Finally, we propose a pioneering morphometric typology of dolines that provides important clues as to pseudokarstic activity. We define collapse, bowl-shaped and flat bottom dolines. Collapse and bowl-shaped dolines are assumed to denote active pseudokarst. They may widen and deepen, or eventually be filled by sediments.They are distinguished from flat bottom dolines that are partially to completely filled, This article is protected by copyright. All rights reserved. which suggests that they are associated with paleo-pseudokarsts. However the groundwater flow paths associated with the genesis and evolution of dolines must be clarified, thus collapse and bowl-shaped dolines should be hydrologically monitored.

This Memoir summarizes our current knowledge of New Caledonia geology, geodynamics and mineral resources based on published and unpublished information. Except for a short paper timed for the 34th International Geological Congress (Cluzel et al. 2012b), there has been no review of the geology of New Caledonia since Paris (1981)that is, for more than 35 years. As such, it is timely that this Memoir is published.This Memoir comprises a collection of ten self-contained chapters written by 28 researchers from New Caledonia, France, New Zealand, Australia and Papua New Guinea. This work is not simply a summation of the factual material acquired since Paris (1981). The purpose of each chapter is to present: (1) a data synthesis from which the reader can make his or her own interpretations and (2) an interpretation by the authors incorporating contemporary datasets and geoscientific concepts. Onshore-offshore connections are emphasized, as are the geological relations with New Zealand, Australia and Papua New Guinea, although this Memoir certainly is not a synthesis of the geodynamics of the SW Pacific.This introductory chapter is a starting point for understanding how the current state of geoscientific knowledge of New Caledonia was reached. It includes a small-scale geological map and proposes a general stratigraphic scheme for New Caledonia. It reviews the advances in knowledge of the geology of the country since the last synthesis of Paris (1981). It also summarizes current problems and issues and the analyses strengths and weaknesses in the state of knowledge of the country's geology.Chapter 2 reviews the geodynamics of the SW Pacific and its relations with New Caledonian geology (Collot et al. 2020). The onshore geology of New Caledonia cannot be separated from its regional and offshore context. This chapter identifies the major geological structures of the SW Pacific from the eastern Australian coast to the Tonga-Kermadec Trench. This mostly submerged system of basins, ridges and seamounts of various ages is interpreted as oceanic and thinned continental crust, continental ridges, volcanic arcs, intra-plate volcanic chains and oceanic plateaus. Part of this region, including New Caledonia, is a submerged continent referred to as Zealandia (Mortimer et al. 2017). This chapter presents and compares tectonic models that attempt to explain the formation and development of this complex area.Chapter 3 considers the Pre-Late Cretaceous basement terranes of the Gondwana active margin (Maurizot et al. 2020a).

The southwestern Pacific Ocean region hosts submerged continental margins, ridges, sedimentary basins, and volcanic arcs located around Papua New Guinea, New Zealand, Australia, and Fiji. The geological history of this vast region has remained controversial, and to improve understanding of the processes that controlled its geodynamical evolution, it is essential to place each piece of available data in a regional spatiotemporal framework. To this end, a new map, entitled “Structural Provinces of the Southwest Pacific,” was released by the Geological Survey of New Caledonia in May 2011. The publication consists of two parts: (1) a 40‐page booklet of geological notes, which documents the nature and age of each structure and contains an associated list of references; and (2) a 3‐ x 4‐foot poster of a structural map revealing the nature of the basement, location, and type of the main structural features (see simplified version in Figure 1) and the age of formation using the international standards for geological color codes established by the Commission for the Geological Map of the World (CGMW) (see http://ccgm.free.fr/index.html).

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