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Earth sciences

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Importance of mechanical disaggregation in chemical weathering in a cold alpine environment, San Juan Mountains, Colorado

Article Abstract:

A study was conducted to determine the weathering of welded tuff gathered near to the Snowshoe Mountain top in the San Juan Mountains, Colorado. Analyses, which involved infiltrating waters in the soil and other solid phases, showed a very high anomalous potassium to silica ratio. Data suggestedthat the anomaly was due to the dissolution of potassium-rich glass under a trace phase in rocks. Results showed that fresh glass is exposed to weathering due to a continuous mechanical disaggregation of rock maintaining potassium content in inflitrating water.

Analysis, Observations, Colorado, Geological research, Weathering

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Magnetostratigraphic constraints on relationships between evolution of the central Swiss Molasse basin and Alpine orogenic events

Article Abstract:

Analysis of the chronostratigrahy of the Swiss Molasse located in the North Alpine foreland basin indicated the presence of petrofacies and large-scale in-sequence and out-sequence thrusting. The Molasse strata of central Switzerland also indicated increased erosion of Eastern Switzerland's Austroalpine and Penninic nappes due to the insumbric phase of backthrusting between 30 and 25 Ma. The synsedimentary deposition of Molasse sequences was also caused by the underplating of the Molasse deposits between 21 and 15.5 Ma.

Research, Switzerland, Geology, Stratigraphic, Stratigraphy, Petrology, Paleomagnetism, Oligocene Epoch

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Documentation of a 1450 Ma contractional orogeny preserved between the 1850 Ma sudbury impact structure and the 1 Ga Grenville orogenic front, Ontario: discussion and reply

Article Abstract:

The conclusions derived by Fueten and Redmond concerning the emplacement of granitoid plutons in the Lake Huron area are based on questionable assumptions. In particular, the assumption that an orogeny happened from 1453 to 1445 Ma which affected North America's Proterozoic crust does not conform to other geochronologic studies which deny such an occurrence. Structural studies on rocks in the areas confirm geochronological research.

Ontario, Lake Huron

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