Long term low latitude and high elevation cosmogenic 3He production rate inferred from a 107 ka-old lava flow in northern Chile; 22°S-3400 m a.s.l

Available geological calibration sites used to estimate the rate at which cosmogenic 3He is produced at the Earth’s surface are mostly clustered in medium to high latitudes. Moreover, most of them have exposure histories shorter than tens of thousands of years. This lack of sites prevents a qualitative assessment of available production models used to convert cosmogenic 3He concentrations into exposure ages and/or denudation rates. It thus limits our ability to take into account the atmospheric, geomagnetic and solar modulation conditions that might have affected the production of cosmogenic nuclides in the past for longer exposure histories and in low latitude regions. We present the cosmogenic 3He production rate inferred from a new geological calibration site located in northern Chile. Five samples were collected on the surface of the largest and best-preserved lava flow of the San Pedro volcano (21.934°S-68.510°W- 3390 m a.s.l), which displays pristine crease-structure features. 40Ar/39Ar dating yield a reliable plateau age of 107±12 ka for the eruption of this lava flow. Eight pyroxene aliquots separated from the surface samples yield a weighted average cosmogenic 3He concentration of 99.3±1.2 Mat.g-1 from which a local cosmogenic 3He production rate of 928±101 at.g-1.yr-1 is calculated. The local production rate is then scaled to a sea level high latitude (SLHL) reference position using different combinations of geographic spatialization schemes, atmosphere models and geomagnetic field reconstructions, yielding SLHL production rates between 103±11 and 130±14 at.g-1.yr-1 consistent with the most recent estimates available from the literature. Finally, we use the same scaling frameworks to re-evaluate the mean global-scale cosmogenic 3He production rate in olivine and pyroxene minerals at 120±16 at.g-1.yr-1 from the compilation of previously published calibration datasets.

Climatic and halokinetic controls on alluvial–lacustrine sedimentation during compressional deformation, Andean forearc, northern Chile

Peer reviewed

Rhode Island, Geology, 1840 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: A geological map of Rhode-Island, by Charles T. Jackson. It was published in 1840. Scale [1:190,080]. Covers Rhode Island and a portion of southeastern Massachusetts. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Rhode Island State Plane Coordinate System (Feet) (FIPS 3800). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, or other information associated with the principal map. This map shows features such as geological features, mines, mills, railroads, hotels, selected residences with names of property owners, drainage, town and county boundaries, and more. Relief shown by hachures. This layer is part of a selection of digitally scanned and georeferenced historic maps of New England from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of regions, originators, ground condition dates, scales, and map purposes.

Chicago, Illinois, surficial geology, 1936 (Raster Image)

This layer is a georeferenced raster image of the historic, paper map entitled: Surficial geology of the Chicago Loop quadrangle, by J. Harlen Bretz. It was published by State Geological Survey Division ca. 1936. Scale 1:24,000. Topographic base surveyed in cooperation with the U.S. Geological Survey, 1926; 1936. Geologically surveyed 1930-1932. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Illinois East State Plane Coordinate System NAD27 (in Feet) (Fipszone 1201). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This is a typical topographic map colored to show surficial geology. It portrays both natural and manmade features. It shows and names works of nature, such as mountains, valleys, lakes, rivers, vegetation, etc. It also identify the principal works of humans, such as roads, railroads, boundaries, transmission lines, major buildings, etc. Relief is shown with standard contour intervals of 5 feet. Includes legend and map index. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

Chile and Argentina, 1779 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Carte du Chili méridional, du Rio de la Plata des Patagons, et du Détroit de Magellan : ce qui fait l'extremité australe de l'Amérique Meridle., par le sr. d'Anville. It was published by P. Santini in 1779. Scale [ca. 1:6,500,000]. Covers southern South America including portions of Chile, Argentina, Brazil, Uruguay, and the Falkland Islands. Map in French. The image inside the map neatline is georeferenced to the surface of the earth and fit to a non-standard 'World Sinusoidal' projection with the central meridian at 58.000000 degrees west. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, cities and other human settlements, territorial boundaries, shoreline features, and more. Relief is shown pictorially. Includes note. This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection and the Harvard University Library as part of the Open Collections Program at Harvard University project: Organizing Our World: Sponsored Exploration and Scientific Discovery in the Modern Age. Maps selected for the project correspond to various expeditions and represent a range of regions, originators, ground condition dates, scales, and purposes.

Atacama Desert and Puna de Atacama Region, Chile and Argentina, 1892 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Carta jeogràfica del desierto i cordilleras de Atacama, levantada por la Comisión Esploradora de Atacama ; dibo. N. Boloña ; grabo A. Németh ; Lit. Alemana, Santiago. It was published by Dirección General de Obras Públicas. Seccion de Jeografia y Minas in 1892. Scale 1:1,000,000. Covers the Atacama Desert and Puna de Atacama region, Chile and Argentina. Map in Spanish. The image inside the map neatline is georeferenced to the surface of the earth and fit to the 'Mercator' projection. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, human settlements, roads, railroads, mines and mineral location, water lines, points of triangulation, territorial boundaries, shoreline features, ports, and more. Relief shown by hachures. Includes 5 insets depiciting mountain ranges entitled : Royeccion Vertical, vista Panorámica ; 2 plans entitled: Rada de Antofagasta -- Plano de la ciudad de Copiapó. This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection and the Harvard University Library as part of the Open Collections Program at Harvard University project: Organizing Our World: Sponsored Exploration and Scientific Discovery in the Modern Age. Maps selected for the project correspond to various expeditions and represent a range of regions, originators, ground condition dates, scales, and purposes.

Isla Grevy and Isla Bayly Region, Islas Wollaston, Tierra del Fuego, Chile, 1891 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Seagull Harbour, Gretton Bay, Wollaston Island : Tierra del Fuego by the U.S. Ex.Ex. 1839 ; R.H. Wyman, Commo. U.S.N. Hydrographer to the Bureau of Navigation. Extensive corr. July 1891. It was published by the Hydrographic Office in 1891. Scale [ca. 1:10,600]. Covers the Isla Grevy and Isla Bayly Region, Islas Wollaston, Tierra del Fuego, Chile. The image inside the map neatline is georeferenced to the surface of the earth and fit to the 'Mercator' projection. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, shoreline features, bays, harbors, inlets, points, rocks, anchorage points and bottom types, and more. Relief shown by hachures. Depths shown by soundings. This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection and the Harvard University Library as part of the Open Collections Program at Harvard University project: Organizing Our World: Sponsored Exploration and Scientific Discovery in the Modern Age. Maps selected for the project correspond to various expeditions and represent a range of regions, originators, ground condition dates, scales, and purposes.

Bahía Orange, Tierra del Fuego, Chile, 1891 (Raster Image)

This layer is a georeferenced raster image of the historic nautical chart entitled: Orange Harbour : Tierra del Fuego, surveyed by the U.S.Ex.Ex. 1839 ; R.H. Wyman U.S.N. Hydrographer to the Bureau of Navigation. It was published by Hydrographic Office in 1891. Scale [ca. 1:18,700]. Covers Bahía Orange, Tierra del Fuego, Chile. The image inside the map neatline is georeferenced to the surface of the earth and fit to the 'Mercator' projection. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows coastal features such as rocks, channels, points, coves, islands, bottom types, and more. Includes also selected land features such as drainage, relief, and more. Relief shown by hachures and spot heights; depths by soundings. Includes inset view: Pack Saddle off Orange Bay N.N.W. dist. 6 miles This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection and the Harvard University Library as part of the Open Collections Program at Harvard University project: Organizing Our World: Sponsored Exploration and Scientific Discovery in the Modern Age. Maps selected for the project correspond to various expeditions and represent a range of regions, originators, ground condition dates, scales, and purposes.

Age model and stable isotopes of sediment cores from north-central Chile and south-central Chile

Terrigenous sediment supply, marine transport, and depositional processes along tectonically active margins are key to decoding turbidite successions as potential archives of climatic and seismic forcings. Sequence stratigraphic models predict coarse-grained sediment delivery to deep-marine sites mainly during sea-level fall and lowstand. Marine siliciclastic deposition during transgressions and highstands has been attributed to sustained connectivity between terrigenous sources and marine sinks facilitated by narrow shelves. To decipher the controls on Holocene highstand turbidite deposition, we analyzed 12 sediment cores from spatially discrete, coeval turbidite systems along the Chile margin (29° - 40°S) with changing climatic and geomorphic characteristics but uniform changes in sea level. Sediment cores from intraslope basins in north-central Chile (29° - 33°S) offshore a narrow to absent shelf record a shut-off of turbidite deposition during the Holocene due to postglacial aridification. In contrast, core sites in south-central Chile (36° - 40°S) offshore a wide shelf record frequent turbidite deposition during highstand conditions. Two core sites are linked to the Biobío river-canyon system and receive sediment directly from the river mouth. However, intraslope basins are not connected via canyons to fluvial systems but yield even higher turbidite frequencies. High sediment supply combined with a wide shelf and an undercurrent moving sediment toward the shelf edge appear to control Holocene turbidite sedimentation and distribution. Shelf undercurrents may play an important role in lateral sediment transport and supply to the deep sea and need to be accounted for in sediment-mass balances.

Geology, hydrology, and quality of water in the Madera area, San Joaquin Valley, California /

Three folded maps in pocket.

Explantory notes to accompany a new geological map of the Commonwealth of Australia : based on the maps already published by the Geological Surveys of the various states, etc. /

Mode of access: Internet.

Geology and mineral resources of the Alexis quadrangle,

Four folded plates (maps, and 2 diagrams) in pocket.