نتایج جستجو برای: middle miocene
تعداد نتایج: 160101 فیلتر نتایج به سال:
Eastern Asia (EA) is a key region for the diversification of flowering plants in the Northern Hemisphere, but few studies have focused on the biogeographic history within EA in the context of the other northern continents. Polygonatum is an important medicinal genus widely distributed in the Northern Hemisphere with its highest species richness in EA, and it represents an excellent model for st...
Climatic and environmental shifts have had profound impacts on faunal and floral assemblages globally since the end of the Miocene. We explore the regional expression of these fluctuations in southwestern Europe by constructing long-term records (from ~11.1 to 0.8 Ma, late Miocene-middle Pleistocene) of carbon and oxygen isotope variations in tooth enamel of different large herbivorous mammals ...
The development of the Ethiopian biogeographic realm since the late Miocene is here explored with the presentation and review of fossil evidence from eastern Africa. Prostrepsiceros cf. vinayaki and an unknown species of possible caprin affinity are described from the hominid-bearing Asa Koma and Kuseralee Members (∼5.7 and ∼5.2 Ma) of the Middle Awash, Ethiopia. The Middle Awash Prostrepsicero...
Introduction Conclusions References
Magnesium/calcium data from Southern Ocean planktonic foraminifera demonstrate that high-latitude (approximately 55 degrees S) southwest Pacific sea surface temperatures (SSTs) cooled 6 degrees to 7 degrees C during the middle Miocene climate transition (14.2 to 13.8 million years ago). Stepwise surface cooling is paced by eccentricity forcing and precedes Antarctic cryosphere expansion by appr...
Zavarian epitermal gold (copper) deposit is located in an intracontinental volcanic cone (stratovolcano) with the Early Miocene age, in the middle of the Urmia-Dokhtar magmatic arc. The host rocks of this mineralization include a set of basaltic, andesitic-basaltic, andesitic, dacitic, as well as granodiorite and tonal units that have been exposed in volcanic form (lava and pyroclastic) and sem...
The intramontane basins of the southern Rocky Mountains, USA, have undergone up to 1.5 km of erosion from the middle Miocene to the present. Here I explore the hypothesis that this erosion could have been caused primarily by an increase in the intensity of snowmelt fl ooding. In the middle Miocene, snowmelt runoff was limited to the highest elevations (>3 km) and hence impacted only a small fra...
[1] Extension during the middle Cenozoic (43–26 Ma) in the north end of the West Antarctic rift system (WARS) is well constrained by seafloor magnetic anomalies formed at the extinct Adare spreading axis. Kinematic solutions for this time interval suggest a southward decrease in relative motion between East and West Antarctica. Here we present multichannel seismic reflection and seafloor mappin...
Marine algae are instrumental in carbon cycling and atmospheric carbon dioxide (CO2) regulation. One group, coccolithophores, uses carbon to photosynthesize and to calcify, covering their cells with chalk platelets (coccoliths). How ocean acidification influences coccolithophore calcification is strongly debated, and the effects of carbonate chemistry changes in the geological past are poorly u...
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