Serpentinites of the Zermatt-Saas ophiolite complex and their texture evolution

被引:179
作者
Li, XP [1 ]
Rahn, M
Bucher, K
机构
[1] Peking Univ, Sch Earth & Space Sci, Dept Geol, Beijing 100871, Peoples R China
[2] Swiss Fed Nucl Safety Inspectorate, CH-5232 Villigen, Switzerland
[3] Univ Freiburg, Inst Mineral Petrol & Geochem, D-79104 Freiburg, Germany
关键词
antigorite; ophiolite; serpentinite; textures; Zermatt-Saas;
D O I
10.1111/j.1525-1314.2004.00503.x
中图分类号
P5 [地质学];
学科分类号
0709 ; 081803 ;
摘要
The Zermatt-Saas serpentinite complex is an integral member of the Penninic ophiolites of the Central Alps and represents the mantle part of the oceanic lithosphere of the Tethys. Metamorphic textures of the serpentinite preserve the complex mineralogical evolution from primary abyssal peridotite through ocean-floor hydration, subduction-related high-pressure overprint, meso-Alpine greenschist facies metamorphism, and late-stage hydrothermal alteration. The early ocean floor hydration of the spinel harzburgites is still visible in relic pseudomorphic bastite and locally preserved mesh textures. The primary serpentine minerals were completely replaced by antigorite. The stable assemblage in subduction-related mylonitic serpentinites is antigorite-olivine-magnetite diopside. The mid-Tertiary greenschist facies overprint is characterized by minor antigorite recrystallization. Textural and mineral composition data of this study prove that the hydrated mineral assemblages remained stable during high-pressure metamorphism of up to 2.5 GPa and 650 degreesC. The Zermatt-Saas serpentinites thus provide a well documented example for the lack of dehydration of a mantle fragment during subduction to 75 km depth.
引用
收藏
页码:159 / 177
页数:19
相关论文
共 67 条
[1]   Rapid exhumation of the Zermatt-Saas ophiolite deduced from high-precision Sm-Nd and Rb-Sr geochronology [J].
Amato, JM ;
Johnson, CM ;
Baumgartner, LP ;
Beard, BL .
EARTH AND PLANETARY SCIENCE LETTERS, 1999, 171 (03) :425-438
[2]  
[Anonymous], SCHWEIZ MINERAL PETR, DOI DOI 10.5169/SEALS-46668
[3]  
[Anonymous], 1989, SCHWEIZ MINER PETROG
[4]   HIGH-PRESSURE METAMORPHISM OF THE ZERMATT-SAAS OPHIOLITE ZONE, SWITZERLAND [J].
BARNICOAT, AC ;
FRY, N .
JOURNAL OF THE GEOLOGICAL SOCIETY, 1986, 143 :607-618
[5]   ZONED HIGH-PRESSURE ASSEMBLAGES IN PILLOW LAVAS OF THE ZERMATT-SAAS OPHIOLITE ZONE, SWITZERLAND [J].
BARNICOAT, AC .
LITHOS, 1988, 21 (03) :227-236
[6]   The gabbro-eclogite transformation: An oxygen isotope and petrographic study of west Alpine ophiolites [J].
Barnicoat, AC ;
Cartwright, I .
JOURNAL OF METAMORPHIC GEOLOGY, 1997, 15 (01) :93-104
[7]  
BARNICOAT AC, 1995, MUSEO REGIONALE SCI, V13, P191
[8]  
BARNICOAT AC, 1988, J METAMORPH GEOL, V6, P454
[9]  
BARNICOAT AC, 1995, BOCHUM GEOL GEOTECHN, V44, P17
[10]  
Bearth P., 1981, ECLOGAE GEOL HELV, V74, P189, DOI [10.5169/SEALS-165098, DOI 10.5169/SEALS-165098]