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High-resolution laser ablation--inductively coupled plasma--mass spectroscopy scanning of resin-embedded laminated sediments is used to detail variability in the composition and magnitude of recent eolian dust deposition in the Eastern Mediterranean. The composition of dust accumulating in the anoxic Atalante basin varies in response to the strength of the summer blocking mode of Mediterranean climate. Dust sources located upwind on the westerly airflow are favored during phases of weaker blocking (hence stronger summer westerlies). This mode is in turn correlated to the pronounced multidecadai oscillation in Mediterranean sea-surface temperature (related to the Atlantic Multidecadal Oscillation), suggesting that coupled ocean-atmosphere dynamics control the large-scale transport of dust in the region. Variable precipitation in dust source regions may also exert an influence on the relative flux of dust from each source, and hence the net composition of dust deposited in the basin. Persistent oscillations in the composition of deeper sediments indicate that the basin offers a high-potential archive for reconstruction of climate-controlled variability in dust transport prior to the instrumental era. doi: 10.1130/G25287.1

Clarification of the factors involved in the formation of unusual ancient organic carbon--rich deposits (like eastern Mediterranean sapropels) is central in understanding oceanic carbon cycling. The role of oxygenation remains a subject of controversy primarily due to two major uncertainties: (1) it is unknown if ancient organic-rich deposits reflect an accumulation of refractory organic matter (OM) or oxygenation-related aberrant sediment OM recycling, and (2) although marine OM degradation may be slower under anoxic conditions, its ultimate impact on organic carbon ([C.sub.org]) preservation over geological time remains unclear. Here we provide direct experimental evidence that the [C.sub.org] in eastern Mediterranean S1 sapropeis (deposited >5 ka) is still highly reactive and that a shutdown in labile organic matter degradation under anoxic conditions played a key role in the formation of these deposits. Keywords: organic carbon, preservation, remineralization, nitrogen isotopes, carbon isotopes, sapropel.

Pyrite within and below sapropels in the eastern Mediterranean is a result of microbial S[O.sub.[4.sup.2-]] reduction within the sapropel, and the subsequent reaction of sulfide (H[S.sup.-]) with detrital Fe and [Fe.sup.2+] diffusing upward from underlying sediments. Below the youngest Mediterranean sapropel, S1, pyrite (as much as 281 [[micro]mol] pyritic S/g) is mostly present as euhedral crystals, whereas within the sapropel only framboidal pyrite (as much as 360 [[micro]mol] pyritic S/g) has been detected. Framboidal microtextures indicate pyrite formation at the site of H[S.sup.-] production within the sapropel. Euhedral pyrite, below the sapropel, forms when sulfate reduction in the sapropel outcompetes iron liberation and supply, and H[S.sup.-] diffuses out of the sapropel. Sulfur isotope values of pyrite are extremely light in the sapropel (-37.3[per thousands] to -38.2[per thousands]) as well as below the sapropel (-45.6[per thousands] and -49.6[per thousands]), indicating that H[S.sup.-] has formed in a system with abundant S[O.sub.[4.sup.2-]] and in the presence of oxidants.