽  
Post Mortem ◽  
Sedimentary Processes ◽  
Shallow Marine ◽  
Fossil Assemblages ◽  
The University ◽  
Sand Bodies

Abstract Studies of Miocene sediments in the Fore-Carpathian Basin, conducted by geologists from the University of Warsaw have provided new insights on the distribution of the facies infilling the basin, particularly in the forebulge and back-bulge zones. The origin of the large-scale sand bodies, evaporitic deposits and large-scale organic buildups is discussed, described and verified. These deposits originated in variable, shallow marine settings, differing in their water chemistry and the dynamics of sedimentary processes, and are unique with regard to the fossil assemblages they yield. Many years of taxonomic, biostratigraphic, palaeoecologic and ecotaphonomic investigations have resulted in the identification of the fossil assemblages of these sediments, their age, sedimentary settings and post-mortem conditions. Detailed studies were focused on corals, polychaetes, most classes of molluscs, crustaceans, echinoderms, and fishes.

APPROACHES TO PALAEOGEOGRAPHIC RECONSTRUCTIONS OF THE LATROBE GROUP, GIPPSLAND BASIN, SOUTHEASTERN AUSTRALIA

2005 ◽  
Vol 45 (1) ◽  
pp. 581 ◽  
Author(s):  
T. Bernecker ◽  
A.D. Partridge
Keyword(s):  
Co2 Storage ◽  
Depositional Environments ◽  
Petroleum Systems ◽  
Fine Grained ◽  
Southeastern Australia ◽  
Depositional System ◽  
Facies Associations ◽  
Marine Fossils ◽  
Coal Accumulation ◽  
Gippsland Basin

In the Gippsland Basin, the seaward extent of paralic coal occurrences can be mapped in successive time slices through the Paleocene and Eocene to provide a series of straight to gently arcuate surrogate palaeoshorelines within the petroliferous Latrobe Group. Palaeogeographic reconstructions that incorporate this information provide a unique perspective on the changes affecting a siliciclastic depositional system on a passive continental margin where basin development has been primarily controlled by thermal sag. In contrast, the absence of calcareous marine fossils and lack of extensive, widespread and thick fine-grained sediments on the marine shelf and continental slope, beyond the seaward limits of coal accumulation, have contributed to the false impression that the Latrobe Group accumulated in a largely non-marine basin. Based on the proposed model for palaeoshoreline delineation, seismic data, sequence analysis, petrography and palynology can be integrated to subdivide the main depositional environments into distinct facies associations that can be used to predict the distribution of petroleum systems elements in the basin. The application of such palaeogeographic models to the older section of the Latrobe Group can improve the identification of these petroleum systems elements in as yet unexplored parts of the Gippsland Basin. Given the recent attention paid to the basin as a CO2 storage province, palaeogeographic interpretations may be able to assist with the selection of appropriate injection sites.

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