RODINIA AND THE MESOPROTEROZOIC EARTH-OCEAN SYSTEM

Abstract

Preface Rodinia and the Mesoproterozoic earth–ocean system www.elsevier.com/locate/precamres We could hardly introduce this volume without mentioning the now infamous words of our respected colleague, Roger Buick, who, in a state-ment somewhere between a tongue-in-cheek caricature and an honest representation of avail-able data, claimed that the Mesoproterozoic Era was 'the dullest time in Earth history' (Buick et al., 1995). If anything is certain, though, it is that the Mesoproterozoic was not dull. Rather, the Mesoproterozoic is emerging as a time of signifi-cant change in terms of global carbon cycling, biogeochemical cycling of redox sensitive ele-ments, and evolutionary diversification in both prokaryotic and eukaryotic communities, includ-ing the appearance of the first unambiguous mul-ticellular algae. Furthermore, many of these major biogeochemical transitions may have been concurrent with, and perhaps causally linked to, the global tectonic events that resulted in the assembly of the supercontinent Rodinia. The contributions to this special issue are, to say the least, an eclectic mix of Mesoproterozoic geology. Rather than finding answers in this vol-ume, we hope that the reader will find questions. We have, therefore, asked the authors, while re-maining acutely aware of the constraints of their data, to broaden the expression of their ideas in order to foster new lines of inquiry. Toward this end, we have not discouraged the presentation of potentially conflicting hypotheses — it is at the points of conflict that breakthrough understand-ing will occur. For those working in Precambrian geology, such an approach is familiar. After all, the con-cept of a Rodinian supercontinent emerged from fragmentary evidence, reconstructed in a new way. Recognized first by the Neoproterozoic rifted margins it left behind, the Mesoproterozoic assembly of Rodinia began to take shape when ancient mobile belts were rejoined in geologic models. The result was the SWEAT hypothesis (Moores, 1991), in which Moores proposed spe-cific tests of his hypothesis, challenged future workers to continue the search for a superconti-nent, and set the SWEAT hypothesis up as the 'straw man' for subsequent hypotheses. Such a simple, elegant model is a tough act to follow. The contributions to this volume reflect the complexity of the questions regarding the Meso-proterozoic era, and perhaps the complexity of the answers. Large-scale tectonic interpretations, grounded in fieldwork and geochronology, provide not only the framework for addressing these questions, but also a wealth of testable hypotheses. Because each tectonic scenario carries specific implications for nearby basins, single-basin studies allow questions of plausibility to be addressed. In this volume, smaller scale studies each focus on aspects of Rodinia, and each draws local or regional conclusions that must be incor-porated into the emerging global framework. This special issue contains 10 papers, with 10 different perspectives on Rodinia. The astute reader will note that there is no consensus on what Rodinia looked like, precisely how it assem-0301-9268/01/$ -see front matter © 2001 Elsevier Science B.V. All rights reserved.