Geology Reference
In-Depth Information
oversimplified understanding of the actual fresh-
water carbonate precipitation process and how it is
controlled by the ever-changing environment. The
traditional view that tufas and speleothems are
formed entirely by physico-chemical precipitation
processes provides the foundation for this research,
but is unlikely to be sustainable indefinitely in the
face of increasing evidence for biological influence
on the precipitation process.
This newly perceived consideration that both
chemical and microbiological processes are
involved in carbonate precipitation (in both marine
systems as well as the freshwater environments con-
sidered in this volume) has resulted in the develop-
ment of a new interface discipline which bridges
both the physical and biological sciences. Its remit
is to view and interpret the planet, in space and
time, as an integrated systemwith life as an essential
driver within all terrestrial and oceanic environ-
mental systems. This interface discipline has
variously been referred to as 'Biogeology', 'Bio-
geoscience' and 'Geomicrobiology' though it is
most frequently referred to as 'Geobiology'
(Noffke 2005), which is our preference. One of the
paramount requirements for future freshwater car-
bonate research in this context is to build a new
foundation for understanding carbonate precipi-
tation processes based on a holistic approach deriv-
ing data from all relevant physical, chemical and
biological processes acting within a system.
Microbial processes fundamentally underpin many
large scale carbonate depositional systems. Conse-
quently, the present need within geosciences is for
detailed assessments of the role of living microbial
communities in modern environments and of how
they act to modify their hydrochemical, geochem-
ical and biochemical environments. Much current
research focuses on exploring the role of microbial
communities in present day sediment-water inter-
face processes. Many of these processes are associ-
ated with carbonate precipitation, thereby providing
a direct link into accumulation styles and deposition
rates of ancient sediments. Equally importantly
these microbial processes strongly influence diagen-
esis within sedimentary successions. Consequently,
the new discipline of Geobiology has the potential
to revolutionize the way we view geological pro-
cesses at the local and regional scales (past,
present and future).
France, Germany, Italy, Poland, Slovenia, Spain,
Switzerland and the UK. It also attracted specialists
from Israel, Turkey and Canada. The remit of the
meeting was to bring tufa and speleothems research-
ers together, and especially sedimentologists and
geochemists, in order to demonstrate that these
increasingly separate research areas were essen-
tially dealing with a single carbonate precipitate
continuum. A one day fieldtrip to the Caerwys
fluvial barrage tufas of North Wales provided
further stimulus to informal discussion and gave
an excellent opportunity for liaison between tufa
and speleothems specialists.
The articles herein reflect the work of 63 spe-
cialists (principally bacteriologists microbiologists,
hydro- and geochemists and sedimentologists)
based mainly in academic institutions. The remit
of this volume is to develop a better understanding
of the biological and chemical influences on carbon-
ate precipitation associated principally with ambient
temperature freshwater carbonates. Many processes
are common to both surface and subterranean situ-
ations yet a research dichotomy has developed
over the past 30 years. Tufa researchers have
tended in the past to be carbonate sedimentologists
or biostratigraphers interested in using facies
models in order to characterise the flow dynamics
and proxy-datable stratigraphy. In contrast, spe-
leothems research has primarily been the domain
of the geochemist. There is now a need to draw
the two research themes together.
The following thirteen chapters of this volume,
dealing principally with carbonate precipitate
associated microbial process and product, range
from studies of individual reactions to overviews
of entire biofilm communities involved with
calcium carbonate precipitation. These are followed
by four papers devoted to the hydrochemistry of
cave waters, the geochemistry of speleothems and
finally, the physical control on depositional mor-
phology using travertine as a case study.
The first paper, by Jones, takes on the thorny
question of what effect microbial processes have
on cave carbonates. The article is a comprehensive
review of previous work to which is added a con-
siderable body of work carried out in the Cayman
Islands. The conclusion is that microbial proces-
ses are widespread both above and below ground.
The article reaffirms the need to reconsider micro-
bial effects when interpreting geochemical data
derived from speleothems. Gonz´ lez-Mu˜oz et al.
show how a single bacterial genus induces a wide
range of mineral precipitates. They conclude by
suggesting that the mechanisms that control
bacterial biomineralization are universal and are
determined principally by the environment in
which the bacteria live. Turning now to the specific
situation of biomediated carbonate, Dittrich &
Contributions in this volume
This volume was conceived at a 'Tufas and Spe-
leothems' workshop organized around 'research in
progress' which was held in the Geography Depart-
ment, University of Hull, UK in May 2008. The
meeting was well attended by researchers from
Search WWH ::
Custom Search