Archaean tonalitic gneiss of Finnish Lapland revisited: zircon ion-microprobe ages

The Bighorn Mountains of the central Wyoming Province expose a large tract of Archean crust that has been tectonically inactive and at relatively high crustal levels since ~2.7 Ga. Seven sensitive high-resolution ion microprobe (SHRIMP) U–Pb zircon and titanite age determinations on samples of the main lithologic units provide a geochronological framework for the evolution of this area. The oldest, precisely dated magmatic event occurred at 2950 ± 5 Ma, when diorite to granite dykes and sills intruded an older gneiss complex exposed in the central and southern Bighorn Mountains. Rocks as old as 3.25 Ga may be present in this gneissic basement, as indicated by the oldest dates obtained on areas of zircon grains that are interpreted as inherited cores. A tonalitic gneiss was intruded into the gneiss complex at 2886 ± 5 Ma. Deformation of the central and southern gneisses preceded the intrusion of the Bighorn batholith, a tonalitic to granitic intrusion that occupies the northern portion of the uplift. This composite batholith was intruded over the period 2.86–2.84 Ga. Ca. 3.0–2.8 Ga crust is also present in the Beartooth Mountains, the Washakie block of the northeastern Wind River Range, the Owl Creek Mountains, and the northern Granite Mountains, but late Archean deformation and plutonism has obscured much of the earlier history in the southern portion of this area. The entire area, referred to as the Beartooth–Bighorn Magmatic Zone, has been undeformed since 2.6 Ga. Proterozoic extension was focused in those parts of the Wyoming Province outside of this domain.

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Microchemistry of ZnO Varistors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133102 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1694-1695

Author(s):

K. K. Soni ◽

J. Hwang ◽

V. P. Dravid ◽

T. O. Mason ◽

R. Levi-Setti

Keyword(s):

Grain Boundaries ◽

Multiple Roles ◽

Grain Boundary Engineering ◽

Ion Microprobe ◽

Dopant Distribution ◽

Important Ingredient ◽

Zno Varistor ◽

Zno Varistors ◽

Zno Powder ◽

The University

ZnO varistors are made by mixing semiconducting ZnO powder with powders of other metal oxides e.g. Bi2O3, Sb2O3, CoO, MnO2, NiO, Cr2O3, SiO2 etc., followed by conventional pressing and sintering. The non-linear I-V characteristics of ZnO varistors result from the unique properties that the grain boundaries acquire as a result of dopant distribution. Each dopant plays important and sometimes multiple roles in improving the properties. However, the chemical nature of interfaces in this material is formidable mainly because often trace amounts of dopants are involved. A knowledge of the interface microchemistry is an essential component in the ‘grain boundary engineering’ of materials. The most important ingredient in this varistor is Bi2O3 which envelopes the ZnO grains and imparts high resistance to the grain boundaries. The solubility of Bi in ZnO is very small but has not been experimentally determined as a function of temperature.In this study, the dopant distribution in a commercial ZnO varistor was characterized by a scanning ion microprobe (SIM) developed at The University of Chicago (UC) which offers adequate sensitivity and spatial resolution.

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Aspects of high-resolution imaging with a scanning ion microprobe

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010014511x ◽

1986 ◽

Vol 44 ◽

pp. 750-751

Author(s):

R. Levi-Setti ◽

J. M. Chabala ◽

Y. L. Wang

Keyword(s):

Metal Ion ◽

Secondary Ion Mass Spectrometry ◽

Chromatic Aberration ◽

Ion Source ◽

Ion Microprobe ◽

Emission Pattern ◽

Intrinsic Resolution ◽

Resolution Imaging ◽

20 Nm ◽

Secondary Ion

We have shown the feasibility of 20 nm lateral resolution in both topographic and elemental imaging using probes of this size from a liquid metal ion source (LMIS) scanning ion microprobe (SIM). This performance, which approaches the intrinsic resolution limits of secondary ion mass spectrometry (SIMS), was attained by limiting the size of the beam defining aperture (5μm) to subtend a semiangle at the source of 0.16 mr. The ensuing probe current, in our chromatic-aberration limited optical system, was 1.6 pA with Ga+ or In+ sources. Although unique applications of such low current probes have been demonstrated,) the stringent alignment requirements which they imposed made their routine use impractical. For instance, the occasional tendency of the LMIS to shift its emission pattern caused severe misalignment problems.

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Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135174 ◽

1990 ◽

Vol 48 (2) ◽

pp. 314-315

Author(s):

K.K. Soni ◽

D.B. Williams ◽

J.M. Chabala ◽

R. Levi-Setti ◽

D.E. Newbury

Keyword(s):

Mass Spectrometry ◽

Secondary Ion Mass Spectrometry ◽

Equilibrium Phase ◽

Icosahedral Symmetry ◽

Ion Microprobe ◽

X Ray ◽

Cu Alloys ◽

Two Phases ◽

The University ◽

Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

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Fluidized Catalytic Cracking Catalyst Microstructure as Determined by A Scanning Ion Microprobe

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135113 ◽

1990 ◽

Vol 48 (2) ◽

pp. 302-303

Author(s):

J.K. Lampert ◽

G.S. Koermer ◽

J.M. Macaoy ◽

J.M. Chabala ◽

R. Levi-Setti

Keyword(s):

Catalytic Cracking ◽

Secondary Ion Mass Spectrometry ◽

Fuel Oil ◽

Ion Microprobe ◽

Fluidized Catalytic Cracking ◽

Ion Probe ◽

Silica Alumina ◽

Resolution Imaging ◽

The University ◽

High Spatial Resolution Imaging

We have used high spatial resolution imaging secondary ion mass spectrometry (SIMS) to differentiate mineralogical phases and to investigate chemical segregations in fluidized catalytic cracking (FCC) catalyst particles. The oil industry relies on heterogeneous catalysis using these catalysts to convert heavy hydrocarbon fractions into high quality gasoline and fuel oil components. Catalyst performance is strongly influenced by catalyst microstructure and composition, with different chemical reactions occurring at specific types of sites within the particle. The zeolitic portions of the particle, where the majority of the oil conversion occurs, can be clearly distinguished from the surrounding silica-alumina matrix in analytical SIMS images.The University of Chicago scanning ion microprobe (SIM) employed in this study has been described previously. For these analyses, the instrument was operated with a 40 keV, 10 pA Ga+ primary ion probe focused to a 30 nm FWHM spot. Elemental SIMS maps were obtained from 10×10 μm2 areas in times not exceeding 524s.

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‘Nature Has Its Own Soul and Speaks Its Own Language’

Anthropological Journal of European Cultures ◽

10.3167/ajec.2010.190205 ◽

2010 ◽

Vol 19 (2) ◽

pp. 62-73

Author(s):

Helena Ruotsala

Keyword(s):

National Park ◽

Tourism Industry ◽

Reindeer Herding ◽

Nature Protection ◽

Economic Interests ◽

Finnish Lapland ◽

The People ◽

Heated Debate ◽

The 1960S ◽

The Relationship

Nature and environment are important for the people earning their living from natural sources of livelihood. This article concentrates on the local perspective of the landscape in the Pallastunturi Fells, which are situated in Pallas-Ylläs National Park in Finnish Lapland. The Fells are both important pastures for reindeer and an old tourism area. The Pallastunturi Tourist Hotel is situated inside the national park because the hotel was built before the park was established 1938. Until the 1960s, the relationship between tourism and reindeer herding had been harmonious because the tourism activities did not disturb the reindeer herding, but offered instead ways to earn money by transporting the tourists from the main road to the hotel, which had been previously without any road connections. During recent years, tourism has been developed as the main source of livelihood in Lapland and huge investments have been made in several parts of Lapland. One example of this type of investment is the plan to replace the old Pallas Tourist hotel, which was built in 1948, with a newer and bigger one. It means that the state will allow a private enterprise to build more infrastructures for tourism inside a national park where nature should be protected and this has sparked a heated debate. Those who oppose the project criticise this proposal as the amendment of a law designed to promote the economic interests of one private tourism enterprise. The project's supporters claim that the needs of the tourism industry and nature protection can both be promoted and that it is important to develop a tourist centre which is already situated within the national park. This article is an attempt to try to shed light on why the local people are so loudly resisting the plans by a private tourism enterprise to touch the national park. It is based on my fieldwork among reindeer herding families in the area.

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