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The south- to southwest-dipping North and South Saros normal faults occupy the southeastern margin of the Gerania Range, a major massif of Mesozoic limestone and ophiolite in the eastern Gulf of Corinth Rift, central Greece. The history of the Saros faults is constrained by adjacent basin-fill sediments and modern drainage patterns. Older basin fill (Pliocene--lower Pleistocene?), which consists of terrestrial fine sands, carbonaceous muds, marls, and micrite limestones, is uplifted on the South Saros fault block and onlaps the North Saros fault footwall block on its northern side to near its crest, suggesting that it predates major fault activity. In contrast, younger basin fill (middle Pleistocene?) was deposited and locally deformed during fault activity in a main basin south of the faults and in a perched basin on the South Saros fault block. Main-basin deposits consist of alluvial-fan, fan-delta, and shallow-marine sediments up to 50 m thick, whereas perched-basin fanglomerates are 5-15 m thick. Fault-scarp retreat and sediment onlap indicate that the faults became inactive late in the history of deposition of the younger basin fill. The perched and main basins are currently undergoing incision, allowing modern sediment to bypass the basins and to be deposited on modern fan deltas and beaches along the Gulf of Megara coast. The absence of knickpoints and upstream deepening of the canyons suggest that a climatically driven increase in catchment runoff was responsible for basin incision, although uplift and sea-level change may have contributed as well. The North and South Saros faults each consist of three segments characterized by different strikes. The major drainages cross the Saros faults at or near segment boundaries, suggesting that the drainages may have initially flowed between the tips of isolated fault segments. As the segments became linked, the antecedent drainages maintained their course and cut deep gorges. At the scale of the entire eastern Gulf of Corinth region, however, older unlinked faults were abandoned, and new faults were created in a general northward and basinward direction; the origin of this process remains controversial.

Tectonics, climate and sea level are dominant controls on the nature and distribution of sedimentary environments. By inverse logic, recognition of influences on sedimentation from the stratigraphic record as a result of perturbations in these variables leads to clarification of past environmental and structural change. The succession of sedimentary environments in time and place is determined by a wider combination of variables; namely, sediment flux, biological evolution, atmosphere and water body productivity and chemistry. The feedbacks and interrelationships between all variables cause the complexity seen in sedimentation processes over geological time. The processes of global tectonics that cause widespread mountain belt and continental plateau uplift have produced numerous 'severe' events during Earth history: these often random workings-out of the plate tectonic cycle define the state of 'Cybertectonic Earth' (from cyber, after the Greek kubernan: to steer or govern). This has worked within a usually zonally arranged series of climatic belts and within the framework provided by biological evolution. At certain times in the geological past, a combination of factors arose as a response to continental uplift and have acted to cause certain Earth surface conditions and variables (notably mean global surface temperature, atmospheric pC[O.sub.2], p[O.sub.2]) to have varied by very large amounts (x2-x10) compared with present values. These large fluctuations, such as those responsible for the Neoproterozoic, Late Palaeozoic and late Tertiary glaciations, lead one to doubt the reality of homeostatic control of surface conditions as proposed in Lovelock's Gaia hypothesis. The Gaian kubernetes (steersman) had a weak hand on the helm, frequently unable to prevent vast areas of the globe experiencing rapid fluctuations in environmental conditions and inimical conditions to life for very long periods during Neoproterozoic and Phanerozoic times. At the same time, biogenic and abiogenic processes have proved capable of returning Earth to states of mean stability, although biogeochemical cycling models seem alarmingly ad hoc and largely untestable as scientific hypotheses in any true geological sense.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.earscirev.2006.07.002 Byline: Greg H. Mack (a), William R. Seager (a), Mike R. Leeder (b), Marta Perez-Arlucea (c), Stephen L. Salyards (d) Keywords: Rio Grande rift; fluvial; Pliocene and Quaternary; New Mexico Abstract: The history of the Rio Grande, the axial river of the southern Rio Grande rift, New Mexico, may be divided into an aggradational phase ([approximately equal to] 5 to [approximately equal to] 0.8 Ma), during which time about 100 m of fluvial sediment was deposited in eight basins, and a degradational phase ([approximately equal to] 0.8 Ma to present), when the river alternately incised and partially backfilled its basins. Reversal magnetostratigraphy, dated volcanic rocks, and vertebrate biostratigraphy allow correlation of sediment of the aggradational phase with the Gilbert, Gauss, and Matuyama Chrons, while the degradational phase primarily encompasses the Brunhes Chron. Tectonics was the primary control on river behaviour during the aggradational phase. In half grabens, multistorey channel sands were deposited in narrow belts near the footwall uplifts, in response to tilt of the basin floor towards the border fault and smaller footwall catchments and their alluvial fans compared to those of the hanging-wall mountains. In contrast, the river traversed almost the entire width of full grabens, depositing interbedded channel and floodplain sediment with moderately mature palaeosols. Condensed sections dominated by floodplain sediment with very mature palaeosols developed in basins largely abandoned by the river due to preferential tilting of the basin floor, lateral growth or renewal of fault activity, or alternating flow of the river between adjacent basins. The degradational phase was dominated by net basin erosion related to glacial-climate cycles, despite continued activity on many of the basin-bounding faults. Author Affiliation: (a) Department of Geological Sciences, New Mexico State University, Las Cruces, NM 88003, USA (b) School of Environmental Sciences, University of East Anglia, Norwich, Norfolk NR4 7TJ, UK (c) Departemento de Geosiencias Marinas, F. Ciencias, Universidad de Vigo, 36200, Vigo, Spain (d) Department of Earth and Space Sciences, UCLA, Los Angeles, CA 90024, USA Article History: Received 29 November 2005; Accepted 4 July 2006

The presence of sand moving at low transport rates over a fiat bed modulates the production of turbulence when compared to clearwater flow at similar mean flow conditions. Phase Doppler anemometry is used to discriminate the turbulence characteristics of the carder fluid from the sediment grains (0.22 mm diameter) and shows that the presence of mobile sediment increases the near-wall velocity gradient and shear velocity when compared with the clearwater values. This increased shear velocity is associated with a greater bed roughness height and near-bed turbulence intensities and smaller mixing lengths. Quantification of slip velocities between the fluid and sediment phases reveals particle Reynolds numbers that range from 1 to 30. Turbulence enhancement is shown to occur at lower values of both the Stokes number and ratio of the particle size-to-turbulent .length scale than in past work. Several mechanisms of turbulence modulation may be invoked to explain these changes, including increased bed roughness, eddy shedding from large grains, grain inertial effects, and particle-coherent structure interactions. These mechanisms may be significantly influenced by both particle-particle and particle-wall interactions. Since mobile sediment modulates the carrier fluid turbulence, there is a need for modification of existing theories of sediment suspension and for caution when interpreting velocity profiles that are obtained without discriminating the fluid and sediment phases.

Since 1978 the results of computational architectural models have been widely used to aid interpretation of ancient alluvial successions: here we present the first quantitative test of such models. We parameterize variables from field and magnetostratigraphic data collected from the well-exposed Pliocene-Pleistocene Camp Rice and Palomas Formations of the Rio Grande rift in south-central New Mexico. Computational runs establish that the LAB (Leeder, Allen, and Bridge) model correctly predicts the gross architectural patterns of ancestral axial Rio Grande half grabens and full grabens. Convergence of tectonic subsidence rate and mean sedimentation rate over the studied interval suggests that the dynamic basis of the models is correct; i.e., it is the tectonic 'draw-down' of axially supplied sediment that controls the net preservation potential of alluvial successions.

Our current understanding on sedimentary deep‐water environments is mainly built of information obtained from tectonic settings such as passive margins and foreland basins. More observations from extensional settings are particularly needed in order to better constrain the role of active tectonics in controlling sediment pathways, depositional style and stratigraphic stacking patterns. This study focuses on the evolution of a Plio‐Pleistocene deep‐water sedimentary system (Rethi‐Dendro Formation) and its relation to structural activity in the Amphithea fault block in the Corinth Rift, Greece. The Corinth Rift is an active extensional basin in the early stages of rift evolution, providing perfect opportunities for the study of early deep‐water syn‐rift deposits that are usually eroded from the rift shoulders due to erosion in mature basins like the Red Sea, North Sea and the Atlantic rifted margin. The depocentre is located at the exit of a structurally controlled sediment fairway, approximately 15 km from its main sediment source and 12 km basinwards from the basin margin coastline. Fieldwork, augmented by digital outcrop techniques (LiDAR and photogrammetry) and clast‐count compositional analysis allowed identification of 16 stratigraphic units that are grouped into six types of depositional elements: A—mudstone‐dominated sheets, B—conglomerate‐dominated lobes, C—conglomerate channel belts and sandstone sheets, D—sandstone channel belts, E—sandstone‐dominated broad shallow lobes, F—sandstone‐dominated sheets with broad shallow channels. The formation represents an axial system sourced by a hinterland‐fed Mavro delta, with minor contributions from a transverse system of conglomerate‐dominated lobes sourced from intrabasinal highs. The results of clast compositional analysis enable precise attribution for the different sediment sources to the deep‐water system and their link to other stratigraphic units in the area. Structures in the Amphithea fault block played a major role in controlling the location and orientation of sedimentary systems by modifying basin‐floor gradients due to a combination of hangingwall tilt, displacement of faults internal to the depocentre and folding on top of blind growing faults. Fault activity also promoted large‐scale subaqueous landslides and eventual uplift of the whole fault block. [ABSTRACT FROM AUTHOR]

Opposing models have been proposed for last glacial paleoclimates in the Mediterranean area. To discriminate between the alternative models, we calculate variations in sediment yield within a high-resolution stratigraphic framework developed for the Alkyonides basin, central Greece. Latest Quaternary highstand deposits are distinguished from lowstand Lake Corinth deposits on the basis of seismic reflection data and micropaleontological and palynological analyses of drop cores. After depth conversion and calculation of solid sediment masses in successive time slices, sediment discharge rates during the last glacial lowstand interval (ca. 70-12 ka) are shown to have exceeded discharge rates during the preceding interglacial highstand interval (ca. 128-70 ka) by [is greater than or equal to] 60%, implying enhanced seasonality during the glacial period, with cool, dry summer and wet winter conditions in the region. Sediment yield calculations can thus provide an empirical test of paleoclimate models and offer input to sequence stratigraphic models. Keywords: last glacial, paleoclimate, sediment yields, Lake Corinth, Greece.

The onshore central Corinth rift contains a syn-rift succession >3 km thick deposited in 5-15 kmwide tilt blocks, all now inactive, uplifted and deeply incised. This part of the rift records upward deepening from fluviatile to lake-margin conditions and finally to sub-lacustrine turbidite channel and lobe complexes, and deep-water lacustrine conditions (Lake Corinth) were established over most of the rift by 3.6 Ma. This succession represents the first of two phases of rift development - Rift 1 from 5.0-3.6 to 2.2-1.8 Ma and Rift 2 from 2.2-1.8 Ma to present. Rift 1 developed as a 30 kmwide zone of distributed normal faulting. The lake was fed by four major N- to NE-flowing antecedent drainages along the southern rift flank. These sourced an axial fluvial system, Gilbert fan deltas and deep lacustrine turbidite channel and lobe complexes. The onset of Rift 2 and abandonment of Rift 1 involved a 30 km northward shift in the locus of rifting. In the west, giant Gilbert deltas built into a deepening lake depocentre in the hanging wall of the newly developing southern border fault system. Footwall and regional uplift progressively destroyed Lake Corinth in the central and eastern parts of the rift, producing a staircase of deltaic and, following drainage reversal, shallow marine terraces descending from >1000 m to present-day sea level. The growth, linkage and death of normal faults during the two phases of rifting are interpreted to reflect self-organization and strain localization along co-linear border faults. In the west, interaction with the Patras rift occurred along the major Patras dextral strike-slip fault. This led to enhanced migration of fault activity, uplift and incision of some early Rift 2 fan deltas, and opening of the Rion Straits at ca. 400-600 ka. The landscape and stratigraphic evolution of the rift was strongly influenced by regional palaeotopographic variations and local antecedent drainage, both inherited from the Hellenide fold and thrust belt. [ABSTRACT FROM AUTHOR]