scholarly journals THE UPPER PALEOGENE AND NEOGENE DEPOSITS IN THE SAMAKHINSKAYA AND DZHAZATOR DEPRESSIONS OF THE SOUTHEAST PART OF GORNYI ALTAI

2021 ◽  
Vol 2 (1) ◽  
pp. 118-124
Author(s):  
Olga B. Kuzmina ◽  
Gennady G. Rusanov ◽  
Marina V. Micharevich
Keyword(s):  
Middle Miocene ◽  
Late Oligocene ◽  
Gorny Altai ◽  
Gornyi Altai ◽  
Upper Paleogene

The paper provides geological description and the results of palynological and carpological studies of natural outcrops of the Koshagach Formation, exposed in the sides of the Samakhinskaya and the Dzhazator depressions in the southeast of Gorny Altai. The deposits are dated to the Early-Middle Miocene. Older layers of the formation corresponding to the Late Oligocene have not been identified.

Variations in elemental and mineralogical compositions of Late Oligocene, Early and Middle Miocene coal seams in the Kale-Tavas Molasse sub-basin, SW Turkey

2020 ◽  
Vol 218 ◽  
pp. 103366 ◽  
Author(s):  
Ali Ihsan Karayigit ◽  
Mustafa Atalay ◽  
Rıza Görkem Oskay ◽  
Patricia Córdoba ◽  
Xavier Querol ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Late Oligocene ◽  
Coal Seams ◽  
Sw Turkey ◽  
Mineralogical Compositions

scholarly journals Re-study of some dinoflagellate cysts from the Oligocene and Miocene of Germany

1984 ◽  
Vol 3 (2) ◽  
pp. 73-94 ◽  
Author(s):  
William A. S. Sarjeant
Keyword(s):  
Middle Miocene ◽  
Type Material ◽  
New Combination ◽  
Late Oligocene ◽  
Dinoflagellate Cysts ◽  
Dinoflagellate Cyst ◽  
Northwest Germany ◽  
Senior Synonym ◽  
First Time

Abstract. The type material of six dinoflagellate cyst species from the Late Oligocene to Middle Miocene of northwest Germany, described originally by Gerlach (1961), is reillustrated and redescribed. It is shown to include representatives of nine species. Areosphaeridium (ex: Baltisphaeridium) pectiniforme is found to be a senior synonym of Areosphaeridium multicornutum Eaton. Systematophora placacantha is considered to be a senior synonym of Cleistosphaeridium (ex: Baltisphaeridium) panniforme (Gerlach). The new combination Rhynchodiniopsis tenuitabulata (Gerlarch) is proposed. Revised diagnoses for these three species and for Leptodinium membranigerum (Gerlach), Achomosphaera triangulata (Gerlach) and Lejeunecysta hyalina (Gerlach) are proposed. The morphology of a form described here for the first time, and tentatively attributed to Phthanoperidinium, is considered perhaps to imply a separate origin for the Phthanoperidiniaceae: for that reason familial, rather than tribal, rank is preferred for that group. The stratigraphical ranges of the nine species here recognised and of two others of Gerlach’s species redescribed in earlier papers are detailed; elimination of misattributed forms means that these ranges are shorter than the published literature suggests.

Development of the New Hebrides archipelago

1975 ◽  
Vol 272 (918) ◽  
pp. 277-285 ◽  
Keyword(s):  
Late Miocene ◽  
Middle Miocene ◽  
First Episode ◽  
Late Oligocene ◽  
Calc Alkaline ◽  
Land Area ◽  
Early Pliocene ◽  
The Third ◽  
New Hebrides ◽  
Volcanic Islands

The general geology of the New Hebrides is summarized in terms of three volcanic and two main sedimentary episodes. Calc-alkaline volcanics ol the first episode occur on the western islands and accumulated mainly on the submarine slopes below small reef-fringed volcanic islands in Late Oligocene to Middle Miocene times. During the Late Miocene and Early Pliocene wholly submarine tholeiitic or high-Al volcanics accumulated in the eastern and southern part of the New Hebrides while calcareous sediments were forming in the western islands. During the third volcanic phase, of Pliocene to Recent age, regional uplift has led to most of the volcanics being subaerial while extensive flights of limestone terraces occur round the older islands. In consequence the land area of the New Hebrides has increased rapidly during Quaternary times. The landforms produced are briefly described.

scholarly journals Diversity and biostratigraphy of the late Oligocene-late Miocene sand dollars (Echinoidea: Scutelliformes) of Argentina and Uruguay

2021 ◽  
Vol 69 (Suppl.1) ◽  
pp. 35-50
Author(s):  
Claudia-J. Del Río ◽  
Sergio Martínez
Keyword(s):  
South America ◽  
Late Miocene ◽  
Middle Miocene ◽  
Field Work ◽  
Early Miocene ◽  
Late Oligocene ◽  
Good Correspondence ◽  
Shallow Marine ◽  
Sand Dollars ◽  
Temporal Dimensions

Introduction: Scutelliforms were diverse and widespread in shallow marine environments during Neogene times in South America. Nevertheless, they have almost never been used as biostratigraphic tools. Objective: To provide a refined stratigraphic frame useful for calibrating temporal dimensions of scutelliform diversity from Argentina and Uruguay and its correlation with the molluscan assemblages previously proposed. Methods: A detailed survey of their geographic and stratigraphic provenance was carried out. We revised both the bibliography and collections (institutional and from our own field work). Results: The group is represented by 14 species belonging to six genera, and four assemblages were identified. Numerical dates of the Neogene marine rocks obtained recently allowed their placement in a chronological scheme: “Iheringiella” sp. A is restricted to the late Oligocene, the genera Camachoaster and “Eoscutella” and the species Monophoraster telfordi to the early Miocene, Abertella gualichensis and Abertella miskellyi to the middle Miocene, and Monophoraster duboisi, Amplaster coloniensis and Amplaster ellipticus to the late Miocene. Non-lunulate scutelliforms are not restricted to the late Oligocene as previously supposed. The oldest occurrence of the genus Monophoraster corresponds to the early Miocene, and along with Iheringiella are long-living taxa that embrace the 25.3 Ma-18.1 Ma (Iheringiella patagonensis) and approximately 15 Ma-6.48 Ma (Monophoraster darwini) intervals. The presence of Iheringiella in the early Miocene of northeastern Patagonia is corroborated, reaching there its northernmost distribution. Monophoraster darwini has a temporal range from the late Miocene (where it was previously thought to be restricted) back to the middle Miocene, since this is the species yielded in the well-known and discussed “Monophoraster and Venericor Beds”. Conclusions: The Paleogene-Neogene scutelliforms of Argentina and Uruguay range from the late Oligocene to the late Miocene. There is a good correspondence among the numerical ages, molluscan biozones and scutelliform assemblages.

scholarly journals The biochronology and palaeobiogeography of Baru (Crocodylia: Mekosuchinae) based on new specimens from the Northern Territory and Queensland, Australia

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3458 ◽  
Author(s):  
Adam M. Yates
Keyword(s):  
Middle Miocene ◽  
New Records ◽  
Drainage System ◽  
Northern Territory ◽  
Valid Species ◽  
Late Oligocene ◽  
Drainage Basins ◽  
Local Fauna ◽  
The North ◽  
North Western

New records of the Oligo–Miocene mekosuchine crocodylian, Baru, from Queensland and the Northern Territory are described. Baru wickeni and Baru darrowi are accepted as valid species in the genus and their diagnoses are revised. Both species are present in Queensland and the Northern Territory but are restricted in time, with B. wickeni known from the late Oligocene and B. darrowi from the middle Miocene. The broad geographic distributions and restricted time spans of these species indicate that this genus is useful for biochronology. The record of B. wickeni from the Pwerte Marnte Marnte Local Fauna in the Northern Territory establishes that the species inhabited the north-western margin of the Lake Eyre Basin (LEB) drainage system. More southerly Oligo–Miocene sites in the LEB contain only one crocodylian species, Australosuchus clarkae. The Pwerte Marnte Marnte occurrence of B. wickeni indicates that the separation of Baru and Australosuchus did not correspond with the boundaries of drainage basins and that palaeolatitude was a more likely segregating factor.

scholarly journals Mid-Tertiary paleoenvironments in Thailand: pollen evidence

2010 ◽  
Vol 6 (4) ◽  
pp. 461-473 ◽  
Author(s):  
P. Sepulchre ◽  
D. Jolly ◽  
S. Ducrocq ◽  
Y. Chaimanee ◽  
J.-J. Jaeger ◽  
...  
Keyword(s):  
Middle Miocene ◽  
High Variability ◽  
Late Oligocene ◽  
Climate Variations ◽  
Tropical Environments ◽  
Palynological Assemblages ◽  
Tropical Woodlands ◽  
Mae Moh ◽  
Warm Temperate ◽  
Northeastern Thailand

Abstract. Only few well-dated records document the evolution of Southeast Asian paleoenvironments during the Cenozoic. Here we analyse continental pollen assemblages from Late Oligocene and Miocene fossil sites of Thailand. In agreement with previous studies, palynoflora from the Oligocene suggests warm temperate forested habitats at 24–26 Ma, whereas Middle Miocene assemblages are made of thermophilous taxa. This change can be linked to the major climate reorganization that brought warmer and wetter conditions over Southeast Asia around 22 Ma. This study also provides the first submillional records from the Middle Miocene of Thailand. Thirteen samples of lignite layers from the sivaladapid-bearing Mae Moh site, dated between 13.3 and 13.1 Ma, and six samples from the hominoid-bearing Chiang Muan deposit, dated between 12.4 and 12.2 Ma, document oscillations between tropical woodlands and grasslands in northern Thailand. These pollen records likely reflect climate variations linked to insolation variations. Late Miocene palynological assemblages from Khorat, northeastern Thailand, document fluviolacustrine paleoenvironments alternatively covered by thermophilous trees and grasslands. These records show that both sivaladapids and early hominoids from Thailand have evolved in tropical environments with high variability in the vegetation cover.

scholarly journals Petrography and palynology of Late Oligocene and Middle Miocene coals in the Gelibolu peninsula, NW Turkey

2015 ◽  
Vol 24 ◽  
pp. 383-397 ◽  
Author(s):  
Ferdi DEMİRTAŞ ◽  
Mustafa BOZCU ◽  
Erdal KOŞUN ◽  
Mehmet Serkan AKKİRAZ
Keyword(s):  
Middle Miocene ◽  
Late Oligocene ◽  
Nw Turkey

Tertiary marine molluscan assemblages of eastern Patagonia (Argentina): A biostratigraphic analysis

2004 ◽  
Vol 78 (6) ◽  
pp. 1097-1122 ◽  
Author(s):  
Claudia Julia del Río
Keyword(s):  
Late Miocene ◽  
Middle Miocene ◽  
Late Eocene ◽  
Early Miocene ◽  
Late Oligocene ◽  
Late Paleocene ◽  
Compositional Changes ◽  
Molluscan Species

Pectinids are the most abundant and widely distributed taxa in the Tertiary marine beds of Patagonia. Along with other very common molluscan species, they characterize five assemblages, from oldest to youngest: 1) the Oligocene Panopea sierrana-Parinomya patagonensis Assemblage; 2) the Late Oligocene–Early Miocene Jorgechlamys centralis–Reticulochlamys borjasensis Assemblage; 3) the Early Miocene Reticulochlamys zinsmeisteri–Struthiolarella patagoniensis–Pleuromeris cruzensis Assemblage; 4) the Early Miocene Pseudoportlandia glabra–Antimelatoma quemadensis Assemblage; and 5) the latest Early Miocene–earliest Middle Miocene Nodipecten sp.–Venericor abasolensis–Glycymerita camaronesia Assemblage. A brief analysis of the origin and composition of these Tertiary Patagonian molluscan faunas is provided. Striking compositional changes occurred through time, recorded mainly in the Late Paleocene, Late Eocene, Late Oligocene–Early Miocene, and Late Miocene.

scholarly journals New information about the skull and dentary of the Miocene platypus Obdurodon dicksoni , and a discussion of ornithorhynchid relationships

1998 ◽  
Vol 353 (1372) ◽  
pp. 1063-1079 ◽  
Author(s):  
A. M. Musser ◽  
M. Archer
Keyword(s):  
Comparative Study ◽  
Middle Miocene ◽  
Coronoid Process ◽  
Dental Material ◽  
Late Oligocene ◽  
Basic Form ◽  
New Information ◽  
Ornithorhynchus Anatinus ◽  
Diet And Lifestyle ◽  
Angular Process

A reconstruction of the skull, dentary and dentition of the middle Miocene ornithorhynchid Obdurodon dicksoni has been made possible by acquisition of nearly complete cranial and dental material. Access to new anatomical work on the living platypus, Ornithorhynchus anatinus , and the present comparative study of the cranial foramina of Ob. dicksoni and Or. anatinus have provided new insights into the evolution of the ornithorhynchid skull. The hypertrophied bill in Ob. dicksoni is seen here as possibly apomorphic, although evidence from ontogenetic studies of Or. anatinus suggests that the basic form of the bill in Ob. dicksoni (where the rostral crura meet at the midline) may be ancestral to the form of the bill in Or. anatinus (where the rostral crura meet at the midline in the embryonic platypus but diverge in the adult). Differences in the relative positions of cranial structures, and in the relationships of certain cranial foramina, indicate that the cranium may have become secondarily shortened in Or. anatinus , possibly evolving from a more elongate skull type such as that of Ob. dicksoni . The plesiomorphic dentary of Ob. dicksoni , with well–developed coronoid and angular processes, contrasts with the dentary of Or. anatinus , in which the processes are almost vestigial, as well as with the dentary of the late Oligocene, congeneric Ob. insignis , in which the angular process appears to be reduced (the coronoid process is missing). In this regard the dentary of Ob. insignis seems to be morphologically closer to Or. anatinus than is the dentary of the younger Ob. dicksoni . Phylogenetic conclusions differ from previous analyses in viewing the northern Australian Ob. dicksoni as possibly derived in possessing a hypertrophied bill and dorsoventrally flattened skull and dentary, perhaps being a specialized branch of the Obdurodon line rather than ancestral to species of Ornithorhynchus . The presence of functional teeth and the robust, flattened skull and dentary in Ob. dicksoni argue for differences in diet and lifestyle between this extinct ornithorhynchid and the living Ornithorhynchus .

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