TY - JOUR

T1 - Organic geochemistry of late Jurassic paleosols (Dirt Beds) of Dorset, UK

AU - Matthewman, Richard

AU - Cotton, Laura J.

AU - Martins, Zita

AU - Sephton, Mark A.

N1 - Funding Information: The authors are very grateful to William Meredith and Armelle Riboulleau for detailed reviews and constructive comments. The authors thank Richard Court for assistance with FTIR, Alex Ball (Natural History Museum, London) for assistance with SEM imaging, and Martin Gill. LC thanks Martin Brasier for fieldwork opportunities. This work was supported by the Science and Technologies Facilities Council and the Royal Society .

PY - 2012

Y1 - 2012

N2 - Paleosols from the lower part of the Purbeck Limestone Group, which crops out extensively in Dorset, southern England, are shown to contain type IV kerogens. Comparisons with Mesozoic organic materials suggest that some of the paleosol kerogen is composed of fossil charcoal. The charcoal would have been produced by wildfires in the undergrowth of Purbeck gymnosperm forests. Contrasting the paleosol charcoal with laboratory produced counterparts suggest that, originally, significant amounts of functionalised organic matter should have persisted. Secondary oxidation and decay processes, therefore, must have removed all but the most resistant aromatic units in the charcoal. The importance of post-fire processes implies a strong influence on preservation from oxygen supply, water washing and host sediment type. These factors may have been related to pedogenesis, relative sea level and local fault movement in the late Jurassic.

AB - Paleosols from the lower part of the Purbeck Limestone Group, which crops out extensively in Dorset, southern England, are shown to contain type IV kerogens. Comparisons with Mesozoic organic materials suggest that some of the paleosol kerogen is composed of fossil charcoal. The charcoal would have been produced by wildfires in the undergrowth of Purbeck gymnosperm forests. Contrasting the paleosol charcoal with laboratory produced counterparts suggest that, originally, significant amounts of functionalised organic matter should have persisted. Secondary oxidation and decay processes, therefore, must have removed all but the most resistant aromatic units in the charcoal. The importance of post-fire processes implies a strong influence on preservation from oxygen supply, water washing and host sediment type. These factors may have been related to pedogenesis, relative sea level and local fault movement in the late Jurassic.

KW - Charcoal

KW - Fusain

KW - Paleosol

KW - Purbeck

KW - Wealden

KW - Wildfire

U2 - 10.1016/j.marpetgeo.2012.05.009

DO - 10.1016/j.marpetgeo.2012.05.009

M3 - Journal article

AN - SCOPUS:84864757214

VL - 37

SP - 41

EP - 52

JO - Marine and Petroleum Geology

JF - Marine and Petroleum Geology

SN - 0264-8172

IS - 1

ER -