Trace element partitioning between apatite and carbonatite melt at 800 °C and 200 MPa
Univ. Orléans, CNRS, BRGM, ISTO, UMR 7327, F-45071, Orléans, France
Apatite is a pivotal mineral in carbonate rocks, because it can incorporate all of the major magmatic volatile species (H, P, F, S, Cl), as well as REE and HFSE into its structure. To quantify the effects of fractional crystallization of apatite crystals on the (H, P, F, S, Cl) volatiles and metal budget in the residue melt, the partition coefficients of a broad range of elements (F, Cl, S, REE, HFSE, Co, Ni, Sr, Mo, Ba, W, Pb, Th and U) between apatite and carbonatite melts were determined at 800 °C and 200 MPa using internally heated pressure vessels. The experimental results show that the partition coefficients of Sr, Y and REE (D) are in the range 2-10, and the partition coefficients of Sc, Mn, Fe, Co, Ni, Mo, W, U and HFSE are <<1. The effects of volatiles and oxygen fugacity on the partition coefficients are insignificant. This study defines the apatite-melt partition coefficients for the halogens: DF= 0.68-1.76; DCl=0.10-0.19; and DS= 0.016-0.05. The P2O5 solubility in carbonatite melt decreases from 6.8 to 1.4 wt% in ‘dry’ carbonate to volatile (H2O, F, Cl and S)-bearing carbonate. The results suggest that apatite is preferred to be saturated in hydrous carbonate, and thus cumulated apatite sequester more REE from the residue melts. Finally, we will show that the experimentally determined partition coefficients make apatite a potential indicator for the volatile and trace element abundances in carbonatite magmas.
Specifics of downhole logging data for time series analysis and cyclostratigraphy
Leibniz Institute for Applied Geophysics, Germany
There is a large amount of downhole logging data gathered for scientific and commercial purposes, but studies applying time series analysis and cyclostratigraphy are not abundant. Especially the fast availability of logging data makes it valuable, also for decisions on which cores to investigate first. Here, we summarize the specific properties of downhole logging data most relevant for time series analysis and cyclostratigraphy. As for data from core- or outcrop analysis, it is important to be aware of both the potential and also possible issues of data. For logging data challenges, include changing borehole diameter, influences of drilling fluids and the fact that logged data may be a composite record. This contribution tries to give a concise summary of chances and possible challenges.
Digging into Eocene hothouse climate variability: Linking X-ray fluorescence (XRF) scanning and palynology of Messel sediment cores
1University of Potsdam, Potsdam, Germany; 2Heidelberg University, Heidelberg, Germany; 3Senckenberg Forschungsinstitut und Naturmuseum, Frankfurt am Main, Germany; 4Technische Universität Darmstadt, Darmstadt, Germany; 5Senckenberg Forschungsstation Grube Messel, Messel, Germany
The late early to early middle Eocene (~48 Ma) maar lake sediments of the famous Messel fossil-pit, located near Darmstadt, SW Germany, represent a prime archive for climate dynamics operating during the geologically most recent greenhouse period of the Earth. In this study, we investigate the potential of geochemical data obtained via high-resolution XRF core scanning to decipher hydrologic variability from the Messel sediments. Such data have the potential to yield insight into the paleoenvironmental and paleoclimatic evolution of Messel in unprecedented temporal resolution. As such, they may provide further help towards understanding potential climatic impact on evolutionary patterns as revealed by the fossil record. Our preliminary results from the research drill core of 2001 show a robust correlation with available data on the vegetation from the pollen and spore record and hence hint at the great potential of using XRF core scanning as a tool to decipher wet-dry variability during the early and middle Eocene on orbital to interannual time scales.