Prograde and retrograde fluid flow during contact metamorphism of siliceous carbonate rocks from the Ballachulish aureole, Scotland

被引:48
作者
Ferry, JM
机构
[1] Department of Earth Sciences, Johns Hopkins University, Baltimore
关键词
D O I
10.1007/s004100050189
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Siliceous dolomites and limestones contain abundant retrograde minerals produced by hydration-carbonation reactions as the aureole cooled. Marbles that contained periclase at the peak of metamorphism bear secondary brucite, dolomite, and serpentine; forsterite-dolomite marbles have retrograde tremolite and serpentine; wollastonite limestones contain secondary calcite and quartz; and wollastonite-free limestones have retrograde tremolite. Secondary tremolite never appears in marbles where brucite has replaced periclase or in wollastonite-bearing limestones. A model for infiltration of siliceous carbonates by CO2-H2O fluid that assumes (a) vertical upwardly-directed flow, (b) fluid flux proportional to cooling rate, and (c) flow and reaction under conditions of local equilibrium between peak temperatures and approximate to 400 degrees C, reproduces the modes of altered carbonate rocks, observed reaction textures, and the incompatibility between tremolite and brucite and between tremolite and wollastonite. Except for samples from a dolomite xenolith, retrograde time-integrated flux recorded by reaction progress is on the order of 1000 mol fluid/cm(2) rock. Local focusing of flow near the contact is indicated by samples from the xenolith that record values an order of magnitude greater. Formation of periclase, Forsterite, and wollastonite at the peak of metamorphism also required infiltration with prograde time-integrated flux approximately 100-1000 mol/cm(2). The comparatively small values of prograde and retrograde time-integrated flux are consistent with lack of stable isotope alteration of the carbonates and with the success of conductive thermal models in reproducing peak metamorphic temperatures recorded by mineral equilibria. Although isobaric univariant assemblages are ubiquitous in the carbonates, most formed during retrograde metamorphism. Isobaric univariant assemblages observed in metacarbonates from contact aureoles may not record physical conditions at the peak of metamorphism as is commonly assumed.
引用
收藏
页码:235 / 254
页数:20
相关论文
共 43 条
[1]  
[Anonymous], EQUILIBRIUM KINETICS
[2]  
[Anonymous], EQUILIBRIUM KINETICS
[3]  
[Anonymous], 1982, REV MINERALOGY
[4]   PHASE-EQUILIBRIA IN THE SYSTEM CACO3-MGCO3-FECO3 [J].
ANOVITZ, LM ;
ESSENE, EJ .
JOURNAL OF PETROLOGY, 1987, 28 (02) :389-414
[5]  
Armstrong JT., 1988, Microbeam analysis, P239
[6]   A MODEL FOR COUPLED FLUID-FLOW AND MIXED-VOLATILE MINERAL REACTIONS WITH APPLICATIONS TO REGIONAL METAMORPHISM [J].
BAUMGARTNER, LP ;
FERRY, JM .
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, 1991, 106 (03) :273-285
[7]   INTERNALLY-CONSISTENT THERMODYNAMIC DATA FOR MINERALS IN THE SYSTEM NA2O-K2O-CAO-MGO-FEO-FE2O3-AL2O3-SIO2-TIO2-H2O-CO2 [J].
BERMAN, RG .
JOURNAL OF PETROLOGY, 1988, 29 (02) :445-522
[8]   MIGRATION OF REACTION AND ISOTOPIC FRONTS IN INFILTRATION ZONES - ASSESSMENTS OF FLUID FLUX IN METAMORPHIC TERRAINS [J].
BICKLE, M ;
BAKER, J .
EARTH AND PLANETARY SCIENCE LETTERS, 1990, 98 (01) :1-13
[9]   ADVECTIVE DIFFUSIVE TRANSPORT OF ISOTOPIC FRONTS - AN EXAMPLE FROM NAXOS, GREECE [J].
BICKLE, MJ ;
BAKER, J .
EARTH AND PLANETARY SCIENCE LETTERS, 1990, 97 (1-2) :78-93
[10]  
BICKLE MJ, 1987, CONTRIB MINERAL PETR, V95, P78