Symposium: 40 years of Milankovitch research in Utrecht - What has been achieved?
HILGEN-MILANKOVITCH SYMPOSIUM Koningsbergergebouw room Cosmos
13:00 - 13:20: Luc Milankovitch Forcing of Extreme Global Temperatures
13:20 - 13:40: Wout Messin' around in the Mediterranean
13:40 - 14:00: Klaudia 28.201 Ma
14:00 - 14:20: Hemmo Digging Deep and Flying High - Unraveling Fluvial Milankovitch
14:20 – 14:35: break
14:35 - 14:55: Christian Cyclostratigraphy: Visual and/or Numerical?
14:55 - 15:15: Joyce Modeling Milankovitch Climate
15:15 - 15:45: Margriet / Bianca The Precambrian - Insights from striped mountains in Australia, South Africa and Namibia
15:45 - 16:00: break
16:00 - 17:00: Frits FEST: 40 years Milankovitch: A personal story and way of life
Abstracts
Lucas Lourens: Milankovitch Forcing of Extreme Global Temperatures
Abstract: The early Eocene (56-48 million years before the present, Ma) is the warmest period of the Cenozoic, characterized by very high CO2 levels (~600-2500 ppm), reduced latitudinal temperature gradients, and the absence of continental ice sheets. As such, the early Eocene hothouse is considered as a potential analogue for our future climate. The early Eocene is also a time period characterized by the occurrence of multiple transient global warming events, so-called hyperthermal events of which the Paleocene–Eocene Thermal Maximum (PETM) is the first and most prominent one of a series of >20 events. Here, I will talk about the underlying Milankovitch forcing of the hyperthermal events, knowing that the astronomical calculations of the Solar System’s dynamical evolution are chaotic beyond ~50 Ma. In addition, I will highlight the new clumped isotope-based deep sea temperature estimates for the early Eocene, suggesting that we may have to worry even more about global warming than we already do.
Wout Krijgsman: Messin' around in the Mediterranean
Abstract: After his pioneering work on the Plio-Pleistocene astronomical time scale, Mediterranean research with Frits Hilgen continued deep into the Miocene. I will present here a tale of hard work with lots of digging, logging, drilling, messing around and having fun in multiple fieldtrips and sections all across the Mediterranean. This finally culminated in the construction of an astronomically tuned geological time scale for the entire Neogene, which is instrumental to understand paleoclimatic and paleoenvironmental changes in the circum-Mediterranean region and its connectivity with the Atlantic and Paratethys. I will also highlight the key sections in the late Messinian that we did not fully solve yet and which still fuel major scientific debates on the Mediterranean water level changes during the Messinian Salinity Crisis.
Klaudia Kuiper: 28.201 Ma
Abstract: When Frits published his first paper on the astronomical calibration of Gauss to Matuyama sapropels in the Mediterranean and the implications for the Geomagnetic Polarity Time Scale in 1991, he immediately realized that the astronomical ages differed considerably from the existing radiometric ages, with the astronomical ages being consistently older by up to 12%. In my presentation I will guide you through the research that we conducted since then to solve this key issue. Clearly the age of the Fish Canyon sanidine dating standard in Ar/Ar geochronology plays a crucial role in solving this problem. This solution is important as the three main numerical dating methods (astronomical, Ar/Ar and U/Pb dating) used to build our standard Geological Time Scale should arrive at the same age when the same event is being dated.
Hemmo Abels: Digging Deep and Flying High - Unravelling Fluvial Cyclicity
Christian Zeeden: Cyclostratigraphy: Visual and/or Numerical?
Abstract: I will give a brief overview of methods used in cyclostratigraphic pattern recognition. Such a pattern recognition can be based on the visual identification of patterns by experts (e.g., Frits), or solely on statistical methods (however, a confidence test does not make a cyclostratigraphic study). In this talk I will briefly summarize this controversy, and give my personal opinion based on experience from Utrecht, Paris and my own thoughts.
Joyce Bosmans: Modeling Milankovitch Climate
Abstract: Paleoclimatologists use a wide range of proxies, including stable oxygen and carbon isotopes, microfossils and geochemical elements, to reconstruct astronomical climate forcing. Such proxies have for instance been used to understand sapropel formation in the Mediterranean. However, this forcing can also be reconstructed using climate modeling of astronomical climate forcing using a range of different types of climate models. This modeling is critically important for data-model comparison and for independently testing hypotheses of in this case sapropel formation. Here I will review the work that we carried out to understand sapropel formation from a climate modeling perspective and compare the outcome of our model simulations with the hypotheses formed based on proxy studies.
Margriet Lantink & Bianca Spiering: The Precambrian - Insights from striped mountains in South Africa and Namibia
Abstract: The Precambrian covers the first 4 billion years (~88%) of Earth’s history, and ended around ~540 million years ago. During this period, the Earth experienced the oxygenation of its oceans and atmosphere, as well as the origin of simple life and the evolution towards the first complex animals. As astronomical climate forcing played an important role in the more recent past, it is also expected to have played a role in the Precambrian. Outcrops of marine sedimentary rocks in Australia, South Africa and Namibia display a regularity – forming ‘striped mountains’ – that could be related to astronomical climate forcing. We will discuss the results of Margriet’s PhD thesis on lower Proterozoic Banded Iron Formations in South Africa and Western Australia, and the ongoing research of Bianca’s PhD thesis on the upper Proterozoic Nama Group in Namibia.
Frits Hilgen: 40 years of Milankovitch - A personal story and way of life
Abstract: Can you spend your entire working career of ~40 years on the fascinating narrative of astronomical (Milankovitch) climate forcing? On how the gravitational influence of the Sun, planets, satellites and asteroids affected Earth’s climate, and how this influence can be almost perfectly recorded in our stunning sedimentary archives and what you can all reconstruct from these archives? Well, at the end, I would definitely say yes, you can! However, during this “farewell” talk, I will not spend that much time on these cycles myself. If you want to hear that part of the story, you better go to the preceding symposium where former PhDs will provide you with a superb overview of that history interspersed I am afraid with some anecdotes.
In my talk I will look back at my personal story of how I decided to study Earth Sciences, to how I completely changed the subject of my PhD thesis, and finally ended up as cyclostratigrapher, or better integrated stratigrapher, spending among others 8 years of my life in the field, including all the fieldwork with students. Where can you better learn the Earth Sciences than during your 1st year “mapping” exercise, being thrown in the depth, taking arduous decisions about what data to collect and at the end of the day write a mission statement in your fieldbook, not only about WHAT you are going to do in the field the next day but especially WHY? In short, an excellent scientific training! At the end of my talk, I will look shortly at a hopefully bright future continuing working with young and motivated PhDs, writing some hopefully interesting papers that you can only write later in your career, like of what would have happened if Earth orbit would have been circular, but also have more time for hobbies as birding and drawing.