JOINT CONTROLLED FLUID FLOW PATTERNS IN JURASSIC NAVAJO SANDSTONE: ANALOG IMPLICATIONS FOR MARS HEMATITE

Prominent clusters of NE striking joints lined with iron oxide have related asymmetrical fluid flow and mineralization patterns in the Jurassic Navajo Sandstone of Grand Staircase Escalante National Monument, Utah. These patterns have implications for understanding the hydrological regime responsible for the formation of iron oxide concretions that show similarities to “blueberries” at Meridiani Planum.

Navajo mineralization includes: ~1-2mm diameter micro-concretions (similar to Mars “micro-berries”), rind/ layered spheroidal concretions (≤1-3+ cm diameter), and thin lining (<1 cm) of joints. Asymmetrical fluid flow emanating from the joints is expressed as: 1) iron oxide “loop” banding that extends on the SE side of the joints, and 2) SE elongate halos around in situ rind/ layered concretions.

Field relationships and geometries indicate a relative timing sequence of events. Spheroidal concretions appear to have formed prior to and independent of the joints, followed by iron mineralizing fluids that lined the joints. Late-stage regional uplift associated with the formation of the NE joints may have created hydraulic head so that advection overpowered diffusion and dominated SE reactant transport to form loop banding instead of spheroidal concretions.

This Utah analog example shows a mix of diffusive and advective events, and suggests that hematite concretions on Mars may be the result of much simpler diagenetic processes than the Navajo Sandstone. Martian hematite blueberries probably formed by simple oxygen diffusion in nearly isotropic fluid flow conditions.