Mercury Spikes Indicate a Volcanic Trigger for the Late Ordovician Mass Extinction Event: An Example from a Deep Shelf of the Peri-Baltic Region.

The Late Ordovician mass extinction (LOME) was the second largest Phanerozoic crisis, but its cause remains elusive. Several triggering mechanisms have been proposed over the years, including bioevolutionary events, oceanographic changes, and geotectonic processes. Here, we report the presence of Hg spikes in the Zbrza PIG-1 borehole from the Upper Ordovician deep shelf sections of the peri-Baltic region. A strong positive anomaly in the lower late Katian (Hg/TOC = 2537.3 ppb/wt%) was noted. No correlation between Hg and TOC (R² = 0.07) was distinguished in the Hirnantian, although several positive anomalies were found. Because the Hg/Mo ratio showed trends very similar to those of Hg/TOC, it seems likely that TOC values reflect the redox conditions. In order to evaluate the role of anoxia in levels of Hg enrichment several redox indicators were measured. These showed that the elevated mercury values in the Hirnantian are not caused by anoxia/euxinia because euxinic biomarkers (maleimides and aryl isoprenoids) are present in very low abundance and pyrite framboids are absent. In total, positive Hg/TOC anomalies occur in the lower late Katian, at the Katian - Hirnantian boundary, and in the late Hirnantian. The lack of a strong Hg/TOC correlation, Ni enrichments, and the absence of 'anoxic indicators' (no biomarkers, no framboids, low Mo concentration) at these levels, supports the interpretation that Hg enrichment is due to enhanced environmental loading. We conclude that our Hg and Hg/TOC values were associated with volcanic pulses which triggered the massive environmental changes resulting in the Late Ordovician mass extinction

The Mission MIRIAM-2: Putting a Gossamer Ballute Through An Atmospheric Entry FLight Test

MIRIAM, short for ‘Main Inflated Re-entry Into the Atmosphere Mission test’, is a validation concept designed for the Mars ballute technology development programme ARCHIMEDES. This development programme is a joint effort of the Mars Society Germany and the University of the Federal Armed Forces of Germany in Munich, with further support by research institutes throughout Europe, the DLR and several industrial companies. The scientific objective of ARCHIMEDES is to obtain measurements of the Martian atmosphere, magnetic environment and surface throughout almost the entire altitude range reaching from outer space to ground. This is facilitated by an instrument carrier attached to a large and gossamer thin film ballute. MIRIAM was designed to validate the theory behind such a vehicle, test the newly developed technology in flight and to gain experience related to manufacturing, handling, flight operations, and gathering new scientific data on Mars and its atmosphere. A first MIRIAM test was flown in October 2008 from ESRANGE. In this paper we focus on the second MIRIAM test, named MIRIAM-2, which is currently slated for launch in October 2014 on a two-stage Taurus-Improved Orion rocket, again from ESRANGE. The main objective of MIRIAM-2 is to obtain realistic flight data for the re-entry of such a low ballistic coefficient design. Aerothermodynamic studies based on different methods have been performed for the entry into both Mars and Earth atmospheres, and flight data is needed to validate those methods. Presented will be the underlying theory, the mission and spacecraft design, the scientific experiments aboard, and expected improvements of the current body of knowledge. We will conclude with an outlook on further development, particularly the transfer of MIRIAM-2 results to a more accurate description of the atmospheric entry on Mars