Abstract
Abstract This study presents a new classification of a ∼100-m-thick crater suevite sequence in the recent International Ocean Discovery Program (IODP)-International Continental Scientific Drilling Program (ICDP) Expedition 364 Hole M0077A drill core to better understand the formation of suevite on top of the Chicxulub peak ring. We provide an extensive data set for this succession that consists of whole-rock major and trace element compositional data (n = 212) and petrographic data supported by digital image analysis. The suevite sequence is subdivided into three units that are distinct in their petrography, geochemistry, and sedimentology, from base to top: the ∼5.6-m-thick non-graded suevite unit, the ∼89-m-thick graded suevite unit, and the ∼3.5-m-thick bedded suevite unit. All of these suevite units have isolated Cretaceous planktic foraminifera within their clastic groundmass, which suggests that marine processes were responsible for the deposition of the entire M0077A suevite sequence. The most likely scenario describes that the first ocean water that reached the northern peak ring region entered through a N-NE gap in the Chicxulub outer rim. We estimate that this ocean water arrived at Site M0077 within 30 minutes after the impact and was relatively poor in rock debris. This water caused intense quench fragmentation when it interacted with the underlying hot impact melt rock, and this resulted in the emplacement of the ∼5.6-m-thick hyaloclastite-like, non-graded suevite unit. In the following hours, the impact structure was flooded by an ocean resurge rich in rock debris, which caused the phreatomagmatic processes to stop and the ∼89-m-thick graded suevite unit to be deposited. We interpret that after the energy of the resurge slowly dissipated, oscillating seiche waves took over the sedimentary regime and formed the ∼3.5-m-thick bedded suevite unit. The final stages of the formation of the impactite sequence (estimated to be <20 years after impact) were dominated by resuspension and slow atmospheric settling, including the final deposition of Chicxulub impactor debris. Cumulatively, the Site M0077 suevite sequence from the Chicxulub impact site preserved a high-resolution record that provides an unprecedented window for unravelling the dynamics and timing of proximal marine cratering processes in the direct aftermath of a large impact event.
Highlights
∼100-m-thick crater suevite sequence in the re- M0077 within 30 minutes after the impact and cent International Ocean Discovery Program was relatively poor in rock debris
The continuous suevite sequence from the International Ocean Discovery Program (IODP)-International Continental Scientific Drilling Program (ICDP) Expedition 364 Hole M0077A, encountered between 715.60 mbsf and 617.33 mbsf depth, provides unique insights into impact cratering processes that were responsible for the melting, brecciation, and subsequent deposition of more or less shocked target lithologies under marine conditions
The secluded position of Site M0077 on a small depression on the northern Chicxulub peak ring, with access to the open ocean from a gap in the N-NE inner rim, enabled the preservation of an exceptional record of marine cratering processes: from the initial seawater ingress after the impact to a powerful debris-laden ocean resurge that transitioned into oscillating seiche wave activity
Summary
∼100-m-thick crater suevite sequence in the re- M0077 within 30 minutes after the impact and cent International Ocean Discovery Program was relatively poor in rock debris. To better understand how this enormous impactinduced energy release disrupted the global Earth system ∼66 million years ago, it is crucial to gain insights into the nature and composition of the different source materials from the crater region This can be established by studying in detail the petrology, geochemistry, and emplacement mechanisms of the sequence of rocks deposited by the impact that is found today within and in close proximity to the ∼200-kmdiameter-sized Chicxulub impact structure (i.e., proximal impactites). We present whole rock major and trace element compositional data (n = 212), high-resolution major element mapping results, and petrographic data supported by quantitative digital image analysis of this suevite core material This extensive data set results in a revised classification of the suevite peak ring sequence This extensive data set results in a revised classification of the suevite peak ring sequence (Figs. 2B–2C) and offers new insights into the complex infill history of the Chicxulub impact structure in the first moments after the impact
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