TY - JOUR
T1 - Cu isotopes and concentrations during weathering of black shale of the Marcellus Formation, Huntingdon County, Pennsylvania (USA)
AU - Mathur, R.
AU - Jin, L.
AU - Prush, V.
AU - Paul, J.
AU - Ebersole, C.
AU - Fornadel, A.
AU - Williams, J. Z.
AU - Brantley, S.
N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2012/4/18
Y1 - 2012/4/18
N2 - The complex weathering processes which govern the production of soil from bedrock have proven difficult to understand for many lithologies. Weathering of black shale is of particular interest because it releases organic carbon and heavy metals as solutes and therefore impacts the health of terrestrial and aquatic ecosystems. To understand black shale weathering, a geochemical survey was initiated for soils developed on shales of the Marcellus Formation at a zero-order catchment at a satellite site of the Susquehanna/Shale Hills Critical Zone Observatory located in Jackson Corner, Pennsylvania. This formation is an organic- and metal-rich, carbonaceous shale that underlies much of New York, Pennsylvania, Ohio and West Virginia. In this paper, we focus on the effects of weathering on variations of Cu isotopes in the shale. Cu concentration data for soil were normalized using Ti concentrations to document the mobility of Cu relative to bedrock. At both the ridgetop and valley floor, depletion profiles for Cu are documented in the soils. The Cu in the soils is depleted in 65Cu (average δ 65Cu=-0.5‰±0.2) compared to the parent material (average δ 65Cu=0.03‰±0.15). Consistent with loss of Cu from soils, the pore waters contain 10ppb Cu on average and are enriched in the heavy isotope (average value δ 65Cu=1.14‰±0.44). Rayleigh fractionation models using the concentration and isotope data of the soils are consistent with pyrite weathering and loss of Cu from the ridgetop, but downslope transport and Cu re-precipitation at the valley floor.
AB - The complex weathering processes which govern the production of soil from bedrock have proven difficult to understand for many lithologies. Weathering of black shale is of particular interest because it releases organic carbon and heavy metals as solutes and therefore impacts the health of terrestrial and aquatic ecosystems. To understand black shale weathering, a geochemical survey was initiated for soils developed on shales of the Marcellus Formation at a zero-order catchment at a satellite site of the Susquehanna/Shale Hills Critical Zone Observatory located in Jackson Corner, Pennsylvania. This formation is an organic- and metal-rich, carbonaceous shale that underlies much of New York, Pennsylvania, Ohio and West Virginia. In this paper, we focus on the effects of weathering on variations of Cu isotopes in the shale. Cu concentration data for soil were normalized using Ti concentrations to document the mobility of Cu relative to bedrock. At both the ridgetop and valley floor, depletion profiles for Cu are documented in the soils. The Cu in the soils is depleted in 65Cu (average δ 65Cu=-0.5‰±0.2) compared to the parent material (average δ 65Cu=0.03‰±0.15). Consistent with loss of Cu from soils, the pore waters contain 10ppb Cu on average and are enriched in the heavy isotope (average value δ 65Cu=1.14‰±0.44). Rayleigh fractionation models using the concentration and isotope data of the soils are consistent with pyrite weathering and loss of Cu from the ridgetop, but downslope transport and Cu re-precipitation at the valley floor.
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U2 - 10.1016/j.chemgeo.2012.02.015
DO - 10.1016/j.chemgeo.2012.02.015
M3 - Article
AN - SCOPUS:84858965606
SN - 0009-2541
VL - 304-305
SP - 175
EP - 184
JO - Chemical Geology
JF - Chemical Geology
ER -