caa a22 4500 475827600 CHVBK 20180406123832.0 cr unu---uuuuu 170329e20000901xx s 000 0 eng 10.1007/s005310000086 doi (NATIONALLICENCE)springer-10.1007/s005310000086 Mortimer N. Institute of Geological and Nuclear Sciences, Private Bag 1930, Dunedin 9020, New Zealand e-mail : n.mortimer@gns.cri.nz, Tel.:+64-3-4774050, Fax:+64-3-4775232, NZ aut Metamorphic discontinuities in orogenic belts: example of the garnet-biotite-albite zone in the Otago Schist, New Zealand [Elektronische Daten] [N. Mortimer] A regional petrographic reconnaissance of psammitic and pelitic rocks in the Otago Schist, New Zealand, has revealed the presence of garnet ("grossalspite” with typical rim composition almandine41, spessartine25, grossular33, pyrope1) and biotite in 37 new samples, more than doubling the previously known number. A new garnet-biotite-albite zone can now be defined in the greenschist facies Otago Schist that is distinct from the better-known biotite, garnet and oligoclase zones in the along-strike Alpine Schist. The garnet-biotite-albite zone is in part metamorphically discontinuous with adjacent schists and does not support models of simple, continuous, progressive Jurassic regional metamorphism in Otago. The structurally higher (lower grade) boundary of the zone coincides in at least three places with previously mapped regional shear zones. The structurally lower (expected higher grade) boundary of the zone appears to be obliterated by a chlorite zone overprint which can be spatially related to Alpine Schist recrystallisation of ?Cretaceous age. The Otago situation serves as an example of the subtle metamorphic discontinuities that probably pervade many orogenic belts. Springer-Verlag Berlin Heidelberg, 2000 Key words New Zealand nationallicence Haast Schist nationallicence Otago Schist nationallicence Metamorphic rocks nationallicence Garnet zone nationallicence Greenschist facies nationallicence Structural discontinuity nationallicence Overprinting nationallicence https://doi.org/10.1007/s005310000086 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s005310000086 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Mortimer N. Institute of Geological and Nuclear Sciences, Private Bag 1930, Dunedin 9020, New Zealand e-mail : n.mortimer@gns.cri.nz, Tel.:+64-3-4774050, Fax:+64-3-4775232, NZ aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer