Haino Uwe Kasper

Rapid ecosystem response to abrupt climate changes during the last glacial period in western Europe, 40-16 ka

We present a high-resolution and independently dated multiproxy lake sediment record from the paleolake at Les Echets in southeastern France that displays synchronous changes in independent limnic and terrestrial ecosystem proxies, in concert with millennial-scale climate oscillations during the last glacial period. Distinct lake-level fluctuations, low lake organic productivity, and open, treeless vegetation indicate cold and dry conditions in response to Heinrich events. Alternating phases of higher and low lake organic productivity, stratified surface waters and long-lasting lake ice cover, decreased or increased catchment erosion, and tree-dominated or herb-dominated vegetation resemble Dansgaard-Oeschger interstadialstadial variability. Transitions between different ecological states occurred in as little as 40–230 yr and seem to have been controlled by the position of the Polar Front. Ecosystem response after 30 ka suggests that local climate conditions became more important. Our results demonstrate that all parts of the terrestrial system responded to the abrupt and dramatic climatic changes associated with Dansgaard-Oeschger and Heinrich events, and that regional factors modulated ecosystem response.

Catastrophic extinction of Caribbean rudist bivalves at the Cretaceous-Tertiary boundary

Strontium isotope ratios ( 87 Sr/ 86 Sr) in pristine low-Mg calcite of shells of rudist bivalves from the Titanosarcolites limestones exposed in the Central, Maldon, and Marchmont inliers of Jamaica indicate that species-rich rudist-coral associations persisted into the latest Maastrichtian (66–65 Ma). This finding contradicts the currently accepted hypothesis of stepwise extinction of rudist bivalves in the middle Maastrichtian and argues for a catastrophic, impact-related demise of Caribbean Cretaceous reefal ecosystems at the Cretaceous-Tertiary boundary.

ESR dating of raised coral reefs from Kish Island, Persian Gulf

Electron spin resonance (ESR) dating of raised coral reefs from Kish Island, Persian Gulf, Iran, was used for the calculation of uplift rates. From the methodological point of view, it has been demonstrated that concentrations of uranium, as needed for the calculation of dose rates, determined by instrumental neutron activation analyses were significantly lower than the results of inductively coupled plasma—mass spectrometry and are probably systematically underestimated. The ESR ages for the corals show no increase with elevation as was expected due to field observations. This apparent discrepancy is explained by the dicyclic nature of the palaeo-reef. Average uplift rates for Kish Island are between ∼0.13 and ∼0.24 mm a−1. This is consistent with previous estimates based on 230Th/234U dating of raised marine deposits from the nearby Iranian mainland and Qeshm Island, Strait of Hormuz, but contrary to results based on 14C dating that predicted uplift rates as high as 3 mm a−1 in that area. It is once more demonstrated that 14C dates >20 ka from this context often have to be interpreted as minimum ages.

Sm-Nd and Lu-Hf isotope and trace-element systematics of Mesoarchaean amphibolites, inner Ameralik fjord, southern West Greenland

Abstract Fragmented supracrustal rocks are typical components of Archaean high-grade gneiss terranes, such as those in the North Atlantic Craton. Here we present the first major, trace element and Nd-Hf isotope data for amphibolites collected in the yet poorly studied southern inner Ameralik fjord region of southern West Greenland. In addition, new U-Pb zircon ages were obtained from the surrounding TTG gneisses. Based on their trace-element patterns, two different groups of amphibolites can be distinguished. Following screening for post-magmatic alteration and outlying e values, a reduced sample set defines a 147Sm/143Nd regression age of 3038 Ma ±310 Ma (MSWD = 9.2) and a 176Lu/176Hf regression age of 2867 ± 160 Ma (MSWD = 5.5). Initial εNd2970Ma values of the least-altered amphibolites range from 0.0 to +5.7 and initial εHf2970Ma range from +0.7 to +10.4, indicating significant isotopic heterogeneity of their mantle sources with involvement of depleted domains as well as crustal sources. Surprisingly, the amphibolites which are apparently most evolved and incompatible element-rich have the most depleted Hf-isotope compositions. This apparent paradox may be explained by the sampling of a local mantle source region with ancient previous melt depletion, which was re-enriched by a fluid component during subduction zone volcanism or alternatively by preferential melting of an ancient pyroxenite component in the mantle source of the enriched rocks.

Chemical characterization of aquifers with the same geological origin

Physical characteristics of the Bicaz dammed lake are described as follows: water volume of 1.150x 109 m 3, 31.1 km in length, 2 km in width. The sluice is at 45 m above the maximal altitude of the lake. The Bistrita River is the main tributary of the lake: mean water contribution of 1.721x109 m3/a, mean suspended matter flow of 291000 t/a. This river drains a catchment rich in formerly mined mineralizations of polymetallic sulfides. The aim of this study is to determine if the lake can be considered as a sink toward trace elements. We analyzed major and minor elements, TOC, organic N, and some trace elements (e.g. As, Ba, Cd, Cr, Co, Cu, Mo, Ni, Pb, Sb, Sn, V, U, Zn) in filtered and bulk water samples. We worked on three locations, an upper site, a middle site, and a down site. Here we present the data for July and October 2005. Some trace elements have smaller dissolved concentrations in lake water than in the Bistrita River. Common associations can be defined in this lake such as: Co is associated with Mn; As is released in solution as Fe oxi-hydroxide is dissolved; V and U are following the same behaviour, etc. However, their distribution is not as regular as in a natural lake. The stratification of the water column at all 3 sampled sites is not as regular as expected. At the upper site (water depth of 33 m), the water column is homogeneous until 20 m, then the redox condition allows having Mn as Mn (+ II ) and Fe as Fe (+III). For some elements a perturbation can be noticed at about 10 m. At the middle site (water depth of 59 m), there is a water section richer in dissolved and particulate Fe and Mn, with a dominant particulate form. This can assess this section, in between 30 to 50 m it is more oxidizing. At the down site, the reverse figure can be seen between 30 and 50 m depth. This redox anomaly is more noticeable for elements with a high solubility difference according to their oxidation rate. Other parameters do not follow this figure. This section could be linked to the sluice drawing off. In the whole lake, the stratification is more and more visible from the up to the down stream but it is not so pronounced than in natural lakes. Water column structuring seems to be disturbed by a lateral flow, induced by the sluice drawing off.

Vorläufige Notiz über ein neues Eklogitvorkommen im Kristallin der Südkarpaten (Rumänien)

Beschreibung eines neuen, in einen Amphibolitkomplex des Mehedinţi Hochlandes (Sudkarpaten) eingeschlossenen Eklogits.