Oxygen Isotopic Studies of Diagenetic Clay Minerals: Implications for Geothermometry, Diagenetic Reaction Mechanisms, and Fluid Migration: ABSTRACT

AAPG Bulletin ◽  
1982 ◽  
Vol 66 ◽  
Author(s):  
Samuel M. Savin
Keyword(s):  
Clay Minerals ◽  
Reaction Mechanisms ◽  
Fluid Migration ◽  
Isotopic Studies ◽  
Oxygen Isotopic ◽  
Diagenetic Reaction

Variation in kaolinite morphology with growth temperature in isotopically mixed pore-fluids, Brent Group, UK North Sea

Clay Minerals ◽  
1994 ◽  
Vol 29 (4) ◽  
pp. 591-608 ◽  
Author(s):  
M. Osborne ◽  
R. S. Haszeldine ◽  
A. E. Fallick
Keyword(s):  
Meteoric Water ◽  
Pore Space ◽  
Pore Waters ◽  
The West ◽  
Rock Interaction ◽  
Isotopic Studies ◽  
Reservoir Sandstones ◽  
Oxygen Isotopic ◽  
Low Degrees ◽  
Water Rock Interaction

AbstractDiagenetic kaolinite in reservoir sandstones of the Brent Group precipitated following the dissolution of detrial feldspar. Two distinct morphologies of kaolinite occur: (1) early diagenetic vermiform kaolinite which is often associated with expanded detrital micas; (2) later diagenetic ‘blocky’ kaolinite. Combined hydrogen and oxygen isotopic studies suggest that vermiform kaolinite precipitated at 25–50°C, and blocky kaolinite at 50–80°C, from pore-waters of a similar isotopic composition (δ18O = −6.5 to −3.5‰). These pore-waters are interpreted to be either a mixture of meteoric and compactional waters, or alternatively a meteoric water that had evolved isotopically due to water-rock interaction. Kaolinite precipitation occurred predominantly during the late Cretaceous to early Eocene. Influx of meteoric water into the Brent Group, probably occurred during the Palaeocene. Fluid flow across the entire basin was driven by a hydrostatic head on the East Shetland Platform palaeo-landmass to the west. The development of the two kaolinite morphologies is possibly related to the degree of supersaturation at the time of precipitation. At low degrees of supersaturation, vermiform kaolinite precipitated slowly upon detrital mica surfaces. Blocky kaolinite precipitated more rapidly into open pore-space at higher degrees of supersaturation. Precipitation of blocky kaolinite was perhaps triggered by the decay of oxalate.

Mobility of Uranium, Thorium and Lanthanides Around the Bangombe Natural Reactor (Gabon)

1994 ◽  
Vol 353 ◽  
Author(s):  
R. Bros ◽  
F. Gauthier-Lafaye ◽  
P. Larque ◽  
J. Samuel ◽  
P. Stille
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Clay Minerals ◽  
Nuclear Reactor ◽  
Black Shales ◽  
Weathering Profile ◽  
The Core ◽  
Reducing Conditions ◽  
Isotopic Studies ◽  
Textural Evidence

AbstractNew mineralogical and isotopic studies were carried out on samples from the Bangombé natural nuclear reactor. This reactor is located at shallow depth in the weathering profile and has been subjected to severe supergene alteration. Textural evidence indicates partial dissolution of uraninite in the Bangombé ore related to precipitation of Fe-Ti oxi-hydroxides and clay minerals (kaolinite and metahalloysite). As a consequence of the alteration of the uraninite, uranium and f issiogenic rare earth elements were released in the clayey border of the reactor, whereas radiogenic 232Th remained confined in the close vicinity of the core. A retention effect is also evidenced, under reducing conditions, in the black shales located above the reactor.

ERRATUM: OXYGEN ISOTOPIC STUDIES OF AMPHIBOLITES

1965 ◽  
Vol 2 (4) ◽  
pp. 410-410
Author(s):  
H. P. Schwarcz ◽  
R. N. Clayton
Keyword(s):  
Isotopic Studies ◽  
Oxygen Isotopic

Paleobiological and isotopic studies of eggshells from a declining dinosaur species

Paleobiology ◽  
1979 ◽  
Vol 5 (4) ◽  
pp. 380-414 ◽  
Author(s):  
H. K. Erben ◽  
J. Hoefs ◽  
K. H. Wedepohl
Keyword(s):  
Isotopic Composition ◽  
Oxygen Isotopic Composition ◽  
Humid Climate ◽  
Physiological Mechanisms ◽  
Extant Species ◽  
Isotopic Studies ◽  
Spanish Pyrenees ◽  
Frequent Absence ◽  
Oxygen Isotopic ◽  
The Mean

Late Cretaceous dinosaur eggshells from southern France and the Spanish Pyrenees, presumably belonging to the sauropodHypselosaurus priscusMatheron, are almost exclusively composed of primary calcite. Besides normal development of these eggshells, there appear two kinds of pathologic tendencies: bi- or multi-shells (infrequent), and shells with a reduced thickness (increasing in frequency until, in the uppermost horizon, they represent more than 90% of the sample). The extinction of the species is attributed primarily to the consequences of thinning of the eggshells.The physiological mechanisms producing pathologic dinosaur eggshells are evaluated in the light of homologous phenomena occurring in living birds and reptiles. On this basis, it is concluded that in the late Maastrichtian populations of“Hypselosaurus,”pathologic eggshells were caused by hormonal imbalances of the vasotocin and of the estrogen levels. On the same basis it is postulated that the teratological shell repetition led to embryo suffocation and that the pathological reduction in shell thickness caused shell breakage and dehydration of the embryo. The lethal results are evident from the frequent absence of “resorption craters” in the mammillary knobs of pathologic shells, a fact which indicates either lack of fertilization of the eggs or the perishing of the embryo prior to the calcification of its skeletal bones. A change in environmental conditions is the ultimate factor which caused hormonal imbalances and extinction. Such a change is indicated by a shift of the mean oxygen isotopic composition (δ18O) of eggshell carbonates from −0.6%oto −5.3%o, and by changes in Sr. Information of palaeo-climate is primarily derived from eggshells of living birds and reptiles. The correlation between temperature and oxygen isotopic composition of waters (and related carbonates) is less distinct than for marine carbonates. δ13C ranges from −16.5 to −4.5 of eggshells of extant species indicate food from “normal” C3metabolism and from C4metabolism of plants in a dry climate.“Hypselosaurus”populations probably consumed “normal” C3plants. Using isotopic calibration of eggshell carbonates for the interpretation of δ13C and δ18O values of dinosaur eggshells, a slight change from higher to lower temperatures or a change from a dry to a more humid climate during the time from Lower (and Middle) to Late Maastrichtian can be assumed. The latter explanation is favored because the exceptionally high Sr in the Early Maastrichtian eggshells could be a potential indicator of co-existing evaporites.

Isotope Paleobiology of the Vertebrates: Ecology, Physiology, and Diagenesis

1998 ◽  
Vol 4 ◽  
pp. 101-137
Author(s):  
Reese E. Barrick
Keyword(s):  
Stable Isotopes ◽  
Tooth Enamel ◽  
Temperature Changes ◽  
Carbon And Nitrogen ◽  
Oxygen Oxygen ◽  
Dinosaur Extinction ◽  
Isotopic Analyses ◽  
Isotopic Studies ◽  
Oxygen Isotopic ◽  
Isotopic Variations

Isotopic studies of vertebrate material have a short history, while isotopic analyses of invertebrates originated in the 1940's. Interestingly, the driving force behind Harold Urey's desire to derive a carbonate paleotemperature scale in the 1940's and 1950's was the hope that it would solve the mystery of dinosaur extinction by demonstrating temperature changes at the K/T boundary. The most useful and commonly investigated stable isotopes for paleobiologic studies of vertebrates are carbon, nitrogen and oxygen. Oxygen is available from the inorganic bone or tooth apatite phase. Carbon is most often derived from tooth enamel carbonate or organic collagen, and nitrogen is derived from collagen. Each of these stable isotopes provides information on different aspects of an animal's biology and when combined, provide powerful analyses for ecological and evolutionary reconstructions. In the 1970's, much work was done describing the carbon and nitrogen variations in plants. This period was followed in the late 1970's and early 1980's by research on these isotopic variables in mammals (e.g., DeNiro and Epstein, 1978, 1981; Vogel, 1978; Van der Merwe, N.J., 1982). The utility of these isotopes for dietary recognition led to their extensive investigation in archeological studies. Not until the mid to late 1980's and 1990's have these isotopes been utilized in both the inorganic component of teeth and bones as well as the organic component of bones in Pleistocene and older paleobiologic studies. The 1980's also saw the emergence of research on the oxygen isotopic variations in mammals. However, the focus of isotopic studies on vertebrates was not for paleobiologic purposes, but rather, for attempts to derive paleohydrologic or paleoclimatic information from them (e.g., Longinelli, 1984; Luz et al., 1984).

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