نتایج جستجو برای: cenozoic
تعداد نتایج: 2977 فیلتر نتایج به سال:
The hypothesis of a Palaearctic origin of Leishmania in the early Cenozoic, dispersal to the Nearctic in the late Eocene and to the Neotropical in the Pliocene is presented. It is further hypothesized that murid rodents and their immediate ancestors have been important mammalian reservoirs since the origination of Leishmania. Biochemical, molecular, biogeographical, entomological, mammalalogica...
We report new examples of Cenozoic cold-seep communities from Colombia, Cuba, the Dominican Republic, Trinidad, and Venezuela, and attempt to improve the stratigraphic dating of Cenozoic Caribbean seep communities using strontium isotope stratigraphy. Two seep faunas are distinguished in Barbados: the late Eocene mudstone-hosted 'Joes River fauna' consists mainly of large lucinid bivalves and t...
The Tien Shan are the quintessential intracontinental range, situated more than 1000 km north of the suture between India and Asia. Their initiation and growth in the Cenozoic, however, remain poorly understood. In this study we present stratigraphic, detrital fission-track, and magnetostratigraphic results that provide a basis for reconstructing the Cenozoic tectonic evolution of the Kyrgyz Ra...
[1] High topography in central Asia is perhaps the most fundamental expression of the Cenozoic Indo-Asian collision, yet anunderstandingof the timingandratesofdevelopmentof theTibetan Plateau remains elusive. Here we investigate the Cenozoic thermal historiesofrocksalongtheeasternmarginof theplateauadjacent to the Sichuan Basin in an effort to determine when the steep topographic escarpment tha...
Lake sediments in 10 Ethiopian, Kenyan, and Tanzanian rift basins suggest that there were three humid periods at 2.7 to 2.5 million years ago (Ma), 1.9 to 1.7 Ma, and 1.1 to 0.9 Ma, superimposed on the longer-term aridification of East Africa. These humid periods correlate with increased aridity in northwest and northeast Africa and with substantial global climate transitions. These episodes co...
Cretaceous-Cenozoic history of angiosperms led to the a certain character of the distribution of taxa of different levels (the number of species and genera in families, species/genera ratio in families, the number of species in the genera). In most cases, these distributions are satisfactorily described by a power law (Pareto distribution). In logarithmic coordinates power function is a straigh...
Mapping in the Homs region of Syria has revealed a hitherto unrecognized staircase of at least 12 gravel terraces of the upper Orontes River. The terrace gravels overlie Pliocene lacustrine marl and have been calcareously cemented into conglomerates, sometimes interbedded with cemented fine-grained alluvium. A tentative dating scheme, based on modelling the regional-scale surface uplift that ha...
Several mechanisms have been proposed to explain the high levels of plant diversity in the Neotropics today, but little is known about diversification patterns of Neotropical floras through geological time. Here, we present the longest time series compiled for palynological plant diversity of the Neotropics (15 stratigraphic sections, 1530 samples, 1411 morphospecies, and 287,736 occurrences) f...
Paleotemperature and paleoprecipitation over the past 40 m.yr. can be inferred from the degree of chemical weathering and depth of carbonate nodules in paleosols of Oregon, Montana, and Nebraska. Paleosol records show that late Eocene (35 Ma), middle Miocene (16 Ma), late Miocene (7 Ma), and early Pliocene (4 Ma) warm climatic episodes were also times of a wet climate in Oregon, Montana, and Ne...
The combination of detailed topographic leveling on the southwest segment of the El Asnam thrust fault with existing seismic and geologic data implies that the geometry of this fault involves shallow dipping flats and steep ramps. The fault appears to be growing along strike toward the southwest end, where the main shock initiated in 1980. From a depth of about 10 km, the main thrust appears to...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید