Viable Halobacteria from Ancient Oceans—and in Outer Space?

Abstract

About 250 million years ago the continents were close together and formed Pangaea, a supercontinent, which persisted for about 100 million years and then fragmented. The landmasses at that time were located predominantly in the southern hemisphere. The climate was arid and dry; the average temperature is thought to have been several degrees higher than at present. This was one of the time periods in the history of the Earth, when huge salt sediments formed. A total of about 1.3 million cubic kilometers of salt were deposited during the late Permian and early Triassic period alone (Zharkov 1981). The thickness of the salt sediments can reach 1000 to 2000 meters. When Pangaea broke up, land masses were drifting in latitudinal and Northern direction. Mountain ranges such as the Alps, the Carpathians and the Himalayas were pushed up due to the forces of plate tectonics. The salt deposits in Austria originated in the Alpine basin, which extended from Innsbruck to Vienna. Some salt mines in the Alps are still in operation, and these were the sources of our samples. In the Alpine basin and in the Central European basin (Zechstein sea), no more salt sedimentation took place after the Triassic period; however, in other locations, e.g. in Poland, significant salt deposits were still formed until about 20 million years ago. Dating of the salt deposits by sulfur-isotope analysis (ratios of ³²S/³⁴S as measured by mass spectrometry), in connection with information from stratigraphy, indicated a Permo-Triassic age for the Alpine and Zechstein deposits, which was independently confirmed by the identification of pollen grains from extinct plants in the sediments (Klaus 1974).