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 (Law 67/88, Law 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 Survey (now absorbed into ISPRA) is the State body officially charged with carrying out geological cartography.
The Survey’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 Survey 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 Survey  (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 Survey, 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 Survey". 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 Survey 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 Survey 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 Survey, 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 Survey. 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 Survey 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.

New guide-lines for the geological mapping of marine areas within CARG sheets at 1:50,000 scale