Select Page

Sustained wet–dry cycling on early Mars

Sustained wet–dry cycling on early Mars

W. Rapin, G. Dromart , B. C. Clark , J. Schieber , E. S. Kite , L. C. Kah , L. M. Thompson , O.…

Wednesday, Aug 09


W. Rapin, G. Dromart ,

B. C. Clark ,

J. Schieber ,

E. S. Kite ,

L. C. Kah ,

L. M. Thompson ,

O. Gasnault , J. Lasue , P.-Y. Meslin , P. J. Gasda & N. L. Lanza Abstract The presence of perennially wet surface environments on early Mars is well documented 1 , 2 , but little is known about short-term episodicity in the early hydroclimate 3 . Post-depositional processes driven by such short-term fluctuations may produce distinct structures, yet these are rarely preserved in the sedimentary record 4 . Incomplete geological constraints have led global models of the early Mars water cycle and climate to produce diverging results 5 , 6 . Here we report observations by the Curiosity rover at Gale Crater indicating that high-frequency wet–dry cycling occurred in early Martian surface environments. We observe exhumed centimetric polygonal ridges with sulfate enrichments, joined at Y-junctions, that record cracks formed in fresh mud owing to repeated wet–dry cycles of regular intensity. Instead of sporadic hydrological activity induced by impacts or volcanoes 5 , our findings point to a sustained, cyclic, possibly seasonal, climate on early Mars. Furthermore, as wet–dry cycling can promote prebiotic polymerization 7 , 8 , the Gale evaporitic basin may have been particularly conducive to these processes. The observed polygonal patterns are physically and temporally associated with the transition from smectite clays to sulfate-bearing strata, a globally distributed mineral transition 1 […]

Share This