Felsite

Berg-kalk, m. rock time (Geol.) mountain limestone. -kiesel, m. rock flint, chert felsite. -kohle,/. (mineral) coal, -kork, m. mountain cork (a light form of asbestos), -kreide, /. rock lime, -kristall, -krystall, m. rock crystal (transparent quartz), -kupfer, n. native copper, -lasur, /. azurite. -leder, n. mountain leather (a form of asbestos), -maun, m miner. 

The time of crystallization of a lunar "granite" has also been determined by the laser method. This "granite" is the K- and Si-rich felsite that forms clasts in 73215, 73255, and Boulder 1 at Station 2. The laser results set a lower limit of 4.00 G.y. on crystallization of the parent body of this felsite, and the Rb-Sr data set an upper limit of 4.05 G.y. [6]. 

ARGILLITE. A dense, fine-grained, hard, sedimentary rock of various colors (usually while, gray or red). Composed of luniule grains of both day and quartz. Certain types of argillites are easily confused with certain types of fine-grained acid lava flows, such as felsites, unless studied microscopically. 

Warren P. H., Jerde E. A., and Kallemeyn G. W. (1987) Pristine Moon rocks a large felsite and a metal-rich ferroan anorthosite. Proc. 17th Lunar Planet. Sci. Corf., E303-E313. 

Dahymple G. B., Grove M., Lovera O. M., Harrison T. M., Hulen J. B., and Lanphere M. A. (1999) Age and thermal history of the Geysers plutonic complex (felsite unit), geysers geothermal field, California a Ar-40/Ar-39 and U-Pb study. Earth Planet. Set Lett 173, 285-298. 

Masvingo bdi Upper Shamvaiart Group FloW bandcd felsite, vent breccia Z1M92/27 36... 

Twist and hhirmer (1987) applied the Rb-(Y + Nb) and Nb-Y diagrams to the Proterozoic Bushveld granites and associated felsite lavas. Their study raises two rather different but important points. Firstly, these diagrams can be applied to felsidc Lavas as well as to plutonic felsic rocks, provided the lavas are not contaminated. Secondly, they found that differences in trace element chemistry could be just as much a function of variable source chemistry as of differences in tectonic environment. 

The basement rocks of the Patuxent Range in Fig. 8.7 consists almost exclusively of the isoclinally folded metasedimentary rocks of the Patuxent Formation (redefined) and are not interbedded with felsite and basalt flows but they are cut by thin porphyritic... 

The Patuxent Formation (redefined) in the Schmidt and Williams hills contains interbedded lava flows of pillow basalt and felsite (e.g., the Gorecki Felsite Member), whereas the Hannah Ridge Formation in... 

Three felsite samples from the Gorecki Rhyolite (352,354,358) which is interbedded with the Patuxent Formation on Mount Gorecki in the Schmidt Hills in Fig. 8.8 (Rowell et al. 1994) are not suitable for dating by the Rb-Sr method because the data points scatter irregularly in coordinates of Rb/ Sr and Sr/ Sr. 

Twenty two years after Eastin (1970) completed his work, Storey et al. (1992) were also unable to derive meaningful whole-rock Rb-Sr dates for felsites, mafic sills, and pillow basalts associated with the Patuxent Formation in the Schmidt and Williams hills. They expressed their conclusion succinctly by stating ... 

The best available evidence for the age of the Patuxent Formation (as redefined by Rowell et al. 2001) arises from age determinations of the Gorecki Rhyolite in the Schmidt Hills. If the Gorecki Rhyolite consists of lava flows or other kinds of volcanogenic surface deposits that are interbedded with the Patuxent Formation at Mount Gorecki and elsewhere, then age determinations of these rhyolites also date the time of deposition of the local Patuxent Formation. On the other hand, if the felsic magma of the Gorecki Rhyolite intruded the Patuxent Formation in the form of sills or small plu-tons, then the Patuxent Formation is older than isotopic dates of the felsites in the Schmidt Hills. 

Schmidt et al. (1978) considered the Gorecki Felsite in the Schmidt Hills to be interbedded with the rocks of the Patuxent Formation and Rowell et al. (1994) asserted emphatically that the age of the Patuxent Formation in the Schmidt Hills is early Paleozoic and not Neoproterozoic because the felsite at Mount Gorecki contains fragments of fossiliferous limestone derived from the Nelson Limestone ... 

The U-Pb date of zircon from the Gorecki Felsite (5(X) 8 Ma) confirmed that the age of the Patuxent Formation in the Schmidt Hills is in fact. Middle to Late Cambrian according to the geologic timescale of the lUGS (2002). 

The U-Pb date of the Gorecki Felsite measured by Millar and Storey (1995) implies that the age of the pillow-basalt flows in the Schmidt and William hills is also Late Cambrian to Early Ordovician. Storey et al. (1992) previously proposed that these pillow basalts were erupted during an episode of the rifting of the continental crust during which the Thiel Mountains Porphyry and the basaltic rocks in the Ellsworth Mountains were also erupted (Section 8.1.6). According to Millar and Story (1995), the episode of extensional tectonics in the far-eastern sector of the Transantarctic Mountains may have been caused by the development of a back-arc basin in response to the active subduction... 

Another point to consider is that the rhyolite lavas of the Gambacorta Formation have the same age (Late Cambrian to Early Ordovician) as the Gorecki Felsite (Eastin 1970 Millar and Storey 1995 Van Schmus et al. 1997). Therefore, the rhyolites of the Gorecki Member of the Patuxent Formation and of the Gambacorta Formation in the eastern Neptune Range were erupted during the same interval of time between 488 4 and 501 3 Ma (Table 8.3). 

Felsites of the Patuxent Formation, Schmidt and Wiiiiams Hiiis... 

Wa.28.1.64) Porphyritic felsite with phenocrysts of quartz, K-feldspar, and plagioclase and black angular inclusions. Hypabyssal porphyry intrusive, 37 m wide, into Patuxent Formation at Pope Nunatak. 

Role of whitlockite and apatite in lunar felsite (abstract), in Lunar... 

Iceland, Group I Olivine basalt (avg. of 2) Dacite (avg. of 2) Granophyre (avg. of 4) Iceland, Group II Olivine basalt (avg. of 3) Andesite Felsite... 

---