174 research outputs found
Preliminary geophysical interpretation of the McKeand River area, southern Baffin Island, Nunavut: insights from gravity, magnetic and geological data
The recently completed McKeand River and Amittok Lake aeromagnetic surveys on southern Baffin Island, Nunavut pro-
vide a new high-resolution magnetic dataset over an area with no previous coverage. Complemented by regional gravity
data, newly acquired rock-property information and geological-mapping products, the aeromagnetic dataset yields qualita-
tive and quantitative information on the structure and geology of the underlying bedrock. This paper presents a preliminary
interpretation of these datasets that delineates three gravimetric and five magnetic domains. The gravity data outline a broad
negative anomaly associated with a plutonic-intrusive suite, as well as several isolated gravity highs associated with
metasedimentary strata. Magnetic domains are defined on the basis of anomaly amplitude, wavelength and texture, and are
correlated to the mapped geology and magnetic properties. Associations between potential-field anomalies, physical prop-
erties and mineral occurrences help define the regional distribution of economically significant horizons
Completing the bedrock mapping of southern Baffin Island, Nunavut; plutonic suites and regional stratigraphy
This paper summarizes the field observations and initial interpretations following eight weeks of regional and targeted bed-
rock mapping on south-central Baffin Island, Nunavut. The 2015 field campaign completes a two-decade mission to update
the geoscience knowledge for the whole of Baffin Island south of latitude 70°N. The bedrock in the area is dominated by a
Paleoproterozoic metaplutonic suite, ranging in composition from gabbro to syenogranite, with crosscutting relations indi-
cating a progression from mafic to silicic magmatism. Phase-equilibria modelling reveals that the prevailing upper-amphi-
bolite– to lower-granulite–facies metamorphic conditions overlap the stability limits of magnetite and orthopyroxene for a
typical granitoid bulk composition, which is consistent with field observations of the discontinuous presence of both phases
throughout the map area. This result is also consistent with regional aeromagnetic data that show complex structures within
relatively homogeneous map units, which are primarily attributed to variations in the abundance of magnetite. The granitoid
rocks are interpreted as part of the middle Paleoproterozoic Cumberland Batholith.
Metasedimentary rocks, including quartzite, pelite, marble and metagreywacke, are present as enclaves and screens within
and between plutonic bodies. An examination of the ‘ghost’stratigraphy suggests that the metasedimentary rocks through-
out most of the map area can be correlated with the middle Paleoproterozoic Lake Harbour Group, except in the northeast,
where the unique presence of greywacke suggests a middle Paleoproterozoic Piling Group affinity. This transition in strata
is consistent with the proposal that a middle Paleoproterozoic tectonic suture (the Baffin suture) associated with the Trans-
Hudson Orogen runs through Cumberland Sound. Completion of the bedrock mapping in southern Baffin Island indicates
that the region offers a world-class exposure of a reworked Paleoproterozoic convergent margin, which affords valuable in-
sight into a variety of magmatic and tectonic processes that can be applied to younger collisional belt
Project X functional requirements specification
Project X is a multi-megawatt proton facility being developed to support a
world-leading program in Intensity Frontier physics at Fermilab. The facility
is designed to support programs in elementary particle and nuclear physics,
with possible applications to nuclear energy research. A Functional
Requirements Specification has been developed in order to establish performance
criteria for the Project X complex in support of these multiple missions, and
to assure that the facility is designed with sufficient upgrade capability to
provide U.S. leadership for many decades to come. This paper will briefly
review the previously described Functional Requirements, and then discuss their
recent evolution.Comment: 3 p
Improved Measurement of the K+ to pi+ nu nubar Branching Ratio
An additional event near the upper kinematic limit for K+ to pi+ nu nubar has
been observed by Experiment E949 at Brookhaven National Laboratory. Combining
previously reported and new data, the branching ratio is B(K+ to pi+ nu nubar)=
1.47 (+1.30, - 0.89) x 10-10 based on three events observed in the pion
momentum region 211<P<229 MeV/c. At the measured central value of the branching
ratio, the additional event had a signal-to-background ratio of 0.9
Search for Light Gluinos via the Spontaneous Appearance of pi+pi- Pairs with an 800 GeV/c Proton Beam at Fermilab
We searched for the appearance of pi+pi- pairs with invariant mass greater
than 648 MeV in a neutral beam. Such an observation could signify the decay of
a long-lived light neutral particle. We find no evidence for this decay. Our
null result severely constrains the existence of an R0 hadron, which is the
lightest bound state of a gluon and a light gluino, and thereby also the
possibility of a light gluino. Depending on the photino mass, we exclude the R0
in the mass and lifetime ranges of 1.2 -- 4.6 GeV and 2E-10 -- 7E-4 seconds,
respectively. (To Appear in Phys. Rev. Lett.)Comment: Documentstyle aps,epsfig,prl (revtex), 6 pages, 7 figure
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