229 resultados para Beijing Mountain Area
em Publishing Network for Geoscientific
Resumo:
Soil-forming processes and soil development rates are compared and contrasted on glacial deposits in two adjacent and coeval valleys of the Quartermain Mountains, which are important because they display Miocene glacial stratigraphy and some of the oldest landforms in the McMurdo Dry Valleys. More than 100 soil profiles were examined on seven drift sheets ranging from 115 000 to greater than 11.3 million years in age in Beacon Valley and Arena Valley. Although the two valleys contain drifts of similar age, they differ markedly in ice content of the substrate. Whereas Arena Valley generally has 'dry-frozen' permafrost in the upper 1 m and minimal patterned ground, Beacon Valley contains massive ice buried by glacial drift and ice-cored rock glaciers and has ice-cemented permafrost in the upper 1 m and considerable associated patterned ground. Arena Valley soils have twice the rate of profile salt accumulation than Beacon Valley soils, because of lower available soil water and minimal cryoturbation. The following soil properties increase with age in both valleys: weathering stage, morphogenetic salt stage, thickness of the salt pan, the quantity of profile salts, electrical conductivity of the horizon of maximum salt enrichment, and depth of staining. Whereas soils less than 200 000 years and older soils derived from sandstone-rich ground moraine are Typic Anhyorthels and Anhyturbels, soils of early Quaternary and older age, particularly on dolerite-rich drifts, are Petronitric Anhyorthels. Arena Valley has the highest pedodiversity recorded in the McMurdo Dry Valleys. The soils of the Quartermain Mountains are the only soils in the McMurdo Dry Valleys known to contain abundant nitrates.
Resumo:
Several bog manganese deposits were discovered in the Riding Mountain area in Manitoba during the spring and summer of 1940. A study was made of the known deposits to determine the grade of the occurrences, a possible source of the manganese oxides in the bog deposits and the possibilities of locating other manganese occurrences. Samples of the bog manganese, of spring waters from which the manganese oxides have apparently been precipitated, of the Odanah shale in which the deposits occur, and of "ironstone" nodules found in the Odanah and Riding Mountain shales were gathered in the field and later analyzed. In addition to chemical analyses of the above-mentioned samples, several polished sections of the manganese oxides were prepared and studied under the microscope, thin-sections of nodules were examined, and spectrographic analyses of both nodules and bog manganese were made. ...
Resumo:
On the Lower Brule Indian Reservation in South Dakota, about 3 million tons of metallic manganese are in low-grade deposits in the DeGrey Member of the Pierre Shale on the reservation. The geology and methods of mining and processing this sub-economic mineral resource have been studied extensively; technologically, extraction of manganese is possible. However, an efficient, economical method to separate manganese-bearing nodules from the shale host rocks has yet to be found. The manganiferous nodules occur in the Oacoma zone of the Sully shale member (De-Grey Member) which is a subdivision of the South Dakota Pierre Shale formation. These nodular deposits have an interesting similarity in stratigraphical position, lithology and manganese content to those of the Porcupine Mountain area in Manitoba.
Resumo:
The pore water chemistry of mud volcanoes from the Olimpi Mud Volcano Field and the Anaximander Mountains in the eastern Mediterranean Sea have been studied for three major purposes: (1) modes and velocities of fluid transport were derived to assess the role of (upward) advection, and bioirrigation for benthic fluxes. (2) Differences in the fluid chemistry at sites of Milano mud volcano (Olimpi area) were compiled in a map to illustrate the spatial heterogeneity reflecting differences in fluid origin and transport in discrete conduits in near proximity. (3) Formation water temperatures of seeping fluids were calculated from theoretical geothermometers to predict the depth of fluid origin and geochemical reactions in the deeper subsurface. No indications for downward advection as required for convection cells have been found. Instead, measured pore water profiles have been simulated successfully by accounting for upward advection and bioirrigation. Advective flow velocities are found to be generally moderate (3-50 cm/y) compared to other cold seep areas. Depth-integrated rates of bioirrigation are 1-2 orders of magnitude higher than advective flow velocities documenting the importance of bioirrigation for flux considerations in surface sediments. Calculated formation water temperatures from the Anaximander Mountains are in the range of 80 to 145 °C suggesting a fluid origin from a depth zone associated with the seismic decollement. It is proposed that at that depth clay mineral dehydration leads to the formation and advection of fluids reduced in salinity relative to sea water. This explains the ubiquitous pore water freshening observed in surface sediments of the Anaximander Mountain area. Multiple fluid sources and formation water temperatures of 55 to 80 °C were derived for expelled fluids of the Olimpi area.
Resumo:
The Kongtong Mountain area is a marginal area of the Asian summer monsoon and is sensitive to monsoon dynamics. The sensitivity highlights the need to establishing long-term climate records there and evaluating links with the Asian monsoon. Using "signal-free" methods, we developed a tree-ring chronology based 52 ring-width series from 23 Pinus tabulaeformis and Pinus armandidi trees in the Kongtong Mountain, northern China. Tree growth is highly correlated (0.844) with the Palmer Drought Severity Index (PDSI) from May to July, demonstrating the strength of PDSI in modeling drought conditions in this region. We therefore developed a robust May-July PDSI reconstruction spanning 1615-2009, which explained 71.2% of the instrumental variance for the period 1951-2005. Extremely dry epochs are found in periods of 1723-1727 and 1928-1932, and significant wet conditions are seen from 1696-1700, 1753-1757 and 1963-1969. These persistent dry and wet epochs were also found in northeastern Mongolia, suggesting similar drought regimes between these two regions. The dryness that occurred in the 1920s-1930s was the most severe and was concurrent with a warming period. This warming/drying relationship of the 1920s-1930s may be an analog to the current drying trend in northern China.