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Chinese Science Bulletin 1993年第24期38卷 2067-2071页

作者：赵靖钟大赉王毅 Department of Geology Peking University Beijing 100871 PRC Institute of Geology. Academia Sinica Beijing 100029. PRC

1 A Method of Determining Early Deformation and Metamorphism History in Orogenic Belts porphyroblast inclusion trails from orogenic belts represent early-formed foliations composed of oriented metamorphic minerals preserved in rocks in the processes of porphyroblast growth (i.e. progressive and retrogressive metamorphism). Since they were studied in the 1920s, such inclusion trails have been recognized as products of syntectonic rotation due to progressive ductile deformation, which may be used as a known

关键词： porphyroblast inclusion trails deformation metamorphism.

Distinguishing and Correlating Multiple Phases of Metamorphism across Multiply Deformed Regions Using the Axes of Inclusion Trails in porphyroblasts

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Acta Geologica Sinica(English Edition) 2011年第4期85卷 784-791页

作者： Ahmad Afroz SHAH Asghar ALI School of Earth and Environmental Sciences James Cook UniversityTownsvilleQld 4811Australia

Successions of FIAs（foliation inflection/intersection axes preserved within porphyroblasts） provide a relative time scale for deformation and ***-situ dating of monazite grains preserved as inclusions within garnet and staurolite porphyroblasts within the foliations defining each FIA from such successions provides a rigorous approach to grouping ages that formed over extended periods of deformation and *** age and FIA progressions confirms the suitability of this approach plus provides access to lengthy histories that cannot otherwise be *** in the Big Thompson region of the Colorado Rocky Mountains,USA began about a SW-NE trending axis defined by FIA set 1 at around 1761±13 *** periods of tectonism occurred around 1712±25 and 1672±21 Ma about W-E and NW-SE trending FIAs 2 and 3, *** in the Balcooma Metamorphic Group NW of Greenvale in NE Queensland, Australia began around 470 Ma with the growth of garnet porphyroblasts about a W-E trending axis defined by FIA set *** monazite grains were preserved as inclusions in this mineral phase but they were in subsequently grown *** then occurred around 443.2±3.8,424±4 and 408.9±8.9 Ma about NNW-SSE,SSW-NNE and W-E trending FIAs 2,3 and 4,*** test of a FIA based approach to monazite dating in tectonic regimes in different parts of the world and with dramatically different ages suggests it can be used in all orogens containing porphyroblasts preserving inclusion trails.

关键词： FIAs porphyroblast monazite Colorado Balcooma Metamorphic Group

FIAs(Foliation Intersection/Inflection Axes) Preserved in porphyroblasts,the DNA of Deformation:A Solution to the Puzzle of Deformation and Metamorphism in the Colorado,Rocky Mountains,USA

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Acta Geologica Sinica(English Edition) 2009年第5期83卷 971-984页

作者： SHAH Afroz Ahmad School of Earth and Environmental Sciences James Cook UniversityTownsville Queensland Australia

FIAs have been used extensively for more than a decade to unravel deformation and metamorphic puzzles. Orogenic processes developing early during the history or orogenesis challenge scientists because compositional layering in rocks always reactivates where multiple deformations have occurred, leaving little evidence of the history of foliation development preserved in the matrix. The foothills of the Rocky Mountains in Colorado, USA contain a succession of four FIA sets （trends） that would not have been distinguishable if porphyroblasts had not grown during the multiple deformation events that affected these rocks or if they had rotated as these events took place. They reveal that both the partitioning of deformation and the location of isograds changed significantly as the deformation proceeded.

关键词： foliation intersection/inflection axes porphyroblast deformational partitioning

Compositional Distribution and Growth Mode of Garnet porphyroblasts during Deformation and Metamorphism

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Acta Geologica Sinica(English Edition) 2004年第1期78卷 186-190页

作者： ZHAOGuiping LIUShuwen LIUXiaohan ComputationalGeodynamicsLaboratory GraduateSchoolofChineseAcademyofSciencesBeijing100039 SchoolofEarthandSpaceSciences PekingUniversityBeijing100871 InstituteofGeologyandGeophysics ChineseAcademyofSciencesBeijing100029

Although porphyroblast microstructures play an important role in structural and metamorphic studies, there are still controversies in the interpretation. The focus is how porphyroblasts grow during deformation and metamorphism. In this paper, we introduce a new approach, the Synchrotron Radiation X-Ray Fluorescence, to a hemi-quantitative interpretation of the growth mode of porphyroblasts. The analysis was done at the Beijing Synchrotron Radiation Facility. The specimens were sampled from metapelite of the Baoyintu Group, northern Urad Middle Banner, Inner Mongolia. The new method is successful for determining the microscopic distribution of trace elements in porphybroblasts. The results support the theory of deformation partition, which has been brought forth by Bell and his colleagues, and demonstrate the existence of porphyroblast growth phases and the growth mode of porphyroblasts by hemi-quantitative mineral chemical analysis. The porphyroblast grows stage by stage in the manner of the distribution of a roseleaf and is controlled by deformation. We call the growth stage of porphyroblast a growth phase.

关键词： Synchrotron Radiation X-ray Fluorescence Analysis deformation partition porphyroblast growth phase,Baoyintu Group

Tectonic evolution of the Karakoram metamorphic complex(NW Himalayas)reflected in the 3D structures of spiral garnets:Insights from X-ray computed micro-tomography

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Geoscience Frontiers 2021年第3期12卷 528-540页

作者： M.Sayab D.Aerden J.Kuva W.U.Hassan Geological Survey of Finland P.O.Box 96FI-02151 EspooFinland Departamento de Geodinámica and IACT-CSIC Universidad de GranadaGranada 18002Spain National Centre of Excellence in Geology University of PeshawarPeshawar 25130Pakistan

Spiral garnet porphyroblasts are known to record lengthy periods of deformation and metamorphism by preserving single or multiple FIAs(Foliation Intersection Axis)formed normal to tectonic shortening *** to technological advances in X-ray computed micro-tomography(XCMT),FIAs can now be readily determined in relatively large samples in contrast to previous methods that require the preparation of a set of radial vertical and horizontal thin sections of *** scanning not only alleviates tedious thin section based procedures but also illuminates the complete internal architecture of a rock sample allowing three-dimensional(3D)quantitative shape analysis of an individual porphyroblast as well as precise measurement of *** applied the technique to a sample from the Hunza Valley in the Karakoram metamorphic complex(KMC),NW Himalayas,containing numerous garnet porphyroblasts with spiral-shaped inclusion *** XCMT imaging reveals an E-W trending FIA within the sample,which is consistent with orthogonal N-S collision of the India-Kohistan Island Arc with *** long axes(X_(GT))have variable plunges that define a broad sub-vertical maximum and a small sub-horizontal *** X_(GT) principle maxima lie at N-090 and *** maxima lie at N-020 and *** relationships between X_(GT) axes and FIA orientation in the sample suggest that porphyroblast shapes are controlled by the geometry of the lens-shaped microlithons in which they tend to nucleate and *** orientation of inclusion trails and matrix foliations in the sample are correlated with three discrete tectono-metamorphic events that respectively produced andalusite,sillimanite and kyanite in the *** staurolite growth in the sample reveals how the rocks extruded to the surface via a significant role of roll-on tectonics,which can be correlated with the Central Himalayas.

关键词： porphyroblast Garnet FIA X-ray tomography Karakoram Himalayas

Survival Conditions of Folding in Different Depth During Orogenesis-Deformation in Texas Creek and Chester Dome, USA

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Acta Geologica Sinica(English Edition) 2014年第1期88卷 103-112页

作者： CAO Hui XU Cuiping State Key Laboratory for Continental Tectonics and Dynamics Institute of Geology Chinese Academy of Geological Sciences School of Earth and Environmental Sciences James Cook University

A succession of 5 FIA trends（foliation intersection or inflection axes in porphyroblasts） preserved in high temperature-low pressure regime PreCambrian rocks in the Texas Creek, Arkansas River region reflected by the fold axial plane traces and schistosity data in this region. Similar fold axial plane trace data measured in Palaeozoic rocks in Chester Dome, Vermont, which is high temperature to medium pressure regime, only preserve the effects of the youngest FIAs of the all 5 FIA sets that obtained in this region. The other three FIA sets have no equivalent fold axial planes. This difference from shallow to deeper orogenic regimes reflects decreasing competency at greater pressure with collapse and unfolding of earlier formed folds. The greater overlying load of rocks has tended to flatten all but the very largest early-formed structures, preserving only those folds that were more recently developed.

关键词： orogenesis fold axial plane foliation intersection or inflection axes gravitational collapse porphyroblast