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Temperatures in the Arctic have increased by an astounding 1[degrees]C in response to anthropogenic forcing over the past 20 years and are expected to rise further in the coming decades. The Pliocene (2.6-5.3 Ma) is of particular interest as an analog for future warming because global temperatures were significantly warmer than today for a sustained period of time, with continental configurations similar to present. Here, we estimate mean annual temperature (MAT) based upon three independent proxies from an early Pliocene peat deposit in the Canadian High Arctic. Our proxies, including oxygen isotopes and annual ring widths (MAT = -0.5 [+ or -] 1.9[degrees]C), coexistence of paleovegetation (MAT = -0.4 [+ or -] 4.1[degrees]C), and bacterial tetraether composition in paleosols (MAT = -0.6 [+ or -] 5.0[degrees]C), yield estimates that are statistically indistinguishable. The consensus among these proxies suggests that Arctic temperatures were ~19[degrees]C warmer during the Pliocene than at present, while atmospheric C[O.sub.2] concentrations were ~390 ppmv. These elevated Arctic Pliocene temperatures result in a greatly reduced and asymmetrical latitudinal temperature gradient that is probably the result of increased poleward heat transport and decreased albedo. These results indicate that Arctic temperatures may be exceedingly sensitive to anthropogenic C[O.sub.2] emissions. doi: 10.1130/G30815.1

We determined the spatial distribution patterns of the Branched and Isoprenoid Tetraether (BIT) index, a specific proxy of riverborne soil organic carbon (OC) input from land to the ocean, by analyzing soils from the Tet watershed (France) and surface sediments from the Gulf of Lions (NW Mediterranean) into which the Tet and Rhone Rivers flow. The BIT index pattern in the Tet watershed is heterogeneously distributed, varying between 0.2 and 1.0, with an average BIT value of 0.84 [+ or -] 0.14 (n = 58). Soil pH is the major factor controlling soil BIT values among the environmental factors considered on the basis of the statistical analysis of environmental parameters and glycerol dialkyl glycerol tetraether concentrations. In the Gulf of Lions, BIT values range from 0.01 to 0.85, with higher values along the coast compared with those offshore. The soil OC contributions to the total organic carbon (TOC), estimated on the basis of the BIT index, are > 10% along the coast, whereas those from the outer shelf and the continental slope are < 10%.

Surface sediments from the eastern south Atlantic are investigated for their lipid biomarker contents and bulk organic geochemical characteristics to identify sources, transport pathways and preservation processes of organic components. The findings of this study provide a base for paleo-environmental reconstructions using lipid biomarkers in Asian marine sediments from this area.

We present new, detailed carbon-isotope records for bulk carbonate, total organic carbon (TOC) and phytane from three key sections spanning the Cenomanian--Turonian boundary, interval (Eastbourne, England; Gubbio, Italy; Tarfaya, Morocco), with the purpose of establishing a common chemostratigraphic framework for Oceanic Anoxic Event (OAE) 2. Isotope curves from all localities are characterized by a positive carbon-isotope excursion of c. 4[per thousand] for TOC and phytane and c. 2.5[per thousand] for carbonate, although diagenetic overprinting appears to have obliterated the primary carbonate carbon-isotope signal in at least part of the Tarfaya section. Stratigraphically, peak [[delta].sup.13]C values for all components are followed by intervals of high, near-constant [[delta].sup.13]C in the form of an isotopic plateau. Recognition of an unambiguous return to background [[delta].sup.13]C values above the plateau is, however, contentious in all sections, hence no firm chemostratigraphic marker for the end-point of the positive isotopic excursion can be established. The stratigraphically consistent first appearance of the calcarcous nannofossil Quadrum gartneri at or near the Cenomanian--Turonian boundary as established by ammonite stratigraphy, in conjunction with the end of the [[delta].sup.13]C maximum characteristic of the isotopic plateau, provides a potentially powerful tool for delimiting the stratigraphic extent and duration of OAE 2. This Oceanic Anoxic Event is demonstrated to be largely, if not wholly, confined to the latest part of the Cenomanian stage. Keywords: Oceanic Anoxic Event 2, Eastbourne, England, Gubbio, Italy, Tarfaya, Morocco, [sup.13]C.

A molecular isotopic study in cold-seep sediments from Kazan mud volcano in the eastern Mediterranean Sea indicates that a significant proportion of methane released in this environment is incorporated into biomass in methane-supported chemosynthetic microbial communities. Furthermore, extremely [sup.13]C depleted biomarkers (as much as -111%[per thousand] Vienna Pee Dee Belemnite (VPDB)) have revealed pathways of methane-derived carbon flow through the microbial community and into eukaryotic biomass. Specifically, we are able to trace the flow of methane-derived carbon through anaerobic methane-oxidizing archaea into sulfate-reducing bacteria, as well as into aerobic methane-oxidizing bacteria. The methane-derived carbon is then incorporated into eukaryotic biomass through heterotrophy by bacterivorous ciliates.

The difference in carbon-13 ([C.sup.13]) contents of hopane and sterane biomarkers in the Monterey formation (Naples Beach, California) parallels the Miocene inorganic record of the change in [O.sup.18] ([delta.sup.18]O), reflecting the Miocene evolution from a well-mixed to a highly stratified photic zone (upper 100 meters) in the Pacific. Steranes ([delta.sup.13]C = 25.4 ± 0.7 per mil versus the Pee Dee belemnite standard) from shallow photic-zone organisms do not change isotopically throughout the Miocene. In contrast, sulfur-bound [C.sub.35] hopanes (likely derived from bacterial plankton living at the base of the photic zone) have systematically decreasing [C.sup.13] concentrations in Middle and Late Miocene samples ([delta.sup.13]C = 29.5 to -31.5 per mil), consistent with the Middle Miocene formation of a carbon dioxide-rich cold water mass at the base of the photic zone., The Miocene marked the transition from an ice-free world with well-mixed oceans to one that was glaciated and had highly temperature-stratified oceans like those of today[1-3]. Paleoenvironmental information on the [...]