December 2008 Geology and GSA Today media ...(arts about 30 million years ago. Sout...)

South Atlantic interocean exchange as the trigger for the Blling warm event

Cristiano M. Chiessi et al., MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen, Germany. Pages 919-922.

14,700 years ago, Greenland experienced a warming of 9 degrees Celsius within a couple of decades, the most striking temperature increase in the Northern Hemisphere high latitudes during the entire last deglaciation. The abrupt warming was probably linked to a sudden strengthening of the Atlantic Ocean circulation, but the ultimate mechanism responsible is not clearly understood. Chiessi et al. show new geochemical records from the South Atlantic that address this issue. According to the new records, the upper South Atlantic also underwent a strong increase in temperature and salinity synchronous to the temperature change in Greenland. While the warming in the South Atlantic is also a consequence of the strengthening of the Atlantic Ocean circulation, the increase in salinity points to a massive inflow of salty Indian Ocean waters into the Atlantic Ocean. High salinities in the upper Atlantic Ocean have been described as a key condition for a strong Atlantic circulation. Chiessi et al.'s records highlight the crucial role played by Indian-Atlantic interocean exchange as the trigger for the strengthening of the Atlantic circulation and the abrupt warming in the Northern Hemisphere high latitudes 14,700 years ago.

The eve of biomineralization: Controls on skeletal mineralogy

Andrey Yu. Zhuravlev and Rachel A. Wood, Area y Museo de Paleontologia, Departamento de Ciencias de la Tierra, Facultad de Ciencias, Universidad de Zaragoza, c/Pedro Cerbuna, E-50009, Zaragoza, Spain. Pages 923-926.

In the first quantitative analysis of the onset of biomineralization -- from the late Precambrian to Ordovician -- Zhuravlev and Wood show that chan
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