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Short-term evolution of primary sedimentary surface textures (microbial, abiotic, ichnological) on a dry stream bed; modern observations and ancient implications

Neil S. Davies, Anthony P. Shillito and William J. McMahon
Short-term evolution of primary sedimentary surface textures (microbial, abiotic, ichnological) on a dry stream bed; modern observations and ancient implications
Palaios (March 2017) 32 (3): 125-134

Abstract

A wide variety of sub-ripple-scale sedimentary surface textures are known from bedding planes in the sedimentary rock record. Many of these textures were traditionally ascribed an abiotic origin (e.g., due to rain drop impact, adhesion, etc.), but in recent decades the role of microbial mats and biofilms in sculpting and mediating some forms has become increasingly recognized. Microbial sedimentary textures are now well-described and understood from modern tidal environments and biological soil crusts, but descriptions from fluvial settings are less common, despite their known occurrence in ancient alluvium. This paper reports a suite of primary sedimentary surface textures which were observed forming in discrete bodies of standing water in the lower reaches of the ephemeral Murchison River, Western Australia. Microbial sedimentary signatures included bubble impressions (burst and intact) and roll-ups, in addition to reduced horizons. Many of these features exhibited rapid temporal evolution of their morphology in the dry days following an interval of heavy rain. Significantly, these microbial features were witnessed in close spatial proximity to other abiotic and biotic sedimentary surface textures including raindrop impressions, adhesion marks, desiccation cracks, and vertebrate and invertebrate traces. Such proximity of abiotic and microbial sedimentary surface textures is rarely reported from bedding planes in the rock record, but these modern observations emphasize the fact that, particularly in non-marine environments, such structures should not be expected to be mutually exclusive. An appreciation of the fact that primary sedimentary surface textures such as these develop during intervals of stasis in a sedimentation system is crucial to our understanding of their significance and diversity in the rock record.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 32
Serial Issue: 3
Title: Short-term evolution of primary sedimentary surface textures (microbial, abiotic, ichnological) on a dry stream bed; modern observations and ancient implications
Affiliation: University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom
Pages: 125-134
Published: 201703
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 35
Accession Number: 2017-026000
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch map
S27°40'00" - S27°30'00", E114°15'00" - E114°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201716
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