A steeply-inclined trajectory for the Chicxulub impact

Abstract

The environmental severity of large impacts on Earth is influenced by their impact trajectory. Impact direction and angle to the target plane affect the volume and depth of origin of vaporized target, as well as the trajectories of ejected material. The asteroid impact that formed the 66 Ma Chicxulub crater had a profound and catastrophic effect on Earth's environment, but the impact trajectory is debated. Here we show that impact angle and direction can be diagnosed by asymmetries in the subsurface structure of the Chicxulub crater. Comparison of 3D numerical simulations of Chicxulub-scale impacts with geophysical observations suggests that the Chicxulub crater was formed by a steeply-inclined (45-60°to horizontal) impact from the northeast; several lines of evidence rule out a low angle (<30°) impact. A steeply-inclined impact produces a nearly symmetric distribution of ejected rock and releases more climate-changing gases per impactor mass than either a very shallow or near-vertical impact.

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

“…Drilling at Chicxulub has confirmed the presence of melt rock and melt‐rich breccias in the central basin and annular trough (Hildebrand et al., 1991; Sharpton et al., 1996), with a thin veneer of melt rock covering the peak ring (Morgan et al., 2016). Three‐dimensional numerical models match asymmetries between the locations of the peak ring center, crater center, and mantle uplift center with a steeply inclined (45°–60° to horizontal) impact from the northeast (Collins et al., 2020). These models predict asymmetries in melt distribution, with thicker melt pools in the downrange direction.…”

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

“…Depositional scenarios of suevite are highly dependent on the characteristics of the target stratigraphy, the presence or absence of (sea)water, and impactor-specific conditions (including bolide size, impact angle, and resulting energy; e.g., Artemieva et al, 2013). For Chicxulub, the impactor is constrained as a CM or CO type carbonaceous chondrite (Shukolyukov and Lugmair, 1998;Trinquier et al, 2006;Quitté et al, 2007;Goderis et al, 2013), and the most recent estimation calls for a projectile 17 km in diameter that impacted at a steep angle of 45-60° from the northeast (Collins et al, 2020). The impact on Yucatán took place in a marine setting with variable water depths.…”

“…During the contact and compression phase, the Chicxulub impactor hit Yucatán following a steeply inclined trajectory from the northeast and generated a shock wave that caused intense compression, vaporization, melting, and brecciation of the target lithologies (Collins et al, 2020). Rarefaction waves following the shock wave initiated an excavation flow that opened a transient cavity and ejected the vaporized, melted, and brecciated target components in a timespan of <1 min (Fig.…”

Magnetic Anomalies in Five Lunar Impact Basins: Implications for Impactor Trajectories and Inverse Modeling

“…The terrestrial Chicxulub basin, like Crisium, was apparently formed by a steeply inclined (<45° from vertical) impact (Collins et al., 2020). It has an inner rim diameter of ∼150 km and an inner peak ring about 80 km across.…”