نتایج جستجو برای: magnetostratigraphy
تعداد نتایج: 280 فیلتر نتایج به سال:
Since the early l990s the Chicxulub crater on Yucatan, Mexico, has been hailed as the smoking gun that proves the hypothesis that an asteroid killed the dinosaurs and caused the mass extinction of many other organisms at the Cretaceous-Tertiary (K-T) boundary 65 million years ago. Here, we report evidence from a previously uninvestigated core, Yaxcopoil-1, drilled within the Chicxulub crater, i...
Six Oligocene sequences and one earliest Miocene sequence were identified at Island Beach, Atlantic City, and Cape May, New Jersey, and correlated to the dO proxy of glacioeustasy and the eustatic record of Haq et al. by integrating lithostratigraphy, biostratigraphy, Sr isotopic stratigraphy, and magnetostratigraphy. Seven global dO increases are recognized by correlating dO records among deep...
The appearance of detritus shed from mountain ranges along the northern margin of the Tibetan Plateau heralds the Cenozoic development of high topography. Current estimates of the age of the basal conglomerate in the Qaidam basin place this event in Paleocene-Eocene. Here we present new magnetostratigraphy and mammalian biostratigraphy that refine the onset of basin fill to ∼25.5 Myr and reveal...
1. Geological Time: A Summary 2. Reconstruction and Relative Dating of Earth History 2.1. Early Ideas and Basic Principles 2.2. Uniformitarianism and Catastrophism 2.3. Geological Catastrophes and Events: Particular Historical Geological Phenomena 2.4. Rates of Geological Processes in Terms of Human Timescales 2.4.1. Earth Crust Movements 2.4.2. Plutonic and Volcanic Processes 2.4.3. Weathering...
This article presents magnetic data of a 300-m-thick Mio-Pliocene red clay and Quaternary loess-paleosol sequence near Chaona town in the Central Chinese Loess Plateau. Detailed magnetostratigraphy shows that the aeolian red clay began to accumulate at ca. 8.1 Ma. Here, we presented a high-resolution rock magnetic data at 20-40 cm intervals within 4.5-8 ka span per sample of this section, which...
Significant climate shifts in the northeastern Tibetan Plateau have taken place during the Cenozoic, but the reasons behind them remain unclear. In order to unravel the mechanisms driving these climate changes, proxy data with accurate age constraint are needed. Here we present magnetostratigraphy, sediment color (redness a*, and lightness L*) and grain-size analysis from an early to middle Mio...
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