Paleoclimatic and Paleoceanographic Reconstruction of the Pleistocene- Holocene Through the Study of Planktonic Foraminifera of Two Sedimentary Cores Collected in North Atlantic Ocean, Southwest of the Azores Islands PDF Download
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Author: Alessandro Bonfardeci Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
In the global climatic system, the North Atlantic Ocean is considered as a highly sensitive region, which plays a crucial role in the Northern Hemisphere dynamics through the so-called Atlantic Meridional Overturning Circulation (AMOC) system, of which the Azores Front/Current System represents an important part. The main aim of the thesis is to reconstruct the complex hydrographic and climatic interactions in such a climatically-sensitive area during middle Pleistocene to Holocene through the analysis of the planktonic foraminifera from two cores collected in the OH1 segment of the Mid-Atlantic Ridge (MAR) south-westward of the Azores archipelago during the Oceanograflu 2013 cruise. The manuscript is structured in three chapters presenting the major results and their interpretation (...).
Author: Alessandro Bonfardeci Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
In the global climatic system, the North Atlantic Ocean is considered as a highly sensitive region, which plays a crucial role in the Northern Hemisphere dynamics through the so-called Atlantic Meridional Overturning Circulation (AMOC) system, of which the Azores Front/Current System represents an important part. The main aim of the thesis is to reconstruct the complex hydrographic and climatic interactions in such a climatically-sensitive area during middle Pleistocene to Holocene through the analysis of the planktonic foraminifera from two cores collected in the OH1 segment of the Mid-Atlantic Ridge (MAR) south-westward of the Azores archipelago during the Oceanograflu 2013 cruise. The manuscript is structured in three chapters presenting the major results and their interpretation (...).
Author: Ann Louise Sabin Publisher: ISBN: Category : Paleoceanography Languages : en Pages : 186
Book Description
Northeast Pacific Ocean sediments were analyzed to determine the past relationship between northeast Pacific sea surface conditions and the climate on the adjacent continent, the Pacific Northwest of North America. Studies of modern ocean-atmosphere interactions demonstrate the significant effect sea surface conditions and atmospheric circulation in the Northeast Pacific Ocean has on the climate of the west coast of North America. Thus, it is likely that past continental climate change can be correlated to changes in sea surface temperature in the northeast Pacific Ocean. We analyzed radiolaria from twelve sediment cores, ranging from 33.62°N to 54.42°N latitude along the west coast of North America to reconstruct past sea surface conditions. Relationships between modern radiolaria and mean annual sea surface temperature calibrate equations used to estimate sea surface conditions for the past 20,000 years. Chronology is controlled by radiocarbon ages from planktonic foraminifera and bulk organic carbon. The reconstructions of sea surface conditions from changes in radiolaria assemblages indicate that the upwelling center off the west coast of North America was further south 15,000 years ago than it is today, and reached its present location 13,000 years ago. We infer that the West Wind Drift and Transition Zone were further south in the latest Pleistocene as a result of a more southerly North Pacific High pressure cell prior to 13,000 years ago. Two Pacific Northwest continental records of paleotemperature are well correlated to the sea surface temperature record the northeast Pacific around 48N latitude, with temperatures increasing over the past 20,000 years. Significant temperature minima and glacial expansions occurred at 13,000 and 4,000 years ago in the records examined, as did a minor minimum at 16,000 years ago. We conclude that changes in the past latitudinal position of the West Wind Drift played a significant role in controlling continental climate immediately to its east, as it does in the present day environment.
Author: Elizabeth Truswell Publisher: ANU Press ISBN: 1760462942 Category : Biography & Autobiography Languages : en Pages : 247
Book Description
In the southern summer of 1972/73, the Glomar Challenger was the first vessel of the international Deep Sea Drilling Project to venture into the seas surrounding Antarctica, confronting severe weather and ever-present icebergs. A Memory of Ice presents the science and the excitement of that voyage in a manner readable for non-scientists. Woven into the modern story is the history of early explorers, scientists and navigators who had gone before into the Southern Ocean. The departure of the Glomar Challenger from Fremantle took place 100 years after the HMS Challenger weighed anchor from Portsmouth, England, at the start of its four-year voyage, sampling and dredging the world’s oceans. Sailing south, the Glomar Challenger crossed the path of James Cook’s HMS Resolution, then on its circumnavigation of Antarctica in search of the Great South Land. Encounters with Lieutenant Charles Wilkes of the US Exploring Expedition and Douglas Mawson of the Australasian Antarctic Expedition followed. In the Ross Sea, the voyages of the HMS Erebus and HMS Terror under James Clark Ross, with the young Joseph Hooker as botanist, were ever present. The story of the Glomar Challenger’s iconic voyage is largely told through the diaries of the author, then a young scientist experiencing science at sea for the first time. It weaves together the physical history of Antarctica with how we have come to our current knowledge of the polar continent. This is an attractive, lavishly illustrated and curiosity-satisfying read for the general public as well as for scholars of science.
Author: Michael R Twarog Publisher: ISBN: Category : Languages : en Pages : 116
Book Description
The last glacial maximum, ca. 21,000 years ago, caused a fall in eustatic sea level of ca. 120 m below present. The low-gradient, shallow Sunda Shelf, Southeast Asia was subaerially exposed during this sea-level lowstand and experienced rising sea level thereafter. Sea level rose to a +1.3––5 m highstand ca. 6,500 cal yr BP, and then fell to modern sea level. The objective of this research is to characterize environmental change on the Sunda Shelf in response to the post-glacial rising eustatic sea level. To address this objective, six gravity cores were collected along a transect crossing the paleo-Chao Phraya incised river valley complex between peninsular Malaysia and southern Vietnam. Thirteen AMS radiocarbon samples, 130 bulk sediment magnetic susceptibility samples (BMS), 66 X-ray fluorescence spectrometry (XRF) samples, and 54 samples for the analysis of foraminiferal assemblages were used to characterize change in the depositional environments of the cored sediments. BMS, XRF, and foraminiferal analysis distinguish two main units. Unit 1 is found in the lower part of the cores and typically contains more terrestrial material than sediments further up-core as shown by higher BMS values, higher % Ti, % Al, % Fe, and lower indicators of marine influence, for example, lower % Ca, % planktonic foraminifera, and percentages of deeper water benthic foraminifera such as Heterolepa dutemplei. Unit 2 is characterized by a significant increase in % Ca, % Heterolepa dutemplei and % planktonic foraminifera ca. 6,500 cal yr BP. Unit 1 is consistent with shallower water depths and is part of a transgressive systems tract (TST, ca. 1 m thick) that terminates ca. 6,500 cal yr BP. Unit 2 represents the overlying highstand systems tract (HST, ca. 1 m thick) and is characterized by an increase in % planktonics, % Ca, and shifts in benthic foraminiferal assemblages, indicating deeper water conditions than the sediments below. This shift from a TST to a HST ca. 6500 cal yr BP is consistent with the Sunda Shelf sea-level record.
Author: Christoph Hemleben Publisher: Springer Science & Business Media ISBN: 9401133506 Category : Science Languages : en Pages : 1002
Book Description
Agglutinated foraminifera are among the most widely distributed and abundant groups of marine meiofauna in some environments (e. g. marshes, deep-sea). They are tolerant of environmental extremes, tending to live where the evolutionarily more advanced calcareous foraminifera cannot survive. However, largely because of historical reasons, the amount of scientific effort invested in this group has been small in comparison to studies of other marine organisms. The NATO Advanced Studies Institute conference on the paleoecology, biostratigraphy, paleoceanography and taxonomy of agglutinated foraminifera in TUbingen September 17-29, 1989, was a direct outgrowth of two previous workshops on agglutinated foraminifers held in Amsterdam in September 1981 (IW AF I) and in Vienna in June 1986 (IW AF 11). As such, the TUbingen conference constitutes the Third International Workshop on Agglutinated Foraminifera (IW AF III) and was organised to provide a platform for synthesizing the current state of knowledge on this group of organisms, and to strengthen interactions between basic research and applied micropaleontology. One of the main underlying themes of the conferen:e was to identify topics in the paleoecology, biostratigraphy, paleoceanography and taxonomy of agglutinated foraminifera which are in urgent need of further research. About 80 scientists and students from 5 continents participated in the TUbingen conference, which is one measure of the growth in interest in agglutinated foraminifers over the past decade. During four days of technical sessions, scientific results were communicated in the form of 34 oral presentations and 15 poster displays.
Author: Priska Schäfer Publisher: Springer Science & Business Media ISBN: 9783540672319 Category : Science Languages : en Pages : 520
Book Description
The northern North Atlantic is one of the regions most sensitive to past and present global changes. This book integrates the results of an interdisciplinary project studying the properties of the Greenland-Iceland-Norwegian Seas and the processes of pelagic and benthic particle formation, particle transport, and deposition in the deep-sea sediments. Ice-related and biogeochemical processes have been investigated to decipher the spatial and temporal variability of the production and fate of organic carbon in this region. Isotopic stratigraphy, microfossil assemblages and paleotemperatures are combined to reconstruct paleoceanographic conditions and to model past climatic changes in the Late Quaternary. The Greenland-Iceland-Norwegian Seas can now be considered one of the best studied subbasins of the world`s oceans.
Author: Alessandro Bonfardeci
Author: Alessandro Bonfardeci
Author: Roger G. Barry
Author: Ann Louise Sabin
Author: Bruce Hayward Corliss
Author: Elizabeth Truswell
Author: Michael R Twarog
Author: Christoph Hemleben
Author: William Winn Hay
Author: Priska Schäfer
Author: Grzybowski Foundation