ISSN:0072-1050    

DOI:10.1002/gj.3350210302

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractOil and gas are produced from Tertiary sandstone reservoirs in deltaic and related depositional systems in the Gulf Coast (U.S.), Niger (Africa), and Beaufort‐Mackenzie (Canada‐Alaska) basins. In each area there is an orderly, predictable interrelationship of sedimentation, stratigraphy, depositional environment, and structure, with the characteristics, ages, and distribution of producing trends.In comparing and contrasting the three areas, it is apparent that they have many essential aspects in common, resulting from the fact that they are relatively young, subsiding paralic basins on 'Atlantic type' or passive margins. They contain thick accumulations of deltaic terrigenous sediments that have prograded in regressive basin‐filling sequences as the basins subsided. Therefore each has a vertical gross lithologic sequence with shale at the base, overlain by interbedded sandstones and shales, overlain by massive sandstones. The vertical sequence is repeated laterally from the basin landward. In each basin the stratigraphic units of the sequences thicken basinward across a series of normal, listric, down‐to‐the‐basin syndepositional faults, with which are associated 'rollover' anticlines which form traps. Trapping associated with diapiric structures is also characteristic of all three areas.Although similarities among these areas is striking, significant differences are related to their different geologic settings and geologic histories. For example, the presence of salt in the Gulf Coast basin has resulted in a wide variety of salt dome‐related trapping mechanisms in addition to the shale diapirs and roll‐over anticlines common to all three areas. Pre‐Tertiary tectonic settings, different in each case, control basin configurations and affect structural trends. Vertical and lateral differences in depositional systems and sequences, as well as variations in delta morphology and sandstone geometries, result from variations in ratios of rates of deposition to rates of subsidence.The framework for the occurrence of oil and gas is well understood in the maturely‐explored and intensively‐studied Gulf Coast Tertiary basin. Concepts developed there can be applied to developing the less‐explored Niger basin and to exploring the frontier Beaufort‐Mackenzie basin. An extensive

ISSN:0072-1050    

DOI:10.1002/gj.3350210303

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractPost World War II oil came to replace coal as the dominant energy source in the U.S.A. Recently, coal in the form of lignite has again become a significant energy resource in the Gulf Coast region, where it occurs in Eocene and Oligocene rocks. Efficient exploitation requires a proper understanding of the facies in which it occurs. Studies of surface outcrops are providing the basis for predicting the nature of the reserves at depth.

ISSN:0072-1050    

DOI:10.1002/gj.3350210304

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe stratigraphic approach toward hydrocarbon exploration and exploitation is a fundamental aspect of the continued development and consequent future addition of new reserves from mature basins. This approach, albeit not novel, involves systematic attempts at locating subtle stratigraphic reservoirs and traps, as well as methods of enhancing hydrocarbon recoveries from existing fields, by coordinating petrophysical studies and conventional subsurface mapping techniques.

ISSN:0072-1050    

DOI:10.1002/gj.3350210305

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractMany contributions that have led to a better understanding of Appalachian geology have resulted directly from work in the folded Appalachian Mountain and Great Valley sections of the Valley and Ridge physiographic province of eastern Pennsylvania. Disagreements have been common since H.D. Rogers first described the geology of the area in 1858. Many differing opinions still exist regarding the stratigraphy, structural geology, geomorphology, and glacial geology.The rocks in the area, which range from Middle Ordovician to Late Devonian in age, are more than 25000 feet (7620 m) thick. This diversified group of sedimentary rocks was deposited in many different environments, ranging from deep sea, through neritic and tidal, to alluvial. In general, the Middle Ordovician through Lower Devonian strata are a sedimentary cycle related to the waxing and waning of Taconic tectonism. The sequence began with a greywacke‐argillite suite (Martinsburg Formation) representing synorogenic basin deepening. This was followed by basin filling and pro‐gradation of a sandstone‐shale clastic wedge (Shawangunk Formation and Bloomsburg Red Beds) derived from the erosion of the mountains that were uplifted during the Taconic orogeny. The sequence ended with deposition of many thin units of carbonate, sandstone, and shale on a shelf marginal to a land area of low relief. Another tectonic‐sedimentary cycle, related to the Acadian orogeny, began with deposition of Middle Devonian rocks. Deep‐water shales (Marcellus Shale) preceded shoaling (Mahantango Formation) and turbidite sedimentation (Trimmers Rock Formation) followed by another molasse (Catskill F

ISSN:0072-1050    

DOI:10.1002/gj.3350210306

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractExtrapolation of the palaeoclimate chronology of the past million years or so seems to leave little doubt that another glacial stage can be expected in the near geologic future. On a shorter time scale it appears that the increasing greenhouse effect from the use of fossil fuel will raise atmospheric temperature by 2 to 3 °K within a hundred years. The possibility of man's reversing or at least weakening these portentous climate changes is investigated here with the use of a thermodynamic climate model. Preliminary results indicate that the climate effects referred to may be reversible if caught early and certainly suggest that further and more sophisticated attention be given the subject

ISSN:0072-1050    

DOI:10.1002/gj.3350210307

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe Charlotte belt in North Carolina and South Carolina, U.S.A. is characterized by numerous plutons with granitic to gabbroic composition that have intruded gneiss, schist, metavolcanic rocks, and metamorphosed mafic complexes (basalt, gabbro, and ultramafic rocks). The exposed rock constitutes a composite batholith which contains three superunits: (1) the Old Plutonic (metaquartz diorite, metagranodiorite, and metagabbro) approximately 550 my old; (2) the Concord‐Salisbury (gabbro and granodiorite) approximately 400 my old; (3) the Landis ('big feldspar') granite approximately 300 my old. Geophysical and geologic studies suggest small bodies of granodiorite and mafic complexes intruding metavolcanic rocks, schist, and gneiss form the upper level of the batholith; a thick metagabbro sill penetrated by gabbro stocks and underlain by poikilitic gabbro and small bodies of syenite form the middle level; and a complex of metaquartz diorite and metagranodiorite intruded by Landis granites form the lowest level. Outcrop patterns and structural profiles based on gravity suggest the batholith forms an east‐dipping monocline. The bimodal suite of gabbro and granodiorite plutons suggest a tensional tectonic environment ∼ 400 my ago, and negates subduction as the only mode of formation for the bath

ISSN:0072-1050    

DOI:10.1002/gj.3350210308

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe Quassaic Group occurs as an outlier in the north‐south trending Marlboro Syncline which extends 40 km between Kingston and Newburgh in southeastern New York. The group is comprised primarily of 3050 m of late Medial to medial Late Ordovician marine arenites. It is subdivided (oldest to youngest) into five formations: Creek Locks, Rifton, Shaupeneak. Slab Sides, and Chodikee. On the western limb of the syncline the group overlies a minimum of 610 m of the early late Medial Ordovician Bushkill Shale and the bottom three formations grade north and south to Bushkill Shale.Abundance of graded but occasionally conglomeratic beds, common tabular cross‐lamination, much less common trough cross‐lamination, comparative lack of channelling, general lack of shales, and scarcity of fossils indicate that the average depositional environment of the formations was near the base of the slope of a sedimentary apron or delta which lay to the southeast. The environment, however, probably extended from a basin plain, in the marginal Bushkill Shale, through the lower and middle slope and, rarely, to the upper slope. The occasional molasse‐like deposits in the Shaupeneak Formation may indicate local transport of molasse to an upper slope position.The Quassaic Group thus records an initial, local extension of arenites of the lower slope of an apron or delta onto a downwarping basin plain in the Bushkill Trough. This was followed by progressive enlargement and extension of the delta slope with attendant shallowing, culminated by the appearance of molasse‐like sediments. Subsequent deposition involved greater slope extension followed by recession with gradual deepening. These activities were prelude to the Hudson Valley Phase of the Taconian Orogeny which downfolded the Quassaic Group into the Marlboro Syncline during latest Ordovic

ISSN:0072-1050    

DOI:10.1002/gj.3350210309

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350210310

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350210311

出版商:John Wiley&Sons Ltd    

年代:1986

数据来源: WILEY