TY - JOUR

T1 - Metamorphosed mantle peridotites from central Iran (Jandaq area, Isfahan province)

AU - Torabi, Ghodrat

AU - Arai, Shoji

AU - Koepke, Jur̈gen

PY - 2011/8/1

Y1 - 2011/8/1

N2 - Mantle peridotites of the Jandaq ophiolite are composed of metamorphosed lherzolite and harzburgite, with lherzolitic mineralogical and bulk chemical compositions prevailing over harzburgite. They are closely associated and isofacial with amphibolites and Paleozoic metasedimentary rocks (schist and marble). Rock forming minerals of metalherzolites are clinopyroxene, Cr-spinel, olivine, tremolite, chlorite, serpentine, magnetite and calcite. Metaharzburgites are composed of olivine, orthopyroxene, talc, anthophyllite, magnetite, Cr-spinel ± low amounts of chlorite and tremolite. The olivine and orthopyroxene in these rocks are metamorphic products, not relicts of the primary igneous mineralogy. Early relict phases (mantle phases) include clinopyroxene and Cr-spinel. Petrography, mineral chemistry, as well as major and trace element geochemistry of the metamorphic lherzolites indicate that they are relicts of undepleted mantle material and have experienced less than 3% partial melting. Metamorphic assemblages in metaperidotites, mineral chemical studies, together with additional geological constraints, indicate that the Jandaq mantle peridotites are metamorphosed under upper amphibolite facies conditions (8 to 9 kbars and 714 to 737 °C), followed by a retrograde metamorphism under greenschist facies conditions. The maximum temperature of regional metamorphism was not sufficient to replace calcic amphibole (tremolite) by calcic pyroxene. Textures (magnetite inclusions in metamorphic olivines) and associated rock types (meta-listwaenite) indicate the studied rocks were partly altered (M1) before being progressively metamorphosed under upper amphibolite facies conditions (M2). Late-stage retrograde metamorphism (M3) led to formation of chlorite and thin irregular serpentine veinlets, partially to serpentinization of metamorphic olivine and orthopyroxene, and partial replacement of chromian spinel by ferritchromite and magnetite. These three metamorphic episodes can be attributed to the Early, Middle and Late Cimmerian orogenies of Iran, respectively.

AB - Mantle peridotites of the Jandaq ophiolite are composed of metamorphosed lherzolite and harzburgite, with lherzolitic mineralogical and bulk chemical compositions prevailing over harzburgite. They are closely associated and isofacial with amphibolites and Paleozoic metasedimentary rocks (schist and marble). Rock forming minerals of metalherzolites are clinopyroxene, Cr-spinel, olivine, tremolite, chlorite, serpentine, magnetite and calcite. Metaharzburgites are composed of olivine, orthopyroxene, talc, anthophyllite, magnetite, Cr-spinel ± low amounts of chlorite and tremolite. The olivine and orthopyroxene in these rocks are metamorphic products, not relicts of the primary igneous mineralogy. Early relict phases (mantle phases) include clinopyroxene and Cr-spinel. Petrography, mineral chemistry, as well as major and trace element geochemistry of the metamorphic lherzolites indicate that they are relicts of undepleted mantle material and have experienced less than 3% partial melting. Metamorphic assemblages in metaperidotites, mineral chemical studies, together with additional geological constraints, indicate that the Jandaq mantle peridotites are metamorphosed under upper amphibolite facies conditions (8 to 9 kbars and 714 to 737 °C), followed by a retrograde metamorphism under greenschist facies conditions. The maximum temperature of regional metamorphism was not sufficient to replace calcic amphibole (tremolite) by calcic pyroxene. Textures (magnetite inclusions in metamorphic olivines) and associated rock types (meta-listwaenite) indicate the studied rocks were partly altered (M1) before being progressively metamorphosed under upper amphibolite facies conditions (M2). Late-stage retrograde metamorphism (M3) led to formation of chlorite and thin irregular serpentine veinlets, partially to serpentinization of metamorphic olivine and orthopyroxene, and partial replacement of chromian spinel by ferritchromite and magnetite. These three metamorphic episodes can be attributed to the Early, Middle and Late Cimmerian orogenies of Iran, respectively.

KW - Central iran

KW - Jandaq

KW - Lherzolite

KW - Mantle peridotite

KW - Metamorphism

KW - Ophiolite

UR - http://www.scopus.com/inward/record.url?scp=80051751250&partnerID=8YFLogxK

U2 - 10.1127/0077-7749/2011/0153

DO - 10.1127/0077-7749/2011/0153

M3 - Article

AN - SCOPUS:80051751250

VL - 261

SP - 129

EP - 150

JO - Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen

JF - Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen

SN - 0077-7749

IS - 2

ER -