Magnetic fabric of OPS mélanges: a tool for unravelling protracted histories of oceanic plates from sea-floor spreading to tectonic emplacement into accretionary wedges
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引用次数: 0
Abstract
Multiple magnetic fabrics, referred to as F1–F5, were revealed through the anisotropy of magnetic susceptibility (AMS) in an Ocean Plate Stratigraphy (OPS) mélange of the Neoproterozoic–Cambrian Blovice accretionary complex, Bohemian Massif. The fabrics postdate the mélange formation and rotation of basalt blocks within the matrix and are interpreted in terms of a complex structural history of the mélange. Excluding local fabrics, the F1 fabric formed earlier along the mélange belt, recording shortening of the accretionary wedge front, whereas the higher-grade F4 fabric pervasively overprinted both blocks and matrix in the SW part of the belt, recording shearing and vertical shortening at deeper structural levels closer to a megathrust surface. The preservation of angular relationships between the F1 and F4 fabrics across different parts of mélange suggests that blocks were only strained and not rotated during deformation, exemplifying the notion that the OPS mélanges may be a product of deformation at very shallow levels. Finally, the F1–F5 fabrics may be viewed as snapshots in a protracted evolution of OPS mélanges, where earlier fabrics in basalt blocks may record the travel path of an oceanic plate from mid-ocean ridge towards the trench, before being overprinted in the accretionary wedge.
Thematic collection:
This article is part of the Ophiolites, melanges and blueschists collection available at:
https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists
Supplementary material:
https://doi.org/10.6084/m9.figshare.c.7008173
期刊介绍:
Journal of the Geological Society (JGS) is owned and published by the Geological Society of London.
JGS publishes topical, high-quality recent research across the full range of Earth Sciences. Papers are interdisciplinary in nature and emphasize the development of an understanding of fundamental geological processes. Broad interest articles that refer to regional studies, but which extend beyond their geographical context are also welcomed.
Each year JGS presents the ‘JGS Early Career Award'' for papers published in the journal, which rewards the writing of well-written, exciting papers from early career geologists.
The journal publishes research and invited review articles, discussion papers and thematic sets.