A Steaming Cauldron Follows the Dinosaurs’ Demise

Hydrothermal minerals (analcime and dachiardite) in 1 centimeter cavity within impact rocks that fill the Chicxulub crater. (Image: David A. Kring)
Hydrothermal minerals (analcime and dachiardite) in 1 centimeter cavity within impact rocks that fill the Chicxulub crater. (Image: David A. Kring)

A new study reveals the Chicxulub impact crater may have harbored a vast and long-lived hydrothermal system after the catastrophic impact event linked to the extinction of dinosaurs 66 million years ago. The Chicxulub impact crater, roughly 180 kilometers in diameter, is the best preserved large impact structure on Earth and a target for exploration of several impact-related phenomena.

Close-up view of hydrothermal minerals (silica and feldspar) in impact melt rock. (Image: David A. Kring)

Close-up view of hydrothermal minerals (silica and feldspar) in impact melt rock. (Image: David A. Kring)

In 2016, a research team supported by the International Ocean Discovery Program and International Continental Scientific Drilling Program drilled into the crater, reaching a depth of 1,335 meters (> 1 kilometer) below the modern-day sea floor. The team recovered rock core samples that can be used to study the thermal and chemical modification of Earth’s crust caused by the impact.

Portion of Expedition 364 rock core. (Image: Kring@ECORD_IODP)

A portion of the Expedition 364 rock cores. (Image: [email protected]_IODP)

The core samples show the crater hosted an extensive hydrothermal system that chemically and mineralogically modified more than 100,000 cubic kilometers of the Earth’s crust. The lead author, Universities Space Research Association’s David Kring at the Lunar and Planetary Institute (LPI), explains:

The team found evidence that subsurface rivers of water were heated and driven upward toward the boundary between the floor of the impact crater and the bottom of the Yucatán sea. The hot water streamed around the edges of an approximate 3-kilometer thick pool of impact-generated magma, percolated through fractured rock, and rose to the seafloor where it vented into the sea. The hot water system was particularly intense in an uplifted range of mountains on the seafloor that form a 90 kilometer-diameter ring around the center of the crater.

Hydrothermal minerals (silica and feldspar) in cavity within impact melt rock core. (Image: ECORD-IODP Exp 364)

Hydrothermal minerals (silica and feldspar) in a cavity within the impact melt rock core. (Image: ECORD-IODP Exp 364)

The rock core recovered from that peak ring is cross-cut by fossil hydrothermal conduits that are lined with multi-colored minerals, some, appropriately enough, a fiery red-orange color. Nearly two dozen minerals precipitated from the fluids as they coursed through the rock, replacing the rock’s original minerals. The peak ring of the crater is composed of fractured granite-like rocks that were uplifted from a depth of approximately 10 kilometers by the impact. Those rocks are covered by porous and permeable impact debris. Both rock units are affected by the hydrothermal system. Former LPI Postdoctoral Researcher Martin Schmieder explained:

Minerals identified in the new rock core indicate the hydrothermal system was initially very hot, with temperatures of 300° to 400°C. Such high temperatures indicate the system would have taken a long time to cool. The team determined the cooling time using a geomagnetic polarity clock. Co-author Sonia Tikoo from Stanford University said:

Further evidence for the hydrothermal system’s longevity comes from an anomalously high concentration of manganese in seafloor sediments, the result of seafloor venting. Co-author Axel Wittmann from Arizona State University explains:

Although the expedition only tapped the hydrothermal system in one location, Kring said:

Yellowstone’s volcanic hydrothermal systems are rich with microbial organisms and imply impact-generated hot water systems have the same biologic potential. Kring concludes:

A three-dimensional cross-section of the hydrothermal system in the Chicxulub impact crater and its seafloor vents. The system has the potential for harboring microbial life. (Image: Victor O. Leshyk for the Lunar and Planetary Institute)

A three-dimensional cross-section of the hydrothermal system in the Chicxulub impact crater and its seafloor vents. The system has the potential for harboring microbial life. (Image: Victor O. Leshyk for the Lunar and Planetary Institute)

The extent and longevity of the Chicxulub hydrothermal system suggest that impact-generated systems early in Earth’s history may have provided niches for life. Thousands of these types of systems were produced during a period of impact bombardment more than 3.8 billion years ago. As each system cooled, it would have provided an environment rich in materials suitable for thermophilic and hyperthermophilic organisms.

Provided by: The Universities Space Research Association [Note: Materials may be edited for content and length.]

Follow us on Twitter or subscribe to our email list

New Sunspots Potentially Herald Increased Solar Activity
Mergers Between Galaxies Trigger Activity in Their Core