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At least 937 records · Page 52Linked to original sources

Geologic map of the Mead quadrangle (V-21), Venus

The Magellan spacecraft orbited Venus from August 10, 1990, until it plunged into the Venusian atmosphere on October 12, 1994. Magellan Mission objectives included (1) improving the knowledge of the geological processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology and (2) improving the knowledge of the geophysics of Venus by analysis of Venusian gravity. The Mead quadrangle (V-21) of Venus is bounded by lat 0 deg and 25 deg N., long 30 deg and 60 deg E. This quadrangle is one of 62 covering Venus at 1:5,000,000 scale. Named for the largest crater on Venus, the quadrangle is dominated by effusive volcanic deposits associated with five major coronae in eastern Eistla Regio (Didilia, Pavlova, Calakomana, Isong, and Ninmah), corona-like tectonic features, and Disani Corona. The southern extremity of Bell Regio, marked by lava flows from Nyx Mons, north of the map area, forms the north-central part of the quadrangle. The shield volcanoes Kali, Dzalarhons, and Ptesanwi Montes lie south and southwest of the large corona-related flow field. Lava flows from sources east of Mead crater flood low-lying areas along the east edge of the quadrangle.

Scientific Investigations Map↗

Geologic map of the Fifteenmile Valley 7.5' quadrangle, San Bernardino County, California

Open-File Report OF 01-132 contains a digital geologic map database of the Fifteenmile Valley 7.5’ quadrangle, San Bernardino County, California that includes: 1. ARC/INFO (Environmental Systems Research Institute, http://www.esri.com) version 7.2.1 coverages of the various elements of the geologic map. 2. A PostScript file to plot the geologic map on a topographic base, and containing a Correlation of Map Units diagram, a Description of Map Units, an index map, and a regional structure map. 3. Portable Document Format (.pdf) files of: a. This Readme; includes in Appendix I, data contained in fif_met.txt b. The same graphic as plotted in 2 above. (Test plots have not produced 1:24,000-scale map sheets. Adobe Acrobat pagesize setting influences map scale.) The Correlation of Map Units (CMU) and Description of Map Units (DMU) is in the editorial format of USGS Miscellaneous Investigations Series (I-series) maps. Within the geologic map data package, map units are identified by standard geologic map criteria such as formation-name, age, and lithology. Even though this is an author-prepared report, every attempt has been made to closely adhere to the stratigraphic nomenclature of the U. S. Geological Survey. Descriptions of units can be obtained by viewing or plotting the .pdf file (3b above) or plotting the postscript file (2 above). If roads in some areas, especially forest roads that parallel topographic contours, do not show well on plots of the geologic map, we recommend use of the USGS Fifteenmile Valley 7.5’ topographic quadrangle in conjunction with the geologic map.

California↗

Geologic map of the Cucamonga Peak 7.5' quadrangle, San Bernardino County, California

Open-File Report OF 01-311 contains a digital geologic map database of the Cucamonga Peak 7.5’ quadrangle, San Bernardino County, California that includes: 1. ARC/INFO (Environmental Systems Research Institute, http://www.esri.com) version 7.2.1 coverages of the various elements of the geologic map 2. A PostScript file to plot the geologic map on a topographic base, and containing a Correlation of Map Units diagram, a Description of Map Units, an index map, and a regional structure map 3. Portable Document Format (.pdf) files of: a. This Readme; includes in Appendix I, data contained in fif_met.txt b. The same graphic as plotted in 2 above. (Test plots have not produced 1:24,000-scale map sheets. Adobe Acrobat pagesize setting influences map scale.) The Correlation of Map Units and Description of Map Units is in the editorial format of USGS Miscellaneous Investigations Series (I-series) maps but has not been edited to comply with I-map standards. Within the geologic map data package, map units are identified by standard geologic map criteria such as formation-name, age, and lithology. Even though this is an author-prepared report, every attempt has been made to closely adhere to the stratigraphic nomenclature of the U. S. Geological Survey. Descriptions of units can be obtained by viewing or plotting the .pdf file (3b above) or plotting the postscript file (2 above). If roads in some areas, especially forest roads that parallel topographic contours, do not show well on plots of the geologic map, we recommend use of the USGS Cucamonga Peak 7.5’ topographic quadrangle in conjunction with the geologic map.

California↗

Geologic map of the Telegraph Peak 7.5' quadrangle, San Bernardino County, California

Open-File Report OF 01-293 contains a digital geologic map database of the Telegraph Peak 7.5’ quadrangle, San Bernardino County, California that includes: ARC/INFO (Environmental Systems Research Institute, http://www.esri.com) version 7.2.1 double precision coverages of the various elements of the geologic map. A PostScript file to plot the geologic map on a topographic base, and containing a Correlation of Map Units diagram, a Description of Map Units, an index map, and a regional structure map. Portable Document Format (.pdf) files of: a. This Readme; includes in Appendix I, data contained in fif_met.txt b. The same graphic as plotted in 2 above. Test plots have not produced 1:24,000-scale map sheets. Adobe Acrobat pagesize setting influences map scale. The Correlation of Map Units and Description of Map Units is in the editorial format of USGS Miscellaneous Investigations Series (I-series) maps but has not been edited to comply with I-map standards. Within the geologic map data package, map units are identified by standard geologic map criteria such as formation-name, age, and lithology. Even though this is an author-prepared report, every attempt has been made to closely adhere to the stratigraphic nomenclature of the U. S. Geological Survey. Descriptions of units can be obtained by viewing or plotting the .pdf file (3b above) or plotting the postscript file (2 above). If roads in some areas, especially forest roads that parallel topographic contours, do not show well on plots of the geologic map, we recommend use of the USGS Telegraph Peak 7.5’ topographic quadrangle in conjunction with the geologic map.

California↗

Bedrock geologic map of the Worcester South quadrangle, Worcester County, Massachusetts

The bedrock geology of the 7.5-minute Worcester South quadrangle, Massachusetts, consists of deformed Neoproterozoic to Paleozoic crystalline metamorphic and intrusive igneous rocks in three fault-bounded terranes (zones), including the Avalon, Nashoba, and Merrimack zones (Zen and others, 1983). This quadrangle spans the easternmost occurrence of Ganderian margin arc-related rocks (Nashoba zone) in the southern New England part of the northern Appalachians, and coincides with the trailing edge of Ganderia (Merrimack and Nashoba zones) where it structurally overlies Avalonia (Hibbard and others, 2006; Pollock and others, 2012; van Staal and others, 2009, 2012). Neoproterozoic intrusive rocks and minor metasedimentary rocks crop out in the Avalon zone and structurally underlie the rocks of the Nashoba zone along the Bluddy Bluff fault. Due to poor exposure, the position of the Bloody Bluff fault is not well-constrained and its location is partly extrapolated from mapping in adjacent areas (Barosh, 2005; Walsh and others, 2011a). Cambrian intrusive rocks and Cambrian to Silurian metasedimentary and metavolcanic rocks crop out in the Nashoba zone, and are overlain by largely Silurian metasedimentary rocks of the Merrimack zone along the Clinton-Newbury fault. Ordovician to Permian(?) plutonic rocks intrude the Merrimack and Nashoba zone rocks. Paleozoic metamorphism in the Merrimack and Nashoba zones peaked during Salinic, Acadian, and Neoacadian orogenesis from the Silurian to Mississippian (Wintsch and others, 2007; Stroud and others, 2009; Walsh and others, 2011a; Hepburn and others, 2014). Metamorphism in the Avalon zone peaked during Alleghanian orogenesis in the Mississippian to Permian (Wintsch and others, 1992, 1993, 2001; Attenoukon, 2008). Evidence for garnet-grade extensional Alleghanian mylonitization showing normal motion along the Clinton-Newbury fault occurred after presumed original terrane juxtaposition by left-lateral Acadian thrusting (Goldstein, 1994). Subsequent post-peak metamorphic deformation produced outcrop-scale open folds and weak cleavage, local faults, veins, shear bands, and pegmatite dikes. Locally, along re-activated ductile faults such as the Bloody Bluff fault and along the Wekepeke fault, late Paleozoic to Mesozoic mainly brittle normal fault motion led to the current configuration of fault-bounded lithotectonic terranes (Goldstein, 1982, 1994, 1998; Goldstein and Hepburn, 1999; Goldsmith, 1991; Attenoukon, 2008; Wintsch and others, 2012). The youngest deformation includes kink bands, brittle faults, and joints. The bedrock geology was mapped to study the tectonic history of the area and to provide a framework for ongoing hydrogeologic characterization of the fractured bedrock of Massachusetts. This report presents mapping by Gregory J. Walsh and Arthur J. Merschat from 2008 to 2010. The report consists of a map and GIS database, both of which are available for download at http://dx.doi.org/ 10.3133/sim3345. The database includes contacts of bedrock geologic units, faults, outcrop locations, structural information, and photographs.

Massachusetts↗