Ordovician ash geochemistry and the establishment of land plants

Geochemical Transactions

Research Article

John Parnell¹  Sorcha Foster² 

[1] School of Geosciences, University of Aberdeen, AB24 3UE, Aberdeen, UK;Victoria College, Cranmore Park, BT9 6JA, Belfast, UK;

关键词: Ash geochemistry;    Tuff;    Land plants;    Chemical index of alteration;    Phosphorus;    Biomass;    Ordovician;   

DOI  :  10.1186/1467-4866-13-7

 received in 2012-06-18, accepted in 2012-08-21,  发布年份 2012

来源: Springer

【 摘 要 】

The colonization of the terrestrial environment by land plants transformed the planetary surface and its biota, and shifted the balance of Earth’s biomass from the subsurface towards the surface. However there was a long delay between the formation of palaeosols (soils) on the land surface and the key stage of plant colonization. The record of palaeosols, and their colonization by fungi and lichens extends well back into the Precambrian. While these early soils provided a potential substrate, they were generally leached of nutrients as part of the weathering process. In contrast, volcanic ash falls provide a geochemically favourable substrate that is both nutrient-rich and has high water retention, making them good hosts to land plants. An anomalously extensive system of volcanic arcs generated unprecedented volumes of lava and volcanic ash (tuff) during the Ordovician. The earliest, mid-Ordovician, records of plant spores coincide with these widespread volcanic deposits, suggesting the possibility of a genetic relationship. The ash constituted a global environment of nutrient-laden, water-saturated soil that could be exploited to maximum advantage by the evolving anchoring systems of land plants. The rapid and pervasive inoculation of modern volcanic ash by plant spores, and symbiotic nitrogen-fixing fungi, suggests that the Ordovician ash must have received a substantial load of the earliest spores and their chemistry favoured plant development. In particular, high phosphorus levels in ash were favourable to plant growth. This may have allowed photosynthesizers to diversify and enlarge, and transform the surface of the planet.

【 授权许可】

CC BY   
© Parnell and Foster; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.