Late Palaeozoic environmental changes: an introduction

Abstract

The idea of this volume arose from our proposal to the palaeoclimatic session held at the European Geosciences Union General Assembly 2011 Conference in Vienna (Austria). Although the original scope was broader, the included contributions focus on palaeoenvironmental changes during the late Palaeozoic. Late Palaeozoic history is especially important in that it records an increase of tectonics/diastrophism, frequent sea-level fluctuations and climatic changes, all finally leading to the most geocratic time of Earth’s history with the formation of the supercontinent Pangaea. This volume includes a number of articles that discuss the fossil record around the Late Palaeozoic Ice Age, and its decline during the Carboniferous with its unusual plant proliferation soon after, when the hottest and driest period in Earth’s history (in the Permian) caused the development of huge ‘sand seas’ on the land. Finally, a biotic event, the largest mass extinction in Earth History at the Permian–Triassic transition, ends the Palaeozoic world. This volume addresses two key issues – the palaeoclimate and depositional cycles – both of which have a strong impact on the record of palaeoenvironmental changes and the understanding of environmental perturbations. The vigorous current debate on the future climate of the globe inevitably increases our interest in past climates. From a geological perspective, climatic perturbations occurred many times before humans were on the planet. Climate varies on several timescales, depends on many high-order factors including tectonic uplift and the orbital wandering of the Earth, and as a result it changes through time. Consequently, palaeoclimatic reconstructions are growing in their importance as they enable us to use the past as a key to the future. The Earth’s system experiences various cycles of very different origin, scale, frequency, amplitude, phase and basic level. From a geological perspective, the cyclicity appears unidirectional, like Brownian motion. However, in the past, the complex interaction of these cycles has led to catastrophic changes in Earth’s systems, such as those during the late Palaeozoic, when palaeoclimatic and geotectonic cycles coincided. These cycles are also influencing our lives, and will do so in our future, so their impact needs to be understood. The geological archives record both the climatic and cyclic phenomena on local to regional scales, including in the late Palaeozoic, as documented in this volume. Understanding these records will improve our predictions about climate phenomena in the future. They also show that the present climatic perturbations are insignificant from a geological point of view. Changes in the late Palaeozoic Earth system are illustrated in this volume by case studies of fossil records from North and South America, East and South Asia, South Africa and Australia, and as regional reviews (section one). The methods include palaeoenvironmental analysis, including palaeobiological, sedimentological, stratigraphic (sequence stratigraphy), palaeomagnetic and geochemical methods. They describe various environmental settings from palaeodeserts, through marine-associated giant salt pans, to shallow to deep marine records. The articles report new data from less known study areas, provide up-to-date data ordering, and expand our knowledge of the evolution of marine and terrestrial environments, climatic changes and biotic events in late Palaeozoic time. This special publication is divided into five chapters, the first comprising articles focused on the broad descriptive character of Late Carboniferous to Early Triassic palaeoclimatic changes and stratigraphy (with the latest part of this period in Europe, i.e. Zechstein). Subsequent articles include more detailed studies of the geological periods grouped into the latest Devonian to Early Carboniferous (section two), Late Carboniferous to Early Permian (section three), Middle to Late Permian (section four), and finally the Permian–Triassic transition (section five). A brief synopsis of individual papers is given below. Wopfner (2012) reviews Westphalian–Early Triassic palaeoclimatic conditions between Samfrau (comprising the southern margins of South America and South Africa, extending via Antarctica