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An evaluation of the origin and post-depositional modification of coal mineral matter using rare earth elements and neodymium isotopes.

机译：使用稀土元素和钕同位素对煤矿物质的来源和沉积后变质进行评估。

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摘要

This study was conducted in western Pennsylvania on the Lower Kittanning Coal bed to address the issue of coal mineral matter origin and depositional environment. Channel samples of the coal, the underlying clay (paleosol) unit, and the overlying shale were retrieved over a 170 km east-west range of sampling sites. Analytical techniques applied to the samples include the megascopic description of coal lithotypes, proximate and ultimate analysis, inductively coupled plasma atomic emission spectroscopy (ICP-AES), coal petrography, instrumental neutron activation analysis (INAA), and thermal ionization mass spectrometry (TIMS).; Major cation concentrations in the coal are generally consistent with depositional environment interpretations made on the overlying shale (e.g., epigenetic mineralization). Titanium and shale overburden-normalized plots of the major cation data show that the coal bed is enriched in Fe and Ca compared to the overlying shale. Magnesium, sodium and potassium were depleted in the coal relative to the shale.; Rare earth element (REE) concentrations and neodymium (Nd) isotopes were used to identify sources of coal mineral matter and processes of alteration. A high degree of similarity exists between chondrite normalized REE plots of the coal, the shale overburden and the North American Shale Composite.; The Nd isotopic data from the Lower Kittanning Coal bed show a range of ϵNd(t) (at time of deposition) from −8.4 to −9.9 at the study sites. The Nd isotopic data from the overlying shale and the underlying clay unit show a range from ϵNd(t) values = −8.2 to −10.2. These data are interpreted to indicate a single mineral source throughout the deposition of all three units. That source appears to be clastic matter derived the Appalachian Mountains. An isochron-style plot of the isotopic data appears to indicate Sm-Nd fractionation occurred at the approximate age of the coal bed. This is interpreted as evidence of mobilization of the Sm and Nd. The mobilization of Sm, Nd and other REE may have been caused by the dewatering of the peat from Lower Kittanning early in the coalification process, the role of plant matter in preferential uptake or retention of heavy REE, or selective sorting of coal mineral matter during deposition.
机译：这项研究是在宾夕法尼亚州西部的下肯丹宁煤层上进行的，目的是解决煤矿物质来源和沉积环境的问题。在东西方170 km的范围内检索了煤，下部粘土（古土壤）单元和上层页岩的航道样本。应用于样品的分析技术包括煤岩型的宏观描述，近邻和最终分析，电感耦合等离子体原子发射光谱法（ICP-AES），煤岩学，仪器中子活化分析（INAA）和热电离质谱法（TIMS） 。;煤中的主要阳离子浓度通常与上覆页岩上的沉积环境解释（例如表观成因矿化）一致。主要阳离子数据的钛和页岩覆盖层归一化图显示，与上覆页岩相比，煤层富含Fe和Ca。相对于页岩，煤中的镁，钠和钾被消耗掉。稀土元素（REE）浓度和钕（Nd）同位素用于确定煤矿物质的来源和蚀变过程。煤，页岩覆盖层和北美页岩组合的球粒陨石归一化REE图之间存在高度相似性。来自下Kittanning煤层的Nd同位素数据显示，研究地点的 Nd （t）（沉积时）范围从-8.4到-9.9。来自上层页岩和下层黏土单元的Nd同位素数据显示范围为＆epsiv; Nd （t）值= -8.2至-10.2。这些数据被解释为表明在所有三个单元的整个沉积过程中只有一个矿物源。该来源似乎是源自阿巴拉契亚山脉的碎屑物质。同位素数据的等时线图似乎表明Sm-Nd分馏发生在煤层的近似年龄。这被解释为动员了Sm和Nd的证据。 Sm，Nd和其他REE的动员可能是由于煤层化过程中早期Kittanning的泥炭脱水，植物在优先吸收或保留重REE中的作用或在开采过程中对煤矿物的选择性分选引起的沉积。

著录项

  • 作者

    Schatzel, Steven Joseph.;

  • 作者单位

    University of Pittsburgh.;

  • 授予单位 University of Pittsburgh.;
  • 学科 Geochemistry.; Geology.; Geophysics.
  • 学位 Ph.D.
  • 年度 2001
  • 页码 176 p.
  • 总页数 176
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;地质学;地球物理学;
  • 关键词

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