Formation of the crater suevite sequence from the Chicxulub peak ring: A petrographic, geochemical, and sedimentological characterization

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.

Mapping the Chicxulub Impact Stratigraphy and Peak Ring Using Drilling and Seismic Data

“…This material is thought to be formed by MWI and high energy transport of fragmented melt rock (Gulick et al, 2019;Osinski et al, 2020;F. M. Schulte et al, 2021) that bear similarities with hyaloclastite deposits (Kaskes et al, 2021). The impact melt rocks at Site M0077 are too thin to be resolved in FWI velocity models (Figures 5 and 9), but we suggest that the material between our interpreted base of the resurge layer and top of melt rock is equivalent to these hyaloclastite-like deposits.…”

Life before impact in the Chicxulub area: unique marine ichnological signatures preserved in crater suevite

“…( B ) Stratigraphy of the impactite sequence between cores 40 and 90 (∼ 616.5–732 m below sea floor [mbsf]) with the degree of core recovery and the initial subdivision of the sequence by Gulick et al (Unit 1G; 2A-2C; 3A). Adjacent, an alternative subdivision of this sequence is shown with the three distinct suevite units suggested by Kaskes et al 12 . The red dashed square indicates the stratigraphic interval in which macroscopic ichnological features are recognized in the suevite clasts.…”

“…Below this suevite sequence, a brecciated impact melt rock is encountered with green bands of sparry calcite (schlieren) and rare carbonate clasts, followed by black impact melt rock containing abundant crystalline basement clasts (Unit 3, Gulick et al 21 ) extending to a depth of 747 mbsf. This impact melt and suevite sequence was formed extremely rapidly within the impact basin in < 1 day post-impact 5 , 12 , 21 , 28 . Unit 4 consists of shocked granitoid basement with pre-impact dikes (including dolerites, dacites and felsites), and intercalations of suevite and impact melt rock 5 , 6 , 21 , 33 .…”

“…This part of the core is the focus of this study (see " Materials and methods " and Supplementary information). More recently, the suevite sequence was subdivided into three units, distinct in their petrography, sedimentology, and geochemistry 12 : a ∼ 3.5 m thick bedded unit, a ∼ 89 m thick graded unit, and a ∼ 5.6 m thick non-graded unit (Fig. 2 B).…”

Petrophysics of Chicxulub Impact Crater's Peak Ring

“…Suevite occurs at several intervals in the core. The top of the peak ring in Hole M0077A is covered with ∼104 m of suevite with variable clast size and lithology (Kaskes et al., 2021). Clast dimensions range from submillimeter to several centimeters; in general, clast size increases with depth (Gulick et al., 2019; Morgan et al., 2017).…”