New guidelines for the geological survey of marine areas falling in CARG 1:50,000 sheets

Detection of marine areas

INTRODUCTION

The guidelines presented in this document are the result of the experience gained so far in the field of marine geological cartography, derived from the project for the realization of a "Geological Map of the Italian Seas" (CARG). Already in 1988 the realization of a new basic geological cartography was started with a series of funds arranged by subsequent legislative interventions (L.67/88, L.305/89).
The CARG project starts from the law n. 183 of 18/3/89 that contains the "rules for the organizational and functional rearrangement of soil defense" and implements the need for a geological and geothematic cartography able to constitute a valid scientific documentation for the knowledge of the territory; for the first time this term is extended to the continental shelf that, also from the point of view of anthropic activities, is now to be considered of equal importance to that of the emerged lands.
The "CIPE Resolution" of August 3 1990, in defining the objectives of the CARG project, provides for the extension of the areas to be mapped in the new geological map at the scale 1:50,000 to the continental shelf in front of the Italian coasts, whose importance for the protection and proper management of the coastal territory is recognized.
The National Geological Survey, now part of ISPRA, is the State body institutionally responsible for geological mapping. The specific task of the Survey is to take information, also from the numerous research bodies on issues of common interest (L. 183/89, art. 9), to make the results of this activity available to public administrations (art. 2 of the same Law) and to suggest plans for research on the areas of interest, according to the priorities of the Nation and in agreement with the Regions and Autonomous Provinces, by examining the proposals of the research bodies.
Already in 1992, (Quaderni, series III, n. 1) to represent the geology of submerged areas it was decided to use two complementary scales of representation: the scale 1:250,000, for a synthesis cartography, and the scale 1:50,000, which is the scale of the basic geological cartography of the Italian territory. The first scale of representation is dedicated entirely to marine areas and allows, among other things, to represent in a synthetic way the deepest geological and structural elements, including seismogenic structures located at sea, which allow to define and report active geological structures, areas of potential risk (seismic, volcanic, underwater landslide), etc..
The scale 1:50.000, instead, besides being adopted as the basis of the new geological cartography of Italy in the emerged areas, is more suitable to represent specific situations of coastal or platform areas; it provides a support for a better management of these areas, affected in almost all their extension by phenomena of setback of the shoreline, with consequent risk for the structures (villages, railways, roads, ports) that insist on it. Moreover, it allows to represent information that can define also the dynamics of current and recent sedimentation; this knowledge is necessary for a sustainable use and for the protection of coastal zones and platform areas.
At the end of the 80's the Geological Survey has produced, collecting the experiences of those who worked in the sector (territorial authorities, CNR, Departments and University Institutes) organized in Commissions and Working Groups, the "Guidelines for the survey of the new Geological Map of Italy at the scale 1:50.000", published in the Quaderni, series III, n. 1 of the National Geological Survey seabed and the immediate marine seabed". It represented a first contribution to define "the criteria and methodologies to be used in the survey and representation of the main geological characteristics of the above mentioned areas". This proposal was the result of a careful analysis of what had been produced until then both on nationally and internationally, as well as the direct experience acquired by the Geological Survey during several years of study in various areas of the Italian seas.
In 1993 the Study Commission for Marine Geological Cartography was established at CNR (President: Prof. R. Catalano - University of Palermo; members: C. Bartolini - University of Firenze, A. Fabbri, M. Marani, M. Roveri - Institute for Marine Geology CNR-Bologna, P. Lembo - National Geological Survey, E. Marsella - Istituto Geomare Sud CNR-Napoli, A. Ulzega - University of Cagliari) who presented in 1996 to the Geological Committee the results of the work, in the final report called "General rules of geological survey guidelines in marine areas to be submitted to the Geological Survey of Italy". The document called for a "particular attention to the immediate background, using the interpretative possibilities of sequential stratigraphy, which allows to recognize the sedimentary successions deposited during a complete cycle of relative sea level variation through the integration of seismic, lithological and biostratigraphic data".
In the following years, the National Geological Survey of ISPRA has had the opportunity to sift the products deriving from the CARG project in marine areas (prototype sheet JOG-33-10 Ravenna at 1:250,000 scale and some sheets related to coastal areas, at 1:50,000 scale, with variously extended strips of marine areas) and this has allowed to have a sufficiently wide case history of the physiographic-depositional situations in the different marine areas. At the same time the National Geological Survey has undertaken the survey of marine areas in prototype sheets. These experiences have highlighted the need to review the regulations published in the Quaderno, serie III, n. 1.
At the meeting of the Geological Committee of 5/6 April 2000 (minutes no. 53) the "Working Group for Marine Geology" (GLM) was established, consisting of the Geological Survey, a member of the Geological Committee and representatives of the CARG Project marine geology, with the task of reviewing the regulations of geological mapping of marine areas at the scale 1:50,000 of the Geological Survey. The following were part of the group, as Directors of survey of marine areas of the CARG sheets activated at that date: F.L. Chiocci (University "La Sapienza" of Roma), R. Catalano (University of Palermo), S. D'Angelo (National Geological Survey), F. Fanucci (University of Trieste), G. B. La Monica (University "La Sapienza" of Roma), M. Roveri (CNR - Institute of Marine Geology of Bologna), M. Sacchi (CNR - Geomare Sud), T. Pescatore (University of Sannio), F. Trincardi (Geological Committee), A. Ulzega (University of Cagliari), G. Ventura (National Geological Survey).
This text is the result of the discussions on the subject that took place during five meetings of the GDL, from 2000 to 2002, and was discussed and reworked by the Geological Survey to make it conform to the guidelines of the different "thematic areas" of which the basic geological map is composed. It is important to point out that the fundamental assumption of this text is to consider the basic geological map as a single object, including emerged and submerged areas, consistent within it in expressing the geological reality of the area represented, the result of a database of continuous renewal. We therefore thank our colleagues of the Geological Survey for the work of homogenization of the different topics of a basic geological map: B. Compagnoni (Geological Survey), S. Falcetti (data representation), F. Ferri (geophysical database), F. Galluzzo (geology of the emerged areas), C. Giovagnoli (geological database), F. Papasodaro (Quaternary geology).
In the period February-December 2003, finally, the text was submitted to the critical review of the Geological Committee that, in the meeting of January 2004, approved its general lines. In particular we thank Dr. F. Trincardi (CNR - ISMAR Bologna) for the critical revision of the text.

New guidelines for the geological survey of marine areas covered by CARG 1:50.000 sheets.