in Jurassic and Cretaceous Stratigraphy

Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321
Proposals for Establishing An International Database of Key Jurassic
Sites and Stratotypes to Aid National and International Research
396
K.N. Page¹, G. Meléndez²
1. School of Geography, Earth and Environmental Sciences, University of Plymouth, Drakes Circus, Plymouth, PL4 8AA, UK
(E-mail: kpage@plymouth.ac.uk)
2. Dpto. Geología (Paleontología), Universidad de Zaragoza, c./ Pedro Cerbuna 12, 50009 Zaragoza, Spain
(E-mail: gmelende@unizar.es)
As the few remaining stage stratotypes (i.e. GSSPs)
for the Jurassic are established over the next few years,
the primary function of the International Subcommision
for Jurassic Stratigraphy (ISJS) will have been fulfilled.
This consequently posses a question – what future roles
could the Subcommission fulfil? As GSSPs establish
globally applicable bases for all Jurassic stages, what
level of international applicability should their com-
ponent ammonite-correlated chronozones have? If
these zonations should really be considered to be
‘standards’, surely some form of international agree-
ment is required to stabilize their usage and ensure that
every time a new review is published zonal boundaries
do not move around? (if they do then the zonation is
certainly not a ‘standard’). Inevitably, due to faunal
provincialism, regional standard schemes may be
necessary, but all must now ‘fit’ within the defined
GSSP isochrons. Commonly, however, some faunas are
shared between adjacent provinces and these can
provide the basis for establishing formal divisions at the
chronozone and subchronozone level. Any regional or
local (i.e. single basin) variations can be accommodated
at the level of ‘horizon’ or ‘biohorizon’, thus providing
a degree of ‘flexibility’ to accommodate new dis-
coveries.
Deciding on what ‘standard’ schemes are appli-
cable would be an ideal role for established stage
working groups within the ISJS, whose multi- disci-
plinary expertise has already led to the establish- ment
of stage GSSPs. Indeed, the formalization of true
Standard Zonations would be a natural extension of this
work, and key review papers and volumes such as
Cariou and Hantzpergue (1997), Westermann (1992)
and Page (1992), can provide a basis on which to build.
Crucially, although ammonites are likely to remain as
the primary stratigraphic indicators – i.e. because they
can be readily identified in the field by appropriate
specialists without the need for expensive sample
processing - the value of establishing defined strato-
types for each chronozone and subchronozone as is
required by chronostratigraphical method, allows a
range of other ‘proxies’ to be used to correlate each unit.
Examples which have been used at this level include
brachiopods, a range of microfossil groups and even
carbon isotopes – as will be apparent from every GSSP
definition. Every definition of every standard chrono-
zone and subchronozone requires a stratotype – a
defined point in a designated section at a geogra-
phically identified location. Just like GSSPs, such
sections are ‘reference sections’ and should, therefore,
remain open and accessible for study and sampling by a
global scientific community. Unfortunately, national
conservation and related heritage management frame-
works and perspectives can often either inappropriate
restrict this use or permit unregulated use of which can,
literally, erode its scientific value. Knowledge of such
frameworks and issues is essential for any scientists
planning any future work at any established stratotype.
Basic information of this type has been provided
for all established and proposed Jurassic GSSPs by
Page, Meléndez and Henriques (2009) and the it is
proposed here that a database is established to provide
similar information for all other Jurassic chrono-
stratigraphic stratotypes (following the agreement on
internationally applicable ‘standard’ zonal schemes by
each stage-focused working group of the ISJS). Such a
database should ideally be accessible – and updatable –
online, thus providing a global resource for Jurassic
science (although some thought may need to be given
as to whether open or ‘controlled’ access is appropriate,
to reduce the risk of any misuse of the included
information, e.g. by commercial fossil collectors). Key
information for each site could include: Name,
Geographical referencing (including map), Status (e.g.
chronozone stratotype), Nature of site (e.g. natural
coastal cliff), Conservation status (e.g. legal
designations), Access and Ownership, Key References,
Contacts (e.g. email, website, etc., including of con-
servation authorities, key researchers, etc). Ultimately,
this information could also be published as a series of
printed, individual stage-focussed volumes. There is
clearly a strong link in such a project between science
and conservation, as the needs of science require an
appropriate conservation process to take place to ensure
that the ‘reference’ localities remain open and available
for study. The establishment of the international value
of the suite of stratotypes recognized and described
could also inform international conservation projects,
such as the global geosites initiative, initially estab-
lished through the International Union of Geological
Sciences (IUGS; Wimbledon et al., 2000) which also,
ultimately, of course, oversees the core work of the
ISJS selecting GSSPs.