TY  - JOUR
A1  - Codeço, Marta S.
A1  - Weis, Philipp
A1  - Trumbull, Robert B.
A1  - Van Hinsberg, Vincent
A1  - Pinto, Filipe
A1  - Lecumberri-Sanchez, Pilar
A1  - Schleicher, Anja Maria
T1  - The imprint of hydrothermal fluids on trace-element contents in white mica and tourmaline from the Panasqueira W–Sn–Cu deposit, Portugal
JF  - Mineralium Deposita
N2  - White mica and tourmaline are the dominant hydrothermal alteration minerals at the world-class Panasqueira W-Sn-Cu deposit in Portugal. Thus, understanding the controls on their chemical composition helps to constrain ore formation processes at this deposit and determine their usefulness as pathfinder minerals for mineralization in general. We combine whole-rock geochemistry of altered and unaltered metasedimentary host rocks with in situ LA-ICP-MS measurements of tourmaline and white mica from the alteration halo. Principal component analysis (PCA) is used to better identify geochemical patterns and trends of hydrothermal alteration in the datasets. The hydrothermally altered metasediments are enriched in As, Sn, Cs, Li, W, F, Cu, Rb, Zn, Tl, and Pb relative to unaltered samples. In situ mineral analyses show that most of these elements preferentially partition into white mica over tourmaline (Li, Rb, Cs, Tl, W, and Sn), whereas Zn is enriched in tourmaline. White mica has distinct compositions in different settings within the deposit (greisen, vein selvages, wall rock alteration zone, late fault zone), indicating a compositional evolution with time. In contrast, tourmaline from different settings overlaps in composition, which is ascribed to a stronger dependence on host rock composition and also to the effects of chemical zoning and microinclusions affecting the LA-ICP-MS analyses. Hence, in this deposit, white mica is the better recorder of the fluid composition. The calculated trace-element contents of the Panasqueira mineralizing fluid based on the mica data and estimates of mica-fluid partition coefficients are in good agreement with previous fluid-inclusion analyses. A compilation of mica and tourmaline trace-element compositions from Panasqueira and other W-Sn deposits shows that white mica has good potential as a pathfinder mineral, with characteristically high Li, Cs, Rb, Sn, and W contents. The trace-element contents of hydrothermal tourmaline are more variable. Nevertheless, the compiled data suggest that high Sn and Li contents are distinctive for tourmaline from W-Sn deposits.
KW  - alteration geochemistry
KW  - tourmaline
KW  - white mica
KW  - Panasqueira
KW  - Tungsten–tin deposits
KW  - magmatic-hydrothermal systems
KW  - trace elements
Y1  - 2020
U6  - https://doi.org/10.1007/s00126-020-00984-8
SN  - 1432-1866
SN  - 0026-4598
VL  - 56
IS  - 3
SP  - 481
EP  - 508
PB  - Springer
CY  - Berlin; Heidelberg
ER  - 
TY  - JOUR
A1  - Warken, Sophie Friederike
A1  - Fohlmeister, Jens Bernd
A1  - Schröder-Ritzrauh, Andrea
A1  - Constantin, Silviu
A1  - Spötl, Christoph
A1  - Gerdes, Axel
A1  - Esper, Jan
A1  - Frank, Norbert
A1  - Arps, Jennifer
A1  - Terente, Mihai
A1  - Riechelmann, Dana Felicitas Christine
A1  - Mangini, Augusto
A1  - Scholz, Denis
T1  - Reconstruction of late Holocene autumn/winter precipitation variability in SW Romania from a high-resolution speleothem trace element record
JF  - Earth & planetary science letters
N2  - We present the first high-resolution trace element (Mg/Ca, Sr/Ca, Ba/Ca) record from a stalagmite in southwestern Romania covering the last 3.6 ka, which provides the potential for quantitative climate reconstruction. Precise age control is based on three independent dating methods, in particular for the last 250 yr, where chemical lamina counting is combined with the identification of the 20th century radiocarbon bomb peak and Th-230/U dating. Long-term cave monitoring and model simulations of drip water and speleothem elemental variability indicate that precipitation-related processes are the main drivers of speleothem Mg/Ca ratios. Calibration against instrumental climate data shows a significant anti-correlation of speleothem Mg/Ca ratios with autumn/winter (October to March) precipitation (r = -0.61, p < 0.01), which is statistically robust when considering age uncertainties and auto-correlation. This relationship is used to develop a quantitative reconstruction of autumn/winter precipitation. During the late Holocene, our data suggest a heterogeneous pattern of past regional winter hydroclimate in the Carpathian/Balkan realm, along with intermittent weakening of the dominant influence of North Atlantic forcing. In agreement with other regional paleo-hydrological reconstructions, the observed variability reveals periodically occurring strong NW-SE hydro-climate gradients. We hypothesize, that this pattern is caused by shifts of the eastern edge of the area of influence of the NAO across central eastern Europe due to the confluence of North Atlantic forcing, and other climatic features such as the East Atlantic/Western Russia (EAWR) pattern. (C) 2018 Elsevier B.V. All rights reserved.
KW  - speleothem
KW  - trace elements
KW  - proxy calibration
KW  - precipitation reconstruction
KW  - Romania
KW  - North Atlantic forcing
Y1  - 2018
U6  - https://doi.org/10.1016/j.epsl.2018.07.027
SN  - 0012-821X
SN  - 1385-013X
VL  - 499
SP  - 122
EP  - 133
PB  - Elsevier
CY  - Amsterdam
ER  -