Understanding Palaeozoic stromatoporoid growth

Journal article
(Original article)


Publication Details

Author(s): Kershaw S, Munnecke A, Jarochowska E
Journal: Earth-Science Reviews
Publication year: 2018
ISSN: 0012-8252
Language: English


Abstract

Stromatoporoids were abundant components of reefs, reef complexes and associated facies for ca. 100 million years between Middle Ordovician
and end-Devonian time. A lot of environmental information stored in
their skeletons may be used to develop: a) understanding of
stromatoporoid growth controls; and b) interpretations of sedimentary environments
in which they lived. General patterns of stromatoporoid distribution
are well known, but knowledge of detailed interactions between
stromatoporoids and their environments is poorly developed and
under-used, potentially of great value in analysis of facies and palaeoecology.
From a pool of several thousand specimens examined over four decades,
this study identifies four key attributes of stromatoporoids that may be
applied to enhance broad-scale knowledge of these fossils and their
environments: 1) Substrates: Most stromatoporoids grew directly on wackestone to packstone substrates comprising micrite,
clay and bioclasts. Evidence from the relationship between
stromatoporoids and sediments demonstrates they were able to grow on
soft substrates, but also leads to interpretation of partial lithification
of the sea floor (and/or stabilisation by microbial filaments that may
not be preserved) in mid-Palaeozoic carbonate facies, with potential
implications for models of oceanic carbonate cycling. 2) Growth interruption: Almost all stromatoporoids examined show growth interruption, mostly caused by sedimentation
and movement. Stromatoporoids normally recovered quickly and completely
from interruption, thus were resilient to interruption events; 3) Associated organisms:
Stromatoporoids have abundant associated organisms in two groups: (i)
epibiotic encrusters and borers; and (ii) endobiotic organisms embedded
in their structure, alive as the stromatoporoids grew. Epibionts
used stromatoporoid surfaces that are presumed dead in almost all
cases; some are associated with interruption events, but in most cases
those were overgrown by successive stromatoporoid growth. Endobionts
(mostly corals, plus spirorbids and others) are common to abundant in
many stromatoporoid taxa. Stromatoporoid growth was little affected by
presence of endobionts but in many cases (commonly restricted to certain
stromatoporoid taxa) there was a complex biological interaction
valuable in understanding controls on stromatoporoid development. 4) Growth form and taxonomy:
Stromatoporoid assemblages are low diversity in almost all cases,
regardless of age and facies, with two or three taxa much more abundant
than the others. Some stromatoporoid taxa are limited to certain growth
forms, thus taxonomic information is very important for facies analysis and palaeobiological interpretations.

Stromatoporoids
occur commonly with rugose and tabulate corals, both of which could
also live on unconsolidated fine-grained substrates, therefore
sediment-tolerance cannot be the only reason for stromatoporoid ability
to outgrow corals in reefs. Arguments in the literature for
photosymbiosis in both stromatoporoids and Palaeozoic
corals are currently inconclusive for both fossil groups. Nevertheless,
the sum of evidence indicates stromatoporoids were fast-growing,
resilient and flexible benthic organisms, in a range of water depths,
capable of dealing with soft substrates and largely unaffected by
presence of endobionts. These characteristics are interpreted to have
made stromatoporoids successful during mid-Palaeozoic time and valuable
as tools in facies analysis. Recognition of the four key attributes
which encompass all aspects of stromatoporoid growth controls makes
palaeobiological study of stromatoporoids, in palaeoenvironmental
reconstructions where they occur, readily accessible to researchers.


FAU Authors / FAU Editors

Jarochowska, Emilia Dr.
Lehrstuhl für Paläoumwelt
Munnecke, Axel Prof. Dr.
Professur für Paläontologie (Schwerpunkt Faziesanalyse)


External institutions
Brunel University London


How to cite

APA:
Kershaw, S., Munnecke, A., & Jarochowska, E. (2018). Understanding Palaeozoic stromatoporoid growth. Earth-Science Reviews. https://dx.doi.org/10.1016/j.earscirev.2018.08.003

MLA:
Kershaw, Stephen, Axel Munnecke, and Emilia Jarochowska. "Understanding Palaeozoic stromatoporoid growth." Earth-Science Reviews (2018).

BibTeX: 

Last updated on 2018-28-10 at 09:38