Climatic and oceanographic isotopic signals from the carbonate rock record and their preservation

1992 ◽  
Vol 129 (2) ◽  
pp. 143-160 ◽  
Author(s):  
James D. Marshall
Keyword(s):  
Ocean Circulation ◽  
Global Climate ◽  
Burial History ◽  
Vegetative Cover ◽  
Isotopic Data ◽  
Rock Interaction ◽  
Diagenetic Alteration ◽  
Wide Range ◽  
History Of ◽  
Diagenetic History

AbstractStable isotopic data from marine limestones and their constituent fossils and marine cements can provide quantitative evidence for changes in global climate and ocean circulation. Oxygen isotopic data can indicate changes in temperature and ocean composition whereas stratigraphic variation in carbon isotope ratios may reflect changes in the carbon cycle that can be linked to changes in oceanic productivity and atmospheric greenhouse gases. Terrestrial carbonates–meteoric cements, calcretes and speleothems–similarly offer significant potential for understanding the evolution of terrestrial climates by providing evidence for the composition of rainwater and the nature of vegetative cover.Primary environmental isotopic signals may be obscured by the effects of post-depositional diagenetic alteration. Cementation and replacement reactions can take place in a wide range of diagenetic environments; the diagenetic history of an individual limestone is determined by a combination of its mineralogical diagenetic potential and depositional setting, together with subsequent changes in relative sea-level and burial history. Carbon isotopic values are less prone to alteration during diagenesis than oxygen values but shifts can be significant where organogenic carbon is incorporated. Linear covariation of carbon and oxygen values is not a reliable indicator of diagenetic alteration: water-rock interaction and fluid mixing may produce non-linear distributions.Attempts to determine long-term changes in climatic and oceanographie conditions through isotope stratigraphy of shallow-water limestones must include an assessment of the diagenetic history of the materials analysed. Pétrographic examination using conventional microscopy backed up, where appropriate, by cathodoluminescence and scanning electron microscopy together with elemental and strontium isotopic analysis can help to identify the effects of diagenetic alteration. Where material with a range of different degrees of alteration is preserved in the same sediment it may be possible to compare patterns of isotopic and elemental variation and to attempt to unravel the effects of diagenesis in order to determine primary, environmental, isotopic signals. Recent research has shown that these techniques can be successfully employed in both Phanerozoic and Precambrian sediments.

Maturation thermique et histoire de l'enfouissement et de la génération des hydrocarbures du bassin de l'archipel de Mingan et de l'île d'Anticosti, Canada

1990 ◽  
Vol 27 (6) ◽  
pp. 731-741 ◽  
Author(s):  
Rudolf Bertrand
Keyword(s):  
Carbonate Platform ◽  
Burial History ◽  
Upper Ordovician ◽  
Southeastern Part ◽  
Middle Ordovician ◽  
Oil Generation ◽  
Wide Range ◽  
History Of ◽  
Anticosti Island ◽  
Depth Of Burial

Carbonate platform sequences of Anticosti Island and the Mingan Archipelago are Early Ordovician to Early Silurian in age. With the exception of the Macasty Formation, the sequences are impoverished in dispersed organic matter, which is chiefly composed of zooclasts. Zooclast reflectances suggest that the Upper Ordovician and Silurian sequences outcropping on Anticosti Island are entirely in the oil window but that the Lower to Middle Ordovician beds of the Mingan Archipelago and their stratigraphic equivalents in the subsurface of most of Anticosti Island belong to the condensate zone. Only the deeper sequences of the southwestern sector of Anticosti Island are in the diagenetic dry-gas zone. The maximum depth of burial of sequences below now-eroded Silurian to Devonian strata increases from 2.3 km on southwestern Anticosti Island to 4.5 km in the Mingan Archipelago. A late upwarp of the Precambrian basement likely allowed deeper erosion of the Paleozoic strata in the vicinity of the Mingan Archipelago than on Anticosti Island. Differential erosion resulted in a southwestern tilting of equal maturation surfaces. The Macasty Formation, the only source rock of the basin (total organic carbon generally > 3.5%, shows a wide range of thermal maturation levels (potential oil window to diagenetic dry gas). It can be inferred from the burial history of Anticosti Island sequences that oil generation began later but continued for a longer period of geologic time in the northeastern part than in the southeastern part of the island. Oil generation was entirely pre-Acadian in the southern and western parts of Anticosti Island, but pre- and post-Acadian in the northern and eastern parts.

Contrasting sources of variability in subtropical and subpolar Atlantic overturning

2020 ◽  
Author(s):  
Yavor Kostov ◽  
Helen L. Johnson ◽  
David P. Marshall ◽  
Gael Forget ◽  
Patrick Heimbach ◽  
...  
Keyword(s):  
Wind Stress ◽  
Ocean Circulation ◽  
Global Climate ◽  
Surface Wind ◽  
Circulation Model ◽  
Ocean Surface ◽  
Meridional Overturning Circulation ◽  
Surface Wind Stress ◽  
History Of ◽  
Meridional Overturning

<p><strong>The Atlantic meridional overturning circulation (AMOC) is pivotal for regional and global climate due to its key role in the uptake and redistribution of heat, carbon and other tracers. Establishing the causes of historical variability in the AMOC can tell us how the circulation responds to natural and anthropogenic changes at the ocean surface. However, attributing observed AMOC variability and inferring causal relationships is challenging because the circulation is influenced by multiple factors which co-vary and whose overlapping impacts can persist for years.  Here we reconstruct and unambiguously attribute variability in the AMOC at the latitudes of two observational arrays to the recent history of surface wind stress, temperature and salinity. We use a state-of-the-art technique that computes space- and time-varying sensitivity patterns of the AMOC strength with respect to multiple surface properties from a numerical ocean circulation model constrained by observations. While on inter-annual timescales, AMOC variability at 26°N is overwhelmingly dominated by a linear response to local wind stress, in contrast, AMOC variability at subpolar latitudes is generated by both wind stress and surface temperature and salinity anomalies. Our analysis allows us to obtain the first-ever reconstruction of subpolar AMOC from forcing anomalies at the ocean surface.</strong></p>

scholarly journals REE Characteristics of Lower Cretaceous Limestone Succession in Gümüşhane, NE Turkey: Implications for Ocean Paleoredox Conditions and Diagenetic Alteration

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 683 ◽  
Author(s):  
Merve Özyurt ◽  
M. Ziya Kırmacı ◽  
Ihsan Al-Aasm ◽  
Cathy Hollis ◽  
Kemal Taslı ◽  
...  
Keyword(s):  
Lower Cretaceous ◽  
Elevated Temperatures ◽  
Basaltic Magma ◽  
Sudden Change ◽  
Hydrothermal Activity ◽  
Rock Interaction ◽  
Diagenetic Alteration ◽  
General Chemical ◽  
Wide Range ◽  
Micritic Limestones

Trace and rare earth elements (REEs) are considered to be reliable indicators of chemical processes for the evolution of carbonate systems. One of the best examples of ancient carbonate successions (Berdiga Formation) is widely exposed in NE Turkey. The Lower Cretaceous limestone succession of Berdiga Formation may provide a case study that reveals the effect of ocean paleoredox conditions on diagenetic alteration. Measurement of major, trace and REEs was carried out on the Lower Cretaceous limestones of the Berdiga Formation, to reveal proxies for paleoredox conditions and early diagenetic controls on their geochemistry. Studied micritic limestone microfacies (MF-1 to MF-3) indicate deposition in the inner platform to a deep shelf or continental slope paleoenvironment during the Hauterivian-Albian. The studied limestone samples mainly exhibit low Mg-calcite characteristics with the general chemical formula of Ca98.35–99.34Mg0.66–1.65(CO3). They are mostly represented by a diagnostic REE seawater signature including (1) slight LREE depletion relative to the HREEs (ave. 0.72 of Nd/YbN and ave. 0.73 of Pr/YbN), (2) negative Ce anomalies (Ce/Ce* = 0.38–0.81; ave. 0.57), (3) positive La anomaly (La/La* = 0.21–3.02; ave. 1.75) and (4) superchondritic Y/Ho (ave. 46.26). Studied micritic limestones have predominantly low Hf (bdl to 0.5 µg/g), Sc (bdl to 2 µg/g) Th (bdl to 0.9 µg/g) contents suggesting negligible to minor shale contamination. These findings imply that micritic limestones faithfully record chemical signals of their parental and diagenetic fluids. The succession also exhibits high ratios of Eu/Eu* (1.01–1.65; ave. 1.29 corresponding to the positive Eu anomalies), Sm/Yb (1.26–2.74; ave. 1.68) and La/Yb ratios (0.68–1.35; ave. 0.9) compared to modern seawater and wide range of Y/Ho ratios (29.33–70.00; ave. 46.26) which are between seawater and hydrogenetic Fe-Mn crusts. Several lines of geochemical evidence suggest water-rock interaction between parental seawater and basaltic rocks at elevated temperatures triggered by hydrothermal activity associated with Early Cretaceous basaltic magma generation. The range of Ce/Ce* values is suggestive of mostly oxic to dysoxic paleoceanographic conditions, with a sudden change to dysoxic conditions (Ce/Ce* = 0.71–0.81), in the uppermost part of the MF-1. This is followed by an abrupt deepening paleoenvironment with a relative increase in the oxic state of the seawater and deposition of deeper water sediments (MF-2 and MF-3) above a sharp transition. The differences in microfacies characteristics and foraminifera assemblage between MF-1 and overlying facies (MF-2 and MF-3) may also confirm the change in paleoceanographic conditions. Therefore, REEs data obtained from studied limestones have the potential to contribute important information as to regional paleoceanographic conditions of Tethys during an important period in Earth history.

Rock-physics modeling guided by depositional and burial history in low-to-intermediate-porosity sandstones

Geophysics ◽  
2014 ◽  
Vol 79 (2) ◽  
pp. D115-D121 ◽  
Author(s):  
Per Avseth ◽  
Tor Arne Johansen ◽  
Aiman Bakhorji ◽  
Husam M. Mustafa
Keyword(s):  
Rock Physics ◽  
Contact Theory ◽  
Well Log ◽  
Tight Gas ◽  
Burial History ◽  
Reservoir Properties ◽  
Rock Physics Modeling ◽  
History Of ◽  
Physics Modeling ◽  
Diagenetic History

We present a new rock-physics modeling approach to describe the elastic properties of low-to-intermediate-porosity sandstones that incorporates the depositional and burial history of the rock. The studied rocks have been exposed to complex burial and diagenetic history and show great variability in rock texture and reservoir properties. Our approach combines granular medium contact theory with inclusion-based models to build rock-physics templates that take into account the complex burial history of the rock. These models are used to describe well log data from tight gas sandstone reservoirs in Saudi Arabia, and successfully explain the pore fluid, rock porosity, and pore shape trends in these complex reservoirs.

scholarly journals Bone microstructure and diagenesis of saurischian dinosaurs from the Upper Cretaceous (Neuquén Group), Argentina

2017 ◽  
Vol 44 (1) ◽  
pp. 39 ◽  
Author(s):  
Elena Previtera
Keyword(s):  
Upper Cretaceous ◽  
Bone Microstructure ◽  
Depositional Environments ◽  
Integral Approach ◽  
Burial History ◽  
Thin Sections ◽  
Diagenetic Processes ◽  
History Of ◽  
Diagenetic History ◽  
Fluvial Environments

The Neuquén Basin in northwestern Patagonia, Argentina, holds the most important record of Cretaceous dinosaurs in South America.The Neuquén Group (Upper Cretaceous) is the richest dinosaur-bearing unit of the basin. It comprises the Río Limay, the Río Neuquén and the Río Colorado subgroups. In this study, dinosaur remains from the Río Neuquén and the Río Colorado subgroups outcropping in Mendoza are examined. In this group, isolated, disarticulated or partially articulated sauropods and theropods are abundant. However, little is known about the diagenetic history of fossil assemblages. In southern Mendoza, three fossiliferous sites were found in the areas of Paso de las Bardas (Quebrada Norte) and Cerro Guillermo (CG1, CG2). This study aims to add to the knowledge of diagenetic processes involving dinosaur remains from the Neuquén Group, as well as their relation to the depositional environment. Histologic features and diagenetic processes of dinosaur bones were analyzed through thin sections in order to interpret the degree of taphonomic alteration. The fossil-diagenetic processes inferred include substitution, fracturing, plastic deformation and different permineralization events. Combined analyses through X-ray diffractometry (XRD) and petrographic studies reveal the substitution of hydroxyapatite by francolite. The presence of fluorine -in one of the cases- suggests a link between the elemental composition and depositional environments: floodplain and fluvial channel. Permineralization stages include infilling of vascular canals, trabeculae and fractures with iron oxides and iron carbonate minerals during the burial history. This contribution represents an integral approach to the study of Cretaceous dinosaurs for assessing the diagenetic changes in the bone microstructure and the differential preservation of fossil remains in fluvial environments.

Group Experiences and Individual Differences in Stuttering

2019 ◽  
Vol 62 (12) ◽  
pp. 4335-4350 ◽  
Author(s):  
Seth E. Tichenor ◽  
J. Scott Yaruss
Keyword(s):  
Individual Differences ◽  
Support Groups ◽  
Support Group ◽  
Affective States ◽  
Life Outcomes ◽  
Self Help ◽  
Wide Range ◽  
Group Experiences ◽  
History Of ◽  
Adults Who Stutter

Purpose This study explored group experiences and individual differences in the behaviors, thoughts, and feelings perceived by adults who stutter. Respondents' goals when speaking and prior participation in self-help/support groups were used to predict individual differences in reported behaviors, thoughts, and feelings. Method In this study, 502 adults who stutter completed a survey examining their behaviors, thoughts, and feelings in and around moments of stuttering. Data were analyzed to determine distributions of group and individual experiences. Results Speakers reported experiencing a wide range of both overt behaviors (e.g., repetitions) and covert behaviors (e.g., remaining silent, choosing not to speak). Having the goal of not stuttering when speaking was significantly associated with more covert behaviors and more negative cognitive and affective states, whereas a history of self-help/support group participation was significantly associated with a decreased probability of these behaviors and states. Conclusion Data from this survey suggest that participating in self-help/support groups and having a goal of communicating freely (as opposed to trying not to stutter) are associated with less negative life outcomes due to stuttering. Results further indicate that the behaviors, thoughts, and experiences most commonly reported by speakers may not be those that are most readily observed by listeners.

Introduction: Emotion, History and the Arts

2018 ◽  
Vol 7 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Erin Sullivan ◽  
Marie Louise Herzfeld-Schild
Keyword(s):  
Historical Change ◽  
Carson Mccullers ◽  
Emotional Life ◽  
Review Section ◽  
The Arts ◽  
Wide Range ◽  
War Correspondents ◽  
History Of ◽  
Johan Huizinga

This introduction surveys the rise of the history of emotions as a field and the role of the arts in such developments. Reflecting on the foundational role of the arts in the early emotion-oriented histories of Johan Huizinga and Jacob Burkhardt, as well as the concerns about methodological impressionism that have sometimes arisen in response to such studies, the introduction considers how intensive engagements with the arts can open up new insights into past emotions while still being historically and theoretically rigorous. Drawing on a wide range of emotionally charged art works from different times and places—including the novels of Carson McCullers and Harriet Beecher-Stowe, the private poetry of neo-Confucian Chinese civil servants, the photojournalism of twentieth-century war correspondents, and music from Igor Stravinsky to the Beatles—the introduction proposes five ways in which art in all its forms contributes to emotional life and consequently to emotional histories: first, by incubating deep emotional experiences that contribute to formations of identity; second, by acting as a place for the expression of private or deviant emotions; third, by functioning as a barometer of wider cultural and attitudinal change; fourth, by serving as an engine of momentous historical change; and fifth, by working as a tool for emotional connection across communities, both within specific time periods but also across them. The introduction finishes by outlining how the special issue's five articles and review section address each of these categories, while also illustrating new methodological possibilities for the field.

History of the Study of Apocrypha in Early Medieval England

2020 ◽  
Vol 48 (3-4) ◽  
pp. 13-26
Author(s):  
Brandon W. Hawk
Keyword(s):  
Old Testament ◽  
Medieval England ◽  
Medieval Period ◽  
Early Medieval ◽  
Future Directions ◽  
Early Judaism ◽  
Wide Range ◽  
History Of ◽  
The Subject ◽  
Early English

Literature written in England between about 500 and 1100 CE attests to a wide range of traditions, although it is clear that Christian sources were the most influential. Biblical apocrypha feature prominently across this corpus of literature, as early English authors clearly relied on a range of extra-biblical texts and traditions related to works under the umbrella of what have been called “Old Testament Pseudepigrapha” and “New Testament/Christian Apocrypha." While scholars of pseudepigrapha and apocrypha have long trained their eyes upon literature from the first few centuries of early Judaism and early Christianity, the medieval period has much to offer. This article presents a survey of significant developments and key threads in the history of scholarship on apocrypha in early medieval England. My purpose is not to offer a comprehensive bibliography, but to highlight major studies that have focused on the transmission of specific apocrypha, contributed to knowledge about medieval uses of apocrypha, and shaped the field from the nineteenth century up to the present. Bringing together major publications on the subject presents a striking picture of the state of the field as well as future directions.

FROM THE HISTORY OF THE FORMATION AND DEVELOPMENT OF PERIODICALS IN NAMANGAN

2019 ◽  
Vol 20 (2) ◽  
pp. 49-54
Author(s):  
Dildora Alinazarova ◽  
Keyword(s):  
The Past ◽  
Wide Range ◽  
History Of ◽  
Printing House

In this article, based on an analysis of a wide range of sources, discusses the emergence and development of periodicals and printing house in Namangan. The activities of Ibrat- as the founder of the first printing house in Namangan are considered. In addition, it describes the functioning and development of "Matbaai Ishokia" in the past and present

Sign in / Sign up

Export Citation Format

Share Document