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首页> 外文学位 >Microbial And Metazoan Influences on Microbialite Growth Structures: Insights from Recent Lacustrine Microbialites in Pavilion Lake, BC, and Cambrian Thrombolites from the Great Basin, CA and NV.
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Microbial And Metazoan Influences on Microbialite Growth Structures: Insights from Recent Lacustrine Microbialites in Pavilion Lake, BC, and Cambrian Thrombolites from the Great Basin, CA and NV.

机译：微生物和后生动物对微生物的生长结构的影响：来自不列颠哥伦比亚省亭湖的最近湖泊湖泊微生物和来自加利福尼亚州和内华达州大盆地的寒武纪血栓石的见解。

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摘要

Microbialites provide a record of microbial ecosystems and sediment-organism interactions through much of Earth history, with abundant microbialites in Precambrian carbonates and microbialites forming today in a wide range of environments. Interpreting the geologic record of microbialites requires understanding how they reflect microbial communities and metazoan interactions as well as post-depositional and diagenetic processes. To better understand how microbialite fabrics and textures reflect ancient ecosystems, I investigate how microbial communities influence mineral fabrics and microbialite growth (Chapter 1) and how metazoans interactions are preserved and expressed in microbialite fabrics (Chapter 2). Finally, I evaluate microbial and metazoan influences on diverse thrombolite textures (Chapter 3). To evaluate how microbial communities influence mineral fabrics and microbialite growth, I characterized microfabrics in modern lacustrine microbialites in Pavilion Lake, BC, that were actively mineralizing under the influence of photosynthetic communities. The suite of microfabrics in Pavilion Lake microbialites demonstrates that microfabric variations can reflect differences in lithification processes as well as microbial community morphology and spatial arrangement. Even when communities are not well preserved in microfabrics, the community arrangement is captured in microbialite growth structures. Some microbialite growth structures can be influenced by metazoans when microbial and metazoan communities co-occur. To investigate how microbial-metazoan interactions are preserved and expressed in microbialite fabrics, I documented Cambrian stromatolites, thrombolites, and dendrolites that grew in shallow marine environments (Great Basin, California and Nevada) closely associated with metazoan burrowers and grazers. Cambrian microbialites preserve evidence of microbial processes and microbial-metazoan interactions in different ways, and include microbial growth structures that formed without an obvious influence of metazoans, growth structures that were obscured by syn-depositional disruption, and examples where neither the growth structure nor features indicative of metazoan interactions could be definitively identified. I propose criteria for distinguishing the degree to which the growth structure is captured in the microbialite fabric versus overprinted by metazoan interactions. Both metazoan interactions and microbial growth have been previously suggested as the dominant influence on thrombolites, microbialites with clotted or patchy fabrics. To evaluate the role of microbial and metazoan influences versus environmental and diagenetic processes on thrombolite origins, I systematically characterized thrombolites in Cambrian carbonates (Great Basin, California and Nevada), and identified eight thrombolite classes based on their internal textures. Several thrombolite classes contain distinct growth components that reflect variable styles of microbial growth, but other thrombolites lack a distinct growth structure and reflect bioturbation of an originally clotted or patchy growth structure. The suite of Cambrian thrombolites demonstrates that thrombolites are much more diverse than has been widely appreciated, both in their internal fabrics and in how they form. Overall, results from modern lacustrine microbialites and Cambrian microbialites indicate that interpreting the geologic record of microbialites requires identifying features that reflect microbial growth, variations in lithification, and metazoan interactions. Teasing apart these various influences requires detailed observation at multiple scales, and is essential for interpreting patterns in microbialite ecosystems throughout Earth history.
机译：微生物通过地球的大部分历史记录提供了微生物生态系统和沉积物-生物相互作用的记录，当今寒武纪碳酸盐中的大量微生物和如今在各种环境中形成的微生物。解释微生物的地质记录需要了解它们如何反映微生物群落和后生动物的相互作用以及沉积后和成岩过程。为了更好地了解微生物的结构和质地如何反映古代生态系统，我研究了微生物群落如何影响矿物织物和微生物的生长（第1章）以及后生动物的相互作用如何在微生物的织物中得以保留和表达（第2章）。最后，我评估了微生物和后生动物对各种血栓石质地的影响（第3章）。为了评估微生物群落如何影响矿物纤维和微辉石的生长，我对不列颠哥伦比亚省亭湖的现代湖相微辉石中的微纤维进行了表征，这些微纤维在光合群落的影响下正在积极地矿化。亭子湖微斜岩中的微结构套件表明，微结构的变化可以反映石化过程以及微生物群落形态和空间排列的差异。即使当社区无法很好地保存在微织物中时，社区安排也会被捕获在微辉石的生长结构中。当微生物和后生动物群落同时发生时，某些微生物的生长结构会受到后生动物的影响。为了研究微生物-金属间的相互作用如何在微辉石织物中得以保留和表达，我记录了在浅海环境（大盆地，加利福尼亚和内华达州）中生长的新生代寒武纪叠层石，血栓岩和树枝状辉石与后生动物的挖掘者和放牧者密切相关。寒武纪微生物岩以不同的方式保存了微生物过程和微生物-金属间卫相互作用的证据，包括在没有明显的后生动物影响的情况下形成的微生物生长结构，被同沉积破坏所掩盖的生长结构，以及既没有生长结构也没有特征的例子可以确定地确定后生动物相互作用的指示。我提出了一些标准，以区分微微晶石织物中捕获的生长结构与后生动物相互作用叠印的程度。先前已经提出了后生动物的相互作用和微生物的生长是对血栓石，具有凝结或不整齐的织物的微生物石的主要影响。为了评估微生物和后生动物的影响相对于环境和成岩过程在凝块岩成因上的作用，我系统地表征了寒武纪碳酸盐岩中的凝块岩（大盆地，加利福尼亚和内华达州），并根据其内部质地确定了八种凝块岩。几种凝块矿物包含不同的生长组分，这些组分反映了微生物生长方式的变化，但是其他凝块组分缺乏独特的生长结构，并反映了原始凝结或斑驳的生长结构的生物扰动。这套寒武纪的血栓形成物表明，在内部结构和形成方式上，血栓形成物的多样性远远超过了人们普遍赞赏的程度。总体而言，现代湖相微辉石和寒武纪微辉石的结果表明，解释微辉石的地质记录需要确定能反映微生物生长，岩化作用和后生动物相互作用的特征。区分这些不同的影响需要在多个尺度上进行详细的观察，这对于解释整个地球历史中的微辉石生态系统的模式至关重要。

著录项

  • 作者

    Harwood, Cara Lynne.;

  • 作者单位

    University of California, Davis.;

  • 授予单位 University of California, Davis.;
  • 学科 Geobiology.;Paleoecology.;Sedimentary Geology.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 351 p.
  • 总页数 351
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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