Methodology and Techniques - Trace Fossils as Indicators of Sedimentary Environments - page 240

procedures. It rather focuses on the review of the most appropriate techniques
and methodologies applicable in ichnology, with emphasis on those introduced
during the past two decades.
2. FIELD TECHNIQUES
2.1 Outcrop Observations
Accurate field observations are crucial in integrated sedimentological-ichno-
logical studies as well as precise ichnotaxonomical assignments. The introduc-
tion given by Stow (2005) may help to organize the field work in an optimal
way, although ichnological investigations in outcrops may require specialized
techniques (see Ekdale et al., 1984 ). Beside conventional preparation of logs,
notes, sketches, and photographs (see Hodges, 2003; Savazzi, 2011 ), many
advanced methods and techniques for investigation of complex ichnological-
sedimentological situations in the field have evolved during the past decades.
The applied technique strongly depends on the nature of the rock (compo-
sition, degree of lithification, weathering, etc.) and its exposure (e.g., natural
outcrop, excavation, quarry, pit, sawn surfaces, etc.). Based on the unique com-
position and diagenetic history of trace fossils and bioturbate textures, freshly
excavated quarry walls may reveal only limited ichnological information,
whereas weathered cliffs can exhibit the full range of features. Sawn walls of
consolidated rock typically expose detailed characteristics which were other-
wise invisible ( Fig. 1 A; Knaust et al., 2012 ), whereas ichnofabrics in poorly
lithified sediments such as sand and clay can be made visible by sectioning with
spades and knives ( Bromley and Uchman, 2003; Netto et al., 2012 ). Much
emphasis has been placed on the analysis of ichnofabrics in order to capture
different aspects of the biogenic sedimentary structures in a systematic way
( Ekdale et al., 2012; McIlroy, 2007; Taylor et al., 2003 ).
A classical method is the collection of slabs with trace fossils from outcrops,
and consequently, numerous collections around the world contain significant
and valuable material. Important is a proper collecting procedure, documenta-
tion, packing and transportation, cleaning, preparation, and storage similar to
the collection of other fossils (cf. Green, 2001 ). Trace fossils can be utilized
to estimate the stratigraphical completeness based on the tiering pattern
( Wetzel and Aigner, 1986 ), to quantify mechanical compaction ( L¨wemark
et al., 2006 ) and synsedimentary deformation ( Gaillard and Jautee, 1987;
Naruse and Nifuku, 2008; Zi ´ łkowski, 2005 ), and to determine finite strain
in bedding surfaces ( Waldron, 1988 ).
2.2 Peels, Molds, and Casts
The preparation of peels, molds, and casts is an effective way of capturing bio-
genic and sedimentary structures (including trace fossils, ichnofabrics, and
modern traces), and different materials and methods have been applied success-
fully in numerous studies.