bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forward modelling of porosity and pore pressure evolution in sedimentary basins
Authors: Audet D. M. , McConnell J. D. C. 
Published: November 2007

ABSTRACTThe gravitational compaction of sediments is an important process in forward basin modelling. This paper presents a mathematical model for the one‐dimensional compaction of an accreting layer of argillaceous sediments. Realistic constitutive laws for the clay compressibility and the clay permeability, based on soil mechanics tests, were incorporated into the model. The governing equations were put in dimensionless form and the extent of abnormal pore fluid pressure development was found to depend on the sedimentation parameter, a dimensionless group representing the ratio of the sediment hydraulic conductivity to the sediment accumulation rate. The effects of clay compressibility were studied and highly colloidal clays such as montmorillonite developed higher overpressures than less compressible materials. The results also showed that overpressuring developed in shales for cases in which the clay permeability did not go to zero in the limit of zero porosity. Linear models based on simplifying assumptions inappropriate for sedimentary basins were found to give significantly different estimates for the conditions leading to overpressuring. Using reasonable parameters, the model adequately reproduced porosity and pore pressure profiles measured in the sand‐shale sequences of the South Caspian Sea.
Differential response of a Devonian‐Carboniferous platform‐deeper basin system to sea‐level change and tectonics, N. Chilean Andes
Authors: Bahlburg HEINRICH , Breitkreuz CHRISTOPH 
Published: November 2007

AbstractDeposition of a 2700‐m‐thick clastic platform succession in a N‐S striking basin in northern Chile began in the Early Devonian during a global sea‐level rise. A transition to terrestrial facies took place at the Early‐Late Carboniferous boundary when the Gondwana glaciation began and global sea‐level dropped. On the platform, interbedded cross‐bedded or bioturbated sandstones, offshore tidal dunes and sand waves, and mudstones and tempestites suggest switching intertidal and shallow or deep subtidal environments. However, evidence for subaerial erosion indicates a significant regression during the Early Devonian.In an adjacent and deeper N‐S striking sub‐basin to the W, up to 3600 m of turbidites were deposited from the Late Devonian to the Late Carboniferous by mainly southerly palaeocurrents. Turbidites accumulated in coarse‐grained proximal sand lobes in the N, and in fine‐grained lobe fringe and basin plain environments in the S, with alternating upward‐thinning and upward‐thickening cycles typical of tectonically controlled aggradational turbidite systems.The sedimentological data indicate that the deeper basin depositional system evolved to a large extent independently from the platform system. Sediment in the deeper basin is less mature and more poorly sorted than that on the platform, suggesting that detritus bypassed the platform and was shed directly from the source areas into the western basin. The only depositional link between the platform and deeper basin systems seems to be longshore platform currents which may have funnelled minor quantities of mature sand into the deeper basin via bypass canyons. Although platform and deeper basin evolved in a common extensional tectonic setting, the platform reflects eustatic changes of sea‐level whereas deposition in the deeper basin records syndepositional tectonics.
The timing and extent of illite formation in Ordovician K‐bentonites at the Cincinnati Arch, the Nashville Dome and north‐eastern Illinois basin
Authors: Elliott W. CRAWFORD , Aronson JAMES L. 
Published: November 2007

AbstractThe K/Ar ages of illite/smectite (I/S) were measured from Middle Ordovician K‐bentonites both west and east of the present crest of the Cincinnati Arch and the Nashville dome to test a previous hypothesis that I/S formed by reaction with migrated saline solutions during the Alleghanian Orogeny. The K/Ar ages of I/S at the distal margin of the southern Appalachian basin and from central Indiana range from 251 to 277 Ma. However, the ages of I/S from west of the crest of the Cincinnati Arch are slightly older (286–301 Ma) and the ages of I/S from north‐eastern Indiana, on the northern edge of the Kankakee Arch and in effect in the Michigan basin, are the oldest measured in this study (315–325 Ma).The westward decrease in the K/Ar ages of I/S from Late Pennsylvanian ages in the proximal basin (286–303 Ma) to Permian (251–277 Ma) at the distal margin suggest that I/S was formed by the westward migration of fluids during the Alleghanian Orogeny as opposed to being formed by projected deep burial by Permian sediments. Moreover, the available thermal maturation data suggest the Cincinnati Arch was not buried deeply. The ages of I/S west of the Cincinnati Arch are an enigma as they are older than the ages in the distal Appalachian basin. The ages of I/S from central Indiana within the Illinois basin suggest the possibility that I/S was formed by reaction with fluids that migrated from the Ouachita orogenic belt in Mississippi. The oldest ages of I/S from north‐eastern Indiana suggest the formation of I/S might have been influenced by the presence of potassic brines from the Michigan basin.
Seismic modeling of Tertiary sandstone clinothems, Spitsbergen
Authors: Helland‐Hansen WILLIAM , Helle HANS B. , Sunde KJELL 
Published: November 2007

AbstractTwo‐dimensional seismic modelling has been undertaken on an overall progradational succession of sloping mudstone and sandstone units from the Palaeogene of Spitsbergen. The modelling shows that the main geometric features of the section would be resolved at 1500 m depth (with frequencies below 60 Hz, which is common in seismic data at these depths). However, interference between the base and top of lithological units gives lateral amplitude variations and discrepancies between the seismic image and the geometrical model. This is particularly prominent in low‐frequency models. Terminations of reflectors, resembling toplap and onlap, may be interpreted, but are artefacts of the general convergence of lithological units present in the geometrical model. The geological section causes a seismic pattern resembling sigmoid progradational seismic facies. Two‐dimensional seismic modelling is an efficient tool in bridging the gap between outcrop observations and subsurface data. Hence, modelled outcrop sections are important as reference points' for improved seismic stratigraphic interpretation.
Tectonic control on sedimentary evolution of three North Atlantic borderland Mesozoic basins1
Authors: Sinclair I. K. , Shannon P. M. , Williams B. P. J. , Harker S. D. , Mooren J. G. 
Published: November 2007

AbstractMultiple episodes of extensional tectonism dominated the formation of Mesozoic fault‐bounded basins on the Grand Banks of Newfoundland, the Irish Continental Shelf and the central North Sea. A range of structural and stratigraphic responses in the Jeanne d'Arc, Porcupine and Moray Firth basins support widespread synchronous tectonic controls on sedimentation during one of these episodes, the Late Cimmerian.Rifting was preceded by a phase of related tectonism during which subsidence rates began to vary across broad areas but without significant fault block rotation. This Late Cimmerian ‘onset warp’ pattern of subsidence is considered to have been essential in the establishment of restricted anoxic basins from latest Oxfordian through Kimmeridgian (sensu gallico) time and the development of one prolific layer of organic‐rich source rocks.The most prominent and widely recognized structural/lithostratigraphic response to Late Cimmerian rifting was the deposition of sediment wedges. Tithonian to early Valanginian strata generally thicken‐ into northerly trending faults in the Jeanne d'Arc and Porcupine basins, indicating that extensional stress was orientated WNW‐ESE across a very broad area. The misalignment of this regional Late Cimmerian extensional stress with local inherited structural fabric may be responsible for transpressional uplift of individual fault blocks in the Outer Moray Firth basin.Sedimentological responses to Late Cimmerian rifting were varied, though a common lithofacies stacking pattern is recognized. Variably thick conglomerates and/or sandstones were widely deposited at the start of rift deformation, while palaeoenvironments ranged from alluvial and braid plain to submarine fan even within individual basins. The relatively coarse basal sediments fine upwards into a second layer of commonly organic‐rich shales and mark The widest variations in palaeoenvironments and sediment thicknesses occurred during the last phase of Late Cimmerian rift tectonism, though all three basins show evidence of decreasing water depths, increasing oxygen levels and increasing grain size. This lithofacies stacking pattern of relatively coarse to fine to coarse (reservoir/source/reservoir) and the development of bounding unconformities are largely attributable to progressive changes in rift‐controlled subsidence. Rift basin subsidence rates are interpreted to increase from a low at initiation of faulting to a mid‐rift peak, followed by slowing subsidence to the end of extension. A number of counteracting crustal mechanisms that may account for progressive variations in rift‐induced subsidence are considered.
Effect of the Cretaceous Serra Geral igneous event on the temperatures and heat flow of the Parana Basin, southern Brazil
Authors: Hurter SUZANNE J. , Pollack HENRY N. 
Published: November 2007

AbstractWe investigate the effects of the cooling of intrusive and extrusive igneous bodies on the temperature history and surface heat flow of the Parana Basin. The Serra Geral igneous event (130–135 Ma) covered most of this basin with flood basalts. Associated with this event numerous sills and dykes intruded the sediments and basement, and extensive underplating may have occurred in the lower crust and upper mantle beneath the basin. We develop an analytical model of the conductive cooling of tabular intrusive bodies and use it to calculate temperatures within the sediments as a function of time since emplacement. Depending on the thickness of these igneous bodies and the timing of sequential emplacement, the thermal history of a given locus in the basin can range from a simple extended period of higher temperatures to multiple episodes of peak temperatures separated by cooling intervals. The cooling of surface flood basalts, sills and dykes is capable of maintaining temperatures abovc the normal geothermal gradient temperatures for a few hundred thousand years, while large‐scale underplating may influence temperatures for up to 10 million years. We conclude that any residual heat from the cooling of the Serra Geral igneous rocks has long since decayed to insignificant values and that present‐day temperatures and heat flow are not affected. However, the burial of the sediments beneath the thick basalt cap caused a permanent temperature increase of up to 50°C in the underlying sediments since the beginning of the Cretaceous.
Brine expulsion, fluid transport and metallization spanning 2.0 Gyr in basins of southern and central Africa
Authors: Duane M. J. , Saggerson E. P. 
Published: November 2007

AbstractMineral provinces in southern and central Africa are strongly controlled by major structural trends, the alignment of sedimentary basins and metamorphically induced thermal regimes deep in the crust. Ore deposits are preferentially located on cooler margins of orogenic belts and are ultimately end‐products of fluid expulsion out of the deeper parts of orogenic axes. Metamorphic and structural vectors within orogenic belts adjacent to major cratons show a trend of high‐grade thermal overprinting in the cores of axes and lower metamorphic regimes acting on the distal margins of orogens (e.g. foreland basins). This apparent pattern is considered to have importance in the expulsion of at least three generations of mineralizing fluids beginning with exhalative migration during diagenesis and culminating much later in thrust‐controlled expulsion onto adjacent craton margins. Fluids within the hydrosphere that accumulate initially through topographic gradients in the sediments mixed with components of the mantle (CO2). After storage within the crust, migration, enforced by metamorphic processes, transferred fluids out of, and away from, high thermal regimes in the axes of belts, leading to their present preservation around the margins of the major cratonic nuclei.
Miocene‐Pliocene half‐graben evolution, detachment faulting and late‐stage core complex uplift from reflection seismic data in south‐east Arizona
Authors: Kruger J. M. , Johnson R. A. , Houser B. B. 
Published: November 2007

AbstractReflection seismic data show that the late Cenozoic Safford Basin in the Basin and Range of south‐eastern Arizona, is a 4.5‐km‐deep, NW‐trending, SW‐dipping half graben composed of middle Miocene to upper Pliocene sediments, separated by a late Miocene sequence boundary into lower and upper basin‐fill sequences. Extension during lower basin‐fill deposition was accommodated along an E‐dipping range‐bounding fault comprising a secondary breakaway zone along the north‐east flank of the Pinaleño Mountains core complex. This fault was a listric detachment fault, active throughout the mid‐Tertiary and late Cenozoic, or a younger fault splay that cut or merged with the detachment fault. Most extension in the basin was accommodated by slip on the range‐bounding fault, although episodic movement along antithetic faults temporarily created a symmetric graben. Upper‐plate movement over bends in the range‐bounding fault created rollover structures in the basin fill and affected deposition within the half graben. Rapid periods of subsidence relative to sedimentation during lower basin‐fill deposition created thick, laterally extensive lacustrine or alluvial plain deposits, and restricted proximal alluvian‐fan deposits to the basin margins. A period of rapid extension and subsidence relative to sediment influx, or steepening of the upper segment of the range‐bounding fault at the start of upper basin‐fill deposition resulted in a large downwarp over a major fault bend. Sedimentation was restricted to this downwarp until filled. Episodic subsidence during upper basin‐fill deposition caused widespread interbedding of lacustrine and fluvial deposits. Northeastward tilting along the south‐western flank of the basin and north‐eastward migration of the depocentre during later periods of upper basin‐fill deposition suggest decreased extension rates relative to late‐stage core complex uplift.
Evolution of a large Miocene growth structure in the upper plate of the Whipple detachment fault, northeastern Whipple Mountains, California
Authors: Dorsey REBECCA J. , Becker ULF 
Published: November 2007

AbstractMiocene sedimentary and volcanic rocks in the north‐eastern Whipple Mountains, California, and the north‐western Aubrey Hills, Arizona, accumulated in the upper plate of the Whipple detachment fault during regional extension and slip on the detachment. Miocene rocks in this area can be divided into three sequences: (1) pre‐18.5‐Ma dominantly volcanic rocks; (2) the 18.5‐Ma Peach Springs Tuff; and (3) post‐18.5‐Ma dominantly sedimentary rocks. Important stratigraphic markers in sequence 3 include a 100‐ to 14–0‐m‐thick basalt unit and the voluminous War Eagle landslide, both of which correlate across Lake Havasu from the north‐east Whipple Mountains to the Aurbrey Hills. We divide clastic sedimentary rocks of sequence 3 into three informal members: (3a) conglomerate and sandstone stratigraphically beneath the basalt; (3b) conglomerate and sandstone above the basalt and below the War Eagle landslide; and (3c) conglomerate and sandstone that overlie the War Eagle landslide. Detailed stratigraphic analysis and field mapping reveal dramatic south‐westward thickening of member 3b strata, from about 50 m in the Aubrey Hills to over 1500 m in the north‐east Whipple Mountains. In the north‐east Whipple Mountains, this thick dipping section is overlain by the War Eagle landslide along a major angular unconformity; in the Aubrey Hills the base of the War Eagle landslide is roughly parallel to bedding dips of underlying strata.The above stratigraphic relationships can be explained by syndepositional growth of a rollover monocline by progressive tilting of the hangingwall above a master listric normal fault (Whipple detachment fault). This phase of upper‐plate deformation began shortly after deposition of the basalt and ended prior to emplacement of the War Eagle landslide. Interbedded breccias low in member 3b, about 100 m above the basalt, record the first appearance of mylonitic detritus in the section. Growth of this upper‐plate rollover was thus initiated at about the same time (shortly after deposition of the basalt) that the lower plate of the Whipple detachment fault was first exposed at the earth's surface by tectonic denudation and large‐scale crustal uplift. These events are interpreted to record initiation of a secondary breakaway fault on the north‐east flank of the growing Whipple detachment dome shortly after deposition of the basalt at about 14.5 (±1.0) Ma.
Example of a supradetachment basin within a pull‐apart tectonic setting: Mormon Point, Death Valley, California
Authors: Burchfiel B. C. , Molnar P. , Zhang P. , Deng Q. , Zhang W. , Wang Y. 
Published: November 2007

AbstractThe geological features now exposed at Mormon Point, Death Valley, reveal processes of extension that continue to be active, but are concealed beneath the east side of Death Valley. Late Cenozoic sedimentary rocks at Mormon Point crop out in the hangingwall of the Mormon Point low‐angle normal fault zone, a fault zone that formed within a releasing bend of the oblique‐slip (right‐normal slip) fault zone along the east side of Death Valley. The late Cenozoic sedimentary rocks were part of the valley when the low‐angle fault zone was active, but during late Quaternary time they became part of the Black Mountains block and were uplifted. Rocks and structures exposed at Mormon Point are an example of the types of features developed in a releasing bend along the margins of a major pull‐apart structure, and in this example they are very similar to features associated with regional detachment faults.The oldest sedimentary rocks in the hangingwall of the Mormon Point low‐angle fault zone dip steeply to moderately east or north‐east and were faulted and rotated in an extensional kinematic environment different from that recorded by rocks and structures associated with younger rocks in the hangingwall. Some of the younger parts of the late Cenozoic sedimentary rocks were deposited, faulted and rotated during movement on the Mormon Point low‐angle normal fault. Progressively, strata are less faulted and less rotated. The Mormon Point low‐angle normal fault has an irregular fault surface whose segments define intersections that plunge 18°‐30°, N10°‐40°W, with a maximum of 22°, N22°W that we interpret to be the general direction of slip. Thus, even though Death Valley trends north, movement on the faults responsible for its formation was at least locally north‐northwest. Gouge and disrupted conglomerates along the faults are interpreted to have formed either as adjustments to accommodate space problems at the corners of blocks or along faults that bounded blocks during their displacement and rotation.The younger units of the late Cenozoic sedimentary rock sequence and the geomorphic surfaces developed on them are rarely faulted, not rotated, and overlap the Mormon Point low‐angle faults. Active faults cut Holocene alluvium north of the late Cenozoic rocks and form the present boundary between Mormon Point and the Black Mountains. The distribution of active faults defines a releasing bend that mimics the older releasing bend formed by the Mormon Point low‐angle fault zone. Rocks and structures similar to those exposed above the Mormon Point low‐angle fault zone are probably forming today beneath the east side of Death Valley north‐west of Mormon Point.
Tectonic transition from the Songpan‐Garzê Fold Belt to the Sichuan Basin, south‐western China
Authors: Chen SHE FA , Wilson CHRISTOPHER J. L. , Worley BRENTON A. 
Published: November 2007

AbstractThe formation of the Songpan‐Garzê Fold Belt and the initiation of the terrestrial Sichuan Basin are related to closing of the Palaeo‐Tethys during the Late Triassic Indosinian orogeny. The Songpan‐Garzê Fold Belt is composed of Triassic (T1‐‐T23) turbiditic deposits and Palaeozoic greywacke‐shale, whereas the Sichuan Basin consists of Sinian to middle Upper Triassic (T23) platform carbonates and Upper Triassic (T3X to Quaternary terrestrial elastics. Three principal deformation episodes during the Late Triassic (Norian to Rhaetian) were progressively localized towards the south‐eastern margin of the fold belt. D1 was a SW‐directed shortening event, related to continuous subduction of the Palaeo‐Tethys, and produced NW‐trending structures. Differential strain between the fold belt and the Sichuan Basin was accommodated by sinistral shearing along a NE‐trending transitional zone during D2. D3 SE‐directed compression was the result of collision between the Cimmerian and Eurasian Continents and initiated the Longmen Mountains Thrust‐Nappe Belt and terrestrial Sichuan Basin. Post‐D3 deformation, related to SE‐directed thrusting in the Longmen Mountains, then propagated from hinterland to foreland. The Indosinian orogeny closed the Palaeo‐Tethys and terminated the marine conditions that dominated the early evolution of the intracratonic Sichuan Basin. Tectonic loading from the exhumed fold belt and Thrust‐Nappe Belt induced substantial subsidence in the Sichuan Basin, especially in the Western Sichuan Foreland Basin, resulting in the deposition of a terrestrial clastic sequence during Late Triassic (T3X to Quaternary times. The foreland basin history comprises an early stage during the Late Triassic (T3x1–2), an over‐fill stage during the latest Triassic to Early Cretaceous (T3X3‐ K1J), and a shrinking stage from the Late Cretaceous to the Quaternary (K2J‐Q). These can be correlated with tectonic events in the Thrust‐Nappe Belt.