نتایج جستجو برای: campanian
تعداد نتایج: 532 فیلتر نتایج به سال:
The fossil record of centrosaurine ceratopsids is largely restricted to the northern region of western North America (Alberta, Montana and Alaska). Exceptions consist of single taxa from Utah (Diabloceratops) and China (Sinoceratops), plus otherwise fragmentary remains from the southern Western Interior of North America. Here, we describe a remarkable new taxon, Nasutoceratops titusi n. gen. et...
Figure 1. A: Map of Charleston-Nebo salient and northernmost Book Cliffs showing rock units, thrust faults (dashed where buried), key seismic coverage (gray lines), measured stratigraphic sections (1–7; 8 is location of additional Blackhawk sandstone samples), and wells. Rock units: KTs—Cretaceous–Tertiary strata (North Horn and younger formations), Kmv—Cretaceous Mesaverde Group (Blackhawk, Ca...
The Late Cretaceous 'greenhouse' world witnessed a transition from one of the warmest climates of the past 140 million years to cooler conditions, yet still without significant continental ice. Low-latitude sea surface temperature (SST) records are a vital piece of evidence required to unravel the cause of Late Cretaceous cooling, but high-quality data remain illusive. Here, using an organic ge...
Marked changes in human dispersal and development during the Middle to Upper Paleolithic transition have been attributed to massive volcanic eruption and/or severe climatic deterioration. We test this concept using records of volcanic ash layers of the Campanian Ignimbrite eruption dated to ca. 40,000 y ago (40 ka B.P.). The distribution of the Campanian Ignimbrite has been enhanced by the disc...
Located in northern Peru, at the lowest segment of Central Andes, Bagua Basin contains a Campanian to Pleistocene sedimentary record that archives local paleoenvironmental and tectonic history. We present new ?18O ?13C signatures pedogenic carbonate nodules from paleosols Campanian–Maastrichtian Fundo El Triunfo Formation upper Eocene–middle Miocene Sambimera reconstruct isotopic composition pa...
The biostratigraphy of the Outer Carpathians is based mainly on ranges agglutinated foraminifera. Species acmes provide opportunity to enhance and support existing biozonations. Assemblages foraminifera from Campanian Eocene various tectonic-structural units were analyzed in terms their qualitative quantitative occurrence. In this stratigraphic interval, 19 species display significantly increas...
The majority of environments are dominated by flowering plants today, but it is uncertain how this dominance originated. This increase in angiosperm diversity happened during the Cretaceous period (ca. 145-65 Ma) and led to replacement and often extinction of gymnosperms and ferns. We propose a scenario for the rise to dominance of the angiosperms from the Barremian (ca. 130 Ma) to the Campania...
The Kyunetsa section, 2.5 km west of Kosharevo, exposes mainly pelagic Upper Cretaceous marly limestones and marls the Srednogorie Zone, part intermediate Balkanides in Bulgaria. Melove Formation Coniacian to early Campanian age involves a prominent Santonian-Campanian boundary interval grey reddish sediments, including CORBs (Cretaceous Oceanic Red Beds). base can be discerned bed 7c by first ...
The Campanian–Maastrichtian (83–66 Ma) was a period of global climate cooling, featuring significant negative carbon-isotope (δ13C) anomalies, such as the Late Campanian Event (LCE) and the Campanian–Maastrichtian Boundary Event (CMBE). A variety of factors, including changes in temperature, oceanic circulation and gateway opening, have been invoked to explain these δ13C perturbations, but no p...
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