Combined paleointensity and40Ar/39Ar age spectrum data from volcanic rocks of the West Eifel field (Germany): Evidence for an early Brunhes geomagnetic excursion

1994 ◽  
Vol 99 (B5) ◽  
pp. 9061-9076 ◽  
Author(s):  
Elisabeth Schnepp ◽  
Helmuth Hradetzky
Keyword(s):  
Volcanic Rocks ◽  
The West ◽  
Geomagnetic Excursion ◽  
Spectrum Data ◽  
West Eifel

scholarly journals HEAVY CLASTIC MINERALS AS AN INDICATOR OF GEODYNAMIC SETTINGS OF ACCUMULATION AND PROVENANCE OF CRETACEOUS SEDIMENTS OF THE WEST SAKHALIN TERRANE

2021 ◽  
pp. 68-86
Author(s):  
A.I. Malinovsky ◽  
Keyword(s):  
Large Scale ◽  
Volcanic Rocks ◽  
Source Area ◽  
Heavy Minerals ◽  
Clastic Material ◽  
The West ◽  
Geodynamic Settings ◽  
Eurasian Continent ◽  
Ocean Boundary ◽  
By Products

The article discusses the results of studying heavy clastic minerals from the Cretaceous sandy rocks of the West Sakhalin Terrane, and also presents their paleogeodynamic interpretation. It is shown that in terms of mineralogical and petrographic parameters, the terrane sandstones correspond to typical graywackes and are petrogenic rocks formed mainly by destruction of igneous rocks of the source areas. The sediments were found to contain both sialic, granite-metamorphic association minerals, and femic, formed by products of the destruction of basic and ultrabasic volcanic rocks. The interpretation of the entire set of data on the content, distribution and microchemical composition of heavy minerals was carried out by comparing them with minerals from older rocks and modern sediments accumulated in known geodynamic settings. The results obtained indicate that during the Cretaceous, sedimentation occurred along the continent-ocean boundary in a basin associated with large-scale left-lateral transform movements of the Izanagi Plate relative to the Eurasian continent. The source area that supplied clastic material to that basin combined a sialic landmass composed of granite-metamorphic and sedimentary rocks, a mature deeply dissected ensialic island arc, and fragments of accretion prisms, in the structure of which involved ophiolites.

New aspects of the volcanism of the West Eifel

2019 ◽  
Vol 101 ◽  
pp. 227-250
Author(s):  
Thomas Lange ◽  
Volker Lorenz ◽  
Karl-Heinz Köppen ◽  
Georg Büchel
Keyword(s):  
The West ◽  
West Eifel

The Beginnings of Microscopic Petrography in the United States, 1870-1885

1994 ◽  
Vol 13 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Carl-Henry Geschwind
Keyword(s):  
United States ◽  
Lake Superior ◽  
Volcanic Rocks ◽  
The United States ◽  
Substantial Portion ◽  
The West ◽  
The U.S

In the 1860's and 70's, microscopic petrography flourished in Germany, where descriptions and classifications of rocks were highly valued for their own sake. American geologists, however, were more interested in stratigraphical correlations and had relatively little use for petrographical details. Thus, such Americans as George Hawes and Alexis Julien, who attempted to introduce the microscope for purely petrographical work in the early 1870's, had great difficulties in finding an audience. During the late 1870's, however, a number of American geologists-including federal geologists working amongst the volcanic rocks of the West, state geologists mapping in the Lake Superior region, and mining geologists examining the Comstock Lode and the Leadville district-came to appreciate the aid microscopic petrography could provide for stratigraphical correlations. This growing interest led to the hiring of a number of microscopic petrographers around 1880. These petrographers were trained in Germany, where they had imbibed the German passion for petrography for its own sake, but most of them adapted themselves to the American practice of using petrography for stratigraphy. Unlike many of their German counterparts, these American petrographers spent a substantial portion of their time in the field and combined mapping with microscopic examinations to solve stratigraphical problems. Thus, the different scientific cultures of Germany and the U.S. significantly affected the ways in which the petrographic microscope was used.

A note on Lower Jurassic magmatism in the Coastal Cordillera of Atacama, Chile

1986 ◽  
Vol 123 (6) ◽  
pp. 699-702 ◽  
Author(s):  
J. A. Naranjo ◽  
A. Puig ◽  
M. Suárez
Keyword(s):  
Genetic Relationship ◽  
Volcanic Rocks ◽  
Lower Jurassic ◽  
The West ◽  
Coastal Cordillera ◽  
Metasedimentary Rocks ◽  
Volcanic Chain ◽  
Back Arc ◽  
Host Rocks ◽  
Previous Idea

AbstractRadiometric dates on specimens of plutons of the Coastal Cordillera of Atacama span the period 300–110 Ma. A group of dates cluster around 190 Ma and evidence is presented which strongly suggests that they represent near crystallization ages. The geographic distribution of these plutons, adjacent to Liassic tuffs and lavas (Pan de Azúcar and Posada de los Hidalgo formations), suggests a genetic relationship between them, and that the plutons were the roots of the Lower Jurassic volcanic chain. The location of these granitoids to the west of the Liassic volcanic rocks, favours a previous idea that the Liassic basin extended eastwards as a back-arc or intra-arc basin. The host rocks to the Lower Jurassic plutons include Palaeozoic granitoids and metasedimentary rocks, indicating that the volcanic chain was founded on continental crust. The distance from the Liassic plutons to the present-day trench is less than 100 km, which indicates the possibility that part of the arc-trench system of that time is missing.

Carbonatite in the tuffs of the West Eifel, Germany

1969 ◽  
Vol 23 (2) ◽  
pp. 136-139 ◽  
Author(s):  
P. E. Lloyd ◽  
D. K. Bailey
Keyword(s):  
The West ◽  
West Eifel
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