Rare earth element systematics of fossil bone revealed by LA-ICPMS analysis
Rare earth element systematics of fossil bone revealed by LA-ICPMS analysis
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DOI：
10.1016/j.gca.2012.10.038
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发表时间：
2013-02-15
影响因子：
5
通讯作者：
Sander, P. Martin
中科院分区：
文献类型：
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作者：
Herwartz, Daniel;Tuetken, Thomas;Sander, P. Martin
利用LA-ICPMS分析方法研究了骨内稀土元素（REE）分馏趋势，以确定骨化石中REE分馏的控制机制、骨化石不同部位REE吸收的相对时间以及骨化石中REE的来源。我们已经评估了从三叠纪到中世纪早期的广泛的特征良好的埋藏环境中的54个化石骨骼的稀土元素骨剖面。稀土元素模式和浓度梯度是高度可变的和骨内分馏趋势（La/Yb）（N）与（La/Sm）（N）空间的几个标本覆盖几乎整个范围内观察到的散装样品。还观察到Ce异常以及变量Y/Ho和（La/La*）N的骨内变异性。有时，成岩流体分馏，重稀土元素富集的组合物已进入骨髓腔的骨，产生二次稀土元素吸收配置文件。理论骨内分馏趋势，采用晶格应变理论建模，同意与大多数稀土元素数据，但有些趋势不能使用现实的边界条件建模。这一事实，以及发生在同一化石样品中的正和负的Ce异常，提示对变化的REE组成的成岩流体的时间尺度上的REE吸收。由于明显的Ce异常经常演变超过骨剖面和Ce异常可以从以前的分馏事件继承，Ce异常是一个高度模糊的示踪剂约束环境氧化还原条件。一般来说，生物磷灰石稀土元素的签名可能并不总是可靠地反映周围的埋藏或氧化还原条件和成岩流体成分。因此，化石骨骼的REE模式和Ce异常必须谨慎解释，因为它们在骨骼遗骸中的空间变化，并受到骨内分馏过程以及成岩流体成分变化的影响。(C)2012爱思唯尔有限公司保留所有权利。
Intra-bone rare earth element (REE) fractionation trends were studied by LA-ICPMS analysis to put constraints on (1) the mechanisms controlling REE fractionation within fossil bones; (2) the relative timing of REE uptake in various parts of fossil bone and (3) the origin of REE in fossil bones. We have evaluated REE bone profiles across 54 fossil bones from a broad range of well-characterised taphonomic settings ranging in age from Triassic to early Medieval. REE patterns and concentration gradients are highly variable and intra-bone fractionation trends in (La/Yb)(N) vs. (La/Sm)(N) space of few specimens cover almost the entire range previously observed for bulk samples. Intra-bone variability of Ce anomalies, as well as variable Y/Ho and (La/La*) N is also observed. Sometimes, diagenetic fluids with fractionated, HREE enriched compositions have entered the bone from the marrow cavity, producing secondary REE uptake profiles. Theoretical intra-bone fractionation trends, modelled using lattice strain theory, concur with most REE data but some trends cannot be modelled using realistic boundary conditions. This fact, as well as the occurence of positive and negative Ce anomalies within the same fossil sample, hint towards changing REE compositions of diagenetic fluids over the timescales of REE uptake. Because apparent Ce anomalies frequently evolve over bone profiles and Ce anomalies can be inherited from previous fractionation events, Ce anomalies are a highly ambiguous tracer for constraining ambient redox conditions. In general, bioapatite REE signatures may not always reliably reflect ambient taphonomic or redox conditions and diagenetic fluid compositions. Therefore REE patterns and Ce anomalies of fossil bones must be interpreted cautiously as they vary spatially within skeletal remains and are affected by intra-bone fractionation processes as well as changing compositions of the diagenetic fluid. (C) 2012 Elsevier Ltd. All rights reserved.