Hematite Mineralized Bacterial Remnants: Implications for Martian Hematite

INTRODUCTION The 2.0 Ga iron-bearing Gunflint Formation was deposited during a transitionary period in Earth history when a stable oxic atmosphere was being established. The Animikie Group, which comprises both the Rove and Gunflint Formations, extends NE-SW for approximately 175 km from Thunder Bay, Ontario to northern Minnesota [1]. The thickness of the Gunflint ranges from 100 to 180 m, with an average thickness of about 122 m [2]. Metamorphism of the Gunflint Formation increases gradationally from east to west. These rocks are essentially undeformed and exhibit a low metamorphic grade ranging from diagenetic to subgreenschist, with maximum temperatures that ranged from 120 to 150 degrees C [3].