Pim KASKES
FWO PhD fellow
Room F8.62; Tel: +31-6-27308040
Project title
Chicxulub impact: ejecta production, transport, deposition and effects on the global environment.
Project summary
The Chicxulub meteorite impact in Mexico, 66 million years ago, marks the sudden termination of the Mesozoic Era in Earth’s history. Since the impact hypothesis was first postulated in 1980 and the subsequent discovery of the meteorite crater on the Yucatán peninsula in 1991, empirical evidence has been accumulated that points towards a single asteroid impact causing a global environmental catastrophe and a mass extinction of many lifeforms, including the iconic dinosaurs. However, questions still remain on the succession of regional and global events that took place across the Cretaceous-Paleogene (K-Pg) boundary. This includes the amount and type of products injected by the cratering event into the atmosphere, their contribution to the proposed ‘Impact Winter’ and the biotic response to the impact-induced environmental perturbation, as well as the potential role of the partly coeval Deccan Traps volcanism on the mass extinction.
In this project, the thick sequence of suevites, impact melts and shocked basement lithologies is examined that was recovered from the c. 830 m long core drilled in 2016 by the joint International Ocean Discovery Program (IODP)–International Continental Scientific Drilling Project (ICDP) within the central peak ring zone of the unique Chicxulub impact crater. This crater of c. 180 km in diameter is an ideal natural laboratory for studying both impact cratering processes and their environmental consequences. Not only is Chicxulub the best preserved large terrestrial impact structure with an intact peak ring, it also has a global ejecta layer and it is the only crater on Earth that has been directly linked to a mass extinction event. Using an extensive geochemical toolbox, including Micro X-Ray Fluorescence (µXRF), Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) and Neutron Activation Analysis (NAA), the major, trace and platinum group elemental (PGE) composition of the core sequence is measured with a focus on the geochemical characterization of the different suevite-clasts. These are the remnants of the mixed target of the Chicxulub impact: a 2-3 km thick Mesozoic carbonate and evaporite platform and a Pan-African gneissic-granitic basement.
Subsequently, the petrographic and geochemical data derived from the IODP-ICDP 364 core is compared with previous core material from the Chicxulub crater and with proximal and distal K-Pg ejecta sites around the globe. By doing so, we aim to better understand the formation of the impact ejecta and its worldwide distribution. Furthermore, we will use the IODP-ICDP material to refine simulations in global climate models by constraining the proportion of the different volatiles (e.g. CO2, H2O, SOx) and silicate dust injected into the atmosphere by the crater excavation process. Finally, we aim to use this new palaeoclimate data to further examine the climatic causes of the demise of vertebrate life on Earth, including the contributions of both the Chicxulub impact as the Deccan Traps volcanism on the mass extinction.
Field sites
The material from the IODP-ICDP 364 drill core was extracted c. 30 km northwest of Progreso on the Yucatán shelf in the Gulf of Mexico. In addition, proximal and distal K-Pg sites are being examined, including a new, fossiliferous section in the Hell Creek Formation of North Dakota (USA). In the last few years, I joined several palaeontological excavations in Upper Maastrichtian dinosaur-rich deposits in Montana and Wyoming (USA), the Lower Triassic of the Netherlands and the Eocene and Miocene of Qatar. This was part of my MSc Thesis (Vrije Universiteit Amsterdam) and my subsequent work for Naturalis Biodiversity Center in Leiden. During my PhD project, I will also work on the research papers of these projects.
Keywords
Chicxulub impact, ejecta geochemistry, integrated stratigraphy, dinosaur taphonomy, µXRF, LA-ICP-MS, NAA, PGE, SEM-EDS