Svenja Rausch

Universität Bremen | Uni Bremen · Petrology of the Ocean Crust, Faculty 05: Geoscience

Numerous calcium carbonate veins were recovered from the igneous basement of the Early Cretaceous Shatsky Rise during Integrated Ocean Drilling Program (IODP) Expedition 324. The chemical (Sr/Ca, Mg/Ca) and isotopic (87Sr/86Sr, 143Nd/144Nd, delta18O, delta13C) compositions of these veins were determined to constrain the timing of vein formation. A...

Deep-Earth convection can be understood by studying hotspot volcanoes that form where mantle plumes rise up and intersect the lithosphere, the Earth’s rigid outer layer. Hotspots characteristically leave age-progressive trails of volcanoes and seamounts on top of oceanic lithosphere, which in turn allow us to decipher the motion of these plates rel...

Chemical (Sr, Mg) and isotopic (δ18O, 87Sr/86Sr) compositions of calcium carbonate veins (CCV) in the oceanic basement were determined to reconstruct changes in Sr/Ca and Mg/Ca of seawater in the Cenozoic. We examined CCV from 10 basement drill sites in the Atlantic and Pacific, ranging in age between 165 and 2.3 Ma. Six of these sites are from col...

Chemical (Sr, Mg) and isotopic (d18O, 87Sr/86Sr) compositions of calcium carbonate veins (CCV) in the oceanic basement were determined to reconstruct changes in Sr/Ca and Mg/Ca of seawater in the Cenozoic. We examined CCV from ten basement drill sites in the Atlantic and Pacific, ranging in age between 165 and 2.3 Ma. Six of these sites are from co...

Hotspots that form above upwelling plumes of hot material from the deep mantle typically leave narrow trails of volcanic seamounts as a tectonic plate moves over their location. These seamount trails are excellent recorders of Earth’s deep processes and allow us to untangle ancient mantle plume motions. During ascent it is likely that mantle plumes...

Carbonates precipitate in fractures, vesicles and matrix of breccias within the basaltic base¬ment of oceanic ridge flanks. They form during low-temperature alteration and can provide in¬sights into processes related to seawater circulation and seawater-basement interaction. It has been proposed that the aging ocean crust is a major sink for CO2 an...

Carbonate veins hosted in ultramafic basement drilled at two sites in the Mid Atlantic Ridge 15 degrees N area record two different stages of fluid-basement interaction. A first generation of carbonate veins consists of calcite and dolomite that formed syn- to postkinematically in tremolite-chlorite schists and serpentine schists that represent gen...

Dolomite is an important component of the global calcium cycle, being a source of Ca to the oceans [Berner, 2004, Amer. J. Sci., 304, 438-453]. Calcium released to the oceans by dolomitization of chalk and limestones can potentially be quantified using marine Ca isotope records [Heuser et al., 2005, Paleoceanography, 20, doi:10.1029/2004PA001048]....

The Louisville Seamount Trail is a 4300 km long volcanic chain that has been built in the past 80 m.y. as the Pacific plate moved over a persistent mantle melting anomaly or hotspot. Because of its linear morphology and its long-lived age-progressive volcanism, Louisville is the South Pacific counterpart of the much better studied Hawaiian-Emperor...

Carbonate veins hosted in ultramafic basement drilled at two sites in the Mid Atlantic Ridge 15°N area record two different stages of fluid-basement interaction. A first generation of carbonate veins consists of calcite and dolomite that formed syn- to postkinematically in tremolite-chlorite schists and serpentine schists that represent gently dipp...

Recently, fractionation of 238U/235U has been observed between oxic and anoxic oceanic environments (Weyer et al., 2008). Sedimentary deposits that formed under oxic conditions (containing U+6) are typically enriched in 235U and anoxic or euxinic sediments (containing U+4) typically show enrichment in 238U. These findings are in agreement with theo...

During low temperature alteration (LTA) of the ocean crust CaCO3 precipitatation in veins and vesicles causes a calcium flux from seawater into the basaltic crust that represents about 10% of the total calcium ouput flux from the oceans [1]. Thus, LTA carbonates may represent a significant factor in the global ocean calcium isotope budget. We analy...

Chemical (Sr, Mg) and isotopic (d 18 O, 87 Sr/ 86 Sr) compositions of calcium carbonate veins (CCV) in the oceanic basement were determined to reconstruct changes in Sr/Ca and Mg/Ca of seawater in the Cenozoic. We examined CCV from 10 basement drill sites in the Atlantic and Pacific, ranging in age between 165 and 2.3 Ma. Six of these sites are fro...

The viscosity of melts in the Na2O-CaO-Al2O3-SiO2 system follows the same trend as a function of composition as that observed in the Na2O-Al2O3-SiO2 system; in that there is a local maximum in viscosity at the condition Na2O+CaO ∼ Al2O3. This is despite the difference in charge of Na+ and Ca2+, the similarity in their radius, and XANES data togethe...