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- Basal thrust (1)
- Basaltic glasses (1)
- Blanco Trough (1)
- Chetco Intrusive Complex (1)
- Gabbroic xenoliths (1)
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- Garnet-bearing xenoliths (1)
- Josephine Ophiolite (1)
- Madstone thrust (1)
- Mauna Kea (1)
- Melt inclusions (1)
- Metamorphic sole (1)
- Ordovician bentonites (1)
- Petrology (1)
- Rayleigh Fractionation Law (1)
- Sedimentary geochemistry (1)
- Taconic Allochthon (1)
- Tectonics (1)
- Trace element fractionation model (1)
- Utica shales (1)
- West central Vermont marble belt (1)
- Zircon morphology (1)
Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
The Geology Of Taconic Thrust Sheets And Surrounding Carbonates Of The West Central Vermont Marble Belt, North Of Rutland, Vermont, Kay Bierbrauer
The Geology Of Taconic Thrust Sheets And Surrounding Carbonates Of The West Central Vermont Marble Belt, North Of Rutland, Vermont, Kay Bierbrauer
Geology Theses and Dissertations
The carbonates of the Vermont Valley and the overlying rocks of the Taconic sequence have been generally believed to lie on the east limb of a major unfaulted syncline (Middlebury Synclinorium). In this view a westward dipping, north-south trending basal Taconic overthrust must be exposed somewhere along the eastern margin of the Taconic Range.
In contrast, this study based on detailed mapping at the north end of the Taconic Allochthon suggests that a folded overthrust surface is only locally seen in fensters; more commonly the basal obduction surface of the Taconic Allochthon has been truncated by later cross-cutting thrust faults. …
Geochemistry Of Garnet Xenocrysts And Garnet-Bearing Xenoliths In Ordovician Bentonites, Barbara Bock
Geochemistry Of Garnet Xenocrysts And Garnet-Bearing Xenoliths In Ordovician Bentonites, Barbara Bock
Geology Theses and Dissertations
Within outcrops of the black Utica shales south of the Mohawk Valley narrow re-entrants parallel with stratification are visible, often accompanied -by a marked orange-staining of the underlying strata. These rentrant features indicate the presence of bentonites weathered back faster then the enclosing shales. These bentonites are presumably magmatic ashes related to extensive volcanism when an island arc collided with the North American continent in the late Ordovician about 450 million years ago (Taconic orogeny).
Bentonites are good stratigraphic markers because of the short time-interval they represent and the large area they cover. Therefore they are commonly used as correlation …
Petrology And Major Element Geochemistry Of Basaltic Glasses From The Blanco Trough, Northeast Pacific, Glenn A. Gaetani
Petrology And Major Element Geochemistry Of Basaltic Glasses From The Blanco Trough, Northeast Pacific, Glenn A. Gaetani
Geology Theses and Dissertations
The original electron microprobe analyses of suite of basaltic glasses recovered in 1968 by W.G. Melson and co-workers from the Blanco Trough have extremely unusual characteristics. Their compositions plot in a region of the normative Ol-Di-Pl-SiO2 tetrahedron which suggests that they represent liquids in equilibrium with an upper mantle assemblage of olivine + orthopyroxene at 10-15 kb. Given the present state of controversy surrounding the composition and depth of origin of primary MORB, natural examples of such liquids would be very important. The major element variations observed in the suite imply that the dominant phases are olivine and an iron-aluminum …
Application Of A Trace Element Fractionation Model To Cumulate Gabbroic Xenoliths Of Mauna Kea, Hawaii, Ulrike Eberle
Application Of A Trace Element Fractionation Model To Cumulate Gabbroic Xenoliths Of Mauna Kea, Hawaii, Ulrike Eberle
Geology Theses and Dissertations
A trace element fractionation model originally designed to relate plutonic rocks containing a trapped glass component to a complementary volcanic rock suite was applied to olivine and opaque-oxide gabbroic xenoliths from the summit cone of Mauna Kea, Hawaii.
The mathematical model which is based on the Rayleigh Fractionation Law was extended to include the various phases present in these two groups of gabbros and was generalized to treat multiple trace elements, in this case four. These results were incorporated in a new FORTRAN program using the interval-bisection method to greatly improve the convergence time in the numerical solutions.
Calculated results …
Geology And Structure Of The Rocks Associated With The Basal (Madstone) Thrust Of The Josephine Ophiolite In Southwestern Oregon: Evidence For A Metamorphic Sole, Kristin A. Grady
Geology And Structure Of The Rocks Associated With The Basal (Madstone) Thrust Of The Josephine Ophiolite In Southwestern Oregon: Evidence For A Metamorphic Sole, Kristin A. Grady
Geology Theses and Dissertations
Many ophiolites have amphibolite at their base which contains a sharp inverted grade of metamorphism. These metamorphic soles are thought to have formed during the detachment and emplacement of the ophiolite. In addition to the sharp inverted grade of metamorphism, other characteristics of metamorphic soles include 1). a highly strained peridotite unit of the hanging wall which has concordant structures with underlying amphibolite and 2). an underlying melange sequence and continental rocks.
The Madstone thrust displaces the Josephine peridotite (Josephine ophiolite-162 Ma) onto amphibolites and underlying deformed gabbros of the Chetco Intrusive Complex. The rocks associated with the Madstone thrust …
Origin, Sedimentary Geochemistry, And Correlation Of Middle And Late Ordovician K-Bentonites: Constraints From Melt Inclusions And Zircon Morphology, Carsten Schirnick
Origin, Sedimentary Geochemistry, And Correlation Of Middle And Late Ordovician K-Bentonites: Constraints From Melt Inclusions And Zircon Morphology, Carsten Schirnick
Geology Theses and Dissertations
The present study of Paleozoic K-bentonites demonstrates that the geochemistry of melt inclusions and the morphology of zircons can be studied by inexpensive and simple-to-use methods, which rely on phenocrysts. Constraints are obtained that lead to (a) the origin of these altered volcanic ashes, (b) the geochemistry of ash-to-K-bentonite-alteration, and (c) the reliable correlation of extensively altered volcanic ashes (i.e. K-bentonites).
Silicic melt inclusions (i.e. non-devitrified) have been found in quartz and zircon phenocrysts contained within Ordovician and Devonian K-bentonites from New York State, the Upper Mississippi Valley, and Pennsylvania. Origin, source, and tectonic setting of the volcanism that produced …