Andalusite in California and kyanite in North Carolina

The Kwoiek Area of British Columbia contains a pendant or screen of metamorphosed sedimentary and volcanic rocks almost entirely surrounded by a portion of the Coast Range Batholith, and intruded by several dozen stocks. The major metamorphic effects were produced by the quartz diorite batholithic rocks, with minor and later effects by the quartz diorite stocks. The sequence of important metamorphic reactions in the metasedimentary and metavolcanic rocks, ranging in grade from chlorite to sillimanite, is: 1. chlorite + carbonate + muscovite → epidote + biotite 2. chlorite + carbonate → actinolite + epidote 3. chlorite + muscovite → garnet + biotite 4. chlorite + epidote → garnet + hornblende 5. chlorite + muscovite → garnet + staurolite + biotite 6. chlorite + muscovite → aluminum silicate + biotite 7. muscovite + staurolite → garnet + aluminum silicate + biotite 8. staurolite → garnet + aluminum silicate Continuous reactions, occurring between reactions 5 and 7, are: A. chlorite + (high Ti) biotite + Al2O3 (from plagioclase?)→ garnet + staurolite + (low Ti) biotite + O2 B. muscovite (phengitic) → garnet + staurolite +muscovite (less phengitic) + O2 (?) Detailed electron microprobe work on garnet, staurolite, biotite, and chlorite shows that: (1) The garnet porphyroblasts are zoned according to a depletion model, called the Rayleigh depletion model, which assumes equilibrium between the edge of a growing garnet and the minerals which are unzoned, notably biotite, chlorite, and muscovite, but which assumes disequilibrium within the garnet. (2) The staurolite porphyroblasts are also zoned, and from their zoning patterns reactions A, B, and 5 are documented. Progressive reduction of iron with increasing grade of metamorphism is also inferred from the staurolite zoning patterns. (3) During a late period of falling temperature garnet continued to grow and the biotite and chlorite reequilibrated. The biotite, chlorite, and garnet edge compositions can vary from point to point in a given thin section, indicating that the volume of equilibrium at the final stage of metamorphism was only a few cubic microns. (4) The horizon within the garnet that grew at maximum temperature can be identified. The Mg/Fe ratio of this horizon, if the garnet composition is a limiting composition in the Al2O3 - K2O - FeO - MgO tetrahedron, increases systematically with increasing metamorphic grade. Biotite and chlorite compositions also show a general increase in Mg/Fe ratio with increasing metamorphic grade, but staurolite appears to show the reverse effect. (5) The Mg/Fe ratio at the maximum temperature horizon of the garnet porphyroblasts is a function of its Mn content as evidenced from the study of five garnet-bearing rocks, collected from one outcrop area, with the same assemblage but with differing proportions of minerals. An important implication of zoned minerals is that the effective composition of a system in a phase lies on the join between the homogeneous minerals (if there are two) and not within three-or- four-phase fields when a zoned mineral, such as garnet or staurolite, is present in the assemblage. Study of the three aluminum silicates found in the Kwoiek Area showed that a constant pressure change in polymorphs from andalusite to kyanite to sillimanite took place with increasing temperature. This transition series is best explained by the metastable formation of andalusite. Photographic materials on pages 15, 121, 160, 162, and 164 are essential and will not reproduce clearly on Xerox copies. Photographic copies should be ordered.

Adsorption of lead(II) as a major heavy metal pollutant onto nano-adsorbents of Andalusite, Kyanite and Sillimanite was studied in a batch system. Nano­-adsorbents were prepared via crushing, using a planetary ball mill and then characterized by different analyses such as: SEM, XRD, XRF and FT-IR. Major factors affecting the adsorption process were studied including pH, adsorbents dosage, initial metal concentration and temperature. Afterward, the adsorption process was studied isothermally, kinetically, and thermodynamically. The results show that aluminum silicates polymorphs are efficient adsorbents for removal of lead(II) and the removal exceeds 90%. The Freundlich isotherm model was best fitted with the experimental data. Chemisorption may control the rate of adsorption due to following the pseudo-second-order kinetic model. Thermodynamic investigation proved low randomness, exothermic and spontaneous nature of the process.

The paper describes the results obtained from the x-ray K-band spectra of Al for andalusite, sillimanite and kyanite. The fine structure of the aluminium K-band is correlated with the crystal structure of these minerals. It is considered that the difference between the energies of the K-and .KTjS'-lines depends on the distance between the aluminium and oxygen atoms. The energy differences between the Al and O atoms in andalusite, sillimanite and kyanite have been determined. The energy differences show a linear correlation to the known interatomic distances.

The PALMEIROPOLIS Cu-Zn (Pb) volcanogenic massive sulfide deposit, Brazil, consists of three ore bodies enclosed by hydrothermal alteration zones. The ore bodies and the alteration zones were metamorphosed under amphibolite fades conditions. The Palmeirdpolis alteration zones are characterized by a great diversity of bulk rock composition that originated a wide variety of low variance mineral assemblages. These assemblages are composed of orthoamphiboles (anthophyllite and gedrite), hornblende, biotite, garnet, staurolite, sillimanite, gahnite and, rarer, cordierite. Based on analyses of mineral chemistry aad mineral assemblages, temperatures are estimated to have been 550 - 625°C and pressures 2 - 5.5 kbar. The temperature of metamorphism that prevailed at the Palmeirdpolis deposit is comparable to other amphibolite fades massive sulfide deposits, such as Geco and Linda, Canada; Falun, Sweden; and Bleikvassli, Norway. The mineralogy of the alteration zones is similar in all these deposits even though they were metamorphosed at different pressure conditions, reflected by the crystallization of one of Al2 SiO5 phase (andalusite, sillimanite or kyanite).

EPR spectra of Fe3+ in andalusite and kyanite (both having formula Al2SiO5) are remeasured at bands which included 60 GHz. Results, besides the unusually large b and other spin-Hamiltonian parameters, include also the (true) g-factors. The spectra due to Fe3+Fe3+ pairs are identified in andalusite and analysed. EPR-Spektren von Fe3+ in Andalusit and Kyanit (beide mit der Formel Al2SiO5) werden erneut bei Frequenzen gemessen, die 60 GHz einschliesen. Als Ergebnis werden, neben dem ungewohnlich grosen b-Wert und anderen Spin-Hamiltonparametern, die (wahren) g-Faktoren erhalten. Durch Fe3+Fe3+-Paare hervorgerufene Spektren werden in Andalusit identifiziert und analysiert.

Kyanite, sillimanite and andalusite

The rate at which North Carolina kyanite of various grain sizes decomposes into mullite and glass in the range 1350° to 1600 °C. is given. Kyanite from other sources is also discussed.

Kyanite mine near Burnsville, Yancey County, North Carolina

Cyanite deposits of North Carolina

Mineralogical notes on cyanite, zircon, and anorthite from North Carolina

The lithologically and tectonically complex crust of southern California and the current broad deformation zone accommodating the relative motion between the Pacific and North American plates, result in significant variations in style, depth distribution, and rate of earthquakes, and thus also in the seismic hazard across southern California. Although the thickness of the seismogenic crust is an important parameter in seismic hazard analysis, it has never been determined systematically for southern California. Seismogenic thickness can be predicted by the depth distribution of the moment release of regional seismicity. The seismogenic thickness of southern California is highly variable, ranging from less than 10 km in the Salton Trough to greater than 25 km at the southwestern edge of the San Joaquin Valley. On average, the seismogenic thickness of southern California is 15.0 km. Seismogenic thickness along the major strike slip systems of southern California can vary significantly along strike. Fault segmentation based upon surface features does not correspond to the variation in seismogenic thickness and thus the potential down-dip width of the fault. A model of the broad scale features of the crust and upper mantle structure of the borderland-continent transition zone adjacent to Los Angeles constrains the crustal thickness and the location and width of the transition zone. The data require the Moho to deepen significantly to the north, dramatically increasing the crustal thickness over a relatively short distance of 20-25 km. The Moho is coherent and laterally continuous beneath the Inner California Borderland and transition zone. The Inner Borderland seems to be modified and thickened oceanic crust, with the oceanic upper mantle intact beneath it. The static stress change triggering model has some validity and can be useful in explaining apparently triggered seismicity within one fault length of a large mainshock. However, because its applicability varies between different sequences, its general application to seismic hazard evaluation requires more refinement and the inclusion of parameters such as tectonic regime, regional stress state, and fault strength.

A number of aspects of seismic surface wave propagation and earthquake mechanism in the Gulf of California region are investigated in this thesis. In addition, several associated problems raised by this study are also explored in some detail. Surface wave dispersion and P-wave travel time delays are measured to delineate the crust and upper mantle structure in the Imperial Valley-Gulf of California region. Crustal thicknesses beneath Baja California and Sonora are comparable and near 25 km, while within the Gulf crustal structure varies laterally from nearly oceanic on the western side to continental shelf thicknesses (~20 km) towards the north and east. Love wave group velocities for Baja California paths are unusually high and were not used to determine structure. Pn and teleseismic P-wave delays are used in a reconnaissance survey of crustal structure in the Imperial Valley and across the Peninsular Range batholith. The data are consistent with an increase in crustal thickness of 12 km from flank to crest in the Peninsular Ranges, and a decrease of 8 km across the Imperial Valley. The high Love wave group velocities measured across Baja California are shown to be similar to velocities of the first higher mode. It is also demonstrated that higher Love modes can have group velocities very close to fundamental mode velocities for a range of wave periods and realistic earth models. The mode interference which is a consequence of this intertwining of group velocity curves has a significant effect on measured phase velocities, and this problem is investigated in detail. An important conclusion of this study is that anomalously high Love wave phase velocities reported for the United States midcontinent and Japan are straightforwardly explained by mode interference without appealing to complex or anisotropic models, as had been done previously. Seismic processes associated with actively spreading oceanic rises are examined in the study of a strong swarm of earthquakes located near an inferred spreading center in the Northern Gulf of California. Close-in travel time data constrain the origin times of swarm events and demonstrate that the epicenters are confined to the upper crust. Teleseismic P-delays suggest unusually low seis1nic velocities beneath the source. The previously suspected normal faulting nature of swarm earthquakes is also confirmed. Seismic coupling across 200 km between adjacent spreading centers in the Northern Gulf is indicated by a survey of recent seismicity. It is noted in the study of the Gulf swarm that these sources have significantly higher surface wave amplitudes than events with similar assigned magnitudes in Northern Baja California. In the final chapter of this thesis a detailed analysis is made of the Baja earthquakes and it is concluded that as a group they have distinctly smaller source dimensions and larger stress drops than events within the Gulf of California. These differences are quite marked and are often very clearly seen even on records from band-limited seismographs. Several examples exist where propagation paths are very similar but the visual appearance of records differs considerably, suggesting that near-source or path effects are not likely explanations of the observed differences. For small magnitude North Baja earthquakes, both source dimensions and long period surface excitation average only about a factor or two larger than corresponding quantities previously measured for underground nuclear explosions of similar magnitude.

[Major thesis] Fauna of the Merychippus zone, north Coalinga district, California: The Merychippus zone occurs at the top of the Temblor sandstones on Domengine Creek, twelve miles north of Coalinga, California. The fauna includes a significant representation of ungulates and carnivores, with the Equidae far outnumbering all other forms. The stratigraphic position of the Merychippus zone in the Tertiary marine series, exposed on the west side of the San Joaquin Valley, lies within a zone whose assignment either to the middle Miocene Temblor or the upper Miocene Monterey is at present disputed among geologists familiar with the area. That its position is close to the dividing line between Temblor and Monterey is deemed significant for this report. In its stage of evolution and in its relationships with Tertiary assemblages of the Great Basin Province, the fauna of the Merychippus zone occupies a position intermediate between the middle Miocene Mascall of eastern Oregon and the upper Miocene Barstow of the Mohave Desert. A study of the occurrence of the material leads to the conclusion that the accumulation of fossil remains took place in the forest portion of a delta of a large river, where remains of land mammals were mingled with those of marine vertebrates. The suggestion is made that during the period of accumulation of the deposits and of the organic remains, the land area contributing this material was one of low relief and characterized by a rainfall of approximately 30 inches. The fauna is described in detail. [Minor thesis] The structural geology of the San Joaquin Hills, Orange County, California: A study of the geology of the San Joaquin Hills, southeastern Orange County, was undertaken originally, in collaboration with Mr. W. A. Findlay, as a research problem to be completed in fulfillment of the requirements for the degree of Bachelor of Science at the California Institute of Technology. The original investigation served mainly to arouse an interest in the problem for Mr. Findlay and the writer. In May, 1932, Mr. Findlay submitted a report on the general areal geology of the area as a thesis for the degree of Master of Science. It was then decided that mapping should be continued in the area in detail, with Mr. Findlay devoting time to a preparation of a thesis on the sedimentary petrography and the writer continuing his study of the structural geology. This paper presents the results of the structural investigation and is submitted as a minor thesis in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

Part 1 of this thesis is about the 24 November, 1987, Superstition Hills earthquakes. The Superstition Hills earthquakes occurred in the western Imperial Valley in southern California. The earthquakes took place on a conjugate fault system consisting of the northwest-striking right-lateral Superstition Hills fault and a previously unknown Elmore Ranch fault, a northeast-striking left-lateral structure defined by surface rupture and a lineation of hypocenters. The earthquake sequence consisted of foreshocks, the M_s 6.2 first main shock, and aftershocks on the Elmore Ranch fault followed by the M_s 6.6 second main shock and aftershocks on the Superstition Hills fault. There was dramatic surface rupture along the Superstition Hills fault in three segments: the northern segment, the southern segment, and the Wienert fault. In Chapter 2, M_L≥4.0 earthquakes from 1945 to 1971 that have Caltech catalog locations near the 1987 sequence are relocated. It is found that none of the relocated earthquakes occur on the southern segment of the Superstition Hills fault and many occur at the intersection of the Superstition Hills and Elmore Ranch faults. Also, some other northeast-striking faults may have been active during that time. Chapter 3 discusses the Superstition Hills earthquake sequence using data from the Caltech-U.S.G.S. southern California seismic array. The earthquakes are relocated and their distribution correlated to the type and arrangement of the basement rocks. The larger earthquakes occur only where continental crystalline basement rocks are present. The northern segment of the Superstition Hills fault has more aftershocks than the southern segment. An inversion of long period teleseismic data of the second mainshock of the 1987 sequence, along the Superstition Hills fault, is done in Chapter 4. Most of the long period seismic energy seen teleseismically is radiated from the southern segment of the Superstition Hills fault. The fault dip is near vertical along the northern segment of the fault and steeply southwest dipping along the southern segment of the fault. Chapter 5 is a field study of slip and afterslip measurements made along the Superstition Hills fault following the second mainshock. Slip and afterslip measurements were started only two hours after the earthquake. In some locations, afterslip more than doubled the coseismic slip. The northern and southern segments of the Superstition Hills fault differ in the proportion of coseismic and postseismic slip to the total slip. The northern segment of the Superstition Hills fault had more aftershocks, more historic earthquakes, released less teleseismic energy, and had a smaller proportion of afterslip to total slip than the southern segment. The boundary between the two segments lies at a step in the basement that separates a deeper metasedimentary basement to the south from a shallower crystalline basement to the north. Part 2 of the thesis deals with the three-dimensional velocity structure of southern California. In Chapter 7, an a priori three-dimensional crustal velocity model is constructed by partitioning southern California into geologic provinces, with each province having a consistent one-dimensional velocity structure. The one-dimensional velocity structures of each region were then assembled into a three-dimensional model. The three-dimension model was calibrated by forward modeling of explosion travel times. In Chapter 8, the three-dimensional velocity model is used to locate earthquakes. For about 1000 earthquakes relocated in the Los Angeles basin, the three-dimensional model has a variance of the the travel time residuals 47 per cent less than the catalog locations found using a standard one-dimensional velocity model. Other than the 1987 Whittier earthquake sequence, little correspondence is seen between these earthquake locations and elements of a recent structural cross section of the Los Angeles basin. The Whittier sequence involved rupture of a north dipping thrust fault bounded on at least one side by a strike-slip fault. The 1988 Pasadena earthquake was deep left-lateral event on the Raymond fault. The 1989 Montebello earthquake was a thrust event on a structure similar to that on which the Whittier earthquake occurred. The 1989 Malibu earthquake was a thrust or oblique slip event adjacent to the 1979 Malibu earthquake. At least two of the largest recent thrust earthquakes (San Fernando and Whittier) in the Los Angeles basin have had the extent of their thrust plane ruptures limited by strike-slip faults. This suggests that the buried thrust faults underlying the Los Angeles basin are segmented by strike-slip faults. Earthquake and explosion travel times are inverted for the three-dimensional velocity structure of southern California in Chapter 9. The inversion reduced the variance of the travel time residuals by 47 per cent compared to the starting model, a reparameterized version of the forward model of Chapter 7. The Los Angeles basin is well resolved, with seismically slow sediments atop a crust of granitic velocities. Moho depth is between 26 and 32 km.

The Paradox No. 3 mine, Atolia, California, was mapped and thin sections of the vein minerals and wall rock were examined. Veins containing quartz, scheelite and carbonate occur along faults and fractures in Atolia quartz monzonite (Upper Jurassic ?), which is an orthoclase-biotite tonalite in the mine area. The mineralization occurs along three principle veins, named for convenience the main vein, north vein and west vein. Both the main and north veins occupy steeply dipping, northwest trending faults and fractures which dip 50 to 60 degrees southward from the surface and upper levels, but the main vein changes dip to the north near the 100 level, and the north vein changes dip to the north near the 200 level. Upward branching and changes in dip of the veins are common and are believed to be the result of nearly equal pressures on the different fracture surfaces at the time of mineralization. The west vein occupies a west to northwest trending thrust fault, which dips northward at 30 to 45 degrees, and an east trending strike-slip fault. The forces causing the faulting and fracturing are believed to be local vertical forces followed by regional compression oriented north to northeast. Localization of ore seems to occur at the junction of the thrust and strike-slip faults and at and above changes in dip of the north and main veins. The vein matter consists of coarse grained scheelite, quartz, and calcite, deposited in that order as open space filling in the fractures. Crustification, comb textures and small filled cavities are common. Wall rock alteration in the quartz monzonite resulted in pervasive alteration of biotite to chlorite and, feldspar to white mica, carbonate and clays. Adjacent to the veins the wall rock consists of illite, calcite, quartz and minor clays, chlorite, pyrite and locally albite. The deformation and mineralization are believed to have occurred during Miocene times at shallow depths. The ore forming fluids were probably hot carbonated aqueous solutions carrying minor quantities of sulphur and tungsten and possibly silica and potash. Suggested sites for exploration for ore are on the north vein at the 100 and 150 levels end the main vein at the east end of the 100 level.