Deformation sequence of Baltimore gneiss domes, USA, assessed from porphyroblast Foliation Intersection Axes

Meng Wan Yeh*

*此作品的通信作者

    研究成果: 雜誌貢獻期刊論文同行評審

    23 引文 斯高帕斯(Scopus)

    摘要

    The NE-SW trending gneiss domes around Baltimore, Maryland, USA, have been cited as classic examples of mantled gneiss domes formed by diapiric rise of migmatitic gneisses [Eskola, P., 1949. The problem of mantled gneiss domes. Quarterly Journal of Geological Society of London 104/416, 461-476]. However, 3-D analysis of porphyroblast-matrix foliation relations and porphyroblast inclusion trail geometries suggests that they are the result of interference between multiple refolding of an early-formed nappe. A succession of six FIA (Foliation Intersection Axes) sets, based upon relative timing of inclusion texture in garnet and staurolite porphyroblasts, revealed 6 superposed deformation phases. The successions of inclusion trail asymmetries, formed around these FIAs, document the geometry of deformation associated with folding and fabric development during discrete episodes of bulk shortening. Exclusive top to NW shear asymmetries of curvature were recorded by inclusion trails associated with the vertical collapsing event within the oldest FIA set (NE-SW trend). This strongly indicates a large NE-SW-striking, NW-verging nappe had formed early during this deformation sequence. This nappe was later folded into NE-SW-trending up-right folds by coaxial shortening indicated by an almost equal proportion of both inclusion trail asymmetries documented by the second N-S-trending FIA set. These folds were then amplified by later deformation, as the following FIA sets showed an almost equal proportion of both inclusion trail asymmetries.

    原文英語
    頁(從 - 到)881-897
    頁數17
    期刊Journal of Structural Geology
    29
    發行號5
    DOIs
    出版狀態已發佈 - 2007 五月

    ASJC Scopus subject areas

    • 地質學

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