Basin Subsidence History Research Articles

Foreland basin—a FORTRAN program to model the formation of foreland basins resulting from the flexural deflection of the lithosphere caused by a time-varying distributed load

A FORTRAN program is described that calculates the deflection of a thin elastic plate resulting from a time-varying distributed load. The program is useful for modeling the subsidence of a foreland basin where the elastic plate is the lithosphere and the distributed load is a wedge-shaped thrust sheet. The deflection is calculated for a specific load distribution, and hence at a specific time but one can prescribe various loads at different times in the loading history so that the basin subsidence history can be shown.

A 3-D Backstripping Method and Its Application to the Eromanga Basin In Central and Eastern Australia

SUMMARY A general 3-D backstripping method, based on a precise model of plate deformation, is developed for analysis of the tectonic history of sedimentary basins, and it has been applied to the Eromanga Basin in central and eastern Australia. The 3-D method is more appropriate when dealing with the subsidence history of basins, since it takes into account both the flexural effect of surface load and the stress relaxation in the lithosphere due to viscous creep of mantle material. Furthermore, this method is more accurate than conventional thin plate models. It is shown that the 3-D model provides a different, yet simple and clear evolving picture of the areal extent of the tectonic subsidence of basins. The 3-D analysis results show that the formation of the Eromanga Basin is characterized by a gradual increase in the extent of sedimentation with localized subsidence from the Late Triassic to the Early Cretaceous and a large extension of sedimentation with rapid subsidence during the Early to Middle Cretaceous, followed by local and gradual subsidence after the Middle Cretaceous.

Three-Dimensional Foreland Basin Stratigraphic Geometry and Subsidence History: Colville Trough, Alaska

Three-Dimensional Foreland Basin Stratigraphic Geometry and Subsidence History: Colville Trough, Alaska

STRATIGRAPHIC MODELLING OF THE GIPPSLAND BASIN

The Gippsland Basin is an asymmetric graben which initially formed during the break-up of Australia and Antarctica in the Early Cretaceous. During continental rifting the basin was filled by volcano-clastics of the Strzelecki Group. The overlying alluvial sediments of the Golden Beach Group represent a second phase of rift fill associated with the Tasman Sea rift. Following continental break-up in the Campanian, the Latrobe Group was deposited as a transgressive sequence of marine and coastal plain sediments. Thermal subsidence from the Oligocene to Recent was accompanied by the deposition of marine marls and limestones of the Lakes Entrance Formation and Gippsland Limestone.A north-south cross-section through the basin, based on regional seismic data and nine exploration wells, has been used to study the tectonic, thermal and basin-fill history. A detailed basin subsidence history based on a crustal rifting model was constructed, constrained by stratigraphic data and palaeo-water depth estimates at well locations. The history of sedimentation was then modelled by a Shell proprietary package, using the subsidence history and published eustatic sea level variations. This numerical model is based on a forward time-stepping scheme using semi-empirical algorithms to define the facies deposited. The gross basin architecture of the Gippsland Basin is successfully reproduced by the model. In addition the model details the timing and extent of marine incursions in the Golden Beach Group and the eustatic control on facies patterns in the Latrobe Group.The method has potential for predicting the sedimentary facies in undrilled parts of the Gippsland Basin and in frontier areas in general.

Comparative Stratigraphy and Subsidence History of Mesozoic Rift Basins of North Atlantic (1)

Mesozoic rift basins around the North Atlantic all possess many of the following Upper Jurassic to Lower Cretaceous (Oxfordian to Albian) stratigraphic elements: (1) an early Oxfordian hiatus, (2) backfill deposits in Upper Jurassic paleovalleys, (3) multiple Tithonian transgressive-regressive sequences, (4) early Berriasian regressive sequences, (5) a sub-Valanginian unconformity overlain by coarse siliciclastic sandstones and conglomerates, (6) Valanginian to Hauterivian fining-upward sequences, (7) condensed Barremian sequences, and (8) prominent Aptian unconformities. More local features include abrupt Kimmeridgian deepening (Lusitanian basin, Portugal), Albian deepening (Cantabrian and Aquitaine basins, northern Spain and southern France), and late Albian-early Cenom nian source rejuvenation (Cantabrian basin, northern Iberia). Decompaction and backstripping of sediments from well and outcrop sections in six basins also reveal broad similarities in trends of rates of apparent basement subsidence. Relatively high rates (50-100 m/m.y.) characterize onset of rift phases in the Triassic and the Kimmeridgian. Locally, in the Lusitanian basin of Portugal, Kimmeridgian rates reach about 250 m/m.y. In the Cantabrian and Aquitaine basins, a third phase of rapid subsidence characterizes the Aptian-Albian interval after the main phase of continental breakup around Iberia. This phase may be due to transtensional stresses as Iberia continued to rotate relative to Europe, tensional intraplate stresses, or gravity driven partial collapse of the new continental marg n. The North Atlantic Mesozoic basins share many features because they had a common origin controlled by intracontinental rifting and subsequent separation of Europe and North America. Pulses of extension generally are reflected in the stratigraphy of all of the basins. Superimposed on this record are the effects of eustatic sea level variations. The main difference between the Canadian Jeanne d'Arc basin and Iberian basins is the significantly greater Early and Middle Jurassic basement subsidence rate in the former (about 40 m/m.y. vs. 0-10 m/m.y.). This difference may result from prolonged extension on the Canadian side, perhaps due to northward transfer of shear stress from left-lateral transform motion between the Grand Banks and northwestern Africa.

Diagenesis of Terry Sandstone (Upper Cretaceous), Spindle Field, Colorado

ABSTRACT This study discusses the influence that sedimentology, diagenesis, and basin subsidence history have on porosity and permeability of the Upper Cretaceous Terry sandstone of Spindle field in the Denver basin. The Terry sandstone consists of lithic subarkoses and feldspathic litharenites deposited in a marine bar complex. The reservoir facies, which was deposited in a marine bar crestal position, is a cross-bedded sandstone with a mixture of primary and secondary macropores. Approximately half of the pore volume is microporosity associated with clay minerals and lithic fragments. The nonreservoir facies was deposited on the bar-flank margin as lower-energy, alternating layers of mud and sand, which were extensively bioturbated to produce muddy sands. Ductile deformation of lithic fragments is a major factor in porosity loss for the reservoir facies. Chlorite and calcite are the most important mineral cements. Authigenic quartz, dolomite, ferroan calcite, kaolinite, feldspar, pyrite, and tourmaline are present in minor to trace amounts. Precipitation of these minerals is believed to be related to the evolution of marine water. Secondary porosity formed by dissolution of pore-filling and replacement calcite and framework feldspars. Sandstones with pervasive calcite cement have no secondary porosity developed, which suggests some permeability may be needed to develop secondary porosity. Plagioclase feldspars become more albitized with increasing depth. A temperature-depth subsidence profile predicts a maximum temperature of only 85°C, at least 15° lower than in Tertiary rocks, which suggests that kinetic considerations may also be important to albitization. Vitrinite reflectance (0.65%) and interbedded shales with ordered mixed-layered illite/smectite with up to 50% expandability also support the lower temperature regime. Calculations suggest that seawater can supply sufficient sodium to account for albitization. Albitization proceeded more rapidly in permeable sandstone, where the plagioclase was in direct contact with the pore fluids. Plagioclase in relatively impervious sandstones eventually became albitized, probably through diffusion.

Deep crustal structure and evolution of the rifted margin northeast of Newfoundland: results from LITHOPROBE East

As part of the LITHOPROBE East project, a marine deep seismic reflection line was run in 1984 across the continental margin northeast of Newfoundland. The seismic data define reflectors both within and below the sedimentary section. The deeper, intracrustal reflectors help determine the nature of extensional tectonics and associated sedimentary basin evolution on the rifted margin. The line also crosses the ocean–continent transition and helps define structure in that region. Interpretation of the seismic data shows that brittle extension of the upper crust was accommodated along at least one subhorizontal level of décollement. The most obvious style of deformation involves the shallowest level of décollement on which high-angle planar normal faults detach. A deeper level of décollement is inferred from the presence of low-angle listric normal faults penetrating the lower crust or deeper. There is no evidence for a unidirectional low-angle shear zone controlling extension. The seismic data are used to constrain a depth-dependent numerical model of extension. Best-fit estimates of the basin subsidence history support a model in which there are several episodes of stretching and in which there is significantly more stretching in the lower lithosphere than in the upper lithosphere. At the ocean–continent transition, the oceanic crust appears to thicken as it dips beneath the rifted continental crust. This may result from the production of basaltic magma and its migration to crustal levels during rifting.

History and controls of subsidence in the Late Cretaceous-Tertiary Great Valley forearc basin, California

Abstract Analysis of the Upper Cretaceous-Tertiary fill of the Great Valley forearc basin of California reveals a complicated history of subsidence partitioned in time and space. Western, oceanward parts of the basin record subsidence, then uplift, in apparent response to the angle and rate of descent of the underlying subducting plate. Specifically, uplift in the forearc basin corresponds to the onset of the Laramide orogeny and inferred low angles of subduction. In contrast, eastern, arcward parts of the basin display subsidence histories suggestive of thermal contraction and compatible with continentward migration of Sierran arc magmatism in the Late Cretaceous. These results imply that subsidence histories of forearc basins are likely to be much more complicated and less predictable than those of rifted continental margins and foreland basins, where single subsidence mechanisms predominate and time-varying subduction is not an underlying controlling factor.

Carboniferous Clastic-Wedge Stratigraphy, Sedimentology, and Foreland Basin Evolution: Black Warrior Basin, Alabama and Mississippi: ABSTRACT

Carboniferous clastic-wedge stratigraphy and sedimentology in the Black Warrior basin of Alabama and Mississippi indicate deposition in an evolving foreland basin flanking the Appalachian-Ouachita fold-thrust belt. The strata reflect specific responses to foreland basin subsidence, orogenic activity, sediment supply, and dispersal systems. Definition of the regional stratigraphy of the clastic wedge provides for interpretation of the foreland basin subsidence history by enabling quantitative reconstruction of regional compaction and subsidence profiles. Comparison of the interpreted subsidence history with model profiles of foreland basin subsidence (predicted from loading and flexure of continental lithosphere) allows evaluation of mechanical models in terms of observed clastic-wedge sedimentology and stratigraphy. Mechanical modeling of foreland basin subsidence predicts formation of a flexural bulge that migrates cratonward ahead of the subsiding foreland basin during loading. In the Black Warrior basin, local stratigraphic thins, pinch-outs, and areas of marine-reworked sediments suggest migration of the flexural bulge. Comparison of flexural bulge migration with thermal maturation history allows evaluation of timing of stratigraphic trapping mechanisms with respect to onset of hydrocarbon generation.

Some Comments on Two-Layer Extensional Models for Evolution of Sedimentary Basins: ABSTRACT

Simple extensional models that involve listric faulting in the brittle upper crust and plastic flow in the lower lithosphere have been shown to account for the subsidence history of various continental sedimentary basins and continental shelves. In this paper we present structural evidence that extension in the continental lithosphere during rifting is not uniform. We review evidence that the rifting process in major intracratonic rift basins is spasmodic rather than continuous, that extension and subsidence within the rift during a tectonic phase are generally accompanied by uplift and erosion of the rift flanks, that subcrustal heat input during rifting occurs over an area much broader than the rift proper, and that there may be broad regional uplift before and/or durin rifting. To explain the uplift of the flanks during rifting and their postrift subsidence, we invoke 2 mechanisms: subcrustal thinning by extension below the flanks and tilted major normal faults in the crust between graben and flanks. The uplift and erosion of the flanks due to tilted faults probably do not significantly affect estimates of extension from subsidence analysis, but uplift due to both sources can, in certain cases, be incorrectly attributed to regional uplift or doming. We present a simplified analysis of the 2-layer extensional model for the elementary case in which extension is instantaneous and the crust is thinned by a different amount from the subcrustal lithosphere. We provide a simple graphical method of data analysis to obtain the parameters that describe thinning of the crust and lithosphere during extension from the subsidence history. Application of this method to the central part of the Pattani Trough in the intracratonic Gulf of Thailand shows that extension and thinning of the lithosphere of a factor of ~2 since late Eocene can account for much of the subsidence history and the present-day heat flow. Our analysis suggests that thinning of the crust in this area is ~20% greater than thinning of the whole lithosphere. Assuming that none of the lithosphere is removed from the region of extension during rifting, we show by simple geometric examples that a process of nonuniform extension implies that much greater thicknesses of sediment can be deposited in the center of a young basin than in the case of uniform extension of both crust and subcrustal lithosphere. Such an extensional process produces significant uplift of the flanks of the rift and, as a result of erosion of the uplifted areas, the effective cross sectional area of the basin can be increased by as much as 10-20%, depending on the rate of erosion, compared to the area that would have been created by a process of uniform extension. Finally, we show that ultimately it may be possible to compute erosion rates from seismic cross sections of asins. End_of_Article - Last_Page 795------------

Role of Depositional-Depth and Source-Terrain Uplift Rates on Sedimentation Patterns in Back-Arc Basins of Western Pacific: ABSTRACT

Nine depositional systems occur in Deep Sea Drilling Project (DSDP) cores recovered from western Pacific back-arc basins. These include submarine fan, debris flow, silty basinal turbidite, biogenic pelagic silica, biogenic pelagic carbonate, redeposited carbonate, pyroclastic, hemipelagic clay, and pelagic clay depositional systems. Correlation of deposition of these systems to times of basin rifting, associated island arc andesitic volcanism, and uplift of source terranes shows that only biogenic carbonate, pelagic clay, submarine fan, and debris flow processes of sedimentation are correlated to specific tectonic processes. Basin subsidence history controlled by heat flow dissipation controls the preservation potential of biogenic carbonates and pelagic clay. Rate of tec onic uplift in andesitic volcanic sources controls the volume and preserved frequency of turbidites on submarine fans and associated debris-flow wedges. A time delay in fan and debris flow sedimentation following maximum uplift in source terranes is governed by development of mature drainage systems and sediment yield into the back-arc basins. The other depositional systems are deposited independent of rifting, subsidence, or uplift history because their distribution is controlled more by regional volcanism, wind dispersal, climatic change, latitudinally-defined biologic productivity, and slope instability. The variety of stratigraphic sequences in back-arc basin DSDP cores can be explained better in terms of all these changing variables coupled with tectonic processes. The combination of depositional depth and source-terrane uplift rate are the only tectonic processes which directly influence specific sedimentation events in this particular domain. End_of_Article - Last_Page 495------------

Some comments on two‐layer extensional models for the evolution of sedimentary basins

Simple extensional models that involve listric faulting in the brittle upper crust and plastic flow in the lower lithosphere have been shown to account for the subsidence history of various continental sedimentary basins and continental shelves. In this paper we present structural evidence that extension in the continental lithosphere during rifting is not uniform. We review evidence that the rifting process in major intracratonic rift basins is spasmodic rather than continuous, that extension and subsidence within the rift during a tectonic phase is generally accompanied by uplift and erosion of the rift flanks, that subcrustal heat input during rifting occurs over an area much broader than the rift proper, and that there may be broad regional uplift before and/or during rifting. To explain the uplift of the flanks during rifting and their postrift subsidence, we invoke two mechanisms: subcrustal thinning by extension below the flanks and tilted major normal faults in the crust between graben and flanks. The uplift and erosion of the flanks due to tilted faults probably do not significantly affect estimates of extension from subsidence analysis, but uplift due to both sources can, in certain cases, be incorrectly attributed to regional uplift or doming. We present a simplified analysis of the two‐layer extensional model for the elementary case in which extension is instantaneous and the crust is thinned by a different amount from the subcrustal lithosphere. We provide a simple graphical method of data analysis to obtain the parameters that describe thinning of the crust and lithosphere during extension from the subsidence history. Application of this method to the central part of the Pattani Trough in the intracratonic Gulf of Thailand shows that extension and thinning of the lithosphere of a factor of ∼2 since late Eocene can account for much of the subsidence history and the present‐day heat flow. Our analysis suggests that thinning of the crust in this area is ∼20% greater than thinning of the whole lithosphere. Assuming that none of the lithosphere is removed from the region of extension during rifting, we show by simple geometric examples that a process of nonuniform extension implies that much greater thicknesses of sediment can be deposited in the center of a young basin than in the case of uniform extension of both crust and subcrustal lithosphere. Such an extensional process produces significant uplift of the flanks of the rift, and as a result of erosion of the uplifted areas, the effective cross‐sectional area of the basin can be increased by as much as 10–20%, depending on the rate of erosion, compared to the area that would have been created by a process of uniform extension. Finally, we show that it may ultimately be possible to compute erosion rates from seismic cross sections of basins.

Evolving Concepts and Teaching Approaches In Tectonics and Sedimentation

Developments in sedimentary geology within the last decade greatly extend our ability to read tectonic events from the sedimentary record. Informally polled, eleven teacher-researchers of sedimentary tectonics cited five key areas of advance: (1) general basin type and setting in plate tectonic context; (2) tectonic setting as reflected in sandstone composition; (3) refinements in facies analysis in conjunction with basin type and setting; (4) quantitative analysis of subsidence histories of sedimentary basins; and (5) stratigraphic analysis of reflection seismic data. These advances in sedimentary tectonics are woven into graduate courses or seminars in basin analysis at many universities. Classes typically include a review of modern depositional systems analysis and a survey of basin types by tectonic setting. As an example, students at Stanford University are exposed to concepts in tectonics and sedimentation in two modes. A graduate level course entitled “Sedimentary Basins” reviews the broad spectrum...

Modeling Basin Subsidence and Stratigraphy: Blake Plateau Basin: ABSTRACT

Blake Plateau basin on the continental margin off Georgia and Florida contains 12 to 13 km (39,000 to 43,00 ft) of Jurassic and younger sedimentary rock. Although such thicknesses of strata are common to sedimentary basins off the eastern United States, the Blake Plateau basin is underlain by unusually thick basement rocks (20 to 24 km; 66,000 to 79,000 ft) and is much wider (350 km; 220 mi) in comparison with other basins. Simple extensional models for the basin's origin would suggest thinner basement to correspond with the observed sedimentary thicknesses, i.e., basement 4 to 16 km (13,000 to 52,000 ft) thick. In contrast, a two-dimensional gravity model across the continental margin details the anomalous crustal structure. The basement is about 30 km (98,000 ft) thick nder the shelf; 18 km (59,000 ft) under the basin, thickening seaward to 24 km (79,000 ft) under the basin's eastern edge; and 6 km (20,000 ft) thick seaward of the Blake Escarpment. The basin's subsidence history places limits on possible models of the crustal development of this part of the margin. Because of the paucity of well data, a detailed backstripping analysis of the stretched continental-crust area is not possible, but an estimation End_Page 555------------------------------ can be made of the post rift, thermal-subsidence history using multichannel seismic data. Stratigraphic control for Cretaceous and younger reflectors observed in these seismic profiles is available from the Continental Offshore Stratigraphic Test GE-1 well on the landwardside and from an eroded exposed escarpment on the seaward edge of the basin. The Jurassic age assignments were based on correlations with Jurassic sea level history. When a different and simplified technique is used, the subsidence due to stretching and cooling, but not to sedimentation, during the pre-, syn-, and post-rift periods combined, can be obtained by calculating the depth of basement that would exist without a sedimentary load. Unlike the other east coast basins, in the Blake Plateau basin this unloaded basement depth indicates local maximum values in both the subsidence due to stretching and cooling and in sedimentary thickness. These maxima occur where the gravity model shows a transition to increasing crustal thickness seaward and near the southwest continuation of the trend of the East Coast Magnetic Anomaly, which marks where, on the rest of the margin, the stretched continental crust finally separated and new oceanic crust began to form. Rifted crust of the Blake Plateau basin never failed, and generation of new oceanic crust seems finally to have begun far to the east, east of the present Blake Plateau and almost against the West African craton. The presence of rift-stage crust on either side of this aborted break, and lack of an extensional basin on the opposing African margin south of Senegal basin, and the paleoreconstruction of the area imply that the Blake Plateau basin continued to be rifted after the rift-to-drift transition had taken place in the basins to the north. This extended period of rifting may be responsible for the anomalous width of the Blake Plateau basin and for continued volcanism (dike injection?) which produced the unusual thickness of its rift stage crust. End_of_Article - Last_Page 556------------

Evolution of Sedimentary Basins: ABSTRACT

Simple extensional models that involve stretching by listric faulting in the brittle upper crust and plastic flow in the lower lithosphere have been shown to account for the subsidence history of various sedimentary basins, continental shelves, and the Central graben in the North Sea. The case where extension thins the crust by a different amount from the subcrustal lithosphere has been considered by several authors, but their treatment of two-layer extension is overly complicated and partly incomplete. In this paper, we present a simplified analysis of the two-layer extensional model for the elementary case in which extension is instantaneous, the crust is thinned by a different amount from the subcrustal lithosphere, the effects of radioactivity and dike intrusion are i nored, and local isostatic compensation is assumed at all times. We show how the thinning parameters can be obtained from the subsidence data through the use of a simple and powerful method of data analysis. We show that conservation of mass during a process of non-uniform extension implies that much greater thicknesses of sediment can be deposited in a young basin than in the case of uniform extension of both crust and subcrustal lithosphere. Further, we show that such an extensional process produces significant uplift of the flanks of a graben and that, as a result of erosion of the uplifted areas, the effective area of the basin can be increased as much as 25 to 30%, depending on the rate of erosion, compared to the area that End_Page 481------------------------------ would have been created by a process of uniform extension. Finally, we consider the forces of uplift on the flanks in the situation where the crust is treated as a thin elastic plate floating on a fluid upper mantle, the graben is bounded by two major normal faults, and there is subcrustal thinning under the flanks. We show that such normal faults produce uplift of the flanks and that this uplift can be significantly increased by the subcrustal thinning. Both kinds of forces give rise to uplift which can, in certain places, be misinterpreted as pre-rift doming. However, the uplift and erosion on the flanks of the graben associated with non-vertical faulting does not introduce significant error into the calculation of extensional parameters from subsidence analysis of a cross section o a basin. End_of_Article - Last_Page 482------------

The evolution of sedimentary basins : Kent, Peter, M.H.P. Bott, D.P. McKenzi and C.A. Williams (eds.), 1981/82. (Symposium 3–4 June 1981.) Phil. Trans. R. Soc., (A)305(1489):3–338; 18 papers

Simple extensional models that involve stretching by listric faulting in the brittle upper crust and plastic flow in the lower lithosphere have been shown to account for the subsidence history of various sedimentary basins, continental shelves, and the Central graben in the North Sea. In this paper, the authors present a simplified analysis of the two-layer extensional model for the elementary case in which extension is instantaneous, the crust is thinned by a different amount from the subcrustal lithosphere, the effects of radioactivity and dike intrusion are ignored, and local isostatic compensation is assumed at all times. The authors show how the thinning parameters can be obtained from the subsidence data through the use of a simple and powerful method of data analysis. The authors show that conservation of mass during a process of non-uniform extension implies that much greater thicknesses of sediment can be deposited in a young basin than in the case of uniform extension of both crust and subcrustal lithosphere. Further, the authors show that such an extensional process produces significant uplift of the flanks of a graben and that, as a result of erosion of the uplifted areas, the effective area of the basin can be more » increased as much as 25 to 30%, depending on the rate of erosion, compared to the area that would have been created by a process of uniform extension. Finally, the authors consider the forces of uplift on the flanks in the situation where the crust is treated as a thin elastic plate floating on a fluid upper mantle, the graben is bounded by two major normal faults, and there is subcrustal thinning under the flanks. The authors show that such normal faults produce uplift of the flanks and that this uplift can be significantly increased by the subcrustal thinning. « less

Latest Jurassic--Early Cretaceous Regressive Facies, Northeast Africa Craton

Nonmarine to paralic detrital deposits accumulated in six large basins between Algeria and the Arabo-Nubian shield during major regression in latest Jurassic and Early Cretaceous time. The Ghadames (northwestern Libya and adjacent Tunisia and Algeria), Sirte (north-central Libya), and Northern (Egypt) basins lay along the cratonic margin of northeastern Africa. The Murzuk (southwestern Libya and northern Chad), Kufra (southeastern Libya and nearby Sudan), and Southern (Egypt) basins lay in the south within the craton. Data for reconstructing distribution, facies, and thickness of relevant sequences are adequate for the three northern basins only; reconstructions of the southern ones are suggestive at best. High detrital influx near the end of Jurassic time and in mid-Cretaceous time produced regressive nubian facies composed largely of low-sinuosity stream and fan-delta deposits. In the west and southwest the Ghadames, Murzuk, and Kufra basins were filled with a few hundred meters of detritus after long-continued earlier Mesozoic aggradation. The three northeastern basins were filled with 1,000 to 2,000 m of detritus. In northern Egypt the regressive sequence succeeded earlier Mesozoic marine sedimentation; in the Sirte and Southern basins correlative deposits accumulated on Precambrian and Variscan terranes after earlier Mesozoic uplift and erosion. Waning of detrital influx into southern Tunisia and adjacent Libya in the west and into Israel in the east initiated an Albian to early Cenomanian transgression of Tethys. By late Cenomanian time it had flooded the entire cratonic margin, and spread southward into the Murzuk and Southern basins, as well as onto the Arabo-Nubian shield. Latest Jurassic--earliest Cretaceous, mid-Cretaceous, and Late Cretaceous transgressions across northeastern Africa recorded in these sequences may reflect worldwide eustatic sea-level rises. In contrast, renewed large supply of detritus during each regression and a comparable subsidence history of intracratonic and marginal basins imply regional tectonic control.