Early Miocene climate estimations in Patagonia: The case of Pico Quemado, Ñirihuau Formation (Lower-Middle Miocene)

2018 ◽  
Vol 88 ◽  
pp. 64-71 ◽  
Author(s):  
Nicolás Caviglia
Keyword(s):  
Middle Miocene ◽  
Early Miocene

Foraminifera Biostratigraphy of Two Wells in Niger Delta

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Dairo VA
Keyword(s):  
Niger Delta ◽  
Middle Miocene ◽  
Early Miocene ◽  
Orbulina Universa ◽  
Exploratory Wells ◽  
Stratigraphic Range

Biostratigraphic studies of foraminifera were carried out on two exploratory wells drilled in the Eastern Niger Delta to establish the age, biozonation and paleoenvironment of the foraminifera present in the strata penetrated by the wells. A total of 80 ditch cutting samples retrieved at 60ft intervals from AX-1 and AX-2 Wells at the depth of 3,600ft to 6,000ft and 4,200ft to 6500ft. respectively were subjected to micropaleontological analysis which involves picking and identification of the foraminifera present. The resulting data were loaded into the Stratabug software and interpreted. The foraminifera recovered and identified from the two wells are made up of both benthic and planktic species. The marker species, whose stratigraphic range are well established were used to describe the biozonation and these includes Heterostegina sp, Catapsydrax stainforthi, Chiloguembelina victoriana, Orbulina universa/suturalis, Praeorbulina sicana,Buliminella subfusiformis, Nonion centrosulcatum, Catapsydrax dissimilis, Globigerinoides bisphericus and Globigerinoides sicanus. Four biozones of foraminifera made up of N8, N7-N8, N6-N7 and N5-N6 were recognised based on the zonation scheme of Grandstein; with their stratigraphic age ranging from early Miocene to middle Miocene. Furthermore, the environment of deposition prevailing in the Formations penetrated by the two wells are predominantly middle neritic with similarity in their ages as observed from the correlation of the biozones from the two wells

Middle Miocene recovery of Caribbean reef corals: New data from the Tamana Formation, Trinidad

2001 ◽  
Vol 75 (3) ◽  
pp. 513-526 ◽  
Author(s):  
Kenneth G. Johnson
Keyword(s):  
Middle Miocene ◽  
New Records ◽  
Early Miocene ◽  
Early Pleistocene ◽  
Reef Corals ◽  
Rigorous Description ◽  
Caribbean Coral Reef ◽  
The Caribbean ◽  
Stratigraphic Ranges ◽  
Biotic Change

Caribbean coral reef communities were restructured by episodes of accelerated biotic change during the late Oligocene/early Miocene and the late Pliocene/early Pleistocene. However, rigorous description of the effects of rapid biotic change is problematic because preservation and exposure of coral-bearing deposits is not consistent in all stratigraphic intervals. In the Caribbean, early and middle Miocene exposures are more rare than late Miocene and Pliocene exposures. One exception is the late early to early middle Miocene Tamana Formation of Trinidad, and old and new collections from this unit were studied to determine the timing of recovery after the Oligocene/Miocene transition. A total of 41 species of zooxanthellate corals were recovered from the unit, including 21 new records. Within these assemblages, species first occurrences outnumber species last occurrences by a factor of four (31 first occurrences and eight last occurrences). The extension of the stratigraphic ranges of species previously first recorded in Pliocene sediments has reduced an apparent Pliocene pulse of origination, indicating that the Pliocene/Pleistocene transition was largely a result of accelerated extinction against a background of near-constant origination. The fact that few species last occur in the Tamana fauna indicates that the Oligocene/Miocene transition was complete by the end of the early Miocene.

scholarly journals A mid-miocene age for the Slanci formation near Belgrade (Serbia), based on a record of the primitive antelope Eotragus cf. Clavatus from Visnjica

2007 ◽  
pp. 53-59
Author(s):  
der van ◽  
Slobodan Knezevic ◽  
Ivan Stefanovic
Keyword(s):  
Middle Miocene ◽  
Lacustrine Sediments ◽  
Early Miocene

In a borhole at Veliko Selo near Belgrade in the Miocene lacustrine sediments Slanci, which are locally known as the Slanacka Serija, a mammal tooth was found. The age of these deposits is under discussion. The fossil is here described and attributed with a query to the primitive antelope Eotragus clavatus (GERVAIS, 1850), which is suggestive of a Early Serravallian ("upper Badenian") or Early Middle Miocene age for these deposits, whereas an Aquitalian or Eggenburgian ("Egerian" or "Eggenburgian") (Early Miocene) age can be ruled out.

scholarly journals The distribution of <i>Triebelina raripila</i> and <i>Carinocythereis carinata</i> (Ostracoda) from the Middle Miocene of the Central Paratethys and their palaeogeographic implications

1998 ◽  
Vol 17 (2) ◽  
pp. 125-130 ◽  
Author(s):  
J. Szczechura
Keyword(s):  
Shallow Water ◽  
Late Miocene ◽  
Middle Miocene ◽  
Early Miocene ◽  
Central Paratethys ◽  
Eastern Paratethys ◽  
Main Species ◽  
Late Middle Miocene ◽  
The Mediterranean

Abstract. Late Middle Miocene (Upper Badenian) strata of the Fore-Carpathian Depression of Poland yield a shallow-water ostracod fauna which contains the species Triebelina raripila (G. W. Müller, 1894) and Carinocythereis carinata (Roemer, 1838). The palaeobiogeographic distribution of the two main species suggests, that in the late Middle Miocene, Central Paratethys was still connected to the Mediterranean, although still separated from the Eastern Paratethys and from southeastern Eurasia. The continuous occurrence of Triebelina raripila and Carinocythereis carinata in the Mediterranean basins, from the Early Miocene to Recent, indicates that marine conditions existed throughout, thereby allowing them to survive the Late Miocene salinity crisis.

scholarly journals A late Burdigalian bathyal mollusc fauna from the Vienna Basin (Slovakia)

2011 ◽  
Vol 62 (3) ◽  
pp. 211-231 ◽  
Author(s):  
Mathias Harzhauser ◽  
Oleg Mandic ◽  
Jan Schlögl
Keyword(s):  
New Species ◽  
Deep Water ◽  
Middle Miocene ◽  
Mediterranean Area ◽  
First Record ◽  
Early Miocene ◽  
Vienna Basin ◽  
Poor Knowledge ◽  
Central Paratethys ◽  
Aquitaine Basin

A late Burdigalian bathyal mollusc fauna from the Vienna Basin (Slovakia)This is the first record of a bathyal mollusc fauna from the late Early Miocene of the Central Paratethys. The assemblage shows clear affinities to coeval faunas of the Turin Hills in the Mediterranean area and the Aquitaine Basin in France. The overall biostratigraphic value of the assemblage is hard to estimate due to the general very poor knowledge of Miocene bathyal faunas. Several species, however, are known from deep water deposits of the Middle Miocene Badenian stage as well. This implies Early Miocene roots of parts of the Middle Miocene deep water fauna and suggests a low turnover for bathyal mollusc communities at the Early-Middle Miocene boundary. The nassariid gastropodNassarius janschloegliHarzhauser nov. sp. and the naticid gastropodPolinices cerovaensisHarzhauser nov. sp. are introduced as new species.

scholarly journals A new fossil dolphin Dilophodelphis fordycei provides insight into the evolution of supraorbital crests in Platanistoidea (Mammalia, Cetacea)

2017 ◽  
Vol 4 (5) ◽  
pp. 170022 ◽  
Author(s):  
Alexandra T. Boersma ◽  
Matthew R. McCurry ◽  
Nicholas D. Pyenson
Keyword(s):  
South Asian ◽  
Middle Miocene ◽  
Sound Propagation ◽  
Early Miocene ◽  
New Taxon ◽  
Internal Morphology ◽  
Computed Tomography Scans ◽  
Evolutionary Context ◽  
And Function ◽  
Insight Into

Many odontocete groups have developed enlarged facial crests, although these crests differ in topography, composition and function. The most elaborate crests occur in the South Asian river dolphin ( Platanista gangetica ), in which they rise dorsally as delicate, pneumatized wings anterior of the facial bones. Their position wrapping around the melon suggests their involvement in sound propagation for echolocation. To better understand the origin of crests in this lineage, we examined facial crests among fossil and living Platanistoidea, including a new taxon, Dilophodelphis fordycei , nov. gen. and sp., described herein, from the Early Miocene Astoria Formation of Oregon, USA. We measured the physical extent and thickness of platanistoid crests, categorized their relative position and used computed tomography scans to examine their internal morphology and relative bone density. Integrating these traits in a phylogenetic context, we determined that the onset of crest elaboration or enlargement and the evolution of crest pneumatization among the platanistoids were separate events, with crest enlargement beginning in the Oligocene. However, we find no evidence for pneumatization until possibly the Early Miocene, although certainly by the Middle Miocene. Such an evolutionary context, including data from the fossil record, should inform modelling efforts that seek to understand the diversity of sound generation morphology in Odontoceti.

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 Revision of the European species of Prosantorhinus (Mammalia, Perissodactyla, Rhinocerotidae)

2017 ◽  
Vol 73 (3-4) ◽  
pp. 236-274
Author(s):  
Kurt Heissig
Keyword(s):  
Type Species ◽  
Western Europe ◽  
Middle Miocene ◽  
Early Miocene ◽  
Distal Limb ◽  
European Species ◽  
Medium Length ◽  
Distal Side ◽  
Upper Molar

t is not size that distinguishes the genus Prosantorhinus from Diaceratherium , but the following characters: a concave dorsal skull profile with upslanting nasals and narrowing on the distal side of the last upper molar. Using these characters, in addition to the type species Prosantorhinus germanicus (), the following species can be added to the genus: Prosantorhinus douvillei () (, .), from the Early and Middle Miocene (MN 3–5) of Western Europe, Prosantorhinus laubei from MN 3 of northern Bohemia, Prosantorhinus aurelianensis () from MN 3–4a of Western Europe, and with some reservation “Rhinoceros” tagicus (), an enigmatic species from the Early Miocene (MN 3) of Portugal, known only by its upper cheek teeth. At the beginning of MN 3 (), the metapodials of Prosantorhinus aurelianensis were considerably more robust than those of the latest Diaceratherium species (Laugnac, MN 2b) (.) Within the genus shortening of the distal limb segments and narrowing of the distal side of M3 increased with time. The metapodials of Prosantorhinus laubei are less robust but of medium length, in contrast to the Middle Miocene (MN 5) Prosantorhinus germanicus in which they are extremely shortened. No transitional species or co-occurrence of Diaceratherium and Prosantorhinus are known.

Biostratigraphically constrained Neogene palaeoenvironments of the Red Sea rift

2021 ◽  
Author(s):  
Geraint Hughes ◽  
Osman Varol
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Debris Flows ◽  
Middle Miocene ◽  
Depositional Environments ◽  
Early Miocene ◽  
Arabian Plate ◽  
Tectonic Activity ◽  
Gulf Of Suez ◽  
Gulf Of Aden

&lt;p&gt;Marine sediments deposited in response to the Neogene opening of the Red Sea during divergence of the African-Arabian plate margin provide micropalaeontological chronological evidence to calibrate synchronous palaeoenvironmental events from the Gulf of Suez to the Gulf of Aden. This facility provides insights to the timing and relative rates of tectonic subsidence associated with the rifting episodes of the region. Biostratigraphic index forms include planktonic and benthonic foraminifera and calcareous nannofossils. These, combined with various associated microfossils and macrofossil fragments, permit interpretation of a range of depositional environments that span intertidal to bathyal regimes. Onset and recovery from various hypersaline events are similarly interpreted by integrating microfossils and lithology. Following an episode of emergence and sporadic volcanicity, subsidence and the first Neogene marine transgression created brackish to shallow marine lagoons during the Early Miocene (Foraminiferal Letter Stage Upper Te). Rapid subsidence and accumulation of deep marine mudstones, of local hydrocarbon source-rock quality, with thinly interbedded siliciclastic and calciclastic debris flows commenced in the Early Miocene (Planktonic foraminiferal zones N5-N8; Nannofossil zones NN3-NN5). The debris flows increased in abundance and provide good hydrocarbon reservoirs. The Gulf of Suez and Red Sea experienced episodic isolation from the Indian Ocean during the latest Early Miocene and earliest Middle Miocene (Planktonic foraminiferal zones N8-N9; Nannofossil zone NN5 Foraminiferal Letter Stage Middle-Upper Tf1), resulting in hypersaline events with precipitation of submarine gypsum and halite. The isolation is attributed to constriction of the southern Red Sea, in the vicinity of the Bab El Mandab Straits, by eustatic sea level fall as well as probable tectonic activity; the synchronous Gulf of Aden succession does not display evidence for such hypersaline events. A prolonged hypersaline phase extended over most of the Middle Miocene, for which absence of biostratigraphic data precludes age control. During the latest Middle Miocene to Late Miocene, rejuvenation of the hinterland cause rapid deposition of terrestrial and fluviatile coarse and fine siliciclastics, with similar biostratigraphic paucity except for rare diatoms and palynomorphs. Renewed subsidence, associated with opening of the Aqaba Fault, combined with eustatic sea level rise caused marine deposition to recommence in the Pliocene.&lt;/p&gt;

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.

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