Krustenbau und sialischer Magmatismus

Abstract

Am Beispiel des zirkumkaribischen Raumes werden Widerspriiche gegen die welt verbreitete Vorstellung aufgezeigt, dal3 sialische Magmen durch Mobilisation von kontinentalen Krustengesteinen oder Sedimenten in Orogenwurzeln gebildet werden. In dem genannten Gebiet tritt sialischer Magmatismus unabh~ingig yon Orogenesen und unabh~ingig yon der Existenz kontinentaler Kruste auf. AbstractMany authors suppose that sialic magmas are formed by more or less complete fusion of deep-seated rocks in the mountain roots which accompanies or precedes orogenic folding. Regarding the circum-Caribbean magmatic provinces we meet serious contradiction to this opinion. These objections are presented only from the view-point of a geologist. ResumenMuchos autores suponen que el magma si~lico se origina por anatexia en las raices de or6genos. En la regi6n circuncaribe se encuentran numerosas contradicciones a este concepto. En la parte norte de Centroam6rica no se reconoce una conexiSn directa entre una orog6nesis y el volcanismo. A1 sur de Centroam6rica yen la parte oriental de las Grandes Antillas se encuentran sedimentos y rocas volc~micas de un geosinclinal inmediatamente sobre la corteza oce~mica, faltando asi rocas si~ilicas como material para una anatexia. Los volcanes de las Pequefias Antillas se levantan directamente sobre el piso oce~mico. No se conoce aqul una orog6nesis. No obstante se produjeron magmas si',ilicos en gran cantidad. IgpaTRoe co~ep~aHHeABTOp No~qepK~BaeT HpOTHBOpeHHH B O~%HCHeHHH ~poHcxo~eHH~ cHa~HO~ MarMH H8 oca~oqHoro noHpoBa B He,pax oporeHa: B pa~oHe, oKpymammeM Hap~6~,cHa~bHHfi MarMaTH3M Hp0HBH~CH HesaBHCHMO 0T ropoo6posoBawe~b-HOrO npo~ecca M Ha~HqH~ HOHTHHOHTa~bH~X OT~O~eHH~. CLOOS und RITTMANN (1939) beendeten ihr bekanntes Gespr~ich fiber die Einteilung und Benennung der Plutone mit der gemeinsamen Feststellung, dab der Entstehungsort der Migmen (= palingenen Magmen) die sialische Oberkruste sei und dab die bier gebildeten Magmen ihrem Chemismus nach der pazifisdaen Gesteinssippe angehSren..~hnlich beantwortete RITT-MANN (1959) die Frage nach der Entstehung der synorogenen oder post-

On the origin and evolution of the earth's crust and magmas

“…WEXL'S papers on the geology and volcanology of the Caribbean province are a good test for this problem (WEYL, 1966(WEYL, , 1967; not only because this author discusses the above mentioned controversy, but also because it shows how this fundamental problem of theoretical voleanology is closely linked to other fundamental problems in the sciences of the Earth. WEYL (1967) questions the generally accepted concept that sia]ic magmas are formed in mountain roots by more or less complete fusion of deepseated sialic rocks.…”

“…WEYL (1967) questions the generally accepted concept that sia]ic magmas are formed in mountain roots by more or less complete fusion of deepseated sialic rocks. His objections are based on his researches in the Caribbean area, where calc-alkaline igneous rocks are wide-spread, but where neither a sialic crust nor orogenic roots are present according to modern geophysical investigations.…”