Four main factors control the accumulation of periplatform sediment on the northeastern Nicaragua Rise: (1) input of carbonate sediment; (2) input of siliciclastic sediment; (3) physical redistribution of sediment; and (4) partial dissolution of carbonate phases (aragonite and magnesian calcite). The intensity of these factors is directly influenced by climatic variations and associated sea-level fluctuations, creating the cyclic glacial/interglacial pattern characteristic of late Quaternary high resolution stratigraphy in periplatform sediments. During interglacial stages, the bank/shelf tops of the Nicaragua Rise were submerged. The northwestward flowing Caribbean Current swept neritic sediments off-bank to the periplatform environment where they accumulated, by settling through the water column or by sediment gravity flow, preferentially in downcurrent areas. These neritic sediments along with pelagic carbonates, form a thick wedge of highstand sediment on the upper slopes. Carbonate input was locally augmented by siliciclastic sediment input from Jamaica during peak sea-level highstands. Finally, neritic aragonite deposited in water depths below 1100 m was subject to partial dissolution. Glacial sea-level lowstands were characterized by bank/shelf top exposure and lower production, therefore, neritic carbonate input to the periplatform environment was reduced. Nannoplankton productivity shows little glacial/interglacial variation, while glacial foraminifer productivity was only half interglacial levels. Consequently, bulk sediment accumulation rates and turbidite frequencies are lower during glacial stages than in interglacial stages. Bank-top exposure restricted flow of the Caribbean Current to seaways between the banks and shelves. This flow constriction considerably increased flow rates, winnowing sediments in areas of Walton Basin with water depths shallower than 600 m today. Partial dissolution of aragonite may be associated with the formation of magnesian calcite cements in current winnowed sediments. The geometry of the late Quaternary sedimentary bodies, displayed on 3.5 kHz seismic lines, can be interpreted in a sequence stratigraphic framework for periplatform carbonate sediments. Lowstands are thin and overlain by thick accumulations of highstand sediments, all of which lap out on the steep bank/shelf margins. Transgressive systems tracts are too thin to be resolved on seismic data, but are revealed by subtle changes in interglacial sediment mineralogy.

Present coastal systems along the east Texas coast evolved during the past 3.5 ky of relative sea-level stillstand following a rapid sea-level rise 4 ka. Closure of proto-Galveston Bay, caused by spit accretion of Galveston Island and Bolivar Peninsula, formed Bolivar Roads approximately 3.3 ka. Increased tidal prism and entrenchment over the Trinity River incised valley led to inlet stabilization and intensification of tidal influence. The present shoreface and inner shelf package is characterized by a paucity of storm deposits. Strong along-shelf storm currents, low sediment supply, and low effective accommodation space in the region are unfavorable for the preservation of storm beds. Higher sand supply during the early establishment of the present coastal lithosomes resulted in a greater occurrence of storm beds lower in the section. Amalgamated storm deposits on the east Texas shelf are associated with reworked coastal lithosomes. Pods of tidal-inlet, tidal-inlet/spit, and tidal-delta deposits mark previous shoreline positions on the continental shelf. Their distribution mimics the along-strike variation of the present coastal systems, defines six relative sea-level stillstands, including the present, during the past 10.2 ky, and supports the model of a step-like sea-level rise. The seismic architecture of pre-8 ka coastal lithosomes provide evidence for greater tidal influence, greater accommodation space, and higher sedimentation rates compared to the present. The preserved coastal lithosomes indicate that the depth of shoreface ravinement decreases with decreasing shelf gradient, increasing rates of sea-level rise, and increasing sediment supply. Better preservation within incised valleys results from greater accommodation space and the soft valley-fill that allows incision of the inlets beyond the depth of shoreface ravinement. The mechanism of shoreline translation (discontinuous erosional shoreface retreat, transgressive submergence, or in-place drowning), is a function mainly of shelf gradient and rate of sea-level rise. Gentle shelf gradient and rapid sea-level rise favor transgressive submergence. In regions with steep shelf gradient, aggradation may produce stratigraphic signatures consistent with in-place drowning and discontinuous erosional shoreface retreat.

Piston cores, bottom grabs, and single-channel seismic data acquired during Deep Freeze/USARP cruises have been used to examine sedimentation and recent climatic history in the bays and fjords of the Gerlache Strait region (Antarctic Pensinsula). The local climate and glacial setting exhibit profound influences on sedimentation via the processes associated with subglacial water. Visible sediment plumes are rare, and glacial ice above sea level is pristine white, indicating that debris is entering the water from the glaciers that are grounded below sea level. In the relatively warm and wet Palmer Archipelago, terrigenous muds and sands with a variable IRD component are ponding in every available bathymetric depression, and sediment gravity flow processes are common. Along the colder and drier Danco Coast, diatomaceous sediments drape uniformly across the rugged basement topography, rather than ponding, and resedimentation is rare. In both areas, sedimentation occurs in quiescent water.

The history of the incised river valley underlying Galveston Bay was determined by examining the distribution of depositional units and the relationships between them. Initial incision of the valley occurred after the previous interglacial stage 5, substage 5e sea level highstand (120 ka, +6m relative to today). Fluvial terraces, present within the incised valley, were left behind by this incision and by subsequent 20 ky sea level cycles. These terrace deposits are bound by sequence boundary unconformities associated with falling sea level, which ultimately fell to 120m below its present level, approximately 18-20 ka. The sediments within the incised valley are associated with the Holocene rise in sea level. They consist of aggradational fluvial deposits overlain by marsh and estuarine sediments. Initial flooding of the estuary occurred 8-10 ka. Maximum flooding occurred at 4 ka. These events appear to represent rapid flooding.

Nine second-order sequences in Central Arabia are in part correlatable with worldwide seismic sequences. Differential uplift and subsidence occurred throughout the Paleozoic and was interrupted by a late Ordovician-early Silurian and an Upper Carboniferous to lower Permian glaciation. The wedge-like sequences A and B represent an incomplete Cambro-Ordovician encroachment cycle. The uppermost Ordovician-lowermost Silurian sequence C represents a thin sequence of glaciogenic clastics. The wedge like sequences D, E and F represent the resumption of passive margin subsidence around the margin of the Central Arabian arch. Sequence G is underlain by a major unconformity (SB 7) which terminates much of the formation of the Central Arabian arch. Sequence H, the upper Permian Khuff carbonates mark the beginning of the wide Mesozoic passive margin of the Tethys.

In order to better define the facies architecture and controlling processes of a wave-dominated delta, a detailed sedimentary and geomorphologic study was undertaken on the New Brazos River delta. The study indicates a much more complex facies architecture than previously postulated and expands the facies model for wave-dominated deltas. The New Brazos delta is primarily composed of fine-grained sediments. Prodelta clay composes more than half of the sediment volume in the delta. Sands are isolated to the bar and nearshore environments. The facies architecture is distinct from adjacent interfluvial zones and not representative of the strandplain model for wave-dominated deltas. The unique facies architecture is a function of the primary depositional process for the delta--floods. In early 1992, statewide flooding facilitated a major constructional phase of the delta. Significant quantities of fine-grained sediments were deposited in the prodelta. One year after the onset of flooding, a bar emerged offshore of the river mouth, and enabled progradation of the delta.

A new tectonic subdivision of the central External Betic Cordillera is proposed based on previous stratigraphic studies, interpretation of seismic reflection profiles and balanced cross-sections. All available surface and subsurface data are used to constrain a balanced cross-section in the central part of the Betic folded belt, and reconstructions are presented to illustrate three optional evolutionary sequences for this folded belt. In the favored option, the outermost allochthonous unit is interpreted to be bounded to the south by a backthrust. In the reconstruction this unit is located immediately south of the undeformed foreland. Furthermore, the dominant structure in the main part of the folded belt is postulated to be a large, elongate klippe emplaced by a north-directed overthrust. Based upon stratigraphic correlations across and along the thrust belt, the paleogeography that results from this structural reconstruction is that of a single basin.

The Mammoth Mountain Tuff (MMT) and Wason Park Tuff (WPT) were the third and fourth, respectively, caldera-forming ash-flow tuffs in the central San Juan Volcanic Field (SJVF) in southwestern Colorado. In this region, 7 large volume ash-flow tuffs were erupted from a common central area, resulting in the formation of a set of nested calderas in less than 2 Ma. The temporal and spatial association of the MMT and WPT with the older and extensively studied Fish Canyon Tuff (FCT) and Carpenter Ridge Tuff (CRT) offers an excellent opportunity to document magmatic evolution of a large volume silicic system through time and to examine the processes involved in the petrogenesis of the individual ash flows. The MMT, previously described as a zoned ash flow from early-erupted, phenocryst-poor rhyolite to later-erupted phenocryst-rich dacite, consists in fact of two unrelated ash flows, referred to in this work as the FMT and PMT. Based on geochemical and mineralogical similarities, the early-erupted rhyolites (FMT) are believed to be CRT equivalents, as supported by stratigraphic relationships (Lippman, GSA, 87). However, later-erupted dacites (PMT) were generated from a separate, deeper and hotter source. Mineralogical relationships and evidence for disequilibrium requires that the PMT resided in a shallow crustal chamber prior to eruption. The FMT and CRT can be derived from the FCT primary magma by crystal-fractionation processes. Trachytic magma intruded the FMT-CRT chamber, and partially quenched forming fiamme found in both ash flows. Petrographic evidence indicates magma mixing was an important process in the WPT, whereas mineralogical evidence indicates the trachytic magma which formed fiamme in the CRT and FMT, was a mixing component in the WPT as well. Therefore, the WPT represents a hybrid between magma of the zoned fractionation sequence FCT-CRT-FMT and the trachytic magma, establishing a genetic relationship between the central SJVF ash flows FCT, CRT, FMT, and WPT.

The Doonerak multiduplex of the central Brooks Range fold and thrust belt in arctic Alaska developed during footwall collapse beneath the Amawk thrust, which underlies the Endicott Mountains allochthon. The Endicott Mountains allochthon transported Devonian clastic rocks northward over a footwall composed of lower Paleozoic clastic and volcanic rocks of the Apoon assemblage and uppermost Devonian to Carboniferous clastic and carbonate strata. The geometry and kinematic development of the Doonerak multiduplex differ from typical duplex models in that the Doonerak example consists of two stacked duplexes that formed simultaneously. The upper duplex (the Blarney Creek duplex) and the lower duplex (the Apoon duplex) are separated by the Blarney Creek thrust zone, which served both as the floor thrust of the upper duplex and as the roof thrust of the lower duplex. The intervening fault zone between the two stacked duplexes changes character along strike, from that of a sharp tectonic contact to a diffuse zone of distributed shear up to 250 meters thick. In most locations, the fault zone is tens of meters thick and characteristically contains deformed conglomerate. The stratigraphic position of the fault zone was controlled by a thin conglomerate unit which forms the interface between the Apoon assemblage and the overlying clastic and carbonate rocks. The fault zone truncates structures at the base of the upper duplex and at the top of the lower duplex, locally omitting up to 30 meters of section. Where it is broadest, the Blarney Creek fault zone contains interleaved thin slices of both upper-duplex and lower-duplex lithologies.

Allowing for the palinspastic restoration of Tertiary strike-slip and extensional faulting it is concluded that the Pannonian Basin is superposed on a Middle Cretaceous thrust and fold belt which is an integral part of the system of the Alps, the Carpathians and the Dinarides. An upper Cretaceous flexural basin is overlying parts of that fold belt. A Paleogene basin is seen as a retroarc flexural basin with respect to the Paleogene Carpathian arc. The transition from an overall compressional to a transitional setting in the intra-Carpathian area occurred during the Early Miocene when large-scale transcurrent movements segmented the Alpine-Carpathian arc. Major transcurrent faults can be deduced from a study of surface and subsurface geology, but the quality of the seismic data does not permit to image them adequately. The Neogene Pannonian Basin proper shows distinct modes of upper crustal extension. In the deep ($>$8 km) subbasins of the Pannonian Basin system like the Danube Basin the Middle Miocene syn-rift extension was accommodated by low-angle detachment faults overlying metamorphic core complexes. Other intra-Carpathian subbasins such as the Zagyva and Derecske troughs related to a transfer fault system and show moderate or negligible extension. The seismic reflection profiles also suggest that the Pannonian Basin of eastern Central Europe is characterized by broad Quaternary to Recent basement upwarps that may have involved compression of the crust as a whole. These features are responsible for the outcrop distribution of the pre-Neogene "basement" of the basin. They also may suggest the beginning of a large-scale basin inversion process propagating from the W.