Premium
An in‐situ record of major environmental transitions on early Mars at Northeast Syrtis Major
Author(s) -
Ehlmann Bethany L.,
Mustard John F.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl051594
Subject(s) - noachian , hesperian , geology , lava , mars exploration program , stratigraphy , volcano , geochemistry , impact crater , earth science , paleontology , astrobiology , martian , physics , tectonics
The Noachian‐Hesperian transition on Mars was a period marked by changes in volcanic processes and styles of aqueous alteration. Understanding the timing and nature of environmental change requires the exploration of units recording both sets of processes. Herein, we report the compositional stratigraphy of distinctive Noachian to Hesperian units along the northeastern margin of the Syrtis Major volcanic flows. A layered, polyhydrated sulfate‐bearing unit with jarosite ridges has been discovered beneath the Syrtis Major lava flows and above the regionally‐extensive stratigraphy of Noachian plains units reported previously. Sequential clay‐, carbonate‐, and sulfate‐bearing units formed in‐situ and record a transition from alkaline pH to acidic pH waters. The sequence is chronologically bookended by the Isidis impact and Syrtis Major flows, and is one of the most temporally‐constrained and well‐preserved stratigraphic sections from early Mars available for landed exploration.