bluuebunny/crossref_metadata_2025 huggingface dataset:
POROSITY MODELS AND OIL EXPLORATION OF AMAPÁ CARBONATES, PALEOGENE, FOZ DO AMAZONAS BASIN, OFFSHORE NW BRAZIL
Authors: Carozzi Albert V.
Published: December 2007

The extensive, thick Paleogene carbonate platform (Amapá Formation) of the Foz do Amazonas Basin, probably the largest coralgal‐foraminiferal platform of the geological record, developed through four depositional cycles expressing global eustatic changes of sea level. It shows five environmental belts: slope, apron, coralgal platform, large foraminifer shoal, finger coral bank and restricted lagoon, all of which associate bioaccumulated and bioclastic microfacies. At all times, a terrigenous environment consisting of fan deltas and lagoonal fine‐grained clastics existed immediately behind the carbonate platform and was connected with the open ocean by transverse troughs filled with shales and carbonate olistoliths. This combination of clastic and carbonate environments is unique in the geological record, and today only the Belize Shelf displays comparable conditions.

The patterns of distribution of porous carbonates are different for each depositional cycle and the percentage of porous carbonates increases from cycle II to cycle IV. This indicates distinct and successive reservoir conditions generated during episodes of subaerial exposure of an expanding platform by large‐scale circulation systems at the end of each depositional cycle when high‐stand sea level changed to low‐stand. Porosity is mainly enlarged interparticle and moldic with a minor contribution of intercrystalline type related to dolomitization by mixing freshwater‐marine waters. It is not known to what extent the terrigenous environment contributed to the meteorically supplied groundwater system and related dolomitization, but the scale of the circulation is comparable to that presently displayed by Florida and Yucatan.

The possibility of hydrocarbon flushing from such carbonate reservoirs is an important factor in the evaluation of the petroleum potential of the Amapá carbonates.
IMPACT CRATERS:IMPLICATIONS FOR BASEMENT HYDROCARBON PRODUCTION
Authors: Donofrio Richard R.
Published: December 2007

The impact cratering process results in unique structures and extensive fracturing and brecciation of the target rock which can be conducive to hydrocarbon accumulations. Examination of Viewfield and Red Wing Creek oil pools in North America reveals that they may have been formed by meteoritic impact in Paleozoic sediments. Additional hydrocarbon traps have most likely been produced by impact but have not been recognized as such because geologists are generally not familiar with crater structures and shock‐metamorphic effects in rocks. It is proposed that petroliferous basement impact craters also exist and that despite arguments to the contrary, at least one may have already been found. Further discoveries are severely limited because of conservative exploration procedures, which characteristically avoid penetrating crystalline basement.

Core analysis from several large impact sites developed in crystalline rocks reveals that while permeability factors are marginal, the reservoir potential of these craters exceeds those of many of the largest known hydrocarbon accumulations. Preservation age studies of craters in conjunction with size frequency distribution curves implies that many will have been buried before erosional eradication. As with normally‐fractured and brecciated basement areas, some will have accumulated hydrocarbons. In addition to classical source rocks flanking or overlying these potential reservoirs, recycled kerogen and the possibility of inorganic sources are also considered. A basement impact crater may afford a unique way of testing the inorganic hydrocarbon proposals.
SOME OPEN QUESTIONS RELATING TO THE PETROLEUM PROSPECTS OF LEBANON*
Authors: Beydoun Z. R.
Published: December 2007

The history of petroleum exploration in Lebanon and the known stratigraphic succession and structural evolution are briefly reviewed. The negative results of the six relatively‐deep exploration boreholes so far drilled cannot be regarded as condemning the petroleum potential of Lebanon, in view of the fact that none explored formations older than the earliest exposed (Lower Jurassic) nor the offshore, and particularly in view of the many hydrocarbon indications encountered, especially when the earlier and recent geochemical work results on source rock potential and origin of shows are considered. Correlation with updated surface and subsurface data from Syria and Jordan enhance the probability of favourable seal formation development in the Late Triassic under Lebanon while favourable location for source/reservoir rock facies emerges when the palaeogeography is considered; postulated Palaeozoic facies also offer favourable potential. The effects of limited extrusive phases in the Late Jurassic/Early Cretaceous and the Late Neogene are examined and considered as non‐critical to hydrocarbon accumulation other than on a very limited local structure scale, while the structural effects of Neogene horizontal displacements along the length of the country are taken into account in the presentation of three exploration options designed to look thoroughly at pre‐Jurassic prospects.
ON THE THEORY OF GROWTH FAULTING PART II(b):GENESIS OF THE “UNIT”*
Authors: Crans W. , Mandl G.
Published: December 2007

This paper comprises a continuation of the second section of a detailed and riegorous geomechenical analysis of the stability of overpressured, gently‐sloping sediment layers presented in the Journal of Petroleum Geology 2, 3, 1980 and 3,2, 1980. The authors continue to describe the delta model which they use to explain and permit quantitative reproduction of the main features associated with growth faulting; part II(a) considered stress equilibrium, related stress equations, types of overpressure, the representation of the stress state in Mohr space and the plastic/elastic stated of frictional materials in long, fluid‐filled layers. The present article continues with the analysis, with a numerical and analytical examination of slip lines and considerations of plastic, flow and slip.

Peak‐strenght phenomena and the effect of purely‐cohesive materials on the theory conclcude the paper in our next issue, together with a discussion of the behaviour of watersaturated soils(as opposed to theoretical solid material with elastic and plastic properties), and the six major conclusions which can be drawn from the work.
LITHOFACIES DISTRIBUTION OF THE PERMIAN‐TRIASSIC ROCKS IN THE MIDDLE EAST
Authors: Sharief Farooq A.
Published: December 2007

The lithofacies distribution of the Permian‐Triassic sequence across the Middle East region shows a great diversity of depositional sedimentary facies laterally as well as vertically. During Permian‐Middle Triassic time, a clastic‐carbonate shelf facies characterizes most of the Middle East region. This platform facies is marked by a number of depositional sedimentary facies which is related to a wide variety of environments, from non‐marine, supratidal and restricted marine shelf to open‐sea and deeper‐shelf deposition.

The distribution of the Upper Triassic lithofacies is marked by sharply‐differentiated depositional patterns. Except for Iran, N Iraq, SE Turkey and central Syria, the passage from the Middle Triassic to the Upper Triassic in the region is marked either by non‐deposition or continental strata, or carbonate‐evaporite sequence. Marine, carbonate and shale deposits of open‐shelf facies continued to be formed in W Iran, N Iraq and SE Turkey. A large amount of richly fossiliferous clastic, neritic deposits accumulated in central and E parts of Iran. In contrast, a terrigenous‐flysch‐like sequence continued to accumulate in the extreme NE Iran since early Triassic time.
A POSSIBLY EXTENSIVE CRUSTAL FAILURE SYSTEM OF ECONOMIC INTEREST
Authors: Khatieb S. O. Al , Norman J. W.
Published: December 2007

Landsat studies of large areas in Nigeria and Saudi Arabia have shown parallel alignments of remarkably‐straight lineaments about 40 km apart of hundreds of kilometres in length, dispersed amongst many members of other systems and randomly‐oriented individuals. These apparent crustal failure zones influence the sites of intrusives (including some economically mineralized), extrusives and some important oilfields. In both main areas studied, families of intrusives aligned along the lineaments system show a minimum age of 520–540 m.y., but evidence of their existence can be detected on images from Quaternary to Cambrian in Saudi Arabia. Although usually there is little ground surface evidence of horizontal dislocation of comparable dimensions, evidence exists of vertical movements of sections bounded by these features.
GEOLOGIC MAP OF SOUTHERN HEMISPHERE
Authors: Mills R. A.
Published: December 2007

A surface geologic map of the Southern Hemisphere should be useful to geologists and geophysicists studying continental drift and petroleum exploration because it relates Antarctic geology to the other continents.

The most dominant feature appears to be the Transantarctic lineament that ties with the South American Andes and, to a lesser degree, with tectonic elements in eastern Australia. From the rocks exposed, it appears that Gondwanaland may have broken up during early Paleozoic time, and then the hemisphere remained stable until the end of Jurassic time when the existence of widespread volcanic rocks suggests that further rifting took place. During early Tertiary time, drifting was renewed and it more or less continued until recent time. Several island arcs and deep trenches indicate that rifting is still active today. There appears to be a significant west‐to‐east drift of crustal material at the far southern latitudes corresponding to the circum‐polar ocean currents.

Offshore petroleum prospects are related to the age of the continental margins as determined by continental drift, i.e. the trailing edges of the continents have the most mature basins beginning with coastal plain sequences that are prograded over isostatically sinking margins. Thick sedimentary columns which began to form in the Mesozoic include reef facies and diapirs. There are exceptions to this model, and various offshore petroleum basins are described with emphasis on the exposed coastal plain morphology as providing the dominant indicator for large reserves.
CANADIAN HYDROCARBON RESOURCE DEVELOPMENT UP TO THE YEAR 2000
Authors: Teitz H. H. , Young F. G.
Published: December 2007

Canada is blessed with numerous large and small sedimentary basins, both onshore and offshore, many of which have hardly been probed for their hydrocarbon potential. Only the most promising aspects of this potential can be highlighted in a brief review such as this, and hence the objectives of the report are (i); to present a regional assessment of the onshore and offshore basins in Canada and to document reservoir units for both conventional and non‐conventional hydrocarbon occurrences within the basin fills which may yield significant discoveries in the future (Map 1), and (ii) to emphasize Canada's political‐investment environment, and the roles of Petro‐Canada, Native Land claims, etc., since most, if not all, of the exploratory targets mentioned require large financial commitments and stable domestic and global conditions.

Previous publications provided essential information to substantiate and/or alter views and projections expressed. Only summary papers are referred to in this review, and we apologize to authors whose views we have used but not acknowledged.
LOW‐RANK SEQUENCES AND SCALES OF ORGANIC METAMORPHISM
Authors: Suggate R. P.
Published: December 2007

Degrees of alteration of carbonaceous material, when compared with scales of organic metamorphism, are used mainly by petroleum geologists for estimating conditions of development of sedimentary basins and for estimating the likelihood of oil and gas generation having taken place. For accurate estimation, especially of geological history, the scales need to be correctly designed, and low‐rank sequences (lignite, sub‐bituminous and high‐volatile bituminous ranks of coal) are critical for this. Scales need review, and data from surface and drillhole sequences in New Zealand are valuable for this. The generally‐accepted influence of time is considered unproved and unlikely to be significant.

In order to relate the concept of “rank” to the geological conditions, it is necessary to use more than one parameter, and the best for use with low‐rank sequences are the dry‐basis calorific value and the bed moisture. Correlation of degrees of metamorphism with particular geological histories is not possible for high‐rank sequences.
GEOLOGIC TIME AS A PARAMETER IN ORGANIC METAMORPHISM AND VITRINITE REFLECTANCE AS AN ABSOLUTE PALEOGEOTHERMOMETER
Authors: Price Leigh C.
Published: December 2007

Substantial published and unpublished data contradict accepted laws of organic metamorphism. Significant amounts of C15+ hydrocarbons and kerogen with significant generation potential exist in sediments which have been buried at high temperatures for long periods of geologic time. Graphite formation and greenschist metamorphism do not occur at model‐predicted burial times and temperatures. Maturation levels for sediments with long (up to 240 million years) burial times are much lower than expected, and conversely, higher than expected for sediments with short (2 million years) burial times. The threshold of intense petroleum generation is not detectable in Plio‐Miocene sediments at minimum temperatures of 160° C.

Literature examination reveals that the only solid documentation of time as a controlling parameter in organic metamorphism is in the works of Karweil (1955), Lopatin (1971) and Connan (1974). Scrutiny of these authors' study areas reveals that all have had moderate to extreme paleogeothermal gradients from incipient and aborted rifting, extrusive and intrusive igneous activity, hydrothermal activity, orogenesis and/or uplift and erosion. Levels of organic metamorphism attributed to geologic time by the above authors are better explained by high paleogeothermal gradients resulting from major geologic activity.

Mean vitrinite reflectance (RO) data have been compiled from different sedimentary basins currently at or near maximum geothermal gradients with sediment burial times ranging from 2–240 million years. The RO data from these basins show a strong correlation (r = 0.97) of increase in R, with increase in temperature. These same data show no correlation of increasing Ro with increasing burial times for any temperature interval. R, data from sedimentary basins affected by high‐temperature geothermal systems with heating times of only 1,000–10,000 years overlie R, data from these petroleum‐bearing sedimentary basins with burial (heating) times of 2–240 million years.

Contrary to accepted thought, there is no evidence from the natural system that petroleum generation‐maturation reactions have first‐order reaction kinetics. By contrast, a substantial body of evidence from petroleum generation‐maturation laboratory studies carried out in closed water‐ wet systems show that these reactions are characterized by multiple‐order reaction kinetics.

Geologically older sediments clearly tend to be more organically mature than younger sediments at the same burial temperatures. However, this correlation ismorea reflection that older sediments have had a greater chance of being affected by a major geologic event with an accompanying high heat flow. The major conclusions of this paper are that: (1) geologic time has no observable effect on organic metamorphism; (2) vitrinite reflectance can be used as an absolute paleogeothermorneter; and (3) the accepted models of organic metamorphism at the very least need substantial revision.
ORGANIC MATIXR CONTENT IN CARBONATE SEDIMENTS IN RELATION TO PETROLEUM OCCURRENCE
Authors: Ibe A. C. , Ferguson J. , Kinghorn R. R. F. , Rahman M.
Published: December 2007

Analyses of recent carbonate sediments of a wide variety of textural types reveal organic carbon content of 0.98–5.23 wt.% which are well above the 0.3 wt.% minimum requirement for carbonate sediments to be considered potential source deposits.

The organic facies consist dominantly of autochthonous marine organic matter, both particulate and dissolved, which is highly pyrolysis‐degradable. Under the correct conditions of burial, temperature and probably catalysis (despite the general absence of clays), commercially‐significant hydrocarbons would be generated and would accumulate as petroleum in those rocks that possess the necessary effective porosity.

This concept of the origin of petroleum in carbonate rocks affords an explanation for the exceptionally rich petroleum accumulations in porous carbonate rocks; it is also consistent with the stratigraphic habitats of most hydrocarbon pools in carbonate petroliferous provinces.
SOME CONTEMPORARY PROBLEMS OF PETROLEUM GEOLOGY IN KUWAIT: A MIDDLE EAST EXAMPLE
Authors: Ibrahim M. W.
Published: December 2007

Paradoxical as it may seem, Kuwait is part of one of the least explored oil‐producing regions on Earth. Contrary to common misconceptions, it has yet to complete the exploration of its hydrocarbon resources.

Due to various factors, a few local and scanty regional studies of the petroleum geology of Kuwait have now been completed by various establishments. Regional studies were based mainly on unevenly distributed and widely spaced control points. They invariably recommended further studies.

It stands to reason that future regional studies should adopt an alternative approach, or otherwise end‐up with similar conclusions.
VARIATIONS IN TECTONIC STYLES IN THE ZAGROS GEOSYNCLINE AND THEIR RELATION TO THE DIAPIRISM OF SALT IN SOUTHERN IRAN
Authors: Kashfi Mansour S.
Published: December 2007

A study of the surface and subsurface geology of the Zagros mountain belt reveals that, from the viewpoint of tectonic fabrics and the cause of diastrophism, the Zagros geosyncline can be divided into NW and SE segments. The NW segment was formed by orogenic compression and the SE segment primarily by epeirogenic uplifts. Movements of Infra‐Cambrian (Hormuz) salt at the base of the sedimentary column in the SE Zagros contributed to the epeirogenesis. Faults in the SE Zagros are of a normal type, whereas in the NW Zagros they are dominantly thrust. Seismic data indicate that movement of salt is the cause of many of the earthquake shocks in the SE Zagros.

Hydrocarbons in the SSE Zagros either escaped through fractures within exposed reservoirs or migrated while epeirogeny was proceeding to be trapped in the western flank of the Oman high in the extreme SE portion of the Zagros belt.
THE PETROLOGY OF THE MIDDLE JURASSIC SANDSTONES FROM THE MURCHISON FIELD, NORTH SEA
Authors: Morton A. C. , Humphreys B.
Published: December 2007

A petrographical investigation of the sandstones of the Brent Group (Middle Jurassic) from the Murchison field has produced evidence for the existence of two transgressive events within the sequence, one occurring immediately above the Etive Fm., the other within the upper part of the Ness Fm. These transgressions have not been previously recorded in Murchison and their discovery demands that some modification be made to the existing depositional model for the Brent Group of this area. A volcanic ash horizon has been found in a similar stratigraphic position to that recorded from Statfjord, and if this, and the two transgressive horizons noted above, are of more than local extent they could prove to be useful stratigraphic markers.

Although the diagenesis of the Brent Group sandstones in Murchison differs little from that recorded elsewhere in the Brent province, the interpretation of the timing of the development of certain phases differs somewhat from those of other authors. In particular, kaolinite development appears to have taken place soon after burial in response to periods of emergence and weathering during Brent Group deposition, rather than through groundwater circulation during the Kimmerian tectonic phase.
PETROGRAPHY AND GEOCHEMISTRY OF SOME JORDANIAN OIL SHALES FROM NORTH JORDAN
Authors: Abed Abdulkader M. , Amireh Bilal S.
Published: December 2007

Twenty‐two “oil shale” samples from north Jordan have been investigated. They are in fact all bituminous limestones, of ages ranging from Uppermost Cretaceous to Paleocene. Major elements, organic matter and trace elements, were determined, together with aspects of mineralogy and petrography. Although macrofossils are rare, trace fossils were encountered. These rocks are postulated to be normal limestones deposited in an oxygenated shallow marine environment. The H2S/O2 interface coincided or lay just below the water/sediment interface. The organic matter is indigenous and not related to migrating oil.
THE MANY ORIGINS OF NATURAL GAS
Authors: MacDonald Gordon J.
Published: December 2007

Thermodynamic calculations for the C‐O‐S‐Hsystem indicate that at a fixed oxygen fugacity methane is in a stable phase relative to carbon dioxide at high pressures and low temperatures. At a constant temperature and pressure, methane is favored at low oxygen fugacities. Volcanic gases and near‐surface igneous rocks exhibit high values of oxygen fugacity. However, direct measurement of the oxygen fugacity of spinels from peridotites of deep origin indicate that the oxygen fugacity of these rocks is low, corresponding to an iron‐wüstite buffer. The relative abundance of the carbon isotopes C12 and C13 varies widely in natural gases. Methane formed by bacterial fermentation is highly enriched in the lighter isotope, while methane from deep deposits is much less so as is the methane flowing from hydrothermal vents on the East Pacific Rise. Except in extreme cases, the carbon isotope ratio cannot be used alone to assess whether methane is biogenic or abiogenic. The carbon isotope ratio in coexisting methane and carbon dioxide can be used to estimate the temperature at which the two gases came into isotopic equilibrium. This ratio indicates a high temperature of equilibration for a number of gas deposits. The carbon and helium isotope ratios together with their geologic settings are strongly suggestive that the large quantities of methane in Lake Kivu and the gases venting along the East Pacific Rise are abiogenic. Methane associated with the Red Sea brines and various geothermal areas may also be in part abiogenic. The high abundance of carbon in the Sun, the atmosphere of the outer planets, carbonaceous chondrites and comets, suggests that carbon may be more abundant in the Earth than it is in near‐surface igneous rocks. Such a high abundance could lead to a progressive outgassing of methane at depth, which then is oxidized near the surface or in the atmosphere. Methane hydrates are stable at low temperatures and high pressures. Today, methane hydrates are found in areas of permafrost and in ocean sediments. Methane hydrates in ocean sediments were first formed about 20 mya (million years ago) when the Antarctic ice sheet reached sea level. Terrestrial methane hydrates formed more recently during the glaciations beginning 1.6 mya. Methane hydrates and trapped gas are probably abundant under the Antarctic ice sheet. The formation of methane hydrates may be related to the low values of carbon dioxide in the atmosphere some 20,000 years ago.
THE ANALYSIS OF C‐H‐O DATA IN KEROGEN STUDIES USING A COEFFICIENT OF ELIMINATION
Authors: Ferguson J.
Published: December 2007

A coefficient of elimination derived from Information Theory is proposed. The coefficient expresses the mixing of the elements C, H and O in kerogen, based on chemical analyses. It is shown to have meaning in terms of the products of kerogen evolution, as well as the changes in the chemistry of the kerogen itself. It is suggested that this parameter, plotted against percentage hydrogen, is a useful addition to the conventional van Krevelen diagram. Points representing the accepted stages of kerogen evolution are indicated with reference to the chemistry of the processes in vol ved and are shown to be similar to those determined from physical studies, in particular reflectivity.
GEOTHERMAL GRADIENTS AND GEOTHERMAL OIL GENERATION IN SOUTHERN IRAQ: A PRELIMINARY INVESTIGATION
Authors: Ibrahim M. W.
Published: December 2007

Local geothermal gradients in South Iraq were used in calculating the time‐temperature indices of source rock maturation, as modified by Waples (1980). Accordingly, Cretaceous, Jurassic, Triassic and probably Paleozoic rocks are calculated to be with in the thermal petroleum generative zone in several parts of southern Iraq.
WATER‐SENSITIVITY AND MIGRATION OF FINES IN THE HOPEMAN SANDSTONE
Authors: Lever Andrew , Dawe Richard A.
Published: December 2007

Water‐sensitivity tests have been performed on samples of the Triassic Hopeman Sandstone from Clashach Quarry near Elgin in Scotland. Despite the apparent lack of clay minerals in the samples, the permeability of core plugs to NaCl and KCl brines decreases with progressive volume of efflunent, and drops dramatically when distilled water is flushed through. The permeability to CalCl brines remains constant, however, emphasising the stabilsing effect of polyvalent cations. These results are explained by cation exchange, expansion of electric double layers and the consequent migration of fines.
A PROBLEM WITH ESTIMATING THE PSEUDO‐ACTIVATION ENERGY OF KEROGEN THERMAL MATURATION FROM CONNASN'S TIME‐TEMPERATURE RELATION IN OIL GENESIS
Authors: Barker Charles E.
Published: December 2007

Conan's time‐temperature relation in oil genesis as derived from first‐order reaction kinetics is algebraically correct, but its application to natural petrolieum generation is invalidated by the assumption that the ratio of initial kerogen concentration to degraded kerogen concentration is constant from deposition to the initiation of intense oil generation. The ratio can only remain constant if no reaction is occurring and, therefore, Connan's data on “reaction time” in petroleum generation (assumed to be the age of the sediment)only measured th time elapsed since the system formed. Thus, the widely cited pseudo‐activation energy of 11–14 kcal/mole computed from Cannan's equation for the start of oil generation from kerogen is meaningless.
SEDIMENTOLOGICAL AND PALEONTOLOGICAL ANALYSIS OF JURASSIC NORTH SEA DEPOSITS FROM DELTAIC ENVIRONMENTS
Authors: Nagy J. , Dypvik H. , Bjaerke T.
Published: December 2007

Core samples from Well 33/9‐3, Norwegian North Sea, have been analysed sedimentologically, palynologically and micro‐paleontologically. The cores cover the Toarcian Drake Member of the Dunlin Formation, and nearly the whole thickness of the Middle Jurassic Brent Formation.

The Drake Member is characterized by pro‐deltaic depositional conditions. In the Brent Formation, five members are recognized (from below): the Broom, Rannoch and Etive Members represent distributary mouth bar facies; while the Ness and Tarbert Members are recognized as interdistributary bay fill sequences.

The composition of the kerogen assemblages is controlled by the changing energy regimes of the different depositional facies. Terrestrial plant débris are dominant throughout the studied interval. Marine palynomorphs are present in the Drake Member and in the lower part of the Broom Member. The development of rich, arenaceous foraminiferal assemblages in the Drake Member are interpreted as a response to shallow, pro‐deltaic conditions. Calcareous foraminifera constitute only a small, accessorial part of these assemblages.
PETROLEUM FORMATION AND THE THERMAL HISTORY OF THE EARTH'S SURFACE
Authors: Melton C. E. , Giardini A. A.
Published: December 2007

Petroleum reservoirs are known to depths of‐10 km, and their ages extend to ‐ 700 m. y. † Since ltemperature is important to petroleum‐forming processes, the thermal history of this region is analyzed. From the geologic record, average surface temperature values are derived for recent geologic time adn 2.5 b. y. BP. These data are applied to the Newton cooling law to obtain a value of 2.63×10‐11 yr‐1 for the heat transfer constant for the Earth surface/space system. This in turn, yield an approximate average cooling rate for the surface of 7°C per b. y. Profiles of average surface temperature over geologic time are constructed for high, middle and low latitudes. Respective initial average surface temperatures at these latitudes were 13.6°, 41.6° and 59.6°C. Two tests are applied to the cooling curves to cheek their validity. First, they are used with teh rate constant for the mantle outgassing of water vapor and the Clausius‐Clapeyron equation ot calculate the accumulation and average temperature of liquid surface water over geologic time. The results are consistent with teh geologic record pertaining ot the history of water‐borne sedimets, glaciation and life. Second, the calcualted thermal characteristics of the surface are compared with publushed date for the mantle. They agree to within 2%. The surface < 10°C for the temperature change of a petroleum resrvoir buried at a depth of 10kkm over the past 700 m. y. The change for reservoirs of resrvoir age ot petroleum‐forming processes lies mainly in the increased opportunity for geologic change such as depth of burial or igneous actifity that would alter conditions within the reservation.
FISSION TRACK DATING OF AN APATITE CRYSTAL FROM HORMUZ ISLAND, IRAN
Authors: Hurford A. J. , Grunau H. R. , Stöcklin J.
Published: December 2007

Geological evidence points to a Late PreCambrian origin for the Hormuz apatites associated with the red iron oxides, salt and other sedimentary and igneous rocks of the Hormuz Complex. Fission track dating of an apatite crystal from Hormuz Island gives an age of 55.4 ± 2.6 MM years for a cooling temperature of approximately 100d̀ C corresponding to the Paleocene‐Eocene boundary. This result is interpreted in the light of the burial and temperature history of the apatite associated with the Hormuz salt. It is concluded that the apatite clock registers the time elapsed since the temperature decreased to 100d̀ C at the Paleocene‐Eocene boundary. Steady cooling took place thereafter due to the continuing upward movement of the salt plug until Quaternary times. The stratigraphic position which the salt diapir (with the associated apatite) had reached 55 MM years ago corresponds to a level somewhere within the Triassic sequence. This would have been the zone of oil generation in Paleocene‐Eocene time, assuming that a source rock was present. Interpretational uncertainties are due to insufficient knowledge of the paleotemperature regime and of the stratigraphy and sedimentary thicknesses of the complete sequence down to the Precambrian. In addition, it is not possible to draw far‐reaching conclusions based on the dating of only one sample.
EVOLUTION OF THE SOUTHERN PASSIVE MARGIN OF THE HIMALAYAN THTHYS: MODEL IMPLICATIONS AND CONSTRAINS‐II
Authors: Bhat M. I.
Published: December 2007

In the first part of this presentation published in July(7, (3), 341–350), the Author proposed a scheme for the structural and tectonic evolution of the southern Himalayas. He now considers the model's constraints. The conclusions and references refer to both parts of the paper.
THE JAPAN BASIN ‐ A TECTONIC TROUGH
Authors: Choi Dong Ryong
Published: December 2007

An integrated analysis of the currently available geological and geophysical data in and around the Japan Sea indicaaaaaaes that the JapanBasin originated as a tectonic trough developed in an area of continental crust, a NE extension of the PreCambrian Ogcheon Trough on the Korean Peninsula.

This conlusion is based on the following evidence: (1) tectonic trends recognized on the surrounding continents are basically traceable over the entire Japan Sea area; (2) the “sub‐oceanic” (“basaltic”) crust replaces all pre‐existing structures without conspicous horizontal displacement; (3) detailed submarine geologic maps show the predominance of vertical tectonics, which were controlled primarilyby makor‐deep seated fault systems coincide with linear magnetic anomalies and high heat‐flow zones, and are loci of volcanic activities; and (5) comparisonof geological and seismic data proves that the acoustic basement in the Japan Basin is provided bythe Paleozoic marine sediments, and not the “basaltic” layer as has hitherto been considered by many geoscientists.

The above geological evidence conflicts with the plate‐tectonics or spreasing‐originhypotheses proposed by many authors. The linear magnetic anomalies generally coincide awithmajor fault zones and appear to show primary fracture patterns of the crust which interacted awith the upper mantle. Therefore, the validity of the linear magnetic anomalies as a criterion for determining spreading centres and rates is quesioned. The large discrepancy in structuralinterpertations derived, on the one hand, from a gephysical approach to the Japan Basin, and, on the other hand, from a geophysical approach, leads us to question whether the identification of continental and oceanic crust based on seismic refraaction data is valid.

All the experience we have had in the controversy over the origin of the Japan Sea teaches us the following impotant lessons: (1) geological and geophsical studies need to be intergrated; and (2) detailed geological studies, especially geologic mapping of the continental shelf, the borderland, and submarine rises in close association with the mapped land geology, need to procede the discussion of any hypothesis.
SUPPRESSION OF VTRINITE REFLECTANCE IN AMORPHOUS RICH KEROGEN ‐ A MAJOR UNRECOGNIZED PROBLEM
Authors: Price Leigh C. , Baker Charles E.
Published: December 2007

Vitrinite reflectance (Ro,) is regarded as one of the most, ifnot the most, powerfultools available to petroleum organic geochemistry. Yet major recognized and unrecognized problems exist concerning use of the technique. One such unrecognized problem is a major suppression of Ro by significant concentrations of exinite macerals (Type I and Type II kerogen) in association with vitrinite macerals.

Ro values have been, and are, for the most part, read from exinite‐rich sediments examined in organic geochemical studies. This has led to the establishment of R0 values of 0.6 (± 0.1) and 1.35 corresponding, respectively, to the regional rank necessary for the onset of significant hydrocarbon generation and for the thermal destruction of petroleum (“oil deadline”). These uniformly quoted Ro values, derived from exinite‐rich (hydrogen‐rich) kerogens, would have far different values if Ro had been read from vitrinite‐rich (oxygen‐rich) kerogen at the same regional rank. The serious miscalibration of the regional ranks necessary for the onset of significant petroleum generation from exinite‐rich kerogen and for the “oil deadline” have major implications for assessment of frontier areas of possible petroleum reserves as well as for petroleum exploration in general and worldwide and basin‐by‐basin resource assessment of undiscovered petroleum reserves.
A NEW CLASSIFICATION FOR THE ORGANIC COMPONENTS OF KEROGEN
Authors: Massoud M. S. , Kinghorn R. R. F.
Published: December 2007

A new classification is proposed for the components of kerogen, in which phytoclasts are separated into four groups: keroginite, liptinite, vitrinite and inertinite. The “keroginite group” includes the finely comminuted or structureless sapropelic material which constitutes the main organic components of hydrogen‐rich oil‐prone kerogens (types I and II). The “liptinitegroup” encompasses all structured sapropelic phytoclasts which are derived from the remains of waxy and fatty plant tissues, such as algae, spores, pollen and cuticles. When found in marine sediments, they are usually hydrogen depleted and gas prone (type III kerogen) due to their degradation during transportation from land. The “vitrinitegroup” incorporatess tructured and apparently unstructured woody tissues which correspond to first and second cycle vitrinites and form the main constituents of the gas‐prone type III kerogen. The “inertiniteg roup” comprises the charcoal‐ or graphite‐like ph ytoclasts which have undergone natural carbonization prior to incorporation into sediments, and have no convertibility to hydrocarbons.
EVAPORITES AS OIL AND GAS SOURCE ROCKS
Authors: Sonnenfeld Peter
Published: December 2007

Shale‐ and micritic limestone‐bound organics have long been considered as hydrocarbon source rocks. However, a conceptual model of hydrocarbon generation in salt basins does not require the entrapment of hydrocarbons in impervious strata, shales or micritic limestones as source rocks.

In evaporite basins, organic matter derived from surface waters is preserved beneath the pycnocline of a density‐stratification in anaerobic hypersaline bottom brines. Not being recycled, it is decomposed by bacteria, goes into solution or settles on the bottom. Montmorillonites, calcites, gypsum and potash deposits can alter organic matter catalytically. Impervious clays and micritic limestones trap large hydrocarbon molecules permanently; smaller molecules are flushed through a permeable substrate into aquifers and delivered to reservoirs. After burial, maturation equal to other hydrocarbons is achieved at a lower vitrinite index.
MESOZOIC COLUMNS BELOW THE SEYCHELLES BANK, WESTERN INDIAN OCEAN
Authors: Kamen‐Kaye Maurice
Published: December 2007

Exploratory drilling on the Seychelles Bank, in a sector west of outcrop granite on Mahé Island, has revealed the presence of substantial Mesozoic colums. Their thicness approaches 3,000m; and total Phanerozoic down to true basement probably exceeds 4,500m. Still greater depths are possible, not only in this drilled NW‐most sector of the island arc of the Mascarene Ridge, but also elsewhere along the arc, whose total cross‐latitudinal dimension is more than 2,000km. Volcanics, like those in the African borderlands, repeatedly enter the Phanerozoic column of the Seychelles. The young “basaltic basement” of geodynamic theory, consequently, cannot exist on the Seychelles Bank. The same negative may hold true for the whole arc of the Mascarene Ridge and for its marginal waters westward as far back as the African borderlands themsleves. In the domain of exploration, the prime parameter of sedimentary volume is acceptable along much of the Mascarene Ridge, for which reason wells drilled to true basement merit consideration in future drilling. Such wells in central and southern sectors might recover basement rocks whose petrology could offer a strong challenge to present concepts of paleogeography in the whole back‐arc area of the western Indain Ocean.
THE TRANSCONTINENTAL ARCH AND ITS RELATION TO THE COLORADO OIL AND MINERAL BELT.
Authors: Billo Saleh M.
Published: December 2007

The Transcontinental Arch and its flanking basins dominated the landscape of North America before the rise of the Ancestral Rockies and the Wichita system. It is the SW extension of the Canadian Shield, and is partly of PreCambrian origin and partly a later development. It is found in a belt extending SW from Minnesota to New Mexico. This concealed structural feature is depicted here from comparisons of stratigraphic sections and well records. It was active from the Camnbrian through the Mississippian. During Cambrian time it was wide and uniform from the Canadian Shield to Arizona. Later, sags developed in Colorado and in Arizona. The changes in size and shape were partly positive and partly negative. PreCambrian rocks and structures have been recorded from geophysical data as well as from holes drilled for oil and gas in the intervening areas, particularly in the western half of the lowlands. The narrow NE‐trending Colorado mineral belt, containing the major mining districts of Colorado is closely related to this continental backbone. It is characterized by NE‐trending faults, and oil and mineral deposits of Laramide age.
KEROGEN FACIES IN THE MAJOR JURASSIC MUDROCK FORMATIONS OF SOUTHERN ENGLAND AND THE IMPLICATION ON THE DEPOSITIONAL ENVIRONMENTS OF THEIR PRECURSORS
Authors: Ebukanson E. J. , Kinghorn R. R. F.
Published: December 2007

Kerogen types and their hydrocarbon‐generating potentials in three main mudrock units in the Jurassic of Southern England ‐ the Lower Lias, the Oxford Clay and the Kimmeridge Clay ‐ have been investigated using elemental analysis, transmitted‐light microscopy, density fractionation and pyrolysis‐gas chromatography. The results show that, as with the lithology, the three formations display variations in their kerogen composition. The kerogen facies range from the chemical Type II to Type IV in the Lower Lias and the Oxford Clay, whereas only Types II to III are identified in the Kimmeridge Clay. Amorphous organic material constitutes the most abundant fraction of all the kerogen samples. All the identified kerogen types show a potential for generating both oil and gas.

The fluctuating oxic‐anoxic depositional bottom conditions during the Jurassic is suggested to have been the major factor controlling the distribution of kerogen facies in the three formations.
HYDRODYNAMIC FRAMEWORK OF THE PETROLEUM RESERVOIRS AND CAP ROCKS OF THE MESOPOTAMIAN BASIN OF IRAQ
Authors: Al‐Mashadani Ali
Published: December 2007

The basic mechanisms governing the hydrodynamic patterns in sedimentary basins are ultimately related to the pressure, reservoirs, water salinity and chemical composition, and the regional geological environment, all of which are interdependent. In Iraq, there are four major hydrogeological units in the Tertiary‐Jurassic section, which are generally governed by two hydrodynamic systems — by gravity and by high‐pressure zones.

1. Slightly saline water moves by the action of gravity from sites of high potential, namely the Zagros foothills zone and the outcrops of the Arabian shield (where reservoirs are recharged) towards the centre of the basin, which is topographically low. The Tigris, Euphrates and Arabian Gulf form a drainage axis due to their comparatively low topographic positions.

The vertical movement of formation water in the basinal area where artesian phenomena exist is effectively possible, favoured by major faults and fractures connecting the deep aquifers to the surface. This mechanism is even more notable in areas of minimum potential.

2. High pressure zones have their origin in the diagenesis of organic matter and “cracking” of hydrocarbons beneath thick sediments, which lead to an increase in pressure within a closed system. Abnormally high pressures have been encountered in the Lower Cretaceous in Southern Iraq, mostly related to the presence of gas.

Pressure anomalies may also be related to the compaction of sedimentary rocks; if during compaction the fluid expulsion can be normally effected due to the presence of satisfactory drainage channels, the hydraulic gradients will be low. On the other hand, if the fluid expelled is drained into a confined reservoir embedded within argillaceous beds, then an abnormally high pressure will be created.

The hydrodynamic systems are related to the geometry of the sedimentary basin; in addition, factors other than compaction (for example, the existence of Miocene saliferous beds, tectonic forces, temperature, etc.) may be involved in the development of high pressures in the Tertiary aquifers of the north and NE of the Mesopotamian basins.

The salt series of the Hormuz and Gotnia formations encountered in the Arabian Gulf, which extend to Southern Iraq, could be one of the factors related to the pressure anomalies, when they remain within a closed system.

The hydrodynamic systems and the geodynamic evolution of the sedimentary rocks are responsible for the confined formation water, the migration of expelled water towards the surface, and the distribution within the basin of various parameters such as the hydraulic potential, salinity, heat flow, and diagenesis.
MATURITY OF ORGANIC MAITER IN THE JURASSIC OF SOUTHERN ENGLAND AND ITS RELATION TO THE BURIAL HISTORY OF THE SEDIMENTS
Authors: Ebukanson E. J. , Kinghorn R. R. F.
Published: December 2007

An investigation of the maturity levels of organic matter in the major potential Jurassic hydrocarbon source rock units in Southern England (i.e. the Lower Lias, Oxford Clay and Kimmeridge Clay) using sporomorph colouration and alkane distribution patterns shows that the Oxford Clay and the Kimmeridge Clay organic materials are immature in most parts of the area. They are mature only in the central parts of the Mesozoic Wealden Basin.

The distribution of mature Lower Lias sections is found to be more extensive. Attempted reconstruction of the burial histories of Jurassic sections across Southern England, and the application of the Lopatin method of theoretical organic maturity prediction, seem to support the observed maturity trends and suggest that the present maturity levels of Jurassic organic matter at any given locality are dependent on the structural development of that area through time.
A JURASSIC DELTA IN THE EASTERN ALBORZ, NE IRAN
Authors: Rad F. K.
Published: December 2007

A clastic dominated Lower‐Middle Jurassic sequence, known as the Shemshak Formation, is extensively exposed in the Eastern Alborz area, NE Iran. The unit represents a deltaic complex sandwiched between carbonate rocks. Sedimentological study of the formation outcrops has revealed that it was deposited in environments ranging from subaerial to subaqueous delta plains.

Potential source, reservoir and cap rocks are present within the Shemshak Formation; under favourable conditions, generation and accumulation of hydrocarbons in significant quantities can be envisaged. It is suggested that the Shemshak delta, buried under the thick Neogene sediments in the Eastern Alborz area, is a highly prospective exploration target with potential for a multipay section.
ORGANIC METAMORPHISM IN THE LOWER MISSISSIPPIAN‐UPPER DEVONIAN BAKKEN SHALES — II: SOXHLET EXTRACTION1
Authors: Price Leigh C. , Ging Tom , Love Alonza , Anders Don
Published: December 2007

In this paper, we report on Soxhlet extraction (and subsequent related analyses) of 39 Lower Mississippian‐Upper Devonian Bakken shales from the North Dakota portion of the Williston Basin, and analyses of 28 oils from the Basin. Because of the influence of primary petroleum migration, no increase in the relative or absolute concentrations of hydrocarbons or bitumen was observed at the threshold of intense hydrocarbon generation (TIHG), or during mainstage hydrocarbon generation in the Bakken shales. Thus, the maturation indices that have been so useful in delineating the TIHG and mainstage hydrocarbon generation in other studies were of no use in this study, where these events could clearly be identified only by Rock‐Eva1 pyrolysis data.

The type of primary petroleum migration operative in the Bakken shales led to the selective concentration of certain compound types in the oils of the basin, as well as the selective concentration of certain compound types in the shale extracts. The compositional differences between the crude oils and shale extracts provide evidence of the primary migration mechanism operative in this case, which is believed to have been gaseous solution, although the actual expulsion of oil from the rock, if observed, would probably have appeared to be bulk phase migration. Gaseous‐solution bulk‐phase primary petroleum migration also left organic‐geochemical imprints on the Bakken shales, observable by Soxhlet extraction and to a lesser extent by pyrolysis. The data of this study demonstrate that primary petroleum migration is a very efficient process.

Four distinctive classes of saturated hydrocarbon gas chromatograms from the Bakken shales arose from facies, maturation, and primary migration controls. As a consequence of maturation, the percentage of saturated hydrocarbons increased in the shale extract at the expense of decreases in the resins and asphaltenes. Measurements involving resins and asphaltenes appear to be excellent maturation indices in the Bakken shales. Two different and distinct organic facies were present in immature Bakken shales.

Rock‐Eval pyrolysis analysis was a critical research tool in this study; however, combined use of pyrolysis and Soxhlet extraction allowed organic‐geochemical features to be distinguished which would not have been possible by using either analysis alone.