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FIGURE 2 Box diagram showing common ichnogenera of the Mermia Ichnofacies. The ichno-
facies can be informally grouped by similar morphologies, sizes, and orientations that show common
associations between ichnotaxa (see Table 2 ). Surface trails (Group 1): Me , Mermia ; He , Helminthoid-
ichnites ; Go , Gordia ; Co , Cochlichnus ; Ac , Archaeonassa . Arthropod trails and trackways (Group 2):
Wa , Warvichnium ; Cr , Cruziana . Horizontal infaunal burrows and surface tunnels (Group 3): Pl , Pla-
nolites ; Pa , Palaeophycus; Tr , Treptichnus ; Va , Vagorichnus . Resting and feeding traces (Group 4):
Lo , Lockeia . Fish swim and resting traces (Group 5): Un , Undichna .
freshwater ponds on alluvial plains ( Buatois and MĀ“ngano, 2002, 2004;
Melchor et al., 2006 ), very shallow films of water in low-energy lake margins
(e.g., Metz, 1996, 2000 ), and littoral zones of hypersaline lakes in regions with
freshwater input ( Scott, 2010 ). In permanently subaqueous zones of lakes, this
ichnofacies is typically exclusive of elements of the Scoyenia Ichnofacies and is
associated with fine-grained deposits in low-energy sublittoral to profundal
zones. In shallow littoral zones or ephemeral water bodies, the Mermia Ichno-
facies may be closely associated with other trace-fossil types (e.g., meniscate-
backfilled burrows, vertebrate footprints), as well as a greater variety of
sedimentary structures (e.g., ripple cross-lamination) and indicators of subaerial
exposure (e.g., desiccation cracks). In these cases, the Mermia Ichnofacies sig-
nifies standing or gently flowing water, with traces produced in very shallow
subaqueous to saturated substrates. Some examples show the Mermia Ichno-
facies in settings influenced by glacial runoff, both in continental (e.g., Benner
et al., 2009; Uchman et al., 2009 ) and freshwater-influenced marginal-marine
environments (e.g., Buatois et al., 2006, 2010; Netto et al., 2012 ).
Bivalve locomotion and resting traces ( Lockeia ) are also produced in littoral
to sublittoral zones of freshwater lakes (e.g., McCall and Tevesz, 1982; White
and Miller, 2008 ) and are presently included in the Mermia Ichnofacies. The
backfilled feeding structures of some modern bivalves, such as Pisidium
( White and Miller, 2008 ), are as yet undescribed in ichnological terms. Other
trace types that have been recorded in low- to moderate-energy littoral to sub-
littoral and profundal zones include those produced by oligochaetes (incipient
cf. Polykladichnus isp. and cf. Labyrintichnus isp.) and insects such as chirono-
mid larvae or mayfly nymphs (diminutive Polykladichnus , Skolithos , Arenico-
lites , Beaconites ) (e.g., Charbonneau and Hare, 1998; Gingras et al., 2007;
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