Geological mapping of marine areas
PREMISE
The guidelines presented in this document represent the outcome
of the experiences acquired in the field of marine geological
cartography resulting from the project for the realization of a
“Geological Map of the Italian Seas” (CARG). From 1988
onwards steps were taken to promote a new basic geological
cartography financed by funds allocated by successive legislative
provisions (L.67/88, L.305/89).
The CARG project was launched by Italian Law No. 183 of 18/3/89,
which included “regulations for the organisational and
functional restructuring of land defence". It acknowledged the need
for a geological and geothematic cartography as a valid scientific
documentation for our knowledge of the territory. For the first
time, the term was extended to the continental platform which, from
the anthropic activities point of view, can now be considered of
equal importance to emerged land.
In defining the objectives of the CARG project, the resolution of
the Interministerial Committee for Economic Planning dated August
3rd 1990 extends the areas to be mapped in the new 1:50,000
geological map to the continental platform in front of
Italy’s coasts, recognising their importance for the
protection and proper management of the coastal area.
The National Geological Service (now absorbed into the Department
for Land Defence, APAT) is the State body officially charged with
carrying out geological cartography.
The Service’s specific task is to acquire information –
some of it proceding from the numerous research bodies that work in
areas of shared interest (Law no.183/89, Art. 9). This is in order
to make the results of these activities available to public
administrations (Art. 2 of the aforementioned law) and put forward
plans for research in areas of interest, on the basis of the
Nation’s priorities and in agreement with the Regions and
autonomous provinces, after assessing the proposals of the research
bodies.
In 1992, (Quaderni, serie III, n. 1) it was decided to use two
complementary scales to represent the geology of submerged areas: a
scale of 1:250,000, for a concise cartography, and a scale of
1:50,000, the same scale used for the basic geological cartography
of the Italian territory. The first scale is wholly dedicated to
marine areas and makes it possible to represent deeper geological
and structural elements concisely, including offshore seismogenetic
structures that make it possible to define and point out active
geological structures, areas of potential risk (seismic, volcanic,
underwater landslides) etc.
The scale of 1:50,000, as well as being adopted as a basis for the
new geological cartography of the emerged areas of Italy, also
provides support for an enhanced management of these areas, nearly
all of which are threatened by phenomena related to coastal erosion
with subsequent risks for coastal structures (towns, railways,
roads, ports). Moreover, this scale allows the representation of
information up to defining also the dynamics of current and recent
sedimentation. This knowledge is necessary for the sustainable use
and protection of coastal and platform areas.
In the late 1980s, the Geological Service used the experiences of
those operating in the sector (local bodies, National Research
Institute, University Departments and Institutes organised in
Commissions and Work Groups) to draw up the “Guidelines for
the mapping of the new 1:50,000 Geological Map of Italy”,
published in Quaderni, serie III, n. 1 of the National Geological
Service (1992). This guide also contained the regulations relative
to “geological information on the seabed and immediate
sub-seabed”. It represented a preliminary step towards
the definition of “criteria and methodologies to be used
in mapping and representing the main geological features of the
aforementioned zones”. It was based on a careful
analysis of the results produced so far, both nationally and
internationally, as well as on the first-hand experience acquired
by the Geological Service in the course of various years of work in
several areas of the Italian seas. In 1993, a Marine Geological
Cartography Study Group was set up by the CNR (Chairman: Prof. R.
Catalano – University of Palermo; members: C. Bartolini
– University of Florence, A. Fabbri, M. Marani, M. Roveri
– CNR Institute for Marine Geology -Bologna, P. Lembo –
National Geological Service, E. Marsella – CNR Geomare Sud
Institute -Naples, A. Ulzega – University of Cagliari). In
1996, the Group presented the results of its work to the Geological
Committee in a final report entitled "General guidelines
regulations for geological mapping in marine areas to be presented
to the Italian Geological Service ". The document also stresses the
need for a “particular attention to the immediate
sub-seabed, using the sequential stratigraphy interpretational
possibilities which make it possible to recognise sedimentary
successions deposited during a complete sea level relative
variation cycle through the inclusion of seismic, lithological and
biostratigraphic data”.
In the following years the National Geological Service (now APAT -
Department of Land Defence) has evaluated products resulting from
the CARG project in marine areas (Prototype sheet JOG-33-10 of
Ravenna on a scale of 1:250,000 and various sheets relative to
coastal areas on a scale of 1:50,000, with marine areas of
differing sizes) making it possible to accede to a sufficient body
of case studies relative to the physiographic-depositional
situations in various marine areas. At the same time the National
Geological Service began mapping marine areas in prototype sheets.
These experiences revealed the need for reviewing the regulations
published in Quaderno, serie III, n. 1.
The meetings of the Geological Committee held on 5-6 April 2000
(minutes no. 53) established the “Marine geology work
group” (GLM), formed by the Geological Service, by a member
of the Geological Committee and by the marine geology
representatives of the CARG project, which had the task of
reviewing the regulations relative to geological cartography of
marine areas on a scale of 1:50,000 of the Geological Service. The
following were in charge of mapping marine areas in the CARG sheets
awaiting completion: F.L. Chiocci (University “La
Sapienza” di Roma), R. Catalano (University of Palermo), S.
D’Angelo (Servizio Geologico Nazionale), F. Fanucci
(University of Trieste), G.B. La Monica (University “La
Sapienza” di Roma), M. Roveri (CNR – Istituto di
Geologia marina di Bologna), M. Sacchi (CNR – Geomare Sud),
T. Pescatore (University of Sannio), F. Trincardi (Comitato
Geologico), A. Ulzega (University of Cagliari), G. Ventura
(Servizio Geologico Nazionale).
This text is the outcome of discussions that took place during five
meetings of the GDL, from 2000 to 2002. It was discussed and
reviewed by the Geological Service to ensure compliance with the
guidelines for the various “thematic areas” forming the
basic geological map. It is important to underline that the
assumption of this text is that the basic geological map is to be
considered as a single whole. It includes both emerged and
submerged areas and represents a consistent description of the
geological reality of the represented area, that is the outcome of
a continuously updated databank. Therefore we would like to thank
our colleagues in the Department of Land Defence for their efforts
to conform the different arguments of the basic geological map: B.
Compagnoni (geological mapping), S. Falcetti (data
representation), F. Ferri (geophysical databank), F. Galluzzo
(geology of emerged areas), C. Giovagnoli (geological databank), F.
Papasodaro (Quaternary geology).
Finally, in the February-December period of 2003, the text
underwent critical revision by the Geological Committee which
approved its overall approach in a meeting held in January
2004. Particular thanks go to Dott. F. Trincardi (CNR – ISMAR
Bologna) for his critical revision of the text.
For easiness of consultation, the document was divided into
sections under the following headings:
Introduction and
Definition
Map contents
Data representation
criteria
Databank and final
products
Bibliographic
references
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