info:eu-repo/semantics/article
GRANITIC MAGMATISM IN THE DAMARAN OROGENIC BELT, NAMIBIA
GRANITIC MAGMATISM IN THE DAMARAN OROGENIC BELT, NAMIBIA
Autor
BRANDT, R.
Institución
Resumen
After the geosynclinal phase of the Darnara Orogeny carne to an end at about 700 Ma, numerous plutonic magmas intruded its sedimentary and volcanic rocks and its underlying Abbabis Complex basement. The igneous activity started with the intrusion of early, I-type, metaluminous, calcic, hornblende-bearing granodiorites to tonalites, which contain mafic enclaves. These rocks make up about 5% of the exposed plutonites. They probably originated in the upper mantle- lower crust level and their crystaiiisation in the middle crust caused partial melting of sedimentary and possibly granitie and volcanic rocks . This resulted in the origin of a wide variety of petrographie different, but geochemically similar granites with S-type characteristics. These alkalic, peraluminous granites intruded higher levels of the crust and caused partial melting in the lower parts of the Damara Sequence. From these melts, the alaskites and leucogranites were formed. The peak of regional metamorphism coincided with the peak of granite intrusions at about 550-530 Ma and is probably caused by it. After the geosynclinal phase of the Darnara Orogeny carne to an end at about 700 Ma, numerous plutonic magmas intruded its sedimentary and volcanic rocks and its underlying Abbabis Complex basement. The igneous activity started with the intrusion of early, I-type, metaluminous, calcic, hornblende-bearing granodiorites to tonalites, which contain mafic enclaves. These rocks make up about 5% of the exposed plutonites. They probably originated in the upper mantle- lower crust level and their crystaiiisation in the middle crust caused partial melting of sedimentary and possibly granitie and volcanic rocks . This resulted in the origin of a wide variety of petrographie different, but geochemically similar granites with S-type characteristics. These alkalic, peraluminous granites intruded higher levels of the crust and caused partial melting in the lower parts of the Damara Sequence. From these melts, the alaskites and leucogranites were formed. The peak of regional metamorphism coincided with the peak of granite intrusions at about 550-530 Ma and is probably caused by it.