Assessing Humidity in an Upper Pleistocene Karst Environment: Palaeoclimates and Palaeomicroenvironments at the cave Divje babe I, Slovenia, 2002, Turk Ivan, Skaberne Dragomir, Blackwell Bonnie A. B. , Dirjec Janez

The article presents a new sedimentary-climatic model for explaining autochthonous clastic sediment in the Upper Pleistocene site, Divje babe I, Slovenia. The sediment analysed here was deposited during Oxygen Isotope Stages 1, 3 and 5 (OIS, OIS 3, OIS 5). The stress is on precipitation, which we explained on the basis of the quantity of authigenic structural aggregates in the sediment. We supported the results with quantitative analysis of clasts with etched surface, which represent corrosion of the cave ceiling, and etched bones, which represent corrosion on the cave ground. We also analysed the relation between climate and cave bears, and Neanderthals and climate, on the basis of mass fossil remains and finds of artefacts. All analyses were made on the basis of three-dimensional sampling, i.e., in horizontal and vertical directions. We sampled 65 profiles over an area of 65 m2. Each profile had 35 arbitrary stratigraphic units (splits) with data on aggregates, etched bones, fossil remains and artefacts. In explaining the sediment characteristics that point to climatic parameters, we consistently took into account the Holocene standards for the site. We found that the climate in OIS 3 was colder and damper than in OIS 1 and OIS 5. People and animals responded to the climatic changes in OIS 3 with more visits to the cave, but not at the same time. The climatic change was presumably reflected in the microlocation of the cave mainly by the longer duration of snow cover.

Quaternary calcarenite stratigraphy on Lord Howe Island, southwestern Pacific Ocean and the record of coastal carbonate deposition, 2003, Brooke Bp, Woodroffe Cd, Murraywallace Cv, Heijnis H, Jones Bg,

Lord Howe Island is a small, mid-ocean volcanic and carbonate island in the southwestern Pacific Ocean. Skeletal carbonate eolianite and beach calcarenite on the island are divisible into two formations based on lithostratigraphy. The Searles Point Formation comprises eolianite units bounded by clay-rich paleosols. Pore-filling sparite and microsparite are the dominant cements in these eolianite units, and recrystallised grains are common. Outcrops exhibit karst features such as dolines, caves and subaerially exposed relict speleothems. The Neds Beach Formation overlies the Searles Point Formation and consists of dune and beach units bounded by weakly developed fossil soil horizons. These younger deposits are characterised by grain-contact and meniscus cements, with patchy pore-filling micrite and mirosparite. The calcarenite comprises several disparate successions that contain a record of up to 7 discrete phases of deposition. A chronology is constructed based on U/Th ages of speleothems and corals, TL ages of dune and paleosols, AMS 14C and amino acid racemization (AAR) dating of land snails and AAR whole-rock dating of eolianite. These data indicate dune units and paleosols of the Searles Point Formation were emplaced during oxygen isotope stage (OIS) 7 and earlier in the Middle Pleistocene. Beach units of the Neds Beach Formation were deposited during OIS 5e while dune units were deposited during two major phases, the first coeval with or shortly after the beach units, the second later during OIS 5 (e.g. OIS 5a) when the older dune and beach units were buried.Large-scale exposures and morphostratigraphical features indicate much of the carbonate was emplaced as transverse and climbing dunes, with the sediment source located seaward of and several metres below the present shoreline. The lateral extent and thickness of the eolianite deposits contrast markedly with the relatively small modern dunes. These features indicate that a slight fall (2-10 m) in sea level may be required to mobilise relatively large volumes of sediment onto the island. The stratigraphy of the calcarenite, combined with the shallow depth of the platform surrounding the island (30-50 m present water depth) and the geochronological data, suggest that cycles of carbonate deposition on the island are linked to interglacial and interstadial periods of high or falling sea level

A 164 ka record of environmental change in the American Southwest from a Carlsbad Cavern speleothem , 2006, Brook George A. , Ellwood Brooks B. , Railsback L. Bruce, Cowart James B.

A horizontal core 2.8 m in length drilled from the Georgia Giant column in Carlsbad Cavern provides climate information for the last 164 ka. Forty-six alpha spectrometric U-series ages determined at intervals of ∼7.6 cm along the core indicate five periods of deposition and five hiatuses, the longest from 136 to 110 ka. Variations in growth rate (0 to 70 mm/ka), in the abundance of aragonite, chalcedony, and Fe-bearing phases, and in 13C indicate that glacial intervals of the last 164 ka, OIS 6, 4, and 2, were much wetter than today, as were the colder substages 5d and 5b of OIS 5. By contrast, during the two warmest periods of the past 164 ka, namely OIS 5e and 1, there was no deposition on either side of the speleothem, suggesting conditions as dry or drier than today. The record from Carlsbad parallels data from many other sites in the southwestern USA and northern Mexico, and data from marine sediments and ice cores, demonstrating the extent to which ice sheet fluctuations influenced conditions in southern New Mexico. Detailed correlation of δ13C values in the Georgia Giant, which range from −6.6 to +0.9‰ relative to PDB, with distant speleothem records and with data from ice cores, further documents the linkage of southwestern climate with global-scale extent of glaciation. Values of δ18O in the Georgia Giant core range from −9.7 to −4.7‰ relative to PDB and average −6.6‰. 18O-depleted carbonate in the Georgia Giant during OIS 6, at a time when the world's oceans were enriched in 18O, suggests that precipitation during cold intervals was brought largely by Pacific air masses in fall, winter and spring as a result of the southward displacement of the polar jet stream by the growth of the Laurentide Ice Sheet. Termination II, marking the end of the penultimate glaciation, is well defined in the core's δ18O data. Analytical uncertainties in the radiometric ages do not preclude a start of Termination II as late as 128 ka, as suggested by SPECMAP data. However, data from the Georgia Giant core are more compatible with an earlier start like that obtained from Devils Hole and Vostok data, raising the possibility that early warming was widespread in the U.S. southwest region by 145 ka.