Entire Quaternary Research Articles

Direct marine-terrestrial correlations, Wanganui Basin, New Zealand: The last 1 million years

Wanganui Basin, a back-arc basin in North Island, New Zealand, contains a detailed sequence of interfingering terrestrial and shallow marine sediments spanning the entire Quaternary. Rhyolite tephras erupted from the Taupo Volcanic Zone, together with magnetostratigraphy and biostratigraphy, facilitate correlations between Wanganui Basin and the astronomically calibrated oxygen isotope chronology of deep sea cores, particularly over the last 1 Ma. Eustatic changes are interpreted from both marine (shelf) sediments and marine terraces within the basin. Non-marine sediments, including loess, dunesand, and alluvial deposits, coupled with pollen analyses, are used to interpret climatic changes; they can also be directly related to the marine record through stratigraphic relations between marine and non-marine deposits in the basin.

Quaternary alkalinity fluctuations recorded in rock varnish microlaminations on western U.S.A. volcanics

Rock varnish contains an alternating micron-scale layering of manganese-rich and manganese-poor microchemical laminations. Holocene varnishes have lower Mn:Fe ratios when exposed to alkaline environments and higher Mn:Fe ratios when exposed to less-alkaline environments. This is consistent with abiotic and biotic mechanisms of varnish formation, as alkalinity inhibits the concentration of manganese in both models. Mn:Fe variations with depth in varnishes in the western U.S. are interpreted as fluctuations in alkalinity or local microenvironmental influences. If enough varnishes are sampled from different rocks in a region, local effects can be ruled out. KAr dating of volcanics in the Coso, Cima, Lunar Crater and Crater Flat volcanic fields in the western Basin and Range provide numerical age control throughout the Quaternary, and allow the number of alkalinity fluctuations to be assessed for given periods of time. Alkalinity fluctuations in varnishes are likely tied to fluctuations in the abundance of alkaline aerosols, which are in turn related to fluctuations in the cover of water over playas and the cover of vegetation over soils. Microchemical laminations in varnish, therefore, have the potential to serve as an indicator of environmental fluctuations for the entire Quaternary.

Quaternary History of Deciduous Forests of Eastern North America and Europe

Quaternary History of Deciduous Forests of Eastern North America and Europe

第四紀研究と古地磁気圏学との境界領域における諸問題

The encounter between the solar wind and the Earth's paleomagnetic field formed the paleomagnetosphere around the Earth. From a paleomagnetospherological viewpoint, the entire Quaternary Period consists of stable stages (intervals when the geomagnetic field polarity was either normal or reversed) and transition stages (transition intervals between the stable stages). Observation of the virtual geomagnetic pole during equatorial crossings in all four recent transition stages suggests that the Earth was in a perpendicular condition for about 2, 000 years during each transitional stages, i.e. the virtual dipole axis was perpendicular to the Earth's rotational axis. This observational inference is verified by a theoretical analysis of three models related to the mechanism of geomagnetic polarity reversal. The magnetosphere in the perpendicular condition is generally called the Type 3 Magnetosphere, in contrast to the Type 1 Magnetosphere in a parallel condition. It can be mathematically demonstrated that both the size and the shape of the paleomagnetosphere show drastic changes only when it changes from Type 1 to Type 3 during transitions. Several possible relationships between drastic changes of the paleomagnetosphere and observed drastic changes in paleoclimateand the fossil record during the transitional stages in the Quaternary were examined. During the transition stages, auroral particles, solar cosmic rays, and galactic cosmic rays are found to precipitate within the equatorial polar caps whose centers are situated on the geographic equator. Cro-Magnon man, in the Ice Age, left scratched drawings resembling auroral patterns on the inner walls of many Lascaux caves. An investigation is being made to determine if such drawings are related to brilliant auroral curtains that could surely have been observed by them in one of the equatorial polar caps during the geomagnetic transitional stage of the Laschamp Event. Finally, it is proposed that missing sunspot phenomena, similar to those that actually occurred in the Seventeenth to Eighteenth centuries, could possibly have also occurred during the Quaternary, giving rise to changes in paleoclimate and the paleontological and archaeological records.