December Geosphere media highlights(nd marine sedimentary records. Two major...)

Date:12/1/2008

nd marine sedimentary records. Two major changes in climate were interpreted: (1) a multiphase climate transition (ca. 17 Ma) caused mainly by changes in ocean circulation due to opening and closing of seaways connecting ocean basins and growth of the East Antarctic Ice Sheetthese climate changes were from warmer and wetter to cooler and drier; and (2) intensification of the North American monsoon caused by opening of the Gulf of California at ca. 6 Ma. A dramatic increase in summer thunderstorm activity resulted in integration of drainages, termination of closed-basin sedimentation, incision of uplifts, and exhumation of basin-fill sedimentary deposits. Such changes are usually interpreted as resulting from tectonic uplift; however, the complex interplay of tectonics and climate, rather than one or the other, was responsible for the Miocene changes in the southwestern United States.

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Evolution and dynamics of the Cenozoic tectonics of the South Balkan extensional system

B.C. Burchfiel et al., Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239, USA. The work reported in this paper received NSF funding.

This paper discusses the tectonic evolution of the Southern Balkan extensional system from its beginning as an Andean margin from Late Cretaceous to early Eocene, through a transition from Andean to extension settings from middle Eocene to Oligocene time, to a regional extensional setting from the early Miocene to present. The regional tectonic setting begins as part of the Aegean extensional system but evolves into a system that is largely decoupled from the Aegean system as the North Anatolian fault develops from Late Miocene to Recent time. Late Cenozoic extension within the South Balkan extensional system is strongly diachronous, with north-south and east-west normal faulting that migrates in tandem from east to west, respectively, an expression of slab dif
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Contact: Christa Stratton cstratton@geosociety.org 303-357-1093 Geological Society of America Source:Eurekalert

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