that 2,500 million years ago only 3% of Earth's surface area was dry. A new geochemical approach to address this issue utilizes the distribution of rare trace elements (zirconium, hafnium, and rare earth elements) and the isotopic composition of hafnium (Hf) and neodymium (Nd) in ancient seawater. Unusually pure iron-rich chemical sediments (banded iron-formation, BIF) from Temagami, Ontario, Canada, are an archive of 2,700 million years-old seawater, which allows us to extend the Hf isotope record of seawater back in time to the Early Earth's ocean. The Temagami BIF shows that 2,700 million years ago, seawater was anomalously enriched in the radiogenic Hf-176 isotope, whereas its Nd isotopic composition was normal. This reveals that the same decoupling of Hf and Nd isotopes that is observed in the modern ocean, did already persist 2,700 million years ago. This required the existence of landmasses that were subjected to terrestrial erosion and weathering, indicating that already 2,700 million years ago, large areas of dry land were emerged above sea level and exposed to wind and rain.
Basin inversion in central Taiwan and its importance for seismic hazard
Giovanni Camanni et al., Institute of Earth Sciences Jaume Almera, ICTJA-CSIC, Lluis Sole i Sabaris s/n, 08028 Barcelona, Spain, email@example.com; firstname.lastname@example.org. Posted online ahead of print on 13 Dec. 2013; http://dx.doi.org/10.1130/G35102.1.
On 27 March 2013, a 6.2 ML earthquake occurred at ~20 km depth in eastern Nantou, central Taiwan, below the ~10-km-deep detachment fault, which is thought to be the deepest level of deformation in this part of the mountain belt. In this paper, Giovanni Camanni and colleagues combine geological and earthquake seismicity data to determine a new model for the structure of centPage: 1 2 3 4 5 6 7 8 9 Related biology news :1
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