Authigenic K-feldspar in the Precambrian basement of Ohio and its effect on tectonic discrimination of the granitic rocks

1991 ◽  
Vol 28 (10) ◽  
pp. 1624-1634 ◽  
Author(s):  
Edward G. Lidiak ◽  
Vincent M. Ceci
Keyword(s):  
United States ◽  
Major Element ◽  
The United States ◽  
Granitic Rocks ◽  
Precambrian Basement ◽  
Grenville Province ◽  
Element Abundances ◽  
Ordinary Light ◽  
Alkaline Earths ◽  
Optic Angle

Authigenic K-feldspar of apparent low-temperature origin is widespread in the uppermost part of the two main Precambrian basement terranes of Ohio: the subsurface extension of the Grenville Province of Canada, and the anorogenic granite–rhyolite terrane of the Transcontinental Proterozoic Province of the United States. The authigenic K-feldspar occurs mainly as a replacement of both primary K-feldspar and albitic plagioclase in a variety of igneous and metamorphic rocks and can be identified by a salmon color in plane or ordinary light, moderate to low optic angle, monoclinic or triclinic symmetry, and Or-rich composition. Its origin has been ascribed to alkali exchange by potassic brines in early Paleozoic time.The K-feldspar authigenesis has changed whole-rock major-elemental compositions by increasing K2O, decreasing Na2O and CaO, and in general modifying SiO2 and Al2O3. These changes rule out using chemical parameters such as alkalis, alkaline earths, alumina, and silica as tectonic or petrologic discriminators on rocks affected by K-feldspar authigenesis. Of the 53 granitoid and felsic extrusive rocks in the basement of Ohio that we analyzed for major-element compositions, only 19 are unaffected by the authigenesis. Among the unaltered granitoids, 13 have major-element abundances and ratios indicative of orogenic paragenesis, and at least three of the granitoids have apparent anorogenic chemical characteristics. All but one of the orogenic granitoids occur east of the Grenville Front and within the Grenville Province. Anorogenic granitoids occur on both sides of the front, and they are probably part of the broad belt of anorogenic igneous rocks that extend from the southwestern United States to Labrador.

Geology and Ages of Buried Precambrian Basement Rocks, Manitoulin Island, Ontario

1975 ◽  
Vol 12 (7) ◽  
pp. 1175-1189 ◽  
Author(s):  
W. R. Van Schmus ◽  
K. D. Card ◽  
K. L. Harrower
Keyword(s):  
Granitic Rocks ◽  
Precambrian Basement ◽  
Aeromagnetic Data ◽  
Grenville Province ◽  
Metasedimentary Rocks ◽  
Basement Rocks ◽  
Metavolcanic Rocks ◽  
Northern Half ◽  
East End ◽  
Archean Basement

The geology of the buried Precambrian basement under Manitoulin Island in northern Lake Huron, Ontario, has been re-evaluated on the basis of aeromagnetic data, well cuttings, core samples, and rubidium–strontium and uranium–lead geochronologic data on some of the subsurface samples. We conclude that the northern half of the island is underlain in part by Huronian metasedimentary rocks, but that these are absent from the southern part of the island, which is underlain by granitic, gneissic, and metavolcanic rocks. Granitic and gneissic rocks are also present under the northern half of the island.Geochronologic data show that rocks underlying major positive aeromagnetic anomalies are quartz-monzonitic composite plutons which are about 1500 ± 20 m.y. old. Surrounding metasedimentary. gneissic, and granitic rocks are at least 1700 m.y. old. No evidence was found for extrapolation of the pre-Huroman Archean basement beneath Manitoulin Island; if it is present it has been affected by younger metamorphic overprinting.The south west ward extension of the boundary zone between the Grenville Province and rocks to the west can he traced along the east end of Manitoulin Island on the basis of aeromagnetic data.

scholarly journals V.—Archæan Rocks

1887 ◽  
Vol 4 (11) ◽  
pp. 503-507
Author(s):  
G. H. Kinahan
Keyword(s):  
United States ◽  
The United States ◽  
Granitic Rocks

At the present time the American geologists, both those of the United States and the Dominion of Canada, are at variance as to the groups the Archæan should be divided into; it is however unnecessary to enter into this controversy, as the strata may be conveniently grouped, as in Selwyn's map (1884), into Norians or Labradorians, excessively coarse gneiss or other granitic rocks; Laurentians, gneisa and granite; and Huronians, schists with subordinate gneiss.

scholarly journals Overview of the United States Department of Energy’s Used Fuel Disposition Research and Development Campaign

2013 ◽  
Author(s):  
Mark Nutt ◽  
Peter Swift ◽  
Jens Birkholzer ◽  
William Boyle ◽  
Timothy Gunter ◽  
...  
Keyword(s):  
United States ◽  
Research And Development ◽  
Nuclear Fuel ◽  
National Policy ◽  
The United States ◽  
Crystalline Rock ◽  
Department Of Energy ◽  
Granitic Rocks ◽  
United States Department ◽  
States Department

The United States Department of Energy (US DOE) is conducting research and development (R&D) activities within the Used Fuel Disposition Campaign (UFDC) to support storage, transportation, and disposal of used nuclear fuel (UNF) and wastes generated by existing and future nuclear fuel cycles. R&D activities are ongoing at nine national laboratories, and are divided into two major topical areas: (1) storage and transportation research, and (2) disposal research. Storage R&D focuses on closing technical gaps related to extended storage of UNF. For example, uncertainties remain regarding high-burnup nuclear fuel cladding performance following possible hydride reorientation and creep deformation, and also regarding long-term canister integrity. Transportation R&D focuses on ensuring transportability of UNF following extended storage, addressing data gaps regarding nuclear fuel integrity, retrievability, and demonstration of subcriticality. Disposal R&D focuses on identifying multiple viable geologic disposal options and addressing technical challenges for generic disposal concepts in various host media (e.g., mined repositories in salt, clay/shale, and granitic rocks, and deep borehole disposal in crystalline rock). R&D will transition to site-specific challenges as national policy advances. R&D goals at this stage are to increase confidence in the robustness of generic disposal concepts, to reduce generic sources of uncertainty that may impact the viability of disposal concepts, and to develop science and engineering tools that will support the selection, characterization, and ultimately licensing of a repository. The US DOE has also initiated activities that can be conducted within the constraints of the Nuclear Waste Policy Act to facilitate the development of an interim storage facility and supporting transportation infrastructure.

Party Strength in the United States: Some Corrections

1975 ◽  
Vol 37 (2) ◽  
pp. 641-642 ◽  
Author(s):  
Paul T. David
Keyword(s):  
United States ◽  
The United States ◽  
Party Strength

Correlative microscopy in distrubuted (client/server) computing environments: tools for catalyzing the rapid dissemination of information about the cell biology of the human prostate

1995 ◽  
Vol 53 ◽  
pp. 682-683
Author(s):  
A. Hakam ◽  
J.T. Gau ◽  
M.L. Grove ◽  
B.A. Evans ◽  
M. Shuman ◽  
...  
Keyword(s):  
United States ◽  
Cell Biology ◽  
Tissue Bank ◽  
The United States ◽  
Prostate Adenocarcinoma ◽  
Correlative Microscopy ◽  
Client Server ◽  
Critical Elements ◽  
Transplant Organ

Prostate adenocarcinoma is the most common malignant tumor of men in the United States and is the third leading cause of death in men. Despite attempts at early detection, there will be 244,000 new cases and 44,000 deaths from the disease in the United States in 1995. Therapeutic progress against this disease is hindered by an incomplete understanding of prostate epithelial cell biology, the availability of human tissues for in vitro experimentation, slow dissemination of information between prostate cancer research teams and the increasing pressure to “ stretch” research dollars at the same time staff reductions are occurring.To meet these challenges, we have used the correlative microscopy (CM) and client/server (C/S) computing to increase productivity while decreasing costs. Critical elements of our program are as follows:1) Establishing the Western Pennsylvania Genitourinary (GU) Tissue Bank which includes >100 prostates from patients with prostate adenocarcinoma as well as >20 normal prostates from transplant organ donors.

Digital image acquisition, processing, and analysis in a polymer microscopy laboratory

1994 ◽  
Vol 52 ◽  
pp. 454-455
Author(s):  
Vinod K. Berry ◽  
Xiao Zhang
Keyword(s):  
United States ◽  
Image Analysis ◽  
Digital Image ◽  
Image Acquisition ◽  
Image Transmission ◽  
The United States ◽  
Quantitative Image Analysis ◽  
Quantitative Image

In recent years it became apparent that we needed to improve productivity and efficiency in the Microscopy Laboratories in GE Plastics. It was realized that digital image acquisition, archiving, processing, analysis, and transmission over a network would be the best way to achieve this goal. Also, the capabilities of quantitative image analysis, image transmission etc. available with this approach would help us to increase our efficiency. Although the advantages of digital image acquisition, processing, archiving, etc. have been described and are being practiced in many SEM, laboratories, they have not been generally applied in microscopy laboratories (TEM, Optical, SEM and others) and impact on increased productivity has not been yet exploited as well.In order to attain our objective we have acquired a SEMICAPS imaging workstation for each of the GE Plastic sites in the United States. We have integrated the workstation with the microscopes and their peripherals as shown in Figure 1.

Silence of the Land: On the Historical Irrelevance of Territory to Congressional Districting and Political Representation in the United States

2001 ◽  
Vol 15 (01) ◽  
pp. 53-87 ◽  
Author(s):  
Andrew Rehfeld
Keyword(s):  
United States ◽  
House Of Representatives ◽  
Political Representation ◽  
The United States ◽  
Representative Government ◽  
Congressional District ◽  
Congressional Districts ◽  
Communities Of Interest

Every ten years, the United States “constructs” itself politically. On a decennial basis, U.S. Congressional districts are quite literally drawn, physically constructing political representation in the House of Representatives on the basis of where one lives. Why does the United States do it this way? What justifies domicile as the sole criteria of constituency construction? These are the questions raised in this article. Contrary to many contemporary understandings of representation at the founding, I argue that there were no principled reasons for using domicile as the method of organizing for political representation. Even in 1787, the Congressional district was expected to be far too large to map onto existing communities of interest. Instead, territory should be understood as forming a habit of mind for the founders, even while it was necessary to achieve other democratic aims of representative government.

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