Peak Chicxulub Crater surprises?

Chicxulub crater peak ringChicxulub Crater, the asteroid impact crater that is suggested to have killed off the dinosaurs, is being drilled and surveyed again. All the previous drilling and geology investigations have been full of surprises.

The latest offshore survey will be guaranteed a surprise for all the geologists and scientists involved. In the search for the Puerto Chicxulub Craters 'peak ring' will we reach the Peak of Chicxulub Crater surprises?

The 2004 drilling survey even found out that the infamous K-T boundary (now known as the Cretaceous–Paleogene (K–Pg) boundary), in theory formed by the Chicxulub impact, does not have the same iridium signatures as found around the rest of the planet?

Where the researchers expected to find the boundary, Smit says, is a 70-centimeter-long segment that does not show the same iridium anomalies seen in the K/T boundary clay level around the world.
Unraveling the Chicxulub Case | Geo Times

So what will they find and not find this time?

How will they interpret what they do and do not find?

Peak Ring surprise?

Chicxulub crater peak rings uplift
Why does this crater not have a central peak but a peak ring of mountains? Does this tell us what type of event created it and what type of crater Chicxulub is? What are the 'sinkholes' around its outer rim?

The Chicxulub impact crater in Mexico is unique. It is the only known terrestrial impact structure that has been directly linked to a mass extinction event and the only terrestrial impact with a global ejecta layer. Of the three largest impact structures on Earth, Chicxulub is the best preserved. Chicxulub is also the only known terrestrial impact structure with an intact, unequivocal topographic “peak ring.”

Chicxulub’s role in the Cretaceous/Paleogene (K-Pg) mass extinction and its exceptional state of preservation make it an important natural laboratory for the study of both large impact crater formation on Earth and other planets and the effects of large impacts on Earth’s environment and ecology.

Our understanding of the impact process is far from complete, and despite more than 30 y of intense debate, we are still striving to answer the question as to why this impact was so catastrophic.
Chicxulub: drilling the K-Pg impact crater | International Ocean Discovery Program

Chicxulub crater peak rings

for the first time, scientists have subsurface images from the offshore part of the crater, so they can pinpoint a spot for sampling. They chose a spot along the crater's peak ring — a ring of mountainlike structures around the center of the crater.

Scientists think that, when a big rock smashes into Earth at high enough velocities, the collision causes the crust temporarily to act sort of like a liquid, first forming a so-called transient crater (like the indentation that forms on a lake surface after a rock is thrown in), and the center rebounds, or splashes, upward and then outward. "We think the peak ring is the record of the material that rebounded and splashed outward," Gulick told Live Science.

All of these ideas are based on models and aren't necessarily what happened. "We've never gotten a rock back from a peak ring to know if that's correct," Gulick said.

The researchers also hope to find details about the process that weakened the granite of the crust to get it to flow like a liquid, Gulick noted. "We don't understand that process," he said.
Dinos Died Here: Getting to the Core of Asteroid Impact Mystery

Chicxulub Crater surprises 2004

Chicxulub impact crater peak ring
When scientists drilled into the Chicxulub Crater on land during the 2004 MCS experiment they were surprised by what they did and didn't find. Even after all sorts of geology surveys before. Including the actual 30,000 event layer that it was said to be responsible for so they knew it had to be there.

The dry land part of the Chicxulub Crater is covered with limestone.

They also looked at seismic profiles and other geophysical data that seemed to indicate that a thick unit of rocks metamorphosed by an impact (impactites) lay beneath 800 meters of Tertiary limestone ... The principal investigators thought they’d find several hundred meters of impact-altered breccia, called suevite, overlying a coherent impact melt sheet. The suevite would help characterize the target rocks and their deformation, Smit says, and learn more about impactite deposition ... The sequence of impactites found in the core is around 100 meters thick, quite different from the 800 meters the principal investigators expected, but still within the range Hildebrand, now at the University of Calgary, predicted for that location in the crater. Additionally, sequences representing roughly 300,000 years of time are missing, arguably including the actual K/T boundary and transition and the sediments that formed at the beginning of the Tertiary.

Where the researchers expected to find the boundary, Smit says, is a 70-centimeter-long segment that does not show the same iridium anomalies seen in the K/T boundary clay level around the world.

... The uppermost 800 meters of the core are mostly shales that filled in the crater after impact. Below that is about a 12-meter layer of redeposited suevite, which researchers think slid back into the crater after the initial ejection and fallout. The 86 meters below the redeposited suevite are suevite that ejected ballistically from the impact crater during formation. The researchers identified the lowermost 600 meters of the core as large ejected and rotated slabs of platform limestone, dolomite and evaporites, of which anhydrites comprise 27 percent.
Unraveling the Chicxulub Case | Geo Times

Chicxulub crater peak ring surprises
Whenever scientists have carried out a super deep drilling experiment as far into the Earth's crust as we have ever gone, they have been surprised by what they did and didn't find. This included the Germans KTB borehole who had everything geologically surveyed and predicted. But they found no boundary layer that they knew had to be there.

Will this newest Chicxulub crater investigation be any different or have less surprises?

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Chicxulub crater peak mountains