Deposition and deformation of an Early Cretaceous trench-slope basin deposit, Torlesse terrane, New Zealand

Abstract

Research Article| May 01, 1992 Deposition and deformation of an Early Cretaceous trench-slope basin deposit, Torlesse terrane, New Zealand ANNETTE D. GEORGE ANNETTE D. GEORGE 1Research School of Earth Sciences, Victoria University of Wellington, P.0. Box 600, Wellington, New Zealand Search for other works by this author on: GSW Google Scholar GSA Bulletin (1992) 104 (5): 570–580. https://doi.org/10.1130/0016-7606(1992)104<0570:DADOAE>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation ANNETTE D. GEORGE; Deposition and deformation of an Early Cretaceous trench-slope basin deposit, Torlesse terrane, New Zealand. GSA Bulletin 1992;; 104 (5): 570–580. doi: https://doi.org/10.1130/0016-7606(1992)104<0570:DADOAE>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Studies of modern convergent margins have highlighted the variety of depositional environments and deformational processes that occur in this tectonic setting and provide analogues by which ancient uplifted sequences can be interpreted. The Whatarangi Formation is an Early Cretaceous trench-slope basin deposit, preserved within accretionary prism rocks of the (Pahau) Torlesse terrane of New Zealand, and is distinguished from the underlying accreted rocks by its younger age, different depositional history, structural style and metamorphic grade, and lack of oceanic volcanic outcrops. Furthermore, the Whatarangi Formation records the types of processes inferred to occur in modern slope basins. Sediments were derived from sources on the western side of the basin and were deposited mainly by gravity flows on channelized base-of-slope aprons. The narrow, elongate shape of the basin resulted in restricted, longitudinal flow of the sandy turbidity currents and deposition of finer sediment farther down the inner trench slope or in the trench. Deformation of the turbidites produced open to tight asymmetric folds that are concentrated along the western margin and lower half of the formation. The folds are best described by a model of simple shear and formed in response to active west-over-east thrusting in the underlying prism. Cleavage was initiated prior to folding in response to overall shortening of the basin, with subsequent development of an axial-planar cleavage in the tightest folds. The compositional similarity between the slope basin strata and accreted sedimentary rocks of the Aorangi Range has important implications for the Early Cretaceous tectonic history of the Torlesse terrane. The sediments were eroded from an uplifted accretionary prism and an acid igneous source, and the deposition of these sediments in upslope basins and the trench suggests that all the Pahau sediments could have been transported from these transversely located sources. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.