An early Proterozoic metagreywacke-slate turbidite sequence: The Tampere schist belt, southwestern Finland
1986; Geological Society of Finland; Volume: 58; Issue: 1 Linguagem: Inglês
10.17741/bgsf/58.1.016
ISSN1799-4632
Autores Tópico(s)Geological Studies and Exploration
ResumoThe metasedimentary sequence of the Tampere Schist belt, where it has undergone only slight metamorphism, clearly consisted of graded graywackes, siltstones and mudstones.These rocks constitute a typical turbidite sequence, with the environment of deposition the mid-fan portion of a submarine fan.Most abundant are Facies C (proximal turbidites), D (distal turbidites) and E (overbank deposits).The source rocks were largely felsic volcanics, perhaps partly still unconsolidated and derived from nearby volcanic centers.Felsic plutonic detritus was derived from either subvolcanic plutons or from an unlocated basement complex.CIA values indicate that some detritus was unweathered and derived directly from volcanic centers, whereas other material had undergone moderate chemical weathering.Analyses of small-scale cross-beds suggest that the dominant sources were located to the east.A sedimentary-tectonic model involving deposition in a forearc basin on a subducting plate margin is likely.
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