Fossil trees in ancient fluvial channel deposits: evidence of seasonal and longer-term climatic variability

Fielding, Christopher R., Nakayama, K. and Alexander, Jan (2001). Fossil trees in ancient fluvial channel deposits: evidence of seasonal and longer-term climatic variability. In: Joseph A. Mason and Robert F. Diffendal, Fluvial Sedimentology 2001. 7th International Conference on Fluvial Sedimentology, University of Nebraska, Nebraska, (101-101). 6 - 10 August, 2001.


Author Fielding, Christopher R.
Nakayama, K.
Alexander, Jan
Title of paper Fossil trees in ancient fluvial channel deposits: evidence of seasonal and longer-term climatic variability
Conference name 7th International Conference on Fluvial Sedimentology
Conference location University of Nebraska, Nebraska
Conference dates 6 - 10 August, 2001
Proceedings title Fluvial Sedimentology 2001
Place of Publication Lincoln, Nebraska
Publisher University of Nebraska
Publication Year 2001
Sub-type Fully published paper
Editor Joseph A. Mason
Robert F. Diffendal
Start page 101
End page 101
Total pages 1
Collection year 2001
Abstract/Summary It has been established that large numbers of certain trees can survive in the beds of rivers of northeastern Australia where a strongly seasonal distribution of precipitation causes extreme variations in flow on both a yearly and longer-term basis. In these rivers, minimal flow occurs throughout much of any year and for periods of up to several years, allowing the trees to become established and to adapt their form in order to facilitate their survival in environments that experience periodic inundation by fast-flowing, debris-laden water. Such trees (notably paperbark trees of the angiosperm genus Melaleuca) adopt a reclined to prostrate, downstream-trailing habit, have a multiple-stemmed form, modified crown with weeping foliage, development of thick, spongy bark, anchoring of roots into firm to lithified substrates beneath the channel floor, root regeneration, and develop in flow-parallel, linear groves. Individuals from within flow-parallel, linear groves are preserved in situ within the alluvial deposit of the river following burial and death. Four examples of in situ tree fossils within alluvial channel deposits in the Permian of eastern Australia demonstrate that specialised riverbed plant communities also existed at times in the geological past. These examples, from the Lower Permian Carmila Beds, Upper Permian Moranbah Coal Measures and Baralaba Coal Measures of central Queensland and the Upper Permian Newcastle Coal Measures of central New South Wales, show several of the characteristics of trees described from modern rivers in northeastern Australia, including preservation in closely-spaced groups. These properties, together with independent sedimentological evidence, suggest that the Permian trees were adapted to an environment affected by highly variable runoff, albeit in a more temperate climatic situation than the modem Australian examples. It is proposed that occurrences of fossil trees preserved in situ within alluvial channel deposits may be diagnostic of environments controlled by seasonal and longer-term variability in fluvial runoff, and hence may have value in interpreting aspects of palaeoclimate from ancient alluvial successions. (C) 2001 Elsevier Science B.V. All rights reserved.
Subjects EX
260104 Sedimentology
780104 Earth sciences
Keyword Seasonal Discharge
Tropical Burdekin River
Permian Coal Measures
Fluvial Channels
Point-bar Deposits
Eastern Australia
Riparian Vegetation
Fossil Trees
North Queensland
British-columbia
Foreland Basin
Sydney Basin
Bowen Basin
In-situ
References Geography, Physical Geosciences, Multidisciplinary Paleontology
Q-Index Code EX

Document type: Conference Paper
Collection: School of Physical Sciences Publications
 
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Created: Thu, 23 Aug 2007, 23:36:52 EST