Igneous and metasedimentary dikes of the Mt. Washington area, New Hampshire

Abstract

Research Article| November 01, 1944 Igneous and metasedimentary dikes of the Mt. Washington area, New Hampshire KATHARINE FOWLER-BILLINGS KATHARINE FOWLER-BILLINGS Search for other works by this author on: GSW Google Scholar GSA Bulletin (1944) 55 (11): 1255–1278. https://doi.org/10.1130/GSAB-55-1255 Article history received: 09 Mar 1944 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation KATHARINE FOWLER-BILLINGS; Igneous and metasedimentary dikes of the Mt. Washington area, New Hampshire. GSA Bulletin 1944;; 55 (11): 1255–1278. doi: https://doi.org/10.1130/GSAB-55-1255 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The igneous and metasedimentary dikes and volcanic vents of the Mount Washington area were studied in detail incidental to mapping the bedrock geology. The igneous dikes are typical of those in other areas in New Hampshire, but metasedimentary dikes have not been described elsewhere in the State. A few volcanic vents have been reported from other localities.One hundred twenty-two dikes were observed. They constitute only from 0.05 per cent to 0.1 per cent of the exposed bedrock. The largest dike is 60 feet wide and is exposed discontinuously for 2½ miles and probably extends for at least 7¾ miles. The average width of dikes is 5 feet.The attitude of only 99 dikes was determined with sufficient precision to plot them on an equal-area diagram. Most dikes strike northeasterly and dip steeply; a second set is horizontal; a third set strikes N.10°E. and dips steeply; and a fourth set strikes N.30°W. and is also steep. The fractures occupied by the four sets apparently originated at various times under different conditions of stress.Tension fractures during north-south doming may be responsible for the N.10°E. set; the horizontal set presumably occupies shear fractures; compression as well as doming may explain the northeasterly set; and the N.30°W. set may occupy fractures formed during northwest-southeast compression of the area.Sixty thin sections were studied, 8 from the volcanic vents. Twenty-five of the dikes are metadiabases; 7 camptonites; 6 kersantites; 10 actinolite-biotite granulites; and there is 1 syenite porphyry, 1 rhyolite, 1 quartz diorite, and 1 amphibolite.The metasedimentary dikes were intruded into the schists of the Devonian Littleton formation after the climax of the late Devonian folding and metamorphism. They were intruded as impure dolomites, later recrystallized to actinolite-biotite granulites. The metadiabases, kersantites, camptonites, and volcanic vents were intruded as part of the Mississippian White Mountain magma series. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.