Download or read book Model of Late Pleistocene Holocene Variations in Rate of Sediment Accumulation Panama Basin Eastern Equitorial Pacific written by Nicklas George Pisias and published by . This book was released on 1974 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Model of Late Pleistocene Holocene Variations in Rate of Sediment Accumulation written by Nicklas George Pisias and published by . This book was released on 1973 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: The assumption of constant quartz accumulation for the deep-sea sediment core Y69-106P, taken in the Panama Basin, has been used to date the core and construct a sedimentation rate versus time curve for it. Stratigraphic control for the calculated time scale includes three carbon-14 measurements, the extinction of the radiolarian Stylatractus universus, and correlation with oxygen isotope curves from other dated cores. The model sedimentation rates and sediment composition data allow the determination of sediment accumulation rates for calcium carbonate, opaline silica, and remaining "detritus". Fluctuations in calcium carbonate accumulation rates correlate closely with variations in oxygen isotope ratios in biogenous carbonate from two other equatorial Pacific sediment cores. High oxygen isotope ratios correlate with high calcium carbonate accumulation rates. Opaline silica accumulation rates reflect changes in the dominance of radiolarian fossil groups which can be related to surface circulation in the Panama Basin. The successive maxima in opal and calcium accumulation rates and the oxygen isotope ratios in Y69-106P suggest that at the end of the last glacial period, the rate of calcium carbonate dissolution increased in the Panama Basin first, to be followed by a decrease in the intensity of the eastern equatorial Pacific upwelling, and finally the volume of continental glaciers decreased. Spectral analysis of the rate of accumulation of calcium carbonate in Y69-106P and of the oxygen isotope record of core V28-238 indicate the presence of a 23,000 year periodicity. Analysis of opal accumulation rate suggest a 100,000 year periodicity. These two periodicities are found in fluctuations in the earth's orbital parameters. The eccentricity of the orbit fluctuates with an average period of 98,000 years and the precession of the equinoxes changes with a 22,000 year period.

Download or read book Studies of Processes Controlling the Composition and Distribution of Deep sea Ferromanganese Nodules written by Michael L. Bender and published by . This book was released on 1983 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cenozoic History and Paleoceanography of the Central Equatorial Pacific Ocean written by Tjeerd Hendrik Van Andel and published by Geological Society of America. This book was released on 1975 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Late Pleistocene Geologic History of the Outer Continental Shelf and Upper Continental Slope Northwest Gulf of Mexico written by Bruce Robert Sidner and published by . This book was released on 1977 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Late Pleistocene to Holocene Climate Variability Recorded in Lake Sediment of Silver Lake Summit County Ohio written by Corinne M. Lally and published by . This book was released on 2016 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: To provide greater spatial coverage of late Pleistocene to Holocene environmental change in the Midwestern United States, a 1350 cm long sediment core was collected from Silver Lake in northeast Ohio. Age control was provided by new radiocarbon dates, correlation to a dated lake record from western Ohio, and a prior study of Silver Lake. Lithologic descriptions and sedimentary profiles of dry bulk density (DBD), organic matter (OM), carbonate, C/N, grain size, magnetic properties, and concentrations of terrigenous derived elements (Al, Ti, and K) allow the core to be divided into six periods. The climate interpretations are compared to published regional and hemispheric climate records. The first period is Deglaciation, which spans from 17,560 -- 13,600 cal year BP (1353 - 1188 centimeters below lake floor (cmblf)). Silty sediment with low OM (average 6 %) and high DBD (average 0.832 g/cm3) are interpreted to reflect cold conditions soon after deglaciation. The Latest Pleistocene Period is the second period and spans from 13,600 -- 12,200 cal yr BP (1188 -- 1103 cmblf). Brown to light brown mud with silty layers, a slight increase in % OM (average 9 %) and decrease in DBD (average 0.694 g/cm3) characterize this interval. The Latest Pleistocene Period may have been a time of increased primary productivity in Silver Lake. The third period is the Younger Dryas, which spans from 12,200 -- 11,500 cal yr BP (1103 -- 1070 cmblf). Gray-brown to light-brown silty mud having low % OM (average 6%), high DBD (average 0.703 g/cm3), high concentrations of magnetic minerals, and elevated concentrations of Al, Ti, and K characterize this period. These sediment characteristics are interpreted as cold and dry conditions, increased terrigenous input, and/or decreased primary productivity. The fourth period is the Early Holocene which spans from 11,500 -- 7,450 cal yr BP (1070 -- 824 cmblf), and is divided into two subperiods. During the first subperiod, from 11,500 -- 10,600 cal yr BP (1070 -- 1016 cmblf), there was an increase in % OM (average 28 %) and decrease in DBD (average 0.311 g/cm3) and concentrations of Al, Ti, and K. The first subperiod of the Early Holocene is interpreted to be a period of brief warming. The second subperiod of the Early Holocene spans from 10,600 -- 7,450 cal yr BP (1016-824 cmblf), and is characterized by highly variable % OM and DBD and increased Al, Ti, and K. This subperiod is interpreted as a period of increased aridity. The fifth period is the Mid to Late Holocene which spans from 7,450 -- 200 cal yr BP (824 -- 128 cmblf). Alternating brown and dark brown mud having no visible silty layers, high % OM (average 51%), low DBD (average 0.116 g/cm3), and decreased Al, Ti, and K and magnetic concentration characterize this period. These sediment characteristics are interpreted to reflect warm and moist conditions when primary productivity increased and/or terrigenous influx decreased. However, within the Mid to Late Holocene Period there are six pronounced intervals of decreased % OM and increased Al, Ti, and K suggestive of millennial-scale increases in terrigenous input and/or decreases in lake productivity. These six intervals may be related in part to rapid global climate changes during the Holocene, when temperatures and moisture balance fluctuated. The sixth period is the Anthropogenic Period, which spans from 200 cal yr BP to the present (128 -- 0 cmblf). The Anthropogenic Period is characterized by a pronounced decrease in % OM (average 19%), increase in DBD (average 0.273 g/cm3), and an increase in the mass accumulation rate (MAR) resulting from Euro-American land clearance enhancing watershed erosion.

Download or read book Oceanography of the Tropical Pacific written by Unni Havem Rowell and published by . This book was released on 1979 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Yedoma Permafrost Landscapes as Past Archives Present and Future Change Areas written by Lutz Schirrmeister and published by Frontiers Media SA. This book was released on 2022-06-30 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Paleoclimatic Inferences for Late Pleistocene and Holocene from California Continental Borderland Basin Sediments written by Donn S. Gorsline and published by . This book was released on 1976 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis of the variation in carbonate Contint versus time in sediments from the basins of the California Continental Borderland reveals that the high carbonate sediments correlate with relatively warm water period. This is verified by oxygen isotopic data and micropaleontologic data. In warm times turbidity current contribution is small and the dilution effect of terrigenous sediments is minimal. Conversely, during periods when sediments have low carbonate content the terrigenous sediment rates are high turbidities are common and the influence of local clay sources increases. Examination of the regional patterns of sedimentation shows that the upwelling intensity increased in the area at least two-fold and terrigenous sediment input also increased as much as five-fold during the most recent cold period. It is suggested that this reflects a movement of climatic belts toward the Equator and a concommittant increase in runnoff and upweeling rate. (Author).

Download or read book HIG Report written by and published by . This book was released on 1979 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Late Pleistocene and Holocene Hydroclimate Change in the Southeastern United States written by James Joseph Kocis and published by . This book was released on 2011 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to understand hydroclimate variability of future climate change, it is important to know the timing and range of natural climate change in the past. The Southeastern United States (SE) is situated along the poleward extent of projected subtropical drying, where the expression of past hydrological balances remains unclear. The lack of high-resolution paleohydroclimate records in the SE forces climate modelers to base interpretations on better-understood regions of North America. The SE likely experienced significant changes in precipitation regimes resulting from its position at the convergence of several oceanic and continental air masses. To reconstruct precipitation variability, this study examines multiple floodplains along the Tennessee River as hydroclimate proxy archives in the SE. Changes in precipitation balances are interpreted from high-resolution trends in sedimentary, pedogenic, and stable carbon datasets that span the last 14 ka BP (kiloannum before present). Variation in overbank sedimentation, identified from grain-size trends indicate precipitation increased from 11.0-8.0 ka BP. During this pluvial interval, stable carbon isotope values of soil organic matter in floodplain paleosols show negative excursions (~1.0-1.5 permil) from average modern values. A period of aridity, evident from an overall excursion to less negative stable carbon isotope values, increased abundance of fine-grain sizes, and increased paleosol development occurs between 8.0-5.0 ka BP. Most notably, the transition out of the mid-Holocene (~5.0 ka BP) is marked by an abrupt change to more negative carbon isotope values (~1.5 permil). Wavelet analysis of composite sedimentary and stable carbon isotope data time series indicate statistically significant (p[less than or equal to]0.1) 200- to 500-yr and ~1000-yr periodicities. Periods of aridity in the SE are correlated with the eastward intensification of the North Atlantic Subtropical High (NASH). Pluvial conditions result from the westward intensification of the NASH. The timing of wet and dry periods recorded by floodplain paleosol is in agreement with the onset and frequency of such changes observed in regional records. The floodplain datasets presented here provide the first long-term record of the onset and duration of centennial-scale changes in precipitation that occurred during the late Pleistocene and Holocene in the SE.

Download or read book Progress in Botany 67 written by Karl Esser and published by Springer Science & Business Media. This book was released on 2006-01-27 with total page 583 pages. Available in PDF, EPUB and Kindle. Book excerpt: With one volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences. The present volume includes reviews on genetics, cell biology, physiology, comparative morphology, systematics, ecology, and vegetation science.

Download or read book Investigation of Late Quaternary Paleoceanography and Paleoclimatology written by R. M. Cline and published by Geological Society of America. This book was released on 1976 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer. This book was released on 1975 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis seminated by the Center for Information and Numerical Data Analysis and Synthesis, (CINDAS) *at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac tivity was transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 19 (thesis year 1974) a total of 10,045 theses titles from 20 Canadian and 209 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work. The organization of Volume 19 is identical to that of past years. It consists of theses titles arranged by discipline and by university within each discipline.

Download or read book Memoir written by and published by . This book was released on 1976 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Baltic Sea Basin written by Jan Harff and published by Springer Science & Business Media. This book was released on 2011-04-15 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports about the results of a Special Symposium “The Baltic Sea Basin”, held on August 11, 2008, within the frame of the 33rd IGC at Oslo, Norway in order to foster the understanding of the Baltic Basin as a unit in terms of genesis, structure, ongoing processes and utilization. It is the first time that in a joint publication, scientists from different disciplines give a comprehensive overview about the Baltic Sea basin in such a general sense. The book will be used not only by students and scientist but also by engineers and decision makers from industry and politics. Summarizing the state of the art in the investigation of the Baltic Sea Basin, but also in the resource utilisation of the basin the book will enhance the development of new monitoring strategies and technical device design including satellite observation methods, the establishment of international research laboratories, innovative topics for interdisciplinary research projects, etc.

Download or read book Sedimentary Record of Glacial Dynamics Lake Level Fluctuations and Tectonics written by Michael H. Hofmann and published by . This book was released on 2005 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: