DOI: 10.1007/s00531-013-0927-z
Scopus记录号: 2-s2.0-84893753883
论文题名: Ophicalcites from the northern Pyrenean belt: A field, petrographic and stable isotope study
作者: Clerc C. ; Boulvais P. ; Lagabrielle Y. ; de Saint Blanquat M.
刊名: International Journal of Earth Sciences
ISSN: 14373254
出版年: 2014
卷: 103, 期: 1 起始页码: 141
结束页码: 163
语种: 英语
英文关键词: Carbon
; Hydrothermalism
; Lherz
; Mantle exhumation
; Matrices
; Ophicalcite
; Ophicarbonate
; Oxygen
; Pyrenees
; Sedimentary deposits
; Stable isotopes
; Tectonic fracturation
; Urdach
; Veins
Scopus关键词: carbon
; exhumation
; hydrothermal system
; mantle structure
; oxygen
; peridotite
; petrography
; stable isotope
; tectonics
; texture
; vein (geology)
; Ariege
; Etang de Lherz
; France
; Midi-Pyrenees
; Pyrenees
英文摘要: Brecciated and fractured peridotites with a carbonate matrix, referred to as ophicalcites, are common features of mantle rocks exhumed in passive margins and mid-oceanic ridges. Ophicalcites have been found in close association with massive peridotites, which form the numerous ultramafic bodies scattered along the North Pyrenean Zone (NPZ), on the northern flank of the Pyrenean belt. We present the first field, textural and stable isotopic characterization of these rocks. Our observations show that Pyrenean ophicalcites belong to three main types: (1) a wide variety of breccias composed of sorted or unsorted millimeter- to meter-sized clasts of fresh or oxidized ultramafic material, in a fine-grained calcitic matrix; (2) calcitic veins penetrating into fractured serpentine and fresh peridotite; and (3) pervasive substitution of serpentine minerals by calcite. Stable isotopic analyses (O, C) have been conducted on the carbonate matrix, veins and clasts of samples from 12 Pyrenean ultramafic bodies. We show that the Pyrenean ophicalcites are the product of three distinct genetic processes: (1) pervasive ophicalcite resulting from relatively deep and hot hydrothermal activity; (2) ophicalcites in veins resulting from tectonic fracturing and cooler hydrothermal activity; and (3) polymictic breccias resulting from sedimentary processes occurring after the exposure of subcontinental mantle as portions of the floor of basins which opened during the mid-Cretaceous. We highlight a major difference between the eastern and western Pyrenean ophicalcites belonging, respectively, to the sedimentary and to the hydrothermal types. Our data set points to a possible origin of the sedimentary ophicalcites in continental endorheic basins, but a post-depositional evolution by circulation of metamorphic fluids or an origin from relatively warm marine waters cannot be ruled out. Finally, we discuss the significance of such discrepancy in the characteristics of the NPZ ophicalcites in the frame of the variable exhumation history of the peridotites all along the Pyrenean realm. © 2013 Springer-Verlag Berlin Heidelberg. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84893753883&doi=10.1007%2fs00531-013-0927-z&partnerID=40&md5=f7e0f1883aef0f64aef8b00b0182e240
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/70476
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Laboratoire de Géologie, CNRS-UMR 8538, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris Cedex 5, France; Géosciences Rennes, CNRS-UMR 6118, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France; Géosciences Montpellier, CNRS-UMR 5243, Université de Montpellier 2, Place Eugène Bataillon, 34095 Montpellier, France; GET, CNRS-UMR 5563, Université Paul Sabatier, 14 avenue Edouard Belin, 31400 Toulouse, France
Recommended Citation:
Clerc C.,Boulvais P.,Lagabrielle Y.,et al. Ophicalcites from the northern Pyrenean belt: A field, petrographic and stable isotope study[J]. International Journal of Earth Sciences,2014-01-01,103(1)