Good exposures of the blockinmatrix fabric of the fjt exist in the soap creek valley, just west of yreka. A pt path for the prasinites is presented indicating epidote blueschist facies at pt conditions of around 7. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. Condie, in earth as an evolving planetary system, 2005. These sessions, entitled facies models revisited, were intended to capture the state of the art with respect to facies modeling in several key depositional environments. We present the first data on bulkrock major and trace element compositions for a suite of eclogite and blueschist facies rocks from the bantimala complex, indonesia, with the aim of better constraining the protolith origins and nature of the subducted c. Home anu research anu scholarly output anu research publications geochemistry of eclogite and blueschistfacies rocks from the bantimala complex, south sulawesi, indonesia. Pdf geochemistry of eclogite and blueschistfacies rocks.
Rocks which contain certain minerals can therefore be linked to certain tectonic settings. Graduate thesis or dissertation structure and petrography. Ductile thrusting recorded by the garnet isograd from blueschist. Metamorphic rocks formed by regional metamorphism in the following condition. Lawsonite, blueschist and eclogite formation in the southern. Uncovering and quantifying the subduction zone sulfur. The groupii fluid inclusions formed at blueschistfacies conditions support the idea that aqueous fluids in the subduction channel have a salinity similar to. The white schist assemblage in the kyanite quartzite from the. Sulfur is one of the most common volatiles on earth. Correlation of the klamath mountains and sierra nevada. Some blocks have been feebly metamorphosed and retain features of the original protolith material. Petrology of blueschist from the western himalaya ladakh. Blueschist blocks within the schistose matrix reveal six deformation events, d1d6. Conference of the canadian society of petroleum geologists and in dallas in 2004 annual conference of the american association of petroleum geologists.
Metamorphic style and development of the blueschist to eclogitefacies rocks, cyclades, greece john c schumacher1, john b brady2, john t cheney3 1dept. These rocks tectonically overlie intact lower grade units including a blueschist facies unit with abundant metavolcanics mov and metachert s in addition. After stacking and recrystallization under fairly comparable blueschistfacies conditions, the different sesia subunits underwent a lowp event of probable latealpine age. This report graphically portrays the broadly parallel tectonic development of the klamath mountains and sierra nevada from early paleozoic to early cretaceous time. Eclogiteblueschist relationships as evidenced by mineral. Blueschist facies article about blueschist facies by the. In the western himalaya, the best occurrence of blueschist is that of the sapishergol ophiolitic melange in ladakh. Pdf early carboniferous blueschist facies metamorphism in. Distribution of metamorphic rocks subjected to blueschist facies regional metamorphism described in this site. Hydrothermal blueschist facies zircons from the franciscan complex, california. Protolith 25 the blueschist facies is a metamorphic realm of. This file may not be posted to any web site, but authors may post the abstracts only of their articles on their own or their organizations web site providing the posting includes a reference to the articles full citation.
The calculated pt conditions of the eclogite facies metamorphism are t500c and. Detrital zircon data are presented from the liberty creek blueschist in the central chugach mountains which indicate two distinct periods of the preservation of blueschist facies metamorphism along the southern alaskan margin. The protolith may be an aplite replaced by highpressure fluid of eclogite facies. Facies represent specific temperature pressure regimes. Thereby, these rocks do not appear blue overall in color. Metamorphism and preservation of lawsonite eclogite, sivrihisar. Process of mineralogical and structural textural changes of rocks in the. I first used the term blueschist in 1961 and defined blueschist facies as including the rocks formed in the stability. Upb dating of zircon from the orthogneiss and a metavolcanic schist indicates a middle jurassic age helper and others, 1989. Blueschisttogreenschist transition and the pt path of. More recently the term blueschist facies has been preferred because glaucophane is not always developed in many important rock types, for example, graywacke sandstones, which may contain other minerals that are characteristic of high pressure and low temperature such as. Metamorphic evolution of blueschists, greenschists, and. Blueschist facies metamorphic rocks are in franciscantype highp metamorphic rocks.
Eclogites and blueschist facies rocks are frequent in the eastern part of the island, whereas greenschist facies rocks are. A greenschist protolith for blueschist in anglesey, u. Formation and subduction p12 5 p12 volume n 3 from do1 to p mesozoic ophiolites, showing peak blueschist metamorphic assemblages related to the alpine subduction. Use these facies if clearly associated with a pluton. Blueschist metamorphism in an active subduction zone nature. The development of a pervasive blueschistfacies d2foliation is in contrast with the eclogitic dominant fabric generally recorded in the emc. Lawsoniteomphacitebearing metabasites of the pam peninsula. Metamorphic conditions which create typical greenschist facies assemblages are called the barrovian facies sequence, and the lowerpressure abukuma facies series. We present the first data on bulkrock major and trace element compositions for a suite of eclogite and blueschistfacies rocks from the bantimala complex, indonesia. Yes, you will have to know the chemical formulae for the common minerals again this semester.
Cordilleran section 109th annual meeting 2022 may 20. Geochemical and isotopic characteristics of blueschist. Lowtemperature blueschistfacies mafic blocks in the franciscan melange, san simeon, california. Felsic rocks and pelitic sediments which are subjected to blueschist facies conditions will form different mineral assemblages than metamorphosed basalt. Rocks resulting from thermal contact metamorphism will. The northern part of the cycladic island of sifnos greece is formed by a coherent sequence of interlayered acid and basic metavolcanic rocks and me.
An oligocene extrusion wedge of blueschistfacies nappes on evia island, aegean sea, greece. Sampling includes the main rock types exposed on groix, concentrating on those metabasic rocks with least dispersed rbsr sys. Temperatures of approximately 400 to 500 c 750 to 930 f and depths of about 8 to 50 kilometres 5 to 31 miles are the typical envelope of greenschist facies rocks. Nine samples of blueschist facies metabasic rocks and four samples of associated metasedimentary lithologies were analysed for ree contents and nd isotopic composition. Pseudosections also indicate that peak p t conditions for the blueschist samples studied here lie in the range 6. This unit is dominated by volcanoclastic sequences rich in mafic material with subordinate interbedding of metasediments, characterized by very fresh lawsonite blueschistfacies assemblages. The path ebs to gs conditions followed under nearly isothermal uplift. Each of these units bears the imprint of blueschistfacies metamorphism, indicating that it has been subducted to.
Whereas blueschist epidotes show very high fe content 79. Petrologic and geochemical comparison of the blueschist. If your web browser has the proper plugin installed, clicking on the pdf will bring the file into your web browser from which you can then print the notes. Data sources and analytical methods many of the data presented here were obtained as part of a study of terrane correlations.
The 114 metabasites contain euhedral lawsonite laths in a matrix of foliated sodic amphibole with 115 variable amounts of phengite and chlorite. Read transitional blueschistepidote amphibolite facies metamorphism in the frankenberg massif, germany, and geotectonic implications, journal of metamorphic geology on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Presentation mode open print download current view. Implications for the early exhumation of highpressure rocks. Petrology of blueschist from the western himalaya ladakh, nw. Bethghinivert, blueschist facies, calcschists, deformationmetamorphism. Pdf hydrothermal blueschist facies zircons from the. A final reequilibration under greenschists facies conditions, locally associated to s3 crenulation cleavage and replacement of synd1 and synd2 assemblages, is recorded in all metabasites fig. Until now, however, the link between blueschistfacies rocks and subduction zones has been indirect, relying on a spatial association of blueschists with. This file contains additional information such as exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. If the plugins are not installed, your web browser will either attempt to download the pdf files or offer to send you to the adobe web site to download the plugins for your browser. Condie, in earth as an evolving planetary system second edition, 2011. Metamorphic facies the metamorphic facies are groups of mineral compositions in metamorphic rocks, that are typical for a certain field in pressuretemperature space.
Such a lowp event caused a metamorphic zonation, with lower t. Eclogiteblueschistfacies rocks from spouthern sifnos. This study confirms the excellent work done by previous researchers e. These two foliations were further folded by large folding during the mesoalpine event e. The cenozoic accretionary wedge of calabria, southern italy, consists of several units of continental and oceanic affinity accreted beneath the former continental margin of the sardiniacorsica block. The blueschist unit contains metagraywacke, metashale, metaconglomerate, greenstone, quartz schist, blueschist, and eclogite blocks in a finegrained, schistose matrix which probably recrystallized from a mixture of ultramafic and clayrich, quartzose detritus. Calculated p t pseudosections show that the assemblage glaucophane pumpellyite chlorite occurs only in a restrictedfield along the lower p t limit of the blueschist facies. Stepheating 40ar39ar spectra were obtained for mica from several lenses of blueschists including greenschist facies rocks. Blueschist facies metamorphism is important in subduction zones, where highpressure, relatively lowtemperature mineral assemblages form. Blueschist accessscience from mcgrawhill education. These rocks were affected by a widespread blueschistfacies metamorphic event, presumably of triassic age. Epidotes in both greenschist and blueschist show fedepleted rims. The blueschistfacies mineral assemblage contains chlorite. The pt history of the blueschistfacies metapelites is estimated using a simplified.
Analysis of fabric evolution and metamorphic reaction. Eclogite facies metamorphism in sugozu nappe, which consists of. Named for equivalent mafic rock type at those conditions. Just in case you forgot them over the last week, you can get a list by clicking here.
Geochemical and isotopic characteristics of blueschist facies. Announcements look here during the semester for announcements concerning this course. A link within the document will lead you to a pdf file geared for printing this list. Purple jade finelycrystalline jadeitekfeldsparlawsoniteaegerine metamorphite 10. Geochemistry of eclogite and blueschistfacies rocks from. A curious, and confusing, feature is the inclusion of two maps for each of the california areas studied, one by the. In the catalina schist terrane, a nappe of blueschist facies melange is overlain by one of isoclinallyfolded greenschist facies rocks.
The cenozoic tectonic history of the calabrian orogen. Klippen of analogous blueschist terrains cravascovoltaggiomontenotte units also overlie the eclogitic. Petrologic and geochemical comparison of the blueschist and. It plays key roles in, for example, the redox evolution of the subarc mantle 1,2, the formation of ore deposits 2, and the composition of the. Early carboniferous blueschist facies metamorphism in. White mica, chlorite and quartz predominate in the phyllites in variable proportions, but na amphibole, epidote, albite and titanite may also be important. We present the first data on bulkrock major and trace element compositions for a suite of eclogite and blueschistfacies rocks from the bantimala complex, indonesia, with the aim of better constraining the protolith origins and nature of the subducted c. Highpressure, lowtemperature metamorphism associated with subduction zones which produces a broad mineral association including glaucophane, actinolite. Volcanic landforms and surface features pdf free download. Pdf few localities in the patagonian andes expose remnants of the mesozoic chilean paleoaccretionary complex. Metamorphic style and development of the blueschist. Miyashiro 1961 proposed five facies series simplified to. Blueschist facies is determined by the particular temperature and pressure conditions required to metamorphose basalt to form blueschist. Structural context and variation of ocean plate stratigraphy, franciscan complex, california.
Lawsonite, blueschist and eclogite formation in the. Amphibolite facies includes calcite marbles, biotite schists and amphibolites. This difference suggests that fe and mt are potentially responsible for kmscale heterogeneities in the tectonometamorphic record. Protolith 25 the blueschist facies is a metamorphic realm. Geochemistry of eclogite and blueschistfacies rocks from the bantimala complex, south. Each of these units bears the imprint of blueschist facies metamorphism, indicating that it has been subducted to. Lawsonite 176lu177hf ratios are elevated and are similar to other minerals commonly used in luhf geochronology such as garnet or apatite. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to. Pdf eclogite, amphibolite and blueschistfacies rocks from diego. Correlation of the klamath mountains and sierra nevada usgs. Metamorphic style and development of the blueschist to. In glaucophanites synd1 and synd2 parageneses, associated with s1 and s2 schistosities, indicate epidote blueschist facies conditions.
The blueschist metamorphic facies are characterized by the minerals jadeite, glaucophane. Structural and geochronologic history of southern alaskan. High pt sanbagawa or franciscan facies series facies series. A maximum depositional age of 6 ma demonstrates that the liberty creek schist was deposited long after the jurassic cooling ages 196185 ma. Pdf ptt evolution of eclogiteblueschist facies metamorphism in. Until now, however, the link between blueschist facies rocks and subduction zones has been indirect, relying on a spatial association of blueschists with old subduction complexes, and estimates of. Protoliths of green dots are igneous rocks and sedimentary rocks. The posteclogitic t decrease inferred here for the southern em is less evident in more northerly parts of this subunit.
1054 1125 1051 805 32 698 923 895 1350 1082 1177 1539 239 877 547 121 1166 115 1039 234 82 636 316 1185 1035 936 1137 330 160 488 847 303 53 839 1304 34 314 1324 281 668