scholarly journals Belemnite geochemistry from Albstadt-Pfeffingen (Middle Jurassic, Baden-Württemberg, Germany)

2019 ◽  
Author(s):  
Jack T R Wilkin ◽  
Stephen P Hesselbo ◽  
Clemens V Ullmann ◽  
Christoph Korte
Keyword(s):  
High Resolution ◽  
Stable Isotope ◽  
Middle Jurassic ◽  
Environmental Stability ◽  
Proxy Data ◽  
Geochemical Proxies ◽  
Recent Developments ◽  
Quantitative Reconstructions

Belemnite calcite is an important source of stable isotope (18O, 13C) and element (Fe, Mg, Mn, S, Sr) proxies with potential for high-resolution quantitative reconstructions of palaeoenvironments and seasonality since Urey et al (1951). Belemnites are also a very important archive for environmental reconstructions of the early Toarcian; it is important, however, to study their calcite over intervals of comparative environmental stability to assess the meaning of proxy data extracted from their calcite. Here, we report on recent developments on geochemical proxies derived from belemnite rostra from Albstadt-Pfeffingen, a potential GSSP for the base of the Callovian, in Baden-Württemberg.

scholarly journals Belemnite geochemistry from Albstadt-Pfeffingen (Middle Jurassic, Baden-Württemberg, Germany)

2019 ◽  
Author(s):  
Jack T R Wilkin ◽  
Stephen P Hesselbo ◽  
Clemens V Ullmann ◽  
Christoph Korte
Keyword(s):  
High Resolution ◽  
Stable Isotope ◽  
Middle Jurassic ◽  
Environmental Stability ◽  
Proxy Data ◽  
Geochemical Proxies ◽  
Recent Developments ◽  
Quantitative Reconstructions

Belemnite calcite is an important source of stable isotope (18O, 13C) and element (Fe, Mg, Mn, S, Sr) proxies with potential for high-resolution quantitative reconstructions of palaeoenvironments and seasonality since Urey et al (1951). Belemnites are also a very important archive for environmental reconstructions of the early Toarcian; it is important, however, to study their calcite over intervals of comparative environmental stability to assess the meaning of proxy data extracted from their calcite. Here, we report on recent developments on geochemical proxies derived from belemnite rostra from Albstadt-Pfeffingen, a potential GSSP for the base of the Callovian, in Baden-Württemberg.

High-resolution microscopy of twin boundaries in gold

1987 ◽  
Vol 45 ◽  
pp. 260-261
Author(s):  
William Krakow ◽  
David A. Smith
Keyword(s):  
High Resolution ◽  
Specimen Preparation ◽  
Gold Films ◽  
Boundary Area ◽  
Transmission Electron ◽  
Recent Developments ◽  
Tilt Boundaries ◽  
High Resolution Microscopy ◽  
Twist Boundaries

Recent developments in specimen preparation, imaging and image analysis together permit the experimental determination of the atomic structure of certain, simple grain boundaries in metals such as gold. Single crystal, ∼125Å thick, (110) oriented gold films are vapor deposited onto ∼3000Å of epitaxial silver on (110) oriented cut and polished rock salt substrates. Bicrystal gold films are then made by first removing the silver coated substrate and placing in contact two suitably misoriented pieces of the gold film on a gold grid. Controlled heating in a hot stage first produces twist boundaries which then migrate, so reducing the grain boundary area, to give mixed boundaries and finally tilt boundaries perpendicular to the foil. These specimens are well suited to investigation by high resolution transmission electron microscopy.

scholarly journals Surface mass balance and water stable isotopes derived from firn cores on three ice rises, Fimbul Ice Shelf, Antarctica

2016 ◽  
Vol 10 (6) ◽  
pp. 2763-2777 ◽  
Author(s):  
Carmen P. Vega ◽  
Elisabeth Schlosser ◽  
Dmitry V. Divine ◽  
Jack Kohler ◽  
Tõnu Martma ◽  
...  
Keyword(s):  
High Resolution ◽  
Stable Isotope ◽  
Mass Balance ◽  
Temporal Variability ◽  
Ice Cores ◽  
Surface Mass Balance ◽  
Ice Shelf ◽  
Climate Signal ◽  
Surface Mass ◽  
Water Stable Isotope

Abstract. Three shallow firn cores were retrieved in the austral summers of 2011/12 and 2013/14 on the ice rises Kupol Ciolkovskogo (KC), Kupol Moskovskij (KM), and Blåskimen Island (BI), all part of Fimbul Ice Shelf (FIS) in western Dronning Maud Land (DML), Antarctica. The cores were dated back to 1958 (KC), 1995 (KM), and 1996 (BI) by annual layer counting using high-resolution oxygen isotope (δ18O) data, and by identifying volcanic horizons using non-sea-salt sulfate (nssSO42−) data. The water stable isotope records show that the atmospheric signature of the annual snow accumulation cycle is well preserved in the firn column, especially at KM and BI. We are able to determine the annual surface mass balance (SMB), as well as the mean SMB values between identified volcanic horizons. Average SMB at the KM and BI sites (0.68 and 0.70 mw. e. yr−1) was higher than at the KC site (0.24 mw. e. yr−1), and there was greater temporal variability as well. Trends in the SMB and δ18O records from the KC core over the period of 1958–2012 agree well with other previously investigated cores in the area, thus the KC site could be considered the most representative of the climate of the region. Cores from KM and BI appear to be more affected by local meteorological conditions and surface topography. Our results suggest that the ice rises are suitable sites for the retrieval of longer firn and ice cores, but that BI has the best preserved seasonal cycles of the three records and is thus the most optimal site for high-resolution studies of temporal variability of the climate signal. Deuterium excess data suggest a possible effect of seasonal moisture transport changes on the annual isotopic signal. In agreement with previous studies, large-scale atmospheric circulation patterns most likely provide the dominant influence on water stable isotope ratios preserved at the core sites.

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