Currently studying the “Pahrump Hills” region at the base of Mount Sharp in the center of Gale Crater, this new view snapped by Curiosity on March 18 shows a work site Curiosity’s mission scientists call “Garden City.” This area is interesting as it shows two-tone mineral veins protruding from the surrounding rock.
The tough mineral veins were formed in Mars’ ancient wet past and they are sticking out of the rock up to 6 centimeters (2.5 inches) high. This means that the veins formed within the rock and the softer surrounding bedrock has since eroded away.
When comparing the geology of this particular area with the rocks that Curiosity has analysed in lower sections of Mount Sharp, a story emerges Mars’ ancient geological history.
“Some of (the mineral veins) look like ice-cream sandwiches: dark on both edges and white in the middle,” said Linda Kah, Curiosity science-team member at the University of Tennessee, Knoxville, in a NASA Jet Propulsion Laboratory news release. “These materials tell us about secondary fluids that were transported through the region after the host rock formed.”
Like previous rocks studied by Curiosity, the prominent veins at Garden City were formed when water flowed through cracks in bedrock, depositing minerals inside these fractures. The chemistry of the rock neighboring the fractures became altered and these tough veins formed. Previously, the robotic geologist has found other bright veins rich in calcium sulfate.
However, Garden City appears to be different from previous samples — the darker material in the veins suggest an early episode of water on Mars, whereas the brighter mineral deposits shows a later episode of water flow.
“At least two secondary fluids have left evidence here,” added Kah. “We want to understand the chemistry of the different fluids that were here and the sequence of events. How have later fluids affected the host rock?”
Curiosity has been studying rocky configurations since landing on the Martian surface in 2012.
Over the past 6 months, the rover has been focused on Pahrump Hills, studying the layers of rock spanning an elevation of only 10 meters. Garden City is the highest point (so far) of this survey and there are very obvious changes in the mineral history over this small cross section.
“We investigated Pahrump Hills the way a field geologist would, looking over the whole outcrop first to choose the best samples to collect, and it paid off,” said David Blake of NASA’s Ames Research Center, Moffett Field, Calif., and principal investigator for Curiosity’s Chemistry and Mineralogy (CheMin) instrument.
Read more at Discovery News
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