bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymmetric distribution of metals in theXenopus laevisoocyte: a synchrotron X-ray fluorescence microprobe study
Authors: Popescu Bogdan Florin Gh. , Belak Zachery R. , Ignatyev Konstantin , Ovsenek Nick , Nichol Helen
Published: September 2007

The asymmetric distribution of many components of the Xenopus oocyte, including RNA, proteins, and pigment, provides a framework for cellular specialization during development. During maturation, Xenopus oocytes also acquire metals needed for development, but apart from zinc, little is known about their distribution. Synchrotron X-ray fluorescence microprobe was used to map iron, copper, and zinc and the metalloid selenium in a whole oocyte. Iron, zinc, and copper were asymmetrically distributed in the cytoplasm, while selenium and copper were more abundant in the nucleus. A zone of high copper and zinc was seen in the animal pole cytoplasm. Iron was also concentrated in the animal pole but did not colocalize with zinc, copper, or pigment accumulations. This asymmetry of metal deposition may be important for normal development. Synchrotron X-ray fluorescence microprobe will be a useful tool to examine how metals accumulate and redistribute during fertilization and embryonic development.
Cytoskeletal rearrangement and cell death induced by Bothrops alternatus snake venom in cultured Madin–Darby canine kidney cells
Authors: Nascimento Juliana Minardi , Franchi Gilberto Carlos , Nowill Alexandre Eduardo , Collares-Buzato Carla Beatriz , Hyslop Stephen
Published: September 2007

Bothrops snake venoms cause renal damage, with renal failure being the main cause of death in humans bitten by these snakes. In this work, we investigated the cytoskeletal rearrangement and cytotoxicity caused by Bothrops alternatus venom in cultured Madin–Darby canine kidney (MDCK) cells. Incubation with venom (10 and 100 µg/mL) significantly (p <0.05) decreased the cellular uptake of neutral red dye after 1 and 3 h. Venom (100 µg/mL) also markedly decreased the transepithelial electrical resistance (RT) across MDCK monolayers. Staining with rhodamine-conjugated phalloidin revealed disarray of the cytoskeleton that involved the stress fibers at the basal cell surface and focal adhesion-associated F-actin in the cell–matrix contact region. Feulgen staining showed a significant decrease in the number of cells undergoing mitosis and an increase in the frequency of altered nuclei. Scanning electron microscopy revealed a decrease in the number of microvilli and the presence of cells with a fusiform format. Flow cytometry with annexin V and propidium iodide showed that cell death occurred by necrosis, with little apoptosis, a conclusion supported by the lack of DNA fragmentation characteristic of apoptosis. Pretreating the cells with catalase significantly attenuated the venom-induced loss of viability, indicating a possible involvement of H2O2 in the cellular damage; less protection was observed with superoxide dismutase or Nω-nitro-l-arginine methyl ester. These results indicate that Bothrops alternatus venom is cytotoxic to cultured MDCK cells, possibly via the action of reactive oxygen species. This cytotoxicity could contribute to nephrotoxicity after envenoming by this species.
Apolactoferrin inhibits the catalytic domain of matrix metalloproteinase-2 by zinc chelation
Authors: Newsome Anthony L. , Johnson Jon Paul , Seipelt Rebecca L. , Thompson Michael W.
Published: September 2007

Lactoferrin (LTF) is a multifunctional iron-binding protein that is also capable of binding other divalent metal cations, especially Zn2+. Recent investigations indicate that lactoferrin levels are elevated in many disease conditions in which matrix metalloproteinases (MMPs), particularly MMP-2, are also elevated, suggesting that the 2 proteins may interact. This possibility was examined by determining the effect of LTF in its holo (metal-bound) and apo (metal-free) forms on the proteolytic activity of MMP-2 and other similar zinc metalloproteases. Pre-incubation with apolactoferrin, but not hololactoferrin, greatly reduced the hydrolysis of a peptide substrate by MMP-2, but not by MMP-1, -8, -9, or -13. This inhibition was specific for the 42 kDa catalytic domain fragment of MMP-2 lacking the hemopexin domain, since the 66 kDa form was poorly inhibited by apolactoferrin. The inhibition of the MMP-2 catalytic domain was strongly temperature sensitive, indicating that the conformation of one or both proteins is crucial to this interaction. To ascertain the mechanism of inhibition, increasing concentrations of ZnCl2and FeCl2were added to the reaction. While addition of Fe2+did not reverse inhibition, the addition of Zn2+resulted in a recovery of MMP-2 activity, and furthermore, zinc-saturated LTF did not inhibit MMP-2. Together, these data strongly suggest that apolactoferrin is capable of removing the catalytic zinc from the active site of MMP-2, although an exosite-based interaction between the 2 proteins cannot be fully ruled out. This inhibitory activity suggests a novel function for LTF and may represent a novel regulatory mechanism that regulates proteolysis by MMP-2 in vivo.
Hydrogen peroxide affects abscisic acid binding to ABAP1 in barley aleurones
Authors: Razem Fawzi A. , Hill Robert D.
Published: September 2007

Dramatic increases in H2O2 levels have been observed following abscisic acid (ABA) treatment of plant tissues. Following ABA treatment in aleurone cells, H2O2 reached transient levels of approximately 115 µmol/L H2O2. To determine whether ABA perception was modified by such changes, the effect of H2O2 on a recently characterized ABA-binding protein (ABAP1), cloned from barley aleurone layers, was examined. ABA binding to the protein was weakened by H2O2 in a concentration-dependent manner. A concentration of 75 µmol/L H2O2 gave a 50% decline in ABA binding in a reaction following first-order kinetics, indicative of binding-site susceptibility to its microenvironment. We monitored the unfolding of ABAP1 using steady-state and time-resolved tryptophan fluorescence, while following the capacity of ABAP1 to bind ABA. ABA binding decreased by 50% following ABAP1 denaturation with 1 mol/L guanidine hydrochloride or 2 mol/L urea, while the maximum emission spectra (λemi) red shifted from 338 to 347 nm at 3.5 mol/L guanidine hydrochloride and 5 mol/L urea. However, only a slight blue shift of λemi was observed following either ABAP1 incubation with H2O2 or binding to (+)-ABA (physiologically active ABA). The equilibrium ABA dissociation rate accelerated in the presence of 250 µmol/L H2O2, with the half-time dissociation reduced to 8 min. A comparison of inactivation kinetics and conformational changes shows that inactivation of ABAP1 occurs before any noticeable conformational change. This suggests that the ABA binding site is highly responsive to its microenvironment and is situated in a region that is more flexible than the protein molecule as a whole. The results demonstrate that H2O2, generated by ABA treatment of aleurone layers, is sufficient to affect the ABA-binding capacity of ABAP1, suggesting that this may be another level of control of ABA signal transduction.
Hydrostatic pressure sensation in cells: integration into the tensegrity model
Authors: Myers Kenneth A. , Rattner Jerome B. , Shrive Nigel G. , Hart David A.
Published: September 2007

Hydrostatic pressure (HP) is a mechanical stimulus that has received relatively little attention in the field of the cell biology of mechanotransduction. Generalized models, such as the tensegrity model, do not provide a detailed explanation of how HP might be detected. This is significant, because HP is an important mechanical stimulus, directing cell behaviour in a variety of tissues, including cartilage, bone, airways, and the vasculature. HP sensitivity may also be an important factor in certain clinical situations, as well as under unique environmental conditions such as microgravity. While downstream cellular effects have been well characterized, the initial HP sensation mechanism remains unclear. In vitro evidence shows that HP affects cytoskeletal polymerization, an effect that may be crucial in triggering the cellular response. The balance between free monomers and cytoskeletal polymers is shifted by alterations in HP, which could initiate a cellular response by releasing and (or) activating cytoskeleton-associated proteins. This new model fits well with the basic tenets of the existing tensegrity model, including mechanisms in which cellular HP sensitivity could be tuned to accommodate variable levels of stress.
Onset–potency relationship of nondepolarizing muscle relaxants: a reexamination using simulations
Authors: Bhatt S.B. , Amann A. , Nigrovic V.
Published: September 2007

Nondepolarizing muscle relaxants (MRs) display an inverse onset–potency relationship, that is, less potent MRs display a more rapid onset. We have conducted the current investigation to estimate the impact of variable pharmacokinetic or pharmacodynamic properties of the MRs on potency and onset time, and on the onset–potency relationship. Using a model of neuromuscular transmission, we changed either the affinity of MRs for the postsynaptic receptors or the pharmacokinetic properties of the MRs. The elimination rate constant, k10, which defines the systemic clearance, was assigned one of 9 values and the transport rate constant, k12, one of 5 values. The transport rate constant into the effect compartment was constant (ke1 = 0.2 min–1). Only one parameter was altered at a time. With constant pharmacokinetics, a 100-fold decrease in affinity caused a proportional decrease in potency, but little change (0.02 min) in onset time. With constant affinity, increasing the clearance from 1 to 250 mL·kg–1·min–1 shortened the onset time from 7.2 to 0.7 min and decreased the potency 12-fold. In a double logarithmic plot, the onset–potency relationship was linear. Lesser affinities produce a nearly parallel rightward shift of the regression lines. The inverse onset–potency relationship may be explained by the pharmacokinetic factors producing changes in both the potency and onset times.
Reduction of asymmetric dimethylarginine involved in the cardioprotective effect of losartan in spontaneously hypertensive rats
Authors: Li Dai , Xia Ke , Li Nian-Sheng , Luo Dan , Wang Shan , Jiang De-Jian , Deng Han-Wu , Li Yuan-Jian
Published: September 2007

Previous studies have indicated that nitric oxide synthase (NOS) inhibitors can induce an increase of blood pressure and exacerbate myocardial injury induced by ischemia and reperfusion, whereas angiotensin II receptor antagonists protect the myocardium against injury induced by ischemia and reperfusion. Isolated hearts from male spontaneously hypertensive rats (SHR) or male Wistar-Kyoto rats (WKY) were subjected to 20 min global ischemia and 30 min reperfusion. Heart rate, coronary flow, left ventricular pressure, and its first derivatives (±dP/dtmax) were recorded, and serum concentrations of asymmetric dimethylarginine (ADMA) and NO and the release of creatine kinase in coronary effluent were measured. The level of ADMA was significantly increased and the concentration of NO was decreased in SHR. Ischemia and reperfusion significantly inhibited the recovery of cardiac function and increased the release of creatine kinase, and ischemia and reperfusion-induced myocardial injury in SHR was aggravated compared with WKY. Vasodilation responses to acetylcholine of aortic rings were decreased in SHR. Treatment with losartan (30 mg/kg) for 14 days significantly lowered blood pressure, elevated the plasma level of NO, and decreased the plasma concentration of ADMA in SHR. Treatment with losartan significantly improved endothelium-dependent relaxation and cardiac function during ischemia and reperfusion in SHR. Exogenous ADMA also aggravated myocardial injury induced by ischemia and reperfusion in isolated perfused heart of WKY, as shown by increasing creatine kinase release and decreasing cardiac function. The present results suggest that the protective effect of losartan on myocardial injury induced by ischemia and reperfusion is related to the reduction of ADMA levels.
Statin treatment increases formation of carbon monoxide and bilirubin in mice: a novel mechanism of in vivo antioxidant protection
Authors: Muchova Lucie , Wong Ronald J. , Hsu Mark , Morioka Ichiro , Vitek Libor , Zelenka Jaroslav , Schröder Henning , Stevenson David K.
Published: September 2007

Heme oxygenase (HO) has a central role in cellular antioxidant defences and vascular protection, and it may mediate pleiotropic actions of drugs used in cardiovascular therapy. We investigated whether long-term use of statins upregulates HO activity and increases carbon monoxide (CO) and bilirubin levels in vivo. Adult FvB mice were given atorvastatin or rosuvastatin (5 mg/kg) daily by i.p. injections for 1, 2, or 3 weeks. HO activity, tissue CO, bilirubin, and antioxidant levels, total plasma bilirubin, and carboxyhemoglobin (COHb) were measured. Fold changes in heart HO activity significantly increased after 1, 2, and 3 weeks of atorvastatin (1.24 ± 0.06 (p ≤ 0.05); 1.29 ± 0.26 (p ≤ 0.03); 1.33 ± 0.08 (p < 0.01), respectively) and 2 and 3 weeks of rosuvastatin (1.23 ± 0.20 (p ≤ 0.03); 1.63 ± 0.42 (p < 0.01), respectively). Heart tissue CO and COHb levels also increased after 3 weeks with atorvastatin (1.30 ± 0.24 (p ≤ 0.05); 1.92 ± 0.17 (p ≤ 0.001), respectively) and rosuvastatin (1.47 ± 0.13 (p ≤ 0.004); 1.63 ± 0.12 (p ≤ 0.001), respectively). Significant increases in heart antioxidant levels were observed after statin treatment and corroborated by heart bilirubin content elevations. Antioxidant level increases were abolished by treatment with an HO inhibitor. These findings suggest that the induction of HO and the production of its products, CO and bilirubin, may be a mechanism by which statins exert antioxidant actions and confer cardioprotection in vivo.
FUTURE-ORIENTED MINDSET'S CONTRIBUTION TO MANAGEMENT OF CORPORATE R&D PERSONNEL MOTIVATION IN JAPAN
Authors: SHIRAHADA KUNIO , NIWA KIYOSHI
Published: September 2007

Addressing the decreasing motivation of R&D personnel in Japan, this paper analyzes the relations between motivation and R&D personnel's future-oriented mindset and the time-climate in their workplace. Questionnaires were given to 240 corporate R&D personnel in six Japanese companies. ANOVA results show that highly motivated personnel have longer-term perspectives about ability growth than do personnel with low motivation levels. In a Japanese automobile company we confirmed the positive impact on work motivation of having managers focus on the future-oriented mindset of subordinates during annual goal-setting interviews.
MEASURING THE SCIENCE-TO-MARKET GAP — THE CASE OF NEW ENERGY TECHNOLOGIES
Authors: INGANÄS MARTIN , HARDER MIKAEL , MARXT CHRISTIAN
Published: September 2007

With the aim of improving our understanding of the factors that affect the commercialization of new energy technologies (NET), this paper investigates the NET science-to-market gap for the European context. The results from interviews as well as a survey indicate that there is substantial disagreement regarding the importance of intellectual property rights and venture capital. We also found strong evidence that the stakeholders have low faith in each other. Arguing that science-industry interaction is a key ingredient for bringing NET to the market, we suggest that the science-to-market gap is rooted in different stakeholder preferences and expectations.
FIRM PERCEPTIONS OF COMPETITIVE ADVANTAGE OF NEW UNIVERSITY TECHNOLOGY AND THEIR IMPACT ON EXCLUSIVITY OF LICENSING TRANSACTIONS
Authors: VAN DEN BERGHE LARRY , GUILD PAUL D.
Published: September 2007

Commercialization of new university technology within the new product development process is an important tool by which established firms can expand their innovative capabilities. The competitive advantage afforded by new university technologies, however, varies considerably. An exclusivity agreement is a useful tool to protect the firm's investment and help ensure that value is appropriated through the commercialization process. An empirical study of 66 technology transfer projects in the information and communications technology industry reveals that when the firm's perception of competitive advantage afforded by the new technology is high, the licensing transaction is usually secured by some form of exclusivity agreement.
The history of attempts to establish a quantitative time-scale
Authors: Wager L. R.
Published: September 2007

The great age of the Earth was first scientifically argued by Hutton in the eighteenth century. Next, a world-wide time-order scale of geological events was established using the biostratigraphic methods of William Smith. In the second half of the last century ‘hour-glass’ methods, based on salinity of the oceans and the maximum thickness of sediment, provided a framework for a rough time-scale, measured in years. The development of a reasonably detailed and satisfactory time-scale for geology is, however, an achievement of the present century and has been accomplished by using as an hour-glass method the rate of radioactive decay of certain elements present in rocks and minerals of known position in the time-order scale.

In 1913, from tentative radiometrically established ages, Holmes produced a quantitative Phanerozoic time-scale, and he and others have gradually refined it. In linking the isolated dates obtained by radiometric methods with the biostratigraphic time-scale, use has usually also been made of the maximum thicknesses of sediments accumulated in the various intervals of the time-order scale, and this is believed to be still the most useful method.
Sedimentation rates in relation to the Phanerozoic time-scale
Authors: Hudson J. D.
Published: September 2007

Sedimentation rates combined with stratigraphical correlation provided the earliest reasonably objective geological time-scales, but these were at best crude approximations. Later, sedimentation rates were used only to interpolate between radiometrically determined ages. The hypothesis that average maximum rates of sedimentation (or subsidence) have increased during Phanerozoic time is discussed and it is concluded that the evidence for it is unsatisfactory.
The relationship between radiometric ages obtained from plutonic complexes and stratigraphical time
Authors: Lambert R. St J.
Published: September 2007

For most of Phanerozoic time errors in radio- metric ages are usually approximately 3 per cent. except for Rb-Sr results from Mesozoic and Tertiary minerals, which must have high Rb/Sr ratios to give such low errors. Rates of uplift appear to be of the order of 10 cm/100 years for sustained movement; in consequence, uplift will normally take place within the error of an age except for post-Jurassic examples. The age obtained for a plutonic complex marks the time of closure of radiogenic systems: the available data indicate that this effectively takes place at about 200°C for the most retentive minerals, but this figure is subject to considerable uncer- tainty. Closure of systems at low temperatures poses several problems, which are discussed. It is concluded that there is much uncertainty about the stratigraphical meaning of ages obtained from minerals from large plutonic complexes.
The rubidium–strontium method
Authors: Moorbath Stephen
Published: September 2007

The principles, applications, and limitations of the Rb-Sr age method are reviewed, with particular reference to the geological time-scale.
Potassium—argon ages of sedimentary and pyroclastic rocks
Authors: Baadsgaard Halfdan , Dodson Martin Henry
Published: September 2007

It is rarely possible to obtain reliable potassiumargon ages from sedimentary rocks. Glauconites generally give dates that are too low and very scattered, though the largest of a group of such measurements may be useful to define minimum ages of sediments that cannot be dated in any other way. Illite dates are subject to opposing systematic errors: because of this they may coincide roughly with the age of the sediment, but they cannot be regarded as reliable. Sylvines lose argon easily, though they may give good potassium-calcium dates.

From bentonites and volcanic ashes biotite, sanidine, and low-potassium feldspars have all been successfully dated. Contamination by old detritus is sometimes a problem, but the dates obtained from different minerals generally agree well, showing that the results are reliable. The wide geographical distribution of bentonites gives them a special value for time-scale work.
Glauconite dates from the Upper Jurassic and Lower Cretaceous
Authors: Dodson Martin Henry , Rex David Charles , Casey Raymond , Allen Percival
Published: September 2007

Few dates are available from stratigraphically well-documented igneous materials of late Jurassic and early Cretaceous age. Glauconite dates therefore have a special interest despite the geochronological limitations of the mineral. Evidence from the Albian and Cenomanian, moreover, shows that some Mesozoic glauconites give results only slightly lower than the probable correct dates.

New glauconite determinations from sedimentary rocks near the Jurassic–Cretaceous boundary include four English dates close to 130 m.y. Those from Greenland and Russia are lower, ranging between 107 and 117 m.y. Published information concerning comparable stratigraphical horizons also includes low values and several near 130 m.y.

Our results suggest that the Jurassic–Cretaceous boundary (sensu borealis) is a little older than 130 m.y. They are thus consistent with the figure of 135 m.y. assigned to the boundary by Holmes and Kulp.
The age of the paroxysmal Variscan orogeny in England
Authors: Fitch Frank Joseph , Miller John Alfred
Published: September 2007

Potassium–argon age-determinations on 10 basic igneous rocks from the English Midlands indicate two distinct episodes of magmatic intrusion. Geological evidence and Permo-Carboniferous isotopic age data from Britain confirm the well-known close relationship between magmatism and earth-movements. It is concluded that the paroxysmal phase of the Variscan orogeny in England occurred in the early Stephanian (Asturic phase), and that late-tectonic granitic magmatism in the active zone was penecontemporaneous with basaltic magmatism on the foreland around 295 m.y. A further period of basaltic magmatism close to 265 m.y. is equated with Saalic movements, and it is suggested that a primary mineralization event at 225 m.y. is of widespread occurrence and might be used to fix the Permo-Triassic boundary in Britain.
The Cretaceous period
Authors: Casey Raymond
Published: September 2007

Fifty significant items from the large body of radiometric data on the Cretaceous period are reviewed and the following dates are acceptedas a basis for discussion: Jurassic-Cretaceous (Volgian-Ryazanian) boundary: 136 m.y.; Lower Cretaceous-Upper Cretaceous (Albian-Cenomanian) boundary: 100 m.y.; Upper Cretaceous-Tertiary (Maestrichtian-Danian) boundary: 64 m.y. A precise scale of geochronology for this period is impeded by inadequate stratigraphical dating of igneous events, unreliability of results from sedimentary sources (glauconite), and lack of international agreement on the limits of the Cretaceous System.
The Jurassic period
Authors: Howarth Michael Kingsley
Published: September 2007

Seven critical biotite ages and five minimum glauconite ages for the Jurassic are discussed in relation to the time-scales of Holmes (1959) and Kulp (1961). It is proposed that the date for the base of the system should be amended to 190-5 m.y., the date for the end of the period remaining at 135 m.y.; the estimate for the length of the Jurassic is thus increased by 10 or 15 m.y. to 55–60 m.y.
The Carboniferous period
Authors: Francis Edward Howel , Woodland Austin William
Published: September 2007

It is estimated that the duration of Carboniferous time was 65 m.y., extending from 345 to 280 m.y. ago. Using age-determinations made on sediments, contemporaneous volcanic rocks, and intrusive rocks that have varying degrees ofstratigraphical control, a provisional Carboniferous time-scale is proposed. In terms of the standard European succession, to which most of the critical data pertains or can be related, it is as follows:
The Devonian period
Authors: Friend Peter Furneaux , House Michael Robert
Published: September 2007

A review of the radiometric evidence suggests that the top of the Devonian should be dated at about 345 m.y. and the base of the system at about 395 m.y. Using cumulative thickness methods the age of the base of the Upper Devonian is estimated at 358 m.y. and that of the base of the Middle Devonian at 370 m.y. Famennian ammonoid species zones must each represent about a million years. Suggestions are made as to where future radiometric work of importance to the time-scale might be undertaken.
The role of the Department of Energy in petroleum exploration of the United Kingdom
Authors: Walmsley P. J.
Published: September 2007

Three Divisions of the U.K. Department of Energy have responsibility for petroleum. Oil Division handles policy including Licence administration. Gas Division handles gas policy. All technical matters relating to exploration, development and safety are handled by Petroleum Engineering Division (PED). Their role is to advise Ministers on exploration and development policy and to carry out the policy so decided.

Exploration Branch of PED has three sections: Geological, Geophysical and the Well Record Centre. To advise Ministers, Exploration Branch requires a comprehensive knowledge of U.K. geology and prospects. All data received from operators is passed on a confidential basis to the hydrocarbons Unit of the Institute of Geological Sciences where the review work is carried out on the Department’s behalf. Exploration Branch recommends areas for licensing, interviews applicants to determine their suitability as licensees and negotiates work programmes with selected applicants. Additional responsibilities include technical appraisal of fields, the determination of field boundaries for tax purposes and the estimation of reserves.

Exploration Branch works closely with the Development, Projects and Administration Branches of PED in the approval of development plans and field monitoring. The Safety, Pipelines, Diving and Research Branches of PED play an active role in the control of exploration and development operations.
Exploration of the Norwegian Shelf
Authors: Rønnevik Hans , Eggen Svein , Vollset Jan
Published: September 2007

The drilling activity on the Norwegian Shelf has reached a level of more than 40 wells per year. Exploration licensing has taken place in seven rounds. The success rate on the Norwegian Shelf are very high both in the North Sea and area to the north.

In the North Sea three exploration models are established, the Chalk play, the Lower Tertiary deep sand play and Jurassic and older pre unconformity sand. Common for all the plays are Jurassic source rocks. In the north the established play types are related to pre unconformity Jurassic-Upper Jurassic sand.
Stratigraphy and Sedimentation of the Palaeocene Sands in the Northern North Sea
Authors: Mudge D. C. , Bliss G. M.
Published: September 2007

The Palaeocene of the North Sea basin between 58°N and 62°N contains a number of reservoir sands. The regional tectonic setting, which was dominated by subsidence in the Viking Graben and Witch Ground Graben areas had an important influence on the thickness and distribution of the Palaeocene sands. Following deposition of the Danian, middle Palaeocene sedimentation was controlled by uplift and faulting along the flanks of these areas with large quantities of sand being shed off the East Shetland Platform. These sands were deposited in a nearshore shallow marine environment. With a decrease in tectonism, late Palaeocene deposition was dominated by the outbuilding of a delta system in the Moray Firth area with the northward spread of sands along the edge of the East Shetland Platform. At this time, the basin became increasingly cut off from open marine circulation. The top of the Palaeocene is marked by a regional unconformity representing a late Palaeocene-early Eocene transgression which affected much of northwestern Europe.
Aspects of Burial Diagenesis, Organic Maturation and Palaeothermal History of an Area in the South Viking Graben, North Sea
Authors: Pearson M. J. , Watkins D. , Pittion J-L , Caston D. , Small J. S.
Published: September 2007

A detailed study has been made of changes in interlayered clay minerals, sediment mineralogy, vitrinite reflectance, kerogen composition, and chemistry of the soluble organic extract through Well 16/22-2 in the South Viking Graben. The well sampled sediments range in age from Oligocene to, at total depth, Middle Jurassic (Dogger).

Lithologies are typical of the South Viking Graben/Central Graben area with Upper Jurassic black pyritic shales, a thick Cretaceous chalk succession and prominent top Palaeocene tuff. Sandstones are common only in the Upper Jurassic Palaeocene and Eocene. Tuffs are sporadically present in the Middle Jurassic. Randomly interlayered illitesmectite is the dominant clay mineral through the Tertiary and Cretaceous and the change to an ordered structure which occurs just above the Jurassic/Cretaceous unconformity is interpreted as a diagenetic reaction. Estimates of illite-smectite composition indicate a reversal to smectite rich clays in the Lower Eocene-Top Palaeocene which is attributed to an insufficient supply of K
+
from detrital feldspar and mica due to the dominance of basic volcanic weathering products.

The vitrinite reflectance profile for this well indicates progressive maturation of kerogen to marginal maturity in the Upper Jurassic. A large jump of 0.2% R
o
occurs at the Upper/Middle Jurassic boundary below which kerogen maturity is at the peak oil-generating stage. This maturation break is supported by an increase in spore colour index. Chemical parameters are strongly influenced by a change in kerogen type from mixed algal and humic to predominantly humic at this stratigraphic level. Very high heat flow due to localized intrusive igneous activity during the late Middle Jurassic is thought to have caused the increased maturity of the Middle Jurassic sediments.
Kerogen Types, Organic Maturation and Hydrocarbon Occurrences in the Moray Firth and South Viking Graben, North Sea Basin
Authors: Fisher M. J. , Miles Jennifer A.
Published: September 2007

Kerogen typing and maturation studies have been conducted in order to rationalise the variations in hydrocarbon types observed in the Moray Firth and South Viking Graben in the U.K. North Sea. The distribution of terrestrially-derived kerogen follows accepted models for water-borne transport. The occurrence of amorphous debris of algal origin in significant amounts is related to variations in the environment of deposition. Although the relationship between the major kerogen groups and their range of hydrocarbon product is established, the type and quantity of generated hydrocarbons could only be predicted from organic facies if the maturity of the source rocks were known. Maturity maps were therefore constructed from thermal gradients, burial histories and measured maturity (spore colour). The resulting predictive model of the distribution of oils, condensate and gas correlates favourably with observed hydrocarbon occurrences and is now an integral part of Britoil’s ongoing exploration programme.
Geochemistry of North and South Brae Areas, North Sea
Authors: Reitsema R. H.
Published: September 2007

The Brae area of the North Sea has at least two types of crude oils present. Kimmeridgian shales are the source for both oils. The geologic setting, based on a fan delta model, is similar for both and, as expected, the oils are similar in many ways. No significant differences appear in maturity, carbon isotopic ratios or gas chromatographic analyses. The oils can be distinguished, however, by use of multiple geochemical parameters. Quantities and various ratios of pristane, phytane, normal paraffins and gasoline range components are characteristic for each area of Brae. Relative amounts of saturates and aromatics and GC/MS patterns are also useful characterization methods.
The Search for Petroleum in Northern Ireland
Authors: Griffith A. E.
Published: September 2007

Although a considerable amount of exploration is currently taking place in Northern Ireland and in the Republic of Ireland, no commercially exploitable petroleum has yet been found on land.

Interest in searching for petroleum in Northern Ireland is relatively recent. In 1957 a number of small American oil companies became interested in the prospects in the South of Ireland and after encountering small flows of gas in two wells drilled in the Carboniferous, exploration was extended to include parts of N. Ireland.

This paper outlines the geological mapping and drilling programme which has been undertaken by the Geological Survey of N. Ireland and which has recently accompanied by experimental vibroseis surveys, some over the Tertiary basalt outcrop. It is hoped that these studies will establish the geological framework to facilitate further petroleum exploration. In particular, the prospect that petroleum sourced by Carboniferous strata, underlying extensive Mesozoic and Cainozoic outcrops in the NE of Ireland will be considered.
Origins of Natural Gas in the Po Valley, N. Italy
Authors: Mattavelli L. , Ricchiuto T. , Grighani D. , Schoell M.
Published: September 2007

A study on natural gases sampled from 48 gas fields in the Po Basin is reported. A total of 155 wells are involved in the present work, representing 90% of the total original gas in place. The chemical and isotopic analyses have been considered based on the regional geological setting.

A correlation between chemical and isotopic composition is shown by the presence of pure and isotopically light methane (13C from −76 to −60 parts/10
18
) in the Plio-Pleistocene fields and by gas less depleted in 13C (13C from −60 to −30 parts/10
18
) and associated with heavier hydrocarbons in Miocene and Mesozoic gas fields.

No relationship exists within the Tertiary sequences between depth and isotopic composition.

The organic matter of the Tertiary sequences is mainly of terrestrial origin and is immature down to 5000 m.

On the basis of these data it is possible to distinguish three types of methane in the Po Basin:

(1)

Biogenetic and/or diagenetic gas (80% of the original gas in place) from Tertiary reservoirs, originated
in situ
from terrestrial immature organic matter of the Tertiary sequence themselves.

(2)

Thermogenetic gas (10% of the original gas in place) which migrated from more than 5000 m depth, associated with heavier hydrocarbons.

(3)

Gas of mixed origin (10% of the original gas in place).

The areal distribution and the amount of the three types of methane are strictly controlled by geological factors. As a matter of fact the synsedimentary tectonics and the turbiditic sedimentation have determined the best conditions for the trapping of the biogenetic gas in the southeastern part of the area, where 70% of the original Tertiary gas in place is present. In the pedealpine homocline sediments have not been affected by strong Plio-Pleistocene folding, and therefore only a small amount of biogenetic gas was accumulated in the stratigraphic and in the rare structural traps. On the other hand the thermogenic methane is found in the vicinity of the Apennines where strong tectonic movements have favoured its migration from deeper zones and into Mezozoic deposits of the pedealpine homocline.

Furthermore for the first time the presence of pure isotopically light methane is here reported at 4500 m depth, that is from depths greater than so far reported in literature (3350 m). This fact is due to peculiar geological settings of the southeastern area comprising the low geothermal gradient, the synsedimentary tectonics and the strong Plio-Pleistocene subsidence (8000 m).
Selection Criteria for the Use of Vitrinite Reflectance as a Maturity Tool
Authors: Buiskool Toxopeus J. M. A.
Published: September 2007

The increase in temperature during burial of a source rock results in a series of progressive diagenetic changes in the organic matter, one of them being the generation of oil and/or gas in the maturity zone. These diagenetic changes (maturity level) can be measured by vitrinite reflectance. Microscopical investigation together with extensive vitrinite reflectance measurements on coals and coaly shales indicate that various types of vitrinite can occur. Two main groups of vitrinite can be distinguished:

Vitrinite-1
is a relatively hydrogen-poor vitrinite formed in the peat swamp environment. In the vitrinite-1 group common submacerals such as telinite, telocollinite and corpocollinite are found.

Vitrinite-2
is relatively hydrogen-rich. Vitrinite-2 can be distinguished from vitrinite-1 by its (weak) fluorescence during ultraviolet irradiation and by a lower reflectance. Detrital vitrinite particles are often vitrinite-2.

In conventional coal petrology, vitrinite reflectance is measured exclusively on telocollinite. As the maturity is measured by the same vitrinite reflectance scale, it is of great importance to select the higher reflecting vitrinite-1 for measurements instead of the lower reflecting vitrinite-2. In this paper selection criteria are described for the use of vitrinite reflectance. In a number of examples the variation of reflectance between these two types of vitrinite and its implication for exploration are reported.
Commercially Available Geological Databanks—U.K.C.S.
Authors: Wigley P.
Published: September 2007

There are two major commercially available databanks which contain geological data from the U.K.C.S. They are operated by Petroconsultants Ltd. and ERICO Research Labs Ltd. This paper deals primarily with the ERICO system, but a brief review of the Petroconsultants’ system is also given.
EXPHST—A Program to Analyse the History of Exploration Success within a Basin or Country
Authors: Chew K. J. , Stephenson H.
Published: September 2007

EXPHST is a program written to search for, extract and manipulate information contained in two of Petroconsultants’ petroleum exploration data banks. The objective of the program is to provide statistical data regarding trends in the exploration history of a basin, country or other areas. The data thus derived describe drilling and discovery rates and various aspects of oil and gas production and reserves.

This paper describes the nature of the data banks from which the data are obtained, the operation of the EXPHST program, and some limitations and possible extensions of the method.

Finally, as an illustration of the program output, the exploration history of the U.K. continental shelf is described.
Oscillating modes of orogeny in the Southwest Pacific and the tectonic evolution of New Caledonia
Authors: Rawling T. J. , Lister G. S.
Published: September 2007

This paper presents a new interpretation of the tectonic evolution of New Caledonia, based on the extrapolation of detailed structural analysis at several different scales. The coherent high-pressure schist belt of northern New Caledonia contains clear evidence for cyclicity in the orogenic process. Two switches from large-scale crustal shortening to extensional tectonism can be recognized. We propose that orogenesis initially resulted in significant crustal thickening, obduction, and high-pressure (15–20 kbar) metamorphism. There is a close temporal link between ophiolite emplacement and high-pressure metamorphism. The high-pressure rocks were exhumed during the first period of extensional tectonism (
c.
40–36 Ma) as a large coherent terrane (>1500 km
2
). During the second period of crustal shortening the New Caledonia orogen was folded into upright megafolds. Basin and Range style normal faulting then took place, bringing the folded extensional terrane and the high-pressure rocks to their present crustal level. Metamorphic grade changes in the high-pressure belt are structurally controlled by these late-stage normal faults. However, movement on these faults is responsible for only the very last stages of exhumation.
Exhumation history of orogenic highlands determined by detrital fission-track thermochronology
Authors: Garver John I. , Brandon Mark T. , Roden-Tice Mary , Kamp Peter J. J.
Published: September 2007

A relatively new field in provenance analysis is detrital fission-track thermochronology which utilizes grain ages from sediment shed off an orogen to elucidate its exhumational history. Four examples highlight the approach and usefulness of the technique. (1) Fission-track grain age (FTGA) distribution of apatite from modern sediment of the Bergell region of the Italian Alps corresponds to ages obtained from bedrock studies. Two distinct peak-age populations at 14.8 Ma and 19.8 Ma give calculated erosion rates identical to
in situ
bedrock. (2) Zircon FTGA distribution from the modern Indus River in Pakistan is used to estimate the mean erosion rate for the Indus River drainage basin to be about 560 m Ma
−1
, but locally it is in excess of 1000 m Ma
−1
. (3) FTGA distribution of detrital apatite and zircon from the Tofino basin records exhumation of the Coast Mountains in the Canadian Cordillera. Comparison of detrital zircon and apatite FT ages gives exhumation rates of
c.
200 m Ma
−1
during the interval between
c.
34 and 54 Ma, but higher rates (
c.
1500 m Ma
−1
) at
c.
56 Ma. (4) FTGA analysis of apatite grain ages from a young basin flanking Fiordland in New Zealand indicates that removal of cover strata was followed by profound exhumation at
c.
30 Ma, which corresponds to plate reorganization at this time. Exhumation rates at the onset of exhumation were
c.
2000–5000 m Ma
−1
. These studies outline the technique of detrital FTGA applied to exhumation studies and highlight practical considerations: (1) well-dated, stratigraphically coordinated suites of samples that span the exhumation event provide the best long-term record; (2) strata from the basin perimeter are the most likely to retain unreset detrital ages; (3) the removal of ‘cover rocks’ precedes exhumation of deeply buried rocks, which retain a thermal signal of the exhumation event; (4) steady-state exhumation produces peak ages that progressively young with time and have a constant lag time; (5) same-sample comparison of zircon and apatite peak ages is best in sequences with high-uranium apatite grains (>50 ppm), and peak-ages statistics can be improved by counting numerous apatite grains (>100).
Detachment faults in the Aegean core complex of Ios, Cyclades, Greece
Authors: Forster M. A. , Lister G. S.
Published: September 2007

Several generations of detachment fault systems have been recognized in the Aegean metamorphic core complex of Ios, Cyclades, Greece. Multiple strands occur in each fault system, with fault-bounded slices often characterized by distinctive lithologies. These faults accomplished significant exhumation, and telescoped the crustal section. Different slices have been deformed at different crustal levels, and then juxtaposed, so that adjacent fault slices display different deformation styles. The Aegean detachment systems differ from equivalent faults observed in the US core complexes in that they separate relatively cohesive tectonic slices. However, the Aegean detachments are dissected by the multiple systems of later high-angle normal faults that define the current geomorphology, and this raises significant difficulties in correlating detachment systems between the different islands of the Cycladic archipelago. A number of distinct extensional events can be defined on Ios. The Cycladic blueschist belt was exhumed relatively early during the history of Alpine orogeny, after it had been thrust over a Hercynian ‘basement’ terrane, with the oldest recognized detachment faults associated with Miocene N-S extension. This led to the exhumation of the ‘basement’ terrane from beneath the blueschist ‘series’ rocks. The Ios Detachment Fault system now separates the metasediments of the Cycladic blueschist belt from the mylonitized ‘basement’ complex. It was associated with the operation of the south-directed, crustal-scale, middle to upper greenschist facies, South Cyclades Shear Zone. The youngest detachment faults formed during late-stage W-directed extension, and formed a prominent sequence of low-angle normal faults termed the Coastal Fault system. These were associated with spectacular breccias, and relatively narrow ductile shear zones which formed during and subsequent to the formation of the Ios dome, under significantly lower grade conditions (lower-greenschist facies assemblages). Final exhumation of the Cycladic blueschist belt appears to have been associated with the detachment faults that led to its exposure beneath non-metamorphic sediments, and remnants of the Cyclades ‘ophiolite nappe’ as observed on adjacent islands.
Controls on pseudotachylyte formation during tectonic exhumation in the South Mountains metamorphic core complex, Arizona
Authors: Goodwin Laurel B.
Published: September 2007

Pseudotachylyte formed during the later stages of extension in the South Mountains metamorphic core complex. Microstructural and microchemical evidence of pseudotachylyte formation processes is well preserved in granitoid mylonite host rocks because of rapid cooling during tectonic exhumation. Petrographic studies indicate a cataclasite precursor to pseudotachylyte. Transmission electron microscope analysis shows glass in pseudotachylyte, providing evidence of melting. Electron microprobe analyses demonstrate variations in glass, microlite, and crystallite composition with proximity to quartz clasts, indicating reaction between clasts and melt. Amphibole crystallites exhibit sieve textures, interpreted as recording rapid crystallization and subsequent decompression. Decompression is postulated to result from drops in fluid pressure along jogs in the slip surface or following formation of injection veins. Both pseudotachylyte and cataclasite are typically subparallel to C-surfaces in the host mylonite. Cataclasite not associated with pseudotachylyte is composed of quartz + feldspars ± biotite. Pseudotachylyte everywhere contains biotite. The model proposed for formation of pseudotachylyte and cataclasite in foliated granitoid protoliths includes seismic failure along C-surfaces. Where biotite is absent, slip produces cataclasite. Where biotite is present, initial cataclasis may be followed by frictional melting, facilitated by biotite’s low melting temperature and lowering of the melting temperatures of other phases by release of water during biotite breakdown.