The Relationship Between Continental Landscape Evolution and the Plant-Fossil Record: Long Term Hydrologic Controls on Preservation
The Relationship Between Continental Landscape Evolution and the Plant-Fossil Record: Long Term Hydrologic Controls on Preservation
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DOI：
10.1007/978-90-481-8643-3_7
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
R. Gastaldo;Timothy Michael Demko
中科院分区：
文献类型：
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作者：
R. Gastaldo;Timothy Michael Demko
大陆沉积环境保存了大部分的macrofloral记录，因为在古生代中期的陆地植物殖民化的到来，和湿地的代表遇到更常见的比那些生长在更季节性的条件下。人们认为，一旦将碎屑引入任何适当的沉积环境（例如，河流-湖泊或沼泽环境），而不考虑侵位时或其后的时间段的主要相关气候、沉积物负荷或地球化学。如果在地层间隔的任何部分鉴定出植物化石，即使它仅仅是作为一种印象出现的，也可以假定有利的条件随着时间的推移而持续存在，以促进这一记录。相反，地层序列中没有化石植物通常被解释为整个景观的灾难性扰动的结果，而不是将它们的缺失归因于埋藏后数千年可能已经运作的埋藏过滤器。陆地景观受到加积、平衡和退化过程的影响，这些过程不仅控制着当地或区域的地下水位，而且还控制着埋藏在这些沉积物中的有机碎片的长期石化潜力。当土壤中长期保持高水位时，化石植物具有最高的保存潜力（例如，有机土、新成土、潜育土），或保持在区域地下水位最大下降以下的环境中（例如，河道沙坝、废弃河道、湖泊）。当景观达到平衡时，广泛的成土作用和深层成熟土壤的发育（例如，由于大气气体的极端渗透，钙土）导致任何先前被掩埋的植物碎片的细菌降解。当沉积物在景观退化过程中被移除时，当地和/或区域的地下水位在松散地层中被重置得更低，再次促进了先前埋藏的碎屑在深度的快速腐烂。这些过程，在几个世纪到几千年甚至更长（lakh）的时间框架下运作，控制着从化石记录中恢复的植物的最终演化模式。本章回顾了影响陆地植物在水下和陆上环境中保存的因素，并基于现实主义的研究，发展了一个概念框架，在大陆政权的景观演变。提出了一个模式，其中的构造模式与植物碎屑埋藏景观的埋藏和沉积历史有关。案例研究的植物化石记录，从三叠纪到始新世，在完全加积和加积/退化景观。
Continental depositional environments preserve the majority of the macrofloral record since the advent of land-plant colonization in the mid-Paleozoic, and wetland representatives are encountered more commonly than those that grew under more seasonal conditions. It has been assumed that preservation potential and future recovery of plant debris are high once detritus is introduced into any appropriate environment of deposition (e.g., fluvial-lacustrine or paludal setting), regardless of prevailing associated climate, sediment load, or geochemistry at the time of emplacement or interval thereafter. If a plant fossil is identified in any part of a stratigraphic interval, even if it occurs solely as an impression, it has been presumed that favorable conditions persisted over time to facilitate this record. Conversely, the absence of fossil plants in a stratigraphic sequence commonly has been interpreted as the result of catastrophic perturbation across the landscape, rather than the ascribing their absence to taphonomic filters that may have operated millennia after burial. Terrestrial landscapes are affected by aggradational, equilibrium, and degradational processes that control not only the local or regional water table, but also the long-term fossilization potential of organic debris entombed within these sediments. Fossil plants have the highest preservation potential when high water tables are maintained long-term within soils (e.g., histosols, entisols, gleyed soils), or in settings that are maintained below the maximum draw down of the regional water table (e.g., channel barforms, abandoned channels, lakes) of aggradational landscapes. When landscapes reach equilibrium, extensive pedogenesis ensues and the development of deep mature soils (e.g., calcisols) results in the bacterial degradation of any previously buried plant debris due to extreme penetration of atmospheric gases. When sediment is removed during landscape degradation, the local and/or regional water table is reset lower in the unconsolidated stratigraphy, once again promoting rapid decay of previously buried detritus at depth. These processes, operating under time frames of centuries to millennia and longer (lakh), control the ultimate preservational mode of plants recovered from the fossil record.This chapter reviews the factors influencing the preservation of terrestrial plants in both subaqueous and subaerial environments based on actualistic studies, and develops a conceptual framework for landscape evolution in continental regimes. A model is presented in which preservational mode is related to the taphonomic and sedimentary history of the landscape in which plant detritus is buried. Case studies of the plant-fossil record, ranging from the Triassic to the Eocene, in exclusively aggradational and in aggradational/degradational landscapes are presented.