IAS Special Lecture Tours
Poppe de Boer - 2016-2017
IAS is proud to announce that long-time IAS member and Past President Poppe de Boer has agreed to conduct the IAS Lecture Tour in 2016-2017.
Lecture 1: “Modern versus ancient controls on sedimentary systems; the present is not always the key to the past.“
The basic idea of uniformitarianism dating back to the late 18th century - when Hutton, Whewell, Lyell and others proposed the idea of uniformitarianism in contrast to catastrophism. The idea is that physical and chemical laws have not changed, and that in the distant past sedimentary processes have acted as they do today. However, obviously all kinds of controls have changed and varied in the course of geological time. E.g. the rate of eustatic sea-level change has varied, with rates up to a metre per 100 years during icehouse periods and rates several orders of magnitude (s)lower during greenhouse periods. Such differences lead to a different response of sedimentary systems.
Why is the Black Sea the only present-day example fitting the so-called Black Sea Model for anoxia and black shale deposition? Why is extensive anoxia, as in the North Atlantic and Tethys Oceans during the middle Cretaceous, not encountered in present-day oceans? Why is there a dominance of reports of orbital cyclicity from the Cretaceous? Is the absence of recent analogues for Saline Giants as in the Mediterranean during the Miocene and in the Permian Paradox Basin accidental or due to different conditions in those days?
The present-day Earth’s surface with high mountains (Himalaya, Andes) is not representative for various other parts of the geological record; for example, after the break-up of Pangea major plate collisions were largely absent, with consequences for the continental relief and the character and extent of terrestrial and shallow marine environments. Such differences may explain biological evolutionary trends and the occurrence of sedimentary facies without recent analogues such as lithographic limestones.
Other lectures/short courses:
Lecture 2: Tide-influenced sedimentary systems; processes and products; sensitivity to other controls: the ocean tide has been active since the early days of our planet, and has influenced the character of a variety of marine sedimentary systems. Features like tidal resonance and amphidromic systems may amplify the tide, and local controls, such as basin subsidence, sediment composition and vegetation may greatly affect the character of the sedimentary record. An overview will be given and prominent questions will be discussed.
Lecture 3: Orbital (Milankovitch) cycles: pathways for the transfer of orbital signals into the sedimentary record; the recognition of orbital signals in sediments often focuses on the (statistical) recognition of cycle patterns. This lecture concentrates on the transfer mechanisms of orbital signals (from decennial to multi-millennial scale) through climate and oceanography, into different sedimentary environments and facies; from alluvial fans to the deep sea.
Poppe de Boer is emeritus Professor in Sedimentology at Utrecht University. He was IAS Treasurer from 1986-1994 and IAS President from 2010-2014. He published on a wide variety of topics among which tide-influenced sedimentary facies, orbital signals in sedimentary successions, organic-rich facies. He co-edited volumes on "Tide-influenced sedimentary environments and facies" (1988), "Orbital forcing and cyclic sequences" (IAS SP 19, 1994), "Analogue and numerical forward modelling of sedimentary systems; from understanding to prediction" (IAS SP 40, 2008), and on "Phanerozoic black shales and oceanic anoxic events: geochemistry, sedimentology and stratigraphy" (2012). Current research interests concern catastrophic events, today’s developing greenhouse, tidal facies, and sedimentary systems in arid environments.