The Carboniferous timescale: an introduction

The Carboniferous chronostratigraphic scale consists of two subsystems, six series and seven stages. Precise numerical age control within the Carboniferous is uneven, and a global magnetic polarity timescale for the Carboniferous is far from established. Isotope stratigraphy based on Sr, C and O isotopes is in an early stage but has already identified a few Sr and C isotope events of use to global correlation. Cyclostratigraphy has created a workable astrochronology for part of Pennsylvanian time that needs better calibration. Chronostratigraphic definitions of most of the seven Carboniferous stages remain unfinished. Future research on the Carboniferous timescale should focus on GSSP selection for the remaining, undefined stage bases, definition and characterization of substages, and further development and integration of the Carboniferous chronostratigraphic scale with radioisotopic, magnetostratigraphic, chemostratigraphic and cyclostratigraphic tools for calibration and correlation and the cross correlation of nonmarine and marine chronologies.

Fish Teeth Sr Isotope Stratigraphy and Nd Isotope Variations: New Insights on REY Enrichments in Deep-Sea Sediments in the Pacific

Rare earth elements and yttrium (REY) are widely recognized as strategic materials for advanced technological applications. Deep-sea sediments from the eastern South Pacific and central North Pacific were first reported as potential resources containing significant amounts of REY that are comparable to, or greater than, those of land-based deposits. Despite nearly a decade of research, quantitative abundances and spatial distributions of these deposits remain insufficient. Age controls are generally absent due to the lack of biostratigraphic constraints. Thus, the factors controlling the formation of REY-rich sediments are still controversial. In this study, the REY contents of surface sediments (<2 m depth) in 14 piston cores from the Middle and Western Pacific were investigated. The results show that deep-sea sediments with high REY contents (>1000 μg/g) were mainly concentrated around seamounts (e.g., the Marshall Islands). The REY contents of surface sediments generally decreased with distance from the seamounts. Biostratigraphic and fish teeth debris (apatite) Sr isotopic stratigraphy of one piston cores (P10) from the Middle Pacific indicate that deep-sea sediments with high REY contents were aged from early Oligocene to early Miocene. Since the opening of the Drake Passage during the early Oligocene, the northward-flowing Antarctic Bottom Water (AABW) would have led to an upwelling of nutrients around seamounts with topographic barriers, and at the same time, AABW would delay the rate of sediment burial to try for enough time for REY entering and enriching in the apatite (fish teeth debris). Understanding the spatial distribution of fertile regions for REY-rich sediments provides guidance for searching for other REY resources in the Pacific and in other oceans.

Early–Middle Pleistocene Magnetostratigraphic and Rock Magnetic Records of the Dolynske Section (Lower Danube, Ukraine) and Their Application to the Correlation of Loess–Palaeosol Sequences in Eastern and South-Eastern Europe

We present new palaeomagnetic and rock magnetic results with a stratigraphic interpretation of the late Early–Middle Pleistocene deposits exposed on the left bank of the River Danube at Dolynske, southern Ukraine. A thick succession of water-lain facies is succeeded by reddish-brown clayey soils, topped by a high-resolution loess–palaeosol sequence. These constitute one of the most complete recently discovered palaeoclimate archives in the Lower Danube Basin. The suggested stratigraphy is based on the position of the Matuyama–Brunhes boundary, rock magnetic, palaeopedological and sedimentological proxies, and it is confidently correlated with other loess records in the region (Roksolany and Kurortne), as well as with the marine isotope stratigraphy. The magnetic susceptibility records and palaeosol characteristics at Dolynske show an outstanding pattern that is transitional between eastern and south-eastern European loess records. Our data confirm that the well-developed S4 soil unit in Ukraine, and S5 units in Romania, Bulgaria and Serbia, correlate with the warm MIS 11. Furthermore, we suggest the correlation of rubified S6 palaeosols in Romania and Bulgaria and the V-S7–V-S8 double palaeosol in Serbia with S6 in Ukraine, a strong Mediterranean-type palaeosol which corresponds to MIS 15. Our new results do not support the hypothesis of a large magnetic lock-in depth like that previously interpreted for the Danube loess, and they prove that the Matuyama–Brunhes boundary is located within the palaeosol unit corresponding to MIS 19. The proposed stratigraphic correlation scheme may serve as a potential basis for further regional and global Pleistocene climatic reconstructions.