Fossil diagenesis in the burgess shale
Fossil diagenesis in the burgess shale
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DOI：
10.1111/j.1475-4983.2007.00656.x
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发表时间：
2007-05-01
期刊：
影响因子：
2.6
通讯作者：
Wilson, Lucy A.
中科院分区：
文献类型：
--
作者：
Butterfield, Nicholas J.;Balthasar, Uwe;Wilson, Lucy A.
目前的模式，伯吉斯页岩化石的特殊保存集中在HF提取的碳质压缩或矿物膜元素映射确定。二维保存Marpolia，Wiwaxia和Burgessia的BSEM，EDX和微探针分析确定了大多数功能的碳质和铝硅酸盐膜的存在下，无论原来的不稳定性。根据Burgess页岩的深埋和绿片岩相变质记录，铝硅酸盐薄膜被确定为晚期挥发和预先存在的压缩化石的同步矿化的产物，而三维保存的Burgessia肠道盲肠系统被解释为预先存在的碳酸盐相的铝硅酸盐替换。晚成岩侵位的铝硅酸盐矿物的情况下，支持广泛的三叶虫壳铝硅化和（最初）在伯吉斯页岩中的钙质细脉，以及其他二次铝硅化压缩化石的文件。通过区分晚成岩蚀变与早期成岩过程中负责异常保存，这是可能的调和目前在伯吉斯页岩中表达的一系列构造模式。
Current models for the exceptional preservation of Burgess Shale fossils have focused on either the HF-extractable carbonaceous compressions or the mineral films identified by elemental mapping. BSEM, EDX and microprobe analysis of two-dimensionally preserved Marpolia, Wiwaxia and Burgessia identifies the presence of both carbonaceous and aluminosilicate films for most features, irrespective of original lability. In the light of the deep burial and greenschist facies metamorphism documented for the Burgess Shale, the aluminosilicate films are identified as products of late-stage volatilization and coincident mineralization of pre-existing compression fossils, whereas the three-dimensionally preserved gut-caecal system of Burgessia is interpreted as an aluminosilicate replacement of a pre-existing carbonate phase. The case for late diagenetic emplacement of aluminosilicate minerals is supported by the extensive aluminosilicification of trilobite shell and (originally) calcareous veinlets in the Burgess Shale, as well as documentation of other secondarily aluminosilicified compression fossils. By distinguishing late diagenetic alteration from the early diagenetic processes responsible for exceptional preservation, it is possible to reconcile the range of preservational modes currently expressed in the Burgess Shale.