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Haggerty, S. E.

Publications and source records attributed to Haggerty, S. E..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Crustal evolution and the eclogite to granulite phase transition in xenoliths from the West African Craton

A suite of eclogite and granulite facies xenoliths from kimberlite pipes in the Archean Man Shield of West Africa is described. The xenoliths include lithologies ranging in composition from komatiite to anorthosite and appear to be geochemically, petrologically, and geophysically related. The suite may represent fractionation of felsic material separated from ancient mantle and added to early Archean crust. The samples can be used to define a xenolith geotherm, which may represent an ancient episode of high heat flow. The samples also imply that the crust-mantle boundary is a gradational and possibly interlayered geochemical, mineralogical, and seismic transition. It is speculated that the depleted subcontinental mantle required by diamond bearing coalescence of smaller depletion cells formed by extraction of ancient crustal components. These depleted zones are surrounded by fertile asthenospheric mantle, which may have given rise to later flood basalts such as the Karroo and Parana Provinces.

Haggerty, S. E.↗
NASA NTRS1986

A remanent and induced magnetization model of Magsat vector anomalies over the west African craton

Scalar and vector Magsat anomalies over the west African craton are analyzed by forward and inverse models. A forward model of the Man shield is based on Liberia. Induced magnetization contrasts due to sporadic iron-formations and to regional metamorphic rocks, and a contrast in remanent magnetization within the lower crust are included. This combination reproduces the location, magnitude and adopted local zero level of anomalies in the initial Magsat maps. An inverse model of the Reguibat shield estimates the magnetization contrast of its lithosphere, and when magnetism is restricted to shallower than 75 km both shields can be represented by a susceptibility contrast of +0.02. A residual anomaly between the shields involves a relative deficiency of induced magnetization along with other causes.

Toft, P. B.↗
NASA NTRS1985

Native iron in the continental lower crust - Petrological and geophysical implications

Lower crustal granulite xenoliths recovered from a kimberlite pipe in western Africa contain native iron (Fe) as a decomposition product of garnet and ilmenite. Magnetic measurements show that less than 0.1 percent (by volume) of iron metal is present. Data from geothermometry and oxygen geobarometry indicate that the oxide and metal phases equilibrated between iron-wuestite and magnetite-wuestite buffers, which may represent the oxidation state of the continental lower crust, and the depleted lithospheric upper mantle. Ferromagnetic native iron could be stable to a depth of about 95 kilometers and should be considered in the interpretation of long-wavelength static magnetic anomalies.

Haggerty, S. E.↗
NASA NTRS1984

The mineralogy of global magnetic anomalies

Experimental and analytical data on magnetic mineralogy was provided as an aid to the interpretation of magnetic anomaly maps. An integrated program, ranging from the chemistry of materials from 100 or more km depth within the Earth, to an examination of the MAGSAT anomaly maps at about 400 km above the Earth's surface, was undertaken. Within this framework, a detailed picture of the pertinent mineralogical and magnetic relationships for the region of West Africa was provided. Efforts were directed toward: (1) examining the geochemistry, mineralogy, magnetic properties, and phases relations of magnetic oxides and metal alloys in rocks demonstrated to have originated in the lower crust of upper mantle, (2) examining the assumption that these rocks portray the nature of their source regions; and (3) examining the regional geology, tectonics, gravity field and the MAGSAT anomaly maps for West Africa.

Haggerty, S. E.↗
NASA NTRS1983

Redox state of earth's upper mantle from kimberlitic ilmenites

Temperatures and oxygen fugacities are reported on discrete ilmenite nodules in kimberlites from West Africa which demonstrate that the source region in the upper mantle is moderately oxidized, consistent with other nodule suites in kimberlites from southern Africa and the United States. A model is presented for a variety of tectonic settings, proposing that the upper mantle is profiled in redox potential, oxidized in the fertile asthenosphere but reduced in the depleted lithosphere.

Haggerty, S. E.↗
NASA NTRS1983

Radioactive nuclear waste stabilization - Aspects of solid-state molecular engineering and applied geochemistry

Stabilization techniques for the storage of radioactive wastes are surveyed, with emphasis on immobilization in a primary barrier of synthetic rock. The composition, half-life, and thermal-emission characteristics of the wastes are shown to require thermally stable immobilization enduring at least 100,000 years. Glass materials are determined to be incapable of withstanding the expected conditions, average temperatures of 100-500 C for the first 100 years. The geological-time stability of crystalline materials, ceramics or synthetic rocks, is examined in detail by comparing their components with similar naturally occurring minerals, especially those containing the same radioactive elements. The high-temperature environment over the first 100 years is seen as stabilizing, since it can recrystallize radiation-induced metamicts. The synthetic-rock stabilization technique is found to be essentially feasible, and improvements are suggested, including the substitution of nepheline with freudenbergite and priderite for alkaline-waste stabilization, the maintenance of low oxygen fugacity, and the dilution of the synthetic-rock pellets into an inert medium.

Haggerty, S. E.↗
NASA NTRS1982

The mineralogy of global magnetic anomalies

The Curie Balance was brought to operational stage and is producing data of a preliminary nature. Substantial problems experienced in the assembly and initial operation of the instrument were, for the most part, rectified, but certain problems still exist. Relationships between the geology and the gravity and MAGSAT anomalies of West Africa are reexamined in the context of a partial reconstruction of Gondwanaland.

Haggerty, S. E.↗
NASA NTRS1982

The mineralogy of global magnetic anomalies

Problems with the Curie balance, which severely hindered the acquisition of data, were rectified. Chemical analytical activities are proceeding satisfactorily. The magnetization characteristics of metamorphic suites were analyzed and susceptibility data for a wide range of metamorphic and igneous rocks. These rock magnetic signatures are discussed as well as the relationships between geology, gravity and MAGSAT anomalies of West Africa.

Haggerty, S. E.↗
NASA NTRS1981

The mineralogy of global magnetic anomalies

Progress is reported in developing predictive abilities to evaluate the potential stabilities of magnetic minerals in the Earth crust and mantle by: (1) computing oxidation state profiling as a function of temperature and pressure; (2) compiling data on basalts to establish validity of the oxidation state profiles; (3) determining Fe-Ni alloys in association with magnetitie as a function of temperature and oxidation state; and (4) acquiring large chemical data banks on the mineral ilmenite which decomposes to mineral spinel in the presence of high sulfur or carbonate environments in the lower crust upper mantle. In addition to acquiring these data which are related to constraining Curie isotherm depths, an excellent correlation was found between MAGSAT anomaly data and the geology of West Africa.

Haggerty, S. E.↗
NASA NTRS1980

Bulk compositions of chondrules in the Allende meteorite

The bulk chemistries of 33 chondrules from the Allende meteorite were determined by electron microbeam analyses and the modal recombination model. Chondrules were selected on the basis of a petrographic study of 2755 inclusions, of which 997 are chondrules, classified as recrystallized olivine chondrules, euhedral olivine chondrules, anhedral olivine chondrules, glassy/skeletal olivine chondrules, barred olivine chondrules, and pyroxene type chondrules. The data indicate that nonequilibrium metastable paths of crystallization were followed, a model which is supported by olivine-liquid (glassy mesostases) relationships. Variations in olivine morphology are related to cooling rate, degree of supercooling, normative olivine, and calculated viscosities. The chondrules in Allende were derived from highly undersaturated ultramafic melts in which Fe-Ni-S-O immiscible liquids were produced. The chondrule suite exhibits systematic variations in volatile loss, and this relationship is used to support a melting event (however, neither the nature of this event nor the mechanism of melt formation is established).

Simon, S. B.↗
NASA NTRS1979

Magnetite-sulfide-metal complexes in the Allende meteorite

A model of liquid immiscibility is presented that seemingly accounts for the sulfide-oxide-metal complexes that are present in olivine-rich chondrules in the Allende meteorite. The four major assemblages that are identified are: (1) magnetite + Ni-Fe metal; (2) magnetite + troilite + Ni-Fe metal; (3) magnetite + troilite + pentlandite + Ni-Fe metal; and (4) troilite + or - pentlandite. Specific attention is focused on oxide-metal associations and experimental data confirm earlier suggestions that magnetite results from the oxidation of an initially high-Fe-content metal alloy. Oxidation decreases the modal abundance of the Fe metal and this is accompanied by substantial increases in Ni contents which reach a maximum of approximately 70 wt % Ni. The proposed oxidation mechanism is entirely consistent with condensation of Fe-metal + olivine (Fa5) that subsequently reequilibrated at lower temperatures. Although the sulfide constituents could also have formed by the reaction of Fe-Ni metal + gaseous H2S, sulfide immiscibility under increased conditions of partial O2 pressure is the preferred process.

Haggerty, S. E.↗
NASA NTRS1979

Petrography and olivine mineral chemistry of chondrules and inclusions in the Allende meteorite

The examination of 19 polished-thin sections from a sample of the Allende meteorite reveals that anhedral olivine chondrules (OCs) are the most abundant chondrule type (19.7% of total chondrules + inclusions), followed by recrystallized OCs (7.5%), euhedral OCs (2.9%), glassy/skeletal OCs (2.7%), and barred OCs (2.3%). The most abundant inclusions are those comprised of many small olivine crystals with varying amounts of opaque minerals and glass (31.5%), followed by fine grained inclusions (16.1%) and single olivine crystals (15.7%). Microprobe analyses of olivines show that recrystallized and barred chondrules are the most forsteritic and exhibit relatively narrow compositional ranges, whereas single crystals have the widest range, from Fa sub 0.3 to Fa sub 49.

Simon, S. B.↗
NASA NTRS1978

The Allende meteorite - Evidence for a new cosmothermometer based on the Ti/3+/ to Ti/4+/ ratio

The mineral thermodynamic condensation sequence is applied to assemblages in Ca-Al-Ti-rich inclusions in the Allende meteorite, and it is suggested that the total amount of titanium and Ti(3+) contents of aluminous clinopyroxenes (fassaites) are temperature sensitive and that the ratio Ti(3+)/Ti(4+) may be used as a qualitative cosmothermometer. The direct gas-to-solid condensation hypothesis is favored because the predicted thermodynamic sequence is followed. Thermodynamic calculations indicate that the condensation interval of Ti(3+) stabilization is 1647-1125 K, while the titanian-fassaites probably condensed in the interval 1625-1349 K. It is suggested that the Allende meteorite has sampled a spectrum of the condensing solar nebula.

Haggerty, S. E.↗
NASA NTRS1978

The redox state of planetary basalts

Redox variations of terrestrial and lunar basalts and the redox variations in single cooling units (e.g., lava flows and lava lakes) are reviewed. Estimates for the redox states of inner solar system planetary basalts are presented; these estimates are based on consideration of a number of cosmogenic properties, models for planetary interiors, and the sequence of condensation with heliocentric distance from the protosun. It is suggested that basalts on Mercury and the Moon crystallized below the iron-wustite buffer curve; Venusian basalts are more oxidized than those on Mercury, less oxidized than those on earth, and crystallization within the field of wustite stability is thought likely; basalts on earth are dominantly in the field of magnetite stability; Martian basalts are estimated to crystallize in the upper regions of magnetite stability and well into the hematite field of stability expressed in terms of temperature and oxygen fugacity.

Haggerty, S. E.↗
NASA NTRS1978

Luna 24 - Systematics in spinel mineral chemistry in the context of an intrusive petrogenetic grid

Spinels in the Luna 24 gabbroic fragments have a restricted bimodal distribution of aluminum chromite and ulvospinel, whereas those in the Luna 24 basalts form a continuous sequence which defines a compositional variation from Al-Mg-chromites to ulvospinels containing 1 wt% Al2O3. A comparison of these spinel mineral chemistries with basaltic spinels from other mare regions and with spinels from other lunar intrusive rocks suggest that the Luna 24 gabbroic spinels lie at the low pressure end of a P-T spinel grid, and that titanium enrichment trends on Mg-Al-Cr rich spinel cores are related to extrusion and formed at the terminal stages of magmatic crystallization.

Haggerty, S. E.↗