EAGER: A Novel Approach to Study Earth's Oldest Environments and Biosphere: Tidal, Shelf, and Deep Ocean Habitats in the >3.7 Ga Isua Greenstone Belt, Greenland

点击翻译按钮获取中文摘要

EAGER: A novel approach to study Earth's oldest environments and biosphere: Tidal, shelf, and deep ocean habitats in the 3.7 Ga Isua Greenstone Belt, GreenlandNora Noffke, Old Dominion UniversityEAR-0929617ABSTRACTThe Isua Greenstone Belt (IGB), Greenland, comprises the oldest, 3.7 Ga sediments preserved in Earth history. Until now the firm dogma is that all IGB rocks would be highly metamorphosed and therefore information on Earth?s oldest paleoenvironment and the origin of life would be erased or so strongly masked that no firm conclusions can be drawn. This proposed project would open a new perspective by demonstrating that the IGB constitutes a valuable archive on Earth?s deepest time, and that it requires only newly developed methods to read this unique information.Indeed, the preliminary work of the PI?s working group points to the possibility that in the IGB already diverse marine paleoenvironments including a tidal, a shelf, and a deep ocean setting, existed. The team has developed a new method to distinguish any type of primary cyclicity in the meta-sediments (tidal and Milancovic cyclicity). Based on those preliminary yet stunning results, PI would like to conduct an exploratory study on those unique rock successions, and to gain appropriate data to confirm our initial observations on photos. The results are not conforming to the current status quo of knowledge of the scientific community. Noffke would travel from Washington, DC to Copenhagen and from there to Nuuk, Greenland. From here, they would be transported by helicopter to the study area itself. The trip should take place from mid of July to mid of August 2010. This is the best window with respect to the local weather in Greenland (the arctic summer). PI would visit three outcrops in the IGB. The locations are known exactly from GPS data. She would measure the rock successions with respect to the tidal and Milancovic cyclicities that she has detected in photo scans. In addition, she would conduct structural geological measurements in the field to gain an overview into the tectonic frame of each setting. This would allow her to later understand textural structures in thin-sections, and to diagnose, if apparent bedding, sedimentary structures such as ripple cross stratification, are of tectonic, metamorphic or indeed primary origin. The team would camp for 2 weeks in the field close to the inland ice. The rock samples would be shipped by GEUS from Isua to Norfolk, Virginia. They would return again by helicopter via the Survey base camp, and then travel back to the USA. The field data on the type and thickness of the bedding at all 3 locations will be used for spectral analyses.