Crater that formed due to dino killing asteroid may yield clues about ancient Maya

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Washington, September 21 (ANI): In a clear case of geology and archaeology complementing each other, scientists have studied the most recent limestone deposits that filled the Chicxulub crater in Mexico, providing accurate dating of the rocks and a valuable basis for archaeologists to research the ancient Maya.

The Chicxulub crater is one of the world's most famous asteroid craters, which is believed to have put an end to the dinosaurs and helped mammals to flourish.

Together with an Anglo-American team, an ETH Zurich researcher has studied the most recent deposits that filled the crater.

Research work has focused mainly on the structure of the crater, which has been buried in a layer of sediment up to two kilometres thick since its formation.

Little is known about the sediments close to the surface.

Together with American and English researchers, Adrian Gilli, Senior Lecturer at the Geological Institute of ETH Zurich, has now filled in a few of the gaps in the knowledge about the near-surface rock deposits.

"The crater ring of the Chicxulub crater is scarcely recognisable in the terrain," Gilli said.

The ring, which is about five kilometres wide and has a radius of approximately 90 kilometres around the port of Chicxulub, is criss-crossed by fractures that also occur frequently outside the crater ring.

The limestone along these faults has been riddled with holes and eroded by rain and groundwater.

A process known as karstification has to date created about 3000 circular collapses forming small basins filled with groundwater.

The Maya called these basins "d'zonot", or "cenotes", regarding them as a direct connection to the underworld and using such places as sacrificial sites.

Previously, the rocks outside the crater ring were suspected to be older than those inside, but now researchers have for the first time been able to determine their precise age using a method based on the isotope ratios of strontium 87 to strontium 86 in the limestone.

The rock samples inside the ring gave an age of between 2.3 and 6 million years.

On the other hand, the rocks outside the ring showed more variable strontium isotope ratios and are from 10 to 33 million years old.

The results help to understand the geology better and to re-draw and refine the outdated maps.

Archaeology research can also benefit from the geologists' work: for example, the life of the Maya, whose important settlements Mayapan und Chichen Itza are located in these two geologically different regions, can be better researched on the basis of the strontium data.

"We can obtain a very large amount of information about the lifestyle of the people from settlements at such boundaries, such as the Maya city of Mayapan," said Gilli. (ANI)

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