Granitoid rocks and associated coper skarn, Whycocomagh Mountain, Cape Breton Island, Nova Scotia

Mineralized (Fe-Cu-W-Mo) skarn in the Whycocomagh Mountain area is associated with a small pluton of Devonian (402±20 Ma) age, which intruded predominantly metasedimentary rocks of the Hadrynian George River Group. The pluton consists largely of granite porphyry with a marginal granodiorite to diorite zone, and minor porphyritlc granodiorite to monzodiorite dykes and pegmatite. The suite is calc-alkalic with I-type characteristics. Although weakly mineralized, the Whycocomagh Mountain pluton has features typical of plutons associated with porphyry-type Cu-Mo deposits. Calc-silicate rocks derived from marbles of the George River Group are the chief hosts for magnetlte ± chalcopyrlte ± scheelite ± molybdenite ± pyrite which occur in veinlets along fractures and as disseminated grains In adjacent alteration envelopes. Characteristics of the pluton and the skarn minerals suggest that the deposit is a copper skarn. RÉSUMÉ Un skarn minéralise (Fe-Cu-W-Mo), situe dans la région de la montagne Whycocomagh, est associé à une petite intrusion ignée d'âge Dévonien (402±20 m.a.) qui pénétre des roches, principalement des métasédiments, du groupe George River (Hadrynien). Le pluton consiste surtout en un granite porphyrique accompagne d'une zone marginale (granodiorite à diorite), de dykes mineurs (granodiorite à monzodiorite porphyrique) et de pegmatite. L'ensemble est calco-alcalln et de "type 1". Blen que faiblement minéralise, le pluton Whycocomagh Mountain possède lea caractérlstiques typiques des plutons associés aux dépôts porphyrlques de type Cu-Mo. Les calco-sflicates dérives des marbres du groupe George River sont les notes principaux du cortege for magnétite ± chalcopyrlte ± scheelite ± molybdenite ± pyrite que L’on retrouve dans des veinules le long des fractures et disséminés dans les enveloppes d'alteratlon volsines. Les caractérlstiques du pluton ainsi que la minéralogle du skarn font croire qu'il s'agit d'un dépôt de skarn cuprifère. (Tradult par le Journal

Glaciotectonic deformation associated with the Orient Point–Fishers Island moraine, westernmost Block Island Sound : further evidence of readvance of the Laurentide ice sheet

This paper is not subject to U.S. copyright. The definitive version was published in Geo-Marine Letters 32 (2012): 279-288, doi:10.1007/s00367-012-0296-9.High-resolution seismic-reflection profiles collected across pro-glacial outwash deposits adjacent to the circa 18 ka b.p. Orient Point–Fishers Island end moraine segment in westernmost Block Island Sound reveal extensive deformation. A rhythmic seismic facies indicates the host outwash deposits are composed of fine-grained glaciolacustrine sediments. The deformation is variably brittle and ductile, but predominantly compressive in nature. Brittle deformation includes reverse faults and thrust faults that strike parallel to the moraine, and thrust sheets that extend from beneath the moraine. Ductile deformation includes folded sediments that overlie undisturbed deposits, showing that they are not drape features. Other seismic evidence for compression along the ice front consists of undisturbed glaciolacustrine strata that dip back toward and underneath the moraine, and angular unconformities on the sea floor where deformed sediments extend above the surrounding undisturbed correlative strata. Together, these ice-marginal glaciotectonic features indicate that the Orient Point–Fishers Island moraine marks a significant readvance of the Laurentide ice sheet, consistent with existing knowledge for neighboring coeval moraines, and not simply a stillstand as previously reported.This work was supported by the Connecticut Department of Environmental Protection, and the Atlantic Hydrographic Branch of the National Oceanic and Atmospheric Administration.2013-06-2

Shoaling of nonlinear internal waves in Massachusetts Bay

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C08031, doi:10.1029/2008JC004726.The shoaling of the nonlinear internal tide in Massachusetts Bay is studied with a fully nonlinear and nonhydrostatic model. The results are compared with current and temperature observations obtained during the August 1998 Massachusetts Bay Internal Wave Experiment and observations from a shorter experiment which took place in September 2001. The model shows how the approaching nonlinear undular bore interacts strongly with a shoaling bottom, offshore of where KdV theory predicts polarity switching should occur. It is shown that the shoaling process is dominated by nonlinearity, and the model results are interpreted with the aid of a two-layer nonlinear but hydrostatic model. After interacting with the shoaling bottom, the undular bore emerges on the shallow shelf inshore of the 30-m isobath as a nonlinear internal tide with a range of possible shapes, all of which are found in the available observational record.A. Scotti began this project as a Postdoctoral Scholar at the Woods Hole Oceanographic Institution, with support from the Johnson Foundation and the USGS. Further support was provided to Scotti by the Office of Naval Research under grants N00014-01-1-0172, N00014-03-1-0553, and N00014-05-1-0361, and by NSF under grant OCE 07-29636. R. Beardsley was supported by ONR under grants N00014-98-1- 0059, N00014-00-1-0210, and the Smith Chair in Coastal Physical Oceanography. J. Pineda was supported by ONR under grants N00014-01-1-0172, and by a WHOIOcean Life Institute Fellowship