P-T conditions of deformation from fluid inclusions in mylonites

Cover of: P-T conditions of deformation from fluid inclusions in mylonites |

Published by Dept. of Geology, University of Maryland in College Park, MD .

Written in English

Read online


  • Fluid inclusions.,
  • Rocks, Metamorphic -- Inclusions.

Edition Notes

Book details

StatementEileen McLellan.
SeriesNASA-CR -- 186377., NASA contractor report -- NASA CR-186377.
ContributionsUnited States. National Aeronautics and Space Administration.
The Physical Object
Pagination1 v.
ID Numbers
Open LibraryOL15283718M

Download P-T conditions of deformation from fluid inclusions in mylonites

Structural petrology of fluid inclusions in deformed rocks can be used to identify inclusions entrapped during various stages of deformation.

Standard thermobarometry on these inclusions can then provide estimates of the P-T (pressure-temperature) conditions of deformation. The application of this technique is illustrated using fluid inclusions in mylonites from the Quetico Fault Zone, : Eileen Mclellan.

P-T condition fo deformation from fluid inclusions in mylonites Structural petrology of fluid inclusions in deformed rocks can be used to identify inclusions entrapped during various stages of deformation.

Standard thermobarometry on these inclusions can then provide estimates of the P-T (pressure-temperature) conditions of deformation. Stage III A yields peak P–T condition of – GPa and –°C.

The P–T conditions of stage IV A are – GPa and –°C, suggesting that this mineral assemblage is a product of retrograde metamorphism after peak UHPM. This stage records the first exhumation and cooling of the UHP Grt peridotite while still lying in the.

In order to determine the entrapment P–T conditions of fluids inclusions, isochores were calculated based on equations by Duan et al. (b, a) for CO 2 –rich inclusions, by Bakker () for H 2 O–CO 2 inclusions, and by Zhang and Frantz () for aqueous inclusions, using the ISOC software (Bakker, ).Cited by: 4.

The retrograde P-T path inferred from fluid inclusion analysis, along with other geological and geochronological evidence, indicates that this deformation is coeval with a reduction in the crustal.

P-T conditions of cataclastic deformation associated with underplating in subduction zone are estimated from fluid inclusions within the post-mélange veins in the Cretaceous Shimanto Belt, Kii Peninsula, SW Japan. Both cataclasite and post-mélange veins cut the mélange fabric and are distributed along the thrusts in duplex structure.

The homogenization temperatures range from (±10)°C. a P—T—t trajectory that describes the dynamic evolution of P—T with time. Flu'd inclusions can be used to constrain P—T points along the P—T—t paths. Most often, fluid inclusions can constrain the retrograde portion of the P—T—t path, and inclusion data from prograde segments of P—T.

Thus, mylonites are typically devoid of pre-deformation fluid inclusions. Pre-deformation inclusions are often preserved, however, where the host quartz has experienced only weak ductile strain, but a theoretical basis to interpret any deformation-induced effects on the inclusions, such as changes in chemical composition and density, is by: P-T conditions of deformation from fluid inclusions in mylonites book estimates based on fluid inclusion data and inferred geothermal gradients are –°C at –3 kbar for CI–CII cracks and –°C at 1–2 kbar for CIII cracks.

Fluid inclusions in olivine aggregates were deformed in high‐temperature torsion Fluid inclusions are aligned into low‐angle, C′‐type bands after deformation. P‐T Conditions of the Deformation and Shear Along the Nobeoka Thrust by Thermobarometry of H 2 O‐CH 4 Fluid Inclusions [44] In this study, microthermobarometry was conducted on primary fluid inclusions [ Roedder, ] in quartz veins that were developed in three different occurrences.

As migration of oil in reservoirs involves a multiphase mixture of oil, gas, and water (e.g., Rudkiewicz et al., ), fluid inclusions entrapped in diagenetic minerals commonly contain arbons are allowed to migrate in a mixed phase of oil and water, and the oil-bearing fluid inclusions formed during diagenetic events are in the immiscible region and can be made up of.

Fluid inclusions within different textural locations also known as decorations, (I) along cleavage planes, (II) along twinning lamelle, (III) along subgrain boundaries, (IV) along deformation. Data from fluid inclusions commonly have been used to constrain cooling—unroofing P—T paths for metamorphic belts (e.g.

Hollister et al., ; Stout et al., ; Hames ). Although fluid inclusion data alone are et al., unlikely to provide an unambiguous exhumation P—T path for a metamorphic terrane, meaningful insights into. The Blégier fault zones, developing at relatively high P/T conditions, may be considered to act as strictly closed systems to fluid circulation during their whole evolution.

The third deformation stage at La Remuque site is characterized by strain localized on relatively long discrete slip surfaces. Role of myrmekite and associated deformation fabrics in controlling development of granitic mylonites in the Pofadder Shear Zone of southern Namibia under fluid-poor mid-crustal conditions.

Fluid Inclusions in Fluid Inclusions in Diagenetic MineralsDiagenetic Minerals ISBNCD catalog P-T Conditions of Diagenesis The book begins with what fluid inclusions are and what geologic history they are. the P-T conditions of initial alteration and brecciation to –– MPa at WE-2 and to – C, – MPa at BWmd-1 (Figure 9).

Evolution of the P - T p a t h followed by the rocks in the CMT, based o n petrological and fluid inclusion evidence. (A-C) The P-T constraints imposed by fluid inclusions from Stages A, B and C, respectively.

(D) The entire P - T history of the CMT. Holdawayâ s () aluminosilicate triple point is shown on all diagrams for reference. P–T conditions for the high-pressure metamorphism in the Sesia Zone in the lower Aosta valley after Compagnoni et al.

(), Pognante ()and Avigad (). The isochores of the fluid inclusions (cf. Fig. 7) and the Si-isopleths (after Massonne, ) for the. Based on the grain size determination, the results demonstrate that helium does not reside within bubbles or fluid inclusions that are larger than ~ 93 µm, the median grain size of the crushed powder.

Such fluid inclusions are commonly observed in peridotites (Roedder, ) but are clearly not an important factor for oceanic mylonites. Intersection of Type 4a isochores with alteration conditions is interpreted to represent conditions at which alteration, mylonitization, and onset of cataclastic deformation overlapped in space and time, and defines a depth of ∼ km.

Type 4b inclusions have the same composition as Type 4a, but were trapped over a range of pressure conditions. According to microthermometric studies, two primary fluid groups are observed in quartz veins: (1) fluids trapped during peak deformation conditions, with higher-salinity, They were initially trapped at ~–°C, (2) smaller fluids by trapping of low-salinity inclusions at ~–°C that related to subsequent phases of shear zone.

Water saturated conditions for the BLG zone quartz mylonites are indicated by abundant water-bearing fluid inclusions. Deformation-related fluid inclusion densities from the SGR and GBM zone samples were largely reequilibrated during the shear zone exhumation history, and they record a decompression on the order of – MPa.

The Ti-in-quartz thermometer is of particular interest for potentially estimating the P-T conditions of ductile deformation in crustal rocks because quartz fabric development and microstructural.

The crystal-plastic behavior of quartz mylonites from the Ribeira Shear Zone (SE Brazil), a major strike–slip structure that was active during a prograde metamorphic phase related to the Neoproterozoic Brasiliano–Pan African Orogeny, was investigated using a multi-method approach.

Geothermobarometry results indicate deformational conditions ranging from ∼ to ∼°C and –MPa. rich system at the transition from purely plastic to purely brittle deformation under fl uid ‐ rich conditions (see also Papeschi et al.,). The structural evolution, controlled in. First, both hydrostatic and uniaxial compression experiments showed that in each re-equilibrated FIA a number of inclusions survive the modified post-entrapment P – T conditions virtually intact, showing that only severe deformation leads to total re-equilibration and complete obliteration of pristine inclusions (i.e.

Δσ > MPa in. P–T Conditions of Deformation [25] Based on the relationship between temperature and LPO patterns corresponding to the dominant slip systems [e.g., Passchier and Trouw, ; Toy et al., ], the dominant slip systems of prism 〈a 〉 and rhomb 〈a 〉 in sample A indicate deformation at temperatures above ∼°C.

Utilizing the fluid inclusion as well as mineral P-TUtilizing the fluid inclusion as well as mineral P-T estimates on the very same set of samples studiedestimates on the very same set of samples studied for fluid inclusions, an IBC path for the evolution onfor fluid inclusions, an IBC path for the evolution on fluids has been recorded for the.

To constrain the depth extent of brittle deformation and fluid infiltration, we analyzed peridotite mylonites dredged from the Shaka Transform Fault, Southwest Indian Ridge.

Samples range from high strain mylonites that preserve ductile microstructures to lower strain mylonites that are fractured and overprinted by hydrothermal alteration.

The understanding of deformation conditions can be enhanced by fluid inclusion studies. Fluid inclusions, especially the reequilibrated ones, provide a fair estimate of P-T conditions of deformation when integrated with microstructures (Boullier, ; Lespinasse, ).

Fluid inclusions in D 2 quartz veins within the proximal zone comprise a unique assemblage of five distinct types of carbonic inclusions containing variable proportions of CO 2, CH 4, graphite daughter products, and H 2 O. Precipitation of thin films of graphite in the inner walls of carbonic inclusions is interpreted to be the result of.

The distinction between blastomylonites and metamorphic foliation is sometimes difficult to make. This author errs on the side of inclusion of many metamorphic foliation as mylonitic foliation, because in many cases shear zones can be many kilometers wide.

69_ Mylonitic granite. Brodill Lake, Sudbury, ONT. [,]. For example, in the water‐deficient, high‐temperature mylonites, no spatial correlation of small fluid inclusions and dislocations was observed [Fitz Gerald et al., ], implying that dislocation generation might not be as intimately tied to (micro) fracturing as in many deformation experiments.

Formation. Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones. There are many different views on the formation of mylonites, but it is generally agreed that crystal-plastic deformation must have occurred, and that fracturing and cataclastic flow are secondary processes in the formation of mylonites.

2 inclusions; and (5) clear, irregularly shaped, three-phase liquid-vapour-solid inclusions. A fluid inclusion assemblage consisting of types 1 and 2 occur in clusters of primary inclusions in quartz grains within D2 NC quartz boudins.

Quartz within the boudins has likely been recrystallized, based on petrographic evidence, therefore, the fluid. As a result, ultramylonite and pseudotachylyte bands were formed at kbar an °C The relatively high temperature of the host rock is probably the main cause for ductile deformation of pseudotachylyte.

Fluid inclusion study can be an important method to. Of the rock With falling P-T conditions as strain softening mechanisms become restricted to narrow zones (White et al, ), Another major effect of uplift is the generation of cata. clasite and pseudotachylyte (Grocott. Sibson. ', Restriction of deformation into narrow shear zones.

with dominantly ductile deformation me. Grt is therefore considered the least useful proxy for P-T-t-D conditions of Neogene high-strain deformation in the AFMZ.

The presence of high phase strength contrast (HPSC) phases like Pl, Grt and Cc in the Qtz-Fsp AS protolith at T.

Two main fluid inclusion types were recognized at Sunrise Dam: low-salinity CO 2-H 2 O inclusions and CO 2 inclusions. CO 2 -H 2 O inclusions are more common in the early Group I orebodies.

These fluids were trapped under high P-T conditions during D 3 (minimum estimates suggest conditions were likely >~°C and >1 to 3 kbars predominantly. Primary fluid inclusions occur as isolated (Fig. 6a), clustered or in short trail-bounds formed on the surface imperfection of a crystal during its growth.

They are between 5 and 20 µm in size (mean at about 10 µm). Secondary fluid inclusions occur in trails (Fig. 6b) in microcracks that intersect the grain boundaries (Fig. 6c). They display.Microtectonics deals with the interpretation of microstructures, small-scale deformation structures in rocks that yield abundant information on the history and type of deformation and metamorphism.

The results are used by geologists to obtain data for large-scale geological interpretations.

27783 views Tuesday, November 17, 2020