[No abstract submitted] / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The main features of the Seagull creek batholith are described. The most noteworthy of these is the abundance of boron in the granites themselves and in the contact aureole. This has led to the formation of miarolitic cavities containing tourmaline, to the formation of tourmaline and axinite veins and disseminations in the surrounding rocks, and to the formation of magnesium iron borates in a contact metamorphic iron deposit. Laboratory studies and reference to literature on similar rocks have led to the following conclusions: 1. Boron was a major constituent of the final residual liquid of the Seagull creek magma. 2. Segregations, either gaseous or liquid, from this final liquid caused the formation of miarolitic cavities in the granite. 3. Fine grained and aplitic phases of the Seagull creek granite are younger than the coarser grained phase. 4. The rocks are similar in many respects to those of Cornwall, Seward peninsula, Alaska, and other tin bearing regions. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 119-130). Also available via World Wide Web.

Thesis (Ph. D.)--University of Minnesota, 1924.

The Guichon Creek Batholith, located in south-central British Columbia, contains several large, low grade copper deposits of extreme economic importance. A three dimensional model for the batholith has been determined on the basis of a gravity survey conducted in 1971. In addition the gravity data has been compared with the filtered aeromagnetic maps of the batholith. A striking correlation between the spatial relationship of the mineral deposits and the core of the batholith has been discovered. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

No description available.

The expected concentration of chlorine in the biotite fraction was not found. The chlorine was not significantly water leachable from the whole rock samples following normal grinding. The Idaho Batholith as a source for mineralizing chlorine was not established. The chlorine distribution supports, but does not prove, a metamorphic origin for the Idaho Batholith. Cretaceous and possibly tertiary thermal events may have homogenized the chlorine in the batholith. Since chlorine seems to be so widely available in source rocks, a better way to correlate its presence to mineralization would be to study the residual chlorine from the ore deposition process.

No description available.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2001. / Restricted until November 2002. Includes bibliographical references. Also available online.

Eocene dykes intruding the Ladakh batholith were sampled along the southern margin of the Trans-himalayan plutonic arc in Ladakh, NW-India. Approximately 30 dykes were encountered in the 40 km trail between Leh and Hemis Shugpachan. The dykes in the east of the field are trending E to NE and those in the west trending N to NW, exhibiting sub-parallel orientations within each area. Eighteen dykes were sampled (two of them multiple times) and subjected to petrographic, geochemical and isotopic analyses. They exhibit various degrees of differentiation from basaltic to rhyolitic compositions and are mainly composed of plagioclase, quartz, hornblende (s.l.) and/or biotite and magnetite. Furthermore, dykes in the eastern part of the field area contain quartz xenocrysts resulting from crustal assimilation, while no relict quartz was found in the west. The dykes exhibit alteration phases and features suggesting that they underwent autometamorphism, i.e. hydration reactions due to igneous cooling. Whereas the dykes in the east of the field area record low-T alteration, the mineral parageneses in the west are typical for alteration at elevated temperatures typical for greenschist metamorphic facies. Al-in-hornblende barometry performed on Magnesio-hornblende and Tschermakitic-hornblende phenocrysts of the least altered dyke indicates formation in upper-amphibolite metamorphic facies conditions and pressures of about 6 kbar corresponding to an intrusion depth of approximately 20 km. Major and trace element analyses and Rb-Sr and Sm-Nd isotope analyses revealed a stunning variability in geochemistry and isotopic composition amongst the coeval dykes. All dykes exhibit LREE enrichment and HREE depletion as well as negative Tb and Nb anomalies characteristic for subduction-related intrusives and extrusives. Their REE patterns support a clear subdivision into chemically distinct groups. The group hypothesis was further tested and found valid using statistical tools designed to assess similarity/dissimilarity amongst individuals of a group with a common ancestor, such as hierarchical cluster analysis and multidimensional scaling. The dykes are cogenetic, but clearly not consanguineous, i.e. have not formed from one, progressively differentiating magma chamber. The variability observed in Sr-Nd isotopes can be explained by the dykes having undergone differing degrees of crustal assimilation. In particular the dykes in the east containing quartz xenocrysts show negative iiNd) and positive N(Sr) values caused by crustal assimilation, whereas the dykes in the west with no quartz xenocrysts exhibit positive qqNd) and N(Sr) near zero. 39Ar-40Ar dating by incremental heating of several hornblende-bearing dykes revealed crystallization ages between 50 and 54 Ma, whereas two biotite-bearing dykes gave ages of 45 and 37 Ma, likely to be cooling or recrystallisation ages. The combination of structural field evidence with petrographic, petrologic, geochemical, isotopic and geochronological analyses demonstrates that the dykes, although sharing a common origin, i.e. having formed in the same tectonic setting at roughly the same time, have undergone further geological processes leading to an unexpected diversification of the dykes. These findings provide ample scope for further in-depth and breadth investigations on “late-magmatic dykes” in the future. / published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy