Crystal size distribution (CSD) in rocks and the kinetics and dynamics of crystallization     

Katharine V. Cashman  John M. Ferry 《Contributions to Mineralogy and Petrology》1988,99(4):401-415

Crystal size distributions (CSDs) measured in metamorphic rocks yield quantitative information about crystal nucleation and growth rates, growth times, and the degree of overstepping (T) of reactions during metamorphism. CSDs are described through use of a population density function n=dN/dL, where N is the cumulative number of crystals per unit volume and L is a linear crystal size. Plots of ln (n) vs. L for olivine+pyroxene and magnetite in high-temperature (1000° C) basalt hornfelses from the Isle of Skye define linear arrays, indicating continuous nucleation and growth of crystals during metamorphism. Using the slope and intercept of these linear plots in conjunction with growth rate estimates we infer minimum mineral growth times of less than 100 years at T<10° C, and nucleation rates between 10^–4 and 10^–1/cm³/s. Garnet and magnetite in regionally metamorphosed pelitic schists from south-central Maine have CSDs which are bell-shaped. We interpret this form to be the result of two processes: 1) initial continuous nucleation and growth of crystals, and 2) later loss of small crystals due to annealing. The large crystals in regional metamorphic rocks retain the original size frequency distribution and may be used to obtain quantitative information on the original conditions of crystal nucleation and growth. The extent of annealing increases with increasing metamorphic grade and could be used to estimate the duration of annealing conditions if the value of a rate constant were known. Finally, the different forms of crystal size distributions directly reflect differences in the thermal histories of regional vs. contact metamorphosed rocks: because contact metamorphism involves high temperatures for short durations, resulting CSDs are linear and unaffected by annealing, similar to those produced by crystallization from a melt; because regional metamorphism involves prolonged cooling from high temperatures, primary linear CSDs are later modified by annealing to bell shapes.  相似文献   

Contact metamorphism of roof pendants at Hope Valley,Alpine County,California, USA     

John M. Ferry 《Contributions to Mineralogy and Petrology》1989,101(4):402-417

Calcareous hornfelses and marbles all contain calcite+K-feldspar+quartz+sphene±diopside±plagioclase ±scapolite±clinozoisite. In addition, rocks on one side of a fault contain combinations of biotite, amphibole, and muscovite while those on the other side contain combinations of grossular, wollastonite, and axinite. At bars, mineral-fluid equilibria in biotite and amphibole-bearing rocks record T= 440° C and garnet-bearing rocks record T=540° C and Conventional volumetric fluid-rock ratios were calculated using measured progress of prograde decarbonation reactions and the conditions of metamorphism: marbles, 0–0.4; amphibole-bearing hornfelses, 1.0–1.4; garnet-bearing hornfelses, 2.8–6.7. Decarbonation reactions were driven by pervasive infiltration of rock by reactive aqueous fluids. Differences in fluid-rock ratio between interbedded marble and hornfels and lack of correlation between fluid-rock ratio and whole-rock Cl-content, however, argue for channelized fluid flow along lithologic layers. A new analysis of reaction progress allows estimation of time-integrated fluxes for a specified temperature gradient along the direction of flow. Results are: marbles, 0–0.1×10⁵ cm³/cm²; amphibole-bearing hornfelses, 0.8–1.3×10⁵ cm³/cm²; garnet-bearing hornfelses, 1.2–2.5 × 10⁵ cm³/cm². Fluid flowed from regions of low to regions of high temperature. Using a simple thermal model for the area, the duration of contact metamorphism was estimated as 10⁵ years. Assuming the time of fluid flow was the same as the duration of the thermal event, the first measurements of average metamorphic fluxes (q) and permeabilities (k) are: average marbles, q=0–0.3×10^–8 cm/s and k =2×10^–6 darcy; hornfels, q=3–8×10^–8 cm/s and k =20–53×10^–6 darcy. Estimated premeabilities are within the range of values measured for metamorphic rocks in the laboratory. Fluxes, permeabilities, and whole-system fluidrock ratios are similar to those estimated for the Skaergaard hydrothermal system by Norton and Taylor (1979).  相似文献   

Comportement piezometrique des nappes d''alterites en zone intertropicale humide d''altitude (hauts plateaux de Madagascar)     

J.C Grillot  M Raunet  L Ferry 《Journal of Hydrology》1990,120(1-4):271-282

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Hydrothermal alteration of Tertiary igneous rocks from the Isle of Skye,northwest Scotland     

John M. Ferry 《Contributions to Mineralogy and Petrology》1985,91(3):264-282

Hydrothermal alteration of Tertiary gabbros from Skye involved the reaction of igneous olivine, augite, hypersthene, plagioclase, magnetite, and ilmenite with aqueous fluid primarily to combinations of talc, chlorite, montmorillonite, calcic amphibole, biotite, and secondary magnetite. Lesser amounts of calcite, epidote, quartz, sphene, prehnite, and garnet also developed. During mineralogical alteration of gabbro there was a net addition to rock of K, Na, Sr, and H₂O and a net loss of Mg. Gabbro was oxidized early in the hydrothermal event and later reduced. Iron and silicon were probably initially lost and later added. There is no evidence for significant change in the Al or Ca content of the gabbros. Hydrothermal alteration of Skye gabbro involved not only large-scale migration of ¹⁸O, ¹⁶O, D and H but also of K, Na, Sr, Mg, and probably Fe and Si.Mineral thermometry indicates that pyroxenes in the gabbros crystallized at 1000° C–1150° C and were very resistent chemically as well as isotopically to later hydrothermal alteration. Hypothetical equilibrium between primary and secondary mafic silicates suggests that mineralogical alteration of gabbro occurred at 450°–550° C. The lack of correlation between mineralogical and isotopic alteration of gabbro requires that much isotopic alteration occurred at temepratures above those at which the secondary minerals developed, 550°–1000° C. The chemical alteration of gabbro is correlated with its mineralogical alteration and therefore occurred at 450°–550° C.Measured progress of the mineral-fluid reactions was used to estimate the amount of H₂O fluid that infiltrated the gabbro as primary olivine was converted to talc+magnetite at 525°–550° C. Calculated fluid-rock ratios are in the range 0.2–6 (volume basis) and are smaller than values estimated from isotopic data (fluid/rock 1–10, volume basis). Both isotopic and petrologic data point to pervasive flow of fluid through crystalline rock at elevated temperatures of 500°–1000° C. Isotopic fluid-rock ratios are larger than petrologic fluid-rock ratios because isotopic alteration of cooling gabbro began earlier and at higher temperatures than did the mineralogical alteration.  相似文献   

Condensed water in tropical cyclone “Oliver”, 8 February 1993     

R. F. Pueschel  D. A. Allen  C. Black  S. Faisant  G. V. Ferry  S. D. Howard  J. M. Livingston  J. Redemann  C. E. Sorenson  S. Verma 《Atmospheric Research》1995,38(1-4)

On February 8, 1993, the NASA DC-8 aircraft profiled from 10,000 to 37,000 feet (3.1–11.3 km) pressure altitude in a stratified section of tropical cyclone “Oliver” over the Coral Sea northeast of Australia. Size, shape and phase of cloud and precipitation particles were measured with a 2-D Greyscale probe. Cloud/ precipitation particles changed from liquid to ice as soon as the freezing level was reached near 17,000 feet (5.2 km) pressure altitude. The cloud was completely glaciated at −5°C. There was no correlation between ice particle habit and ambient temperature. In the liquid phase, the precipitation-cloud drop concentration was 4.0 × 10³ m⁻³, the geometric mean diameter D_g=0.5−0.7 mm, and the liquid water content 0.7−1.9 g m⁻³. The largest particles anywhere in the cloud, dominated by fused dendrites at concentrations similar to that of raindrops (2.5 × 10³ m⁻³) but a higher condensed water content (5.4 g m⁻³ estimated) were found in the mixed phase; condensed water is removed very effectively from the mixed layer due to high settling velocities of the large mixed particles. The highest number concentration (4.9 × 10⁴ m⁻³), smallest size (D_g=0.3−0.4 mm), largest surface area (up to 2.6 × 10² cm² m⁻³ at 0.4−1.0 g m⁻³ of condensate) existed in the ice phase at the coldest temperature (−40°C) at 35,000 feet (10.7 km). Each cloud contained aerosol (haze particles) in addition to cloud particles. The aerosol total surface area exceeded that of the cirrus particles at the coldest temperature. Thus, aerosols must play a significant role in the upscattering of solar radiation. Light extinction (6.2 km⁻¹) and backscatter (0.8 sr⁻¹ km⁻¹) was highest in the coldest portion of the cirrus cloud at the highest altitude.  相似文献   

A 48-kyr-long slip rate history for the Jordan Valley segment of the Dead Sea Fault     

Matthieu Ferry  Mustapha Meghraoui  Najib Abou Karaki  Masdouq Al-Taj  Hani Amoush  Salman Al-Dhaisat  Majdi Barjous 《Earth and Planetary Science Letters》2007,260(3-4):394-406

We investigate the late Quaternary active deformation along the Jordan Valley segment of the left-lateral Dead Sea Fault and provide new insights on the behaviour of major continental faults. The 110-km-long fault segment shows systematic offsets of drainage systems surveyed at three sites along its southern section. The isotopic dating of six paleoclimatic events yields a precise chronology for the onset of six generations of gully incisions at 47.5 ka BP, 37.5 ka BP, 13 ka BP, 9 ka BP, 7 ka BP, and 5 ka BP. Additionally, detailed mapping and reconstructions provide cumulative displacements for 20 dated incisions along the fault trace. The individual amounts of cumulative slip consistently fall into six distinct classes. This yields: i) an average constant slip rate of 4.7 to 5.1 mm/yr for the last 47.5 kyr and ii) a variable slip rate ranging from 3.5 mm/yr to 11 mm/yr over 2-kyr- to 24-kyr-long intervals. Taking into account that the last large earthquake occurred in AD 1033, we infer 3.5 to 5 m of present-day slip deficit which corresponds to a Mw  7.4 earthquake along the Jordan Valley fault segment. The timing of cumulative offsets reveals slip rate variations critical to our understanding of the slip deficit and seismic cycle along major continental faults.  相似文献   

Correlation of reefal Oxfordian episodes and climatic implications in the eastern Paris Basin (France)     

Cdric Carpentier  Bertrand Martin‐Garin  Bernard Lathuilire  Serge Ferry 《地学学报》2006,18(3):191-201

Oxfordian reefal episodes of Lorraine and Burgundy have a long time been considered as contemporaneous. Biostratigraphic data and sequential evolutions peculiar to each region indicate their structural autonomy during Oxfordian times. A north‐south‐oriented well‐logging transect shows that, during the Middle Oxfordian, a shallow reefal platform developed in Lorraine while thin deeper deposits occurred in Burgundy. In spite of their different ages, reefal episodes of Middle Oxfordian in Lorraine and Upper Oxfordian in Burgundy exhibit a broadly similar vertical evolution of coral communities. During the Late Oxfordian, the contemporaneous occurrence of a diversified assemblage in the Burgundy region, a colder coral assemblage characterized by eurytopic genera and the decrease in seawater isotopic temperatures in Lorraine can be explained by a shift in trophic conditions, a climatic change related to structural rearrangements in this strategic place and a modification of oceanic circulations between the arctic and the Tethyan regions.  相似文献   

The effect of net-transfer reactions on the isotopic composition of minerals     

C. Page Chamberlain  John M. Ferry  Douglas Rumble III 《Contributions to Mineralogy and Petrology》1990,105(3):322-336

To interpret correctly the isotopic composition of metmorphic rocks and minerals, the effect of nettransfer reactions must be quantitatively evaluated. Such evaluation requires a complete set of linearly independent, net-transfer reactions that fully describe the reacting system. The set of net-transfer reactions is then coupled with mass-balance equations for stable isotopes. Reaction spaces can be contoured with isopleths of °¹⁸O, °¹³C, and D of minerals which allows evaluation of the effect of different reactions and bulk compositions on the stable isotopic composition of minerals and rocks. Using this approach, we examined the effect of fractionation of isotopes due to net-transfer reactions at the biotite and second-sillimanite isograds in northern New England. Our analysis shows that the shift in °¹³C and °¹⁸O at an isograd depends strongly upon the overall net-transfer reaction at the isograd and the bulk composition of the rock. The use of model isograd reactions to determine isotopic shifts, therefore, can lead to serious errors in the interpretation of isotopic data. At the second-sillimanite isograd °¹⁸O _qtz (quartz), °¹⁸O _kspar (K feldsdpar), and °¹⁸O _wr (whole rock) decrease by 0.5, 1.0, and 0.8 per mil, respectively. Quantitative evaluation of the effect of fractionation of isotopes by net-transfer reactions shows that: (1) the relative changes in oxygen isotopes across the isograd could be caused by distillation of fluids during develatilization reactions; (2) the magnitude of the observed isotopic shifts often differs by a factor of 2 from the calculated shifts due to reaction progress alone. The difference between observed and calculated shifts is attributed to either, differences in bulk composition between individual rocks, or, to isotopic exchange between minerals after peak metamorphism. At the biotite isograd the shifts in carbon and oxygen isotope values are different from predicted shifts caused by net-transfer reactions alone. This discrepancy suggests that fluids infiltrated the rocks during the formation of the biotite isograd.  相似文献   

Evidence from mineral assemblages for infiltration of pelitic schists by aqueous fluids during metamorphism   总被引：1，自引：0，他引：1  

Gregory H Symmes  John M Ferry 《Contributions to Mineralogy and Petrology》1991,108(4):419-438

Prograde mineral assemblages and compositions have been predicted for pelitic schist in the 10 component system Na₂O–K₂O–CaO–MnO–FeO–MgO–Al₂O₃–SiO₂–CO₂–H₂O for three cases of prograde metamorphism and fluid-rock interaction: (1) increasing temperature (T) at constant pressure (P) and constant pore fluid volume (1%) without infiltration (no-infiltration case); (2) increasing T at constant P accompanied by sufficient fluid infiltration that fluid composition is at all times constant (large-flux case); and (3) increasing T at constantP accompanied by a timeintegrated fluid flux f 10⁴ cm^{3 cm 2} (intermediate-flux case). Stable mineral assemblages and compositions were calculated by solving a system of non-linear equations that specify mass balance and chemical equilibrium between minerals and fluid. The model pelitic system includes quartz, muscovite, plagioclasc, chlorite, ankerite, siderite, biotite, garnet, staurolite, andalusite, kyanite, sillimanite, K-feldspar, and a coexisting, binary H₂O–CO₂ fluid. Specifically, prograde thermal metamorphism was modelled for Shaw's (1956) average low-grade pelite and for a moderate range of bulk rock compositions at P=3, 5, and 7 kb and initial fluids with Xco ₂ ^o =0.02–0.40. The model predicts a carbonate-bearing mineral assemblage for average pelite under chlorite zone conditions composed of quartz, muscovite, albite, chlorite, ankerite, and siderite. The mineral assemblages predicted for the noinfiltration case are unlike those typically observed in regional metamorphic terranes. Simulations of metamorphism for the large-flux and intermediate-flux cases, however, reproduce the sequence of mineral assemblages observed in normal Barrovian regional metamorphic terranes. These results suggest that regional metamorphism of pelitic schists is typically associated with infiltration of significant quantities of aqueous fluid.  相似文献   

Production of Reactive Oxygen Species in the Rhizosphere of a <Emphasis Type="Italic">Spartina-</Emphasis>Dominated Salt Marsh Systems     

Dewamunnage Muditha C. Dias  Justin M. Copeland  Carrie L. Milliken  Xiangming Shi  John L. Ferry  Timothy J. Shaw 《Aquatic Geochemistry》2016,22(5-6):573-591

This paper reports the presence of a metastable mixture of Fe(II), O₂, superoxide and hydrogen peroxide in sediment pore water in organic carbon-rich sediments in Spartina alterniflora-dominated salt marsh systems. Field measurements at two different estuarine sites in South Carolina (one heavily urbanized and a protected research reserve) showed a broad region of reactive oxygen species (ROS) production more than 15 cm below the sediment surface within and immediately adjacent to the rhizospheres of S. alterniflora. Dissolved Fe(II) was positively correlated with hydrogen peroxide indicating a possible abiotic pathway to ROS production (r ² = 0.94). The null hypothesis was tested that Fe(II) inventories were maintained by protective ligands and thus unreactive with respect to O₂ consumption and ROS production. The addition of an Fe-binding ligand, DTPA, resulted in rapid decline of ROS in pore water, indicating that Fe(II) was labile. The half-life of superoxide under the measured solution conditions was calculated and found to be less than a second. The combination of high lability and persistent ROS was interpreted to indicate a high rate of Fe(II) and O₂ supply to the pore water. The ²²⁴Ra/²²⁸Th disequilibrium was measured to determine the potential for advective mass transfer of dissolved oxygen via pore water exchange. The estimated pore water exchange of 54 L m^?2 day^?1 was significant but could not support the measured production of ROS alone, the direct exchange of O₂ from the S. alterniflora root system may have contributed significantly to ROS production in the sediments.  相似文献