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On Xisha Islands, located in the South China Sea, the Neogene succession includes the unconformity-bounded Huangliu Formation that is 210.5 m thick in well CK-2 and formed almost entirely of dolostones. The diverse biota in the Huangliu Formation, which includes corals, algae, bivalves and foraminifera, indicates that the original carbonate sediments accumulated in water that was < 30 m deep. The dolostones are formed of various mixtures of low- and high-calcium calcian dolomite with limpid dolomite lining the walls of many cavities. The O-18 and C-13 stable isotopes suggest that dolomitization was mediated by slightly modified seawater. The Sr-87/Sr-86 ratios from the dolostones suggest that dolomitization took place similar to 9.4 and 2.3 Ma ago, with the age of dolomitization becoming progressively younger towards the top of the formation. "Island dolostones" like these, found on many islands throughout the Pacific Ocean and the Caribbean Sea, have commonly been linked to eustatic changes in sea-level with dolomitization taking place during lowstands, highstands, or transgressive phases. Data from the Huangliu Formation in well CK-2 suggests that dolomitization was associated with (semi-) continuous transgressive conditions that were controlled by the interaction of tectonic subsidence and eustatic changes in sea level.

Inner shelf to shelf-margin delta and slope-fan deposits in the Cenozoic Pearl River Mouth Basin in the northern continental margin of the South China Sea comprise the most important petroleum reservoirs in the basin and their evolution reflects a changing interplay of tectonics, sea level change and sediment supply. Integrated analysis of 3D seismic, well logs and core data allows interpretation of depositional architecture and evolution of the delta systems as they responded to the major controls. Inner shelf-delta systems, sited on the landward reaches of the continental margin, are characterized by thickly stacked distributary channel, thin (20-40 m) but relatively coarse delta-front and thin, fine-grained, distal delta to prodelta deposits. In contrast, outer shelf to shelf-margin deltaic systems formed 200 m (merging outwards to 1000 m) high clinoforms with steep slopes imaged on 3D seismic profiles as S-shape or tangential progradational reflections. Slumps and debris flow as well as sandy turbidite slope-fan deposits are common on the slopes of the clinoforms. Basinward and landward, cross-shelf transits of the delta systems are evident, as they formed some 18–20 stacked, high-frequency transgressive-regressive deltaic cycles (0.8–3 Myr) and five megacycles (3 to 10 Myr). Development of the deltaic cycles is interpreted as the result of high-amplitude sea level falls and rises related to glacio-eustasy as well as to changing sediment supply. The large-scale transgressive-regressive evolution of the deltaic clastic wedge is likely to have been controlled mainly by long-term changes in tectonic subsidence rate and sediment supply. The shelf-edge deltaic regressions are likely to have developed during sea level fall, but also during periods of high sediment input enhanced by uplifted tectonic relief and catchment enlargement or at times by monsoonal intensification events.

The South Yellow Sea (SYS) Basin, which is part of the West Pacific Continental Margin, began to form in the late Mesozoic to early Cenozoic as a result of regional tectonic activity in Asia. The pre-Middle Pleistocene sedimentary history of the area remains poorly understood or controversial, mainly due to a lack of long borehole cores penetrating pre-Quaternary strata. Borehole core CSDP-1 (300.10 m long), the longest sediment core recovered thus far from the SYS, was drilled in 2013 in the western SYS. Recently, a reliable timescale for the core for the last ~ 3.50 Myr was obtained by magnetostratigraphy (Liu et al., 2016a). Here we report the results of integrated analyses of the core, including sedimentary characteristics, downcore changes in environmental proxies (benthic foraminifera and ostracods), and accelerator mass spectrometry 14C and optically stimulated luminescence dates. In addition, we analyze 546 km of single-channel seismic profiles and ~ 50 km of a boomer seismic profile around the core site, and correlate the regional stratigraphy. The core sedimentary succession contains 17 depositional units (lithofacies associations) corresponding to three major seismic units, reflecting a variety of depositional environments during the last ~ 3.50 Myr. Our results show that fluvial environments prevailed in the western SYS from ~ 3.50 to 1.66 Ma, followed by alternations of tidal-flat to shallow-subtidal environments with fluvial environments from ~ 1.66 to 0.83 Ma, and alternations of modern-like marine environments and fluvial environments from ~ 0.83 Ma to the present-day in response to glacio-eustatic sea-level cycles. The depositional succession during the last ~ 3.50 Myr was dominantly controlled by tectonism and glacio-eustatic sea-level cycles. The presumed first marine transgression since the Neogene in the western SYS at ~ 1.66 Ma is interpreted to suggest that sea water could partially flood the Zhe-Min Uplift (ZMU) into the SYS due to tectonic subsidence, and further subsidence of the ZMU and the SYS shelf is inferred to have resulted in establishment of normal marine environments in the SYS during the highstands of glacio-eustatic sea-level cycles since ~ 0.83 Ma. The average subsidence rates in the western SYS were ~ 120–165 m/Myr during the last ~ 1.66 Myr. The sedimentary succession comprises fifth- and fourth-order sequences, which are interpreted to have been driven by the 20-kyr or 41-kyr and by the 100-kyr glacio-eustatic sea-level cycles, respectively, since the late Pliocene. The sequences deposited since the Late Pleistocene are relatively complete, recording deposits from MIS 5 to MIS 1. However, the pre-Upper Pleistocene sequences show significant stratigraphic hiatuses, presumably caused by fluvial erosion during the glacial sea-level lowstands and subsequent transgressive erosion. This type of significant discontinuity in the sedimentary record can be considered to be diagnostic of shelf sequences controlled by glacio-eustatic sea-level cycles.

We coupled analysis of regional reflection seismic data with core data from International Ocean Discovery Program (IODP) Expedition 349 and found differences in both depositional features and calculated subsidence between the East and Southwest Subbasins. We calculated the original (decompacted) thicknesses of sediment for different time slices. The depositional features of the basin show that the sedimentation is controlled by both climate and tectonics. Decoupling of sedimentation rates and fluxes is often observed between the continental margin and deep basin. An abrupt increase in sedimentation rates since the Pliocene suggests that glacial–interglacial climate variability impacted erosion rates. The sedimentation rate peaked during the Pliocene in the Southwest Subbasin, but peaked during the Quaternary in the East Subbasin, showing strong influence of surrounding tectonic events, such as the buildup of Taiwan Orogen, on erosion rates. We examine thermal subsidence of the two subbasins by fitting the isostatically balanced basement depths from the seismic profiles with the half space cooling model. The estimated thermal diffusivity of the lithosphere in the Southwest Subbasin is much higher than in the East Subbasin. These contrasting observations suggest that lithospheric rock compositions may contribute to different tectonic subsidence curves between the East and the Southwest Subbasins.

Sedimentary, geochemical, microfossil and geochronological analyses were carried out on 10 sediment cores across the south-eastern corner of Mataora-Wairau Lagoon (M-WL), South Island, Aotearoa-New Zealand. This multi-proxy approach provides strong evidence for three late Holocene palaeotsunamis (two previously unreported) and a historical tsunami generated by rupture of the Wairarapa Fault in 1855 CE. The main scientific evidence for these events consists of anomalous, high-energy marine sediment layers that overlie material of contrasting composition. These layers coincide with peaks in planktonic and benthic marine to brackish-marine diatoms and geochemical signatures indicative of sudden changes in environmental conditions. Palaeotsunami I (maximum date 2095 cal. BP) and Palaeotsunami II (maximum date 915 cal. BP - previously identified by Clark et al., 2015) appear to represent large events contemporaneous with major earthquakes inducing tectonic uplift and coseismic subsidence around the Cook Strait region. Palaeotsunami II is close to the date of the earliest settlement of the M-WL area by Māori, and a traditional narrative that references loss of life following waves over-washing the Wairau boulder bank. Given the boulder bank was likely to have been seaward of its current position during events I and II, we surmise that the inundation distances would have been greater than the most landward extent (340 m) inferred from the deposits found in this study. Palaeotsunami III (maximum date 525 cal. BP) was associated with tectonic subsidence across the study site, most likely associated with rupture of the southern Hikurangi subduction zone. We expect the ongoing refinement of the methods used in this study, and the results from future studies of analogue sites and offshore fault systems, will improve our understanding of the significant tsunami hazard facing this region.

The stacking pattern of shoreline progradational sequences in subsiding basins have been used as a chronologic tool in the Mediterranean region. Most previous studies have used a few key seismic lines seaward of deltas, where the record is complicated by deltaic distributary switching. Southeastern Saronikos Gulf, in the western Aegean Sea at the northwestern end of the South Aegean Arc, lacks large river input of sediment. The ENE-WSW and NW-SE trending neotectonic Aegina and Methana basins lie between the tectonically active Gulf of Corinth and the relatively stable Cyclades plateau. New high-resolution seismic profiles from southeastern Saronikos Gulf have been interpreted according to the principles of seismic and sequence stratigraphy. Alpine basement and marine Pliocene sediments have been recognized in the surrounding basin margins and more than 300 m and 150 m of unconsolidated sediments have been mapped in Aegina and Methana basin respectively. Progradational clinoforms that toplap against transgressive surfaces, have been traced along strike, leading to the establishment of a robust chronostratigraphic framework further controlled by sedimentation rates as extracted from cores. Southeastern Saronikos Gulf poses an outstanding example of development of progradational wedges formed within a microtidal, wave dominated regime of low sedimentation rates, between 2.8 cm/ka and 3.2 cm/ka, within the framework of low subsiding basins with rates between 0.03 and 0.31 m/ka. In this environment, more than 180 well preserved shoreline progradational units, with attributes similar to the ones reported from the Aegean and Eastern Mediterranean seas, have been mapped and correlated to sea level lowstands back to 866 ka. Deeper Mid-Pleistocene progradational units are also recognized, tentatively back to 1.4 Ma. Subsidence rate shows a dramatic decrease in the last 1 Ma and significant numbers of faults became inactive during the last 130 ka. In Early-Middle Quaternary, Methana basin was an isolated lake and extended terrestrial areas were shaped in the Poros-Agios Georgios plateau during sea level lowstands. Aegina basin was continuously connected to the Aegean through the Agios Georgios fault valley. This study demonstrates the robustness of chronology based on stacked shoreline progradational sequences and its applicability to determining rates of tectonic subsidence.

The early-stage shelf-margin prism in the Pearl River Mouth Basin (PRMB), northern South China Sea, formed from the Late Oligocene to Early Miocene, comprises a set of shelf-edge delta and slope fan wedges of the Zhuhai Formation and records the development of the continental slope in response to the interaction of sea-level change, tectonic subsidence and sediment supply. Based on integrated analysis of seismic, well logging and core data, the stratigraphic architecture, depositional systems and controlling processes are documented. The Zhuhai Formation is a composite sequence bounded by regional unconformity, and can be further divided into five sequences (CS3-1-CS3-5). The depositional genetic units (transgression, ascending normal regression and descending forced regression) are identified within sequences based on variation in shelf edge trajectories. The shelf deltaic clinoforms are characterized by oblique-tangential reflections in seismic profiles with a thickness of 100–150 m. In contrast, the shelf-margin delta and slope clinoforms generally are 300–1200 m thick and mainly display as sigmoid or sigmoid-tangential seismic reflections. The delta deposits usually consist of thick beds of delta front deposits and prodelta slump and deformed sediments, and are associated with sandy slope fan systems. Eleven delta complexes are distinguished by tracking the distribution of the deltaic clinoforms in each sequence, and these deltaic deposits tend to extend along their strike direction which may be related to the reworking of strong waves and coastal currents. Slope fan systems consist mainly of turbidite channel fills, frontal splay and debris flow deposits, and generally develop along the slope in CS3-3-CS3-5, which may be triggered by steep shelf margin slope and fault activity. The stratigraphic pattern of the shelf margin prism and depositional evolution of the deltaic systems from the Late Oligocene to Early Miocene were controlled by the interaction of sea level changes, sediment supply and tectonic subsidence. The ascending trajectory from the CS3-1 (30 Ma) to the top of the CS3-5 indicates that the relative sea level continued to rise generally but the shelf margin prograded basinward rapidly due to the great amount of sediment supply and lower subsidence rate. Tectonic uplift of the source area and strengthened physical erosion during this period may be the reason for the large sediment supply.

Detailed interpretation and mapping of multi-channel seismic reflection profiles from the Adana Basin show that a south-verging linked imbricate thrust stack existed across the northern portion of the Adana Basin prior to the deposition of early Miocene sedimentary successions. Following the development of the basement-cored fold–thrust belt the region was irregularly denuded. Paleohighs and lows delineate the axis of hanging wall culminations and intervening structural depressions between forelimbs and backlimbs of the stacked sheets, with residual topographic relief locally reaching 1500 m. The stratigraphic and structural architecture of the early to middle Miocene successions in the Adana Basin records a significant phase of tectonic subsidence that initiated in the early Miocene, followed by deposition of a thick deep water succession in an underfilled basin. Then, relatively rapid uplift gave rise to basin inversion and erosion prior to or during the early Tortonian. The upper Miocene global eustatic sea-level fall initiated in the Tortonian. The transition from deep water to fluvio-deltaic sedimentation in the early Tortonian recorded the combined effects of a global eustatic sea-level fall and regional tectonic uplift, presumably related to renewed activity in the Tauride orogen to the north. It led to widespread erosion giving rise to a smooth unconformity surface in most of the Adana Basin. The stratigraphic and structural relationships suggest that the onset of east-directed thrusting in the trailing portion of the Misis fold–thrust belt occurred sometime during the lower Tortonian, coinciding with the switch from marine to terrestrial sedimentation. The truncation by this unconformity of the folded–thrusted successions of both Miocene successions across the trailing thrust sheets marks the effect of progressive erosion as the thrust sheets are uplifted above base level. A prominent progressive syntectonic unconformity is developed extending from the region of main thrust culminations westward into the depocentre situated on the backlimb of the leading thrust of the Misis fold–thrust belt. Much of the Tortonian deposition took place within this trailing piggy-back basin and the easterly onlap and the westerly tilt of this succession mark the progressive uplift of the fold–thrust belt during the remainder of the Tortonian. Terrestrial and fluvio-deltaic deposition in the Tortonian was succeeded in the Messinian by the deposition of mixed evaporite–carbonate–clastic succession in the Adana Basin. The base of this succession is a local unconformity across the Tortonian succession that marks the cessation of the fold–thrust activity in the east and ensuing erosion across the fill of the Tortonian piggy-back basin. The subcrop of the Messinian succession marks the edge of deposition in a paleotopographic depression situated between the Tortonian Misis fold–thrust belt in the east and the paleoslope over the front of the reactivated Tauride fold–thrust belt in the north. The western margin of deposition of the Messinian succession was probably controlled by the development of the Kozan Fault zone. Plio-Quaternary subsidence created the accommodation space that allowed rapid delta progradation.

The Rijeka Bay coast is formed predominately in carbonate rocks. Due to relatively sheltered position, processes of bioerosion dominate while mechanical wave action has low impact. Biological zone limits in Rijeka Bay are well expressed and they reflect the local biological mean sea-level (BMSL). Therefore, they were used as referent levels for measurement of submerged tidal notch position. These in situ biological indicators could be more useful than sea-level mareograph data. Well developed tidal notches are permanently submerged and quite ubiquitous in the whole Rijeka Bay area, i.e. they are situated in the infralittoral zone. They have elongated, asymmetric shape. Since the roof top of the notches is well preserved, they were correlated with well defined biological zone limit (upper limit of white zone, WE sensu Schneider, 1976). Results of survey showed that in most of the area tidal notches are located 50 to 60 cm below BMSL. However, within the Bakar Bay notches are from 103 to 115 cm below BMSL. Regional occurrence of well preserved tidal notches at 0.5-0.6 m below BMSL indicates their possible coseismic origin (rapid tectonic subsidence). It is possible that this regional coseismic subsidence occurred in 4th century AD, which is simultaneous with the presumed uplift in the Eastern Mediterranean. Deeper positions of tidal notches in NE part of Rijeka Bay and within Bakar Bay indicate enhanced subsidence of that zone. This zone was assumed to be the most seismotectonicaly active within the larger area of shallow continental subduction

Sarcya 1 dive explored a previously unknown 12 My old submerged volcano, labelled Cornacya. A well developed fracturation is characterised by the following directions: N 170 to N–S, N 20 to N 40, N 90 to N 120, N 50 to N 70, which corresponds to the fracturation pattern of the Sardinian margin. The sampled lavas exhibit features of shoshonitic suites of intermediate composition and include amphibole-and mica-bearing lamprophyric xenoliths which are geochemically similar to Ti-poor lamproites. Mica compositions reflect chemical exchanges between the lamprophyre and its shoshonitic host rock suggesting their simultaneous emplacement. Nd compositions of the Cornacya K-rich suite indicate that continental crust was largely involved in the genesis of these rocks. The spatial association of the lamprophyre with the shoshonitic rocks is geochemically similar to K-rich and TiO2-poor igneous suites, emplaced in post-collisional settings. Among shoshonitic rocks, sample SAR 1-01 has been dated at 12.6±0.3 My using the 40Ar/39Ar method with a laser microprobe on single grains. The age of the Cornacya shoshonitic suite is similar to that of the Sisco lamprophyre from Corsica, which similarly is located on the western margin of the Tyrrhenian Sea. Thus, the Cornacya shoshonitic rocks and their lamprophyric xenolith and the Sisco lamprophyre could represent post-collisional suites emplaced during the lithospheric extension of the Corsica–Sardinia block, just after its rotation and before the Tyrrhenian sea opening. Drilling on the Sardinia margin (ODP Leg 107) shows that the upper levels of the present day margin (Hole 654) suffered tectonic subsidence before the lower part (Hole 652). The structure of this lower part is interpreted as the result of an eastward migration of the extension during Late Miocene and Early Pliocene times. Data of Cornacya volcano are in good agreement with this model and provide good chronological constraints for the beginning of the phenomenon.

The carbonate platforms and adjacent troughs off northeast Australia record a phase of accelerated tectonic subsidence in the late Miocene/Pliocene. Previous attempts to analyse tectonic subsidence in this area were hampered by poor core recovery and dating uncertainties at some of the ODP (Ocean Drilling Program) Leg 133 sites on the Queensland Plateau, in particular at sites 812 and 814. In order to establish a general chronostratigraphy for these sites, we have integrated geophysical logs, biostratigraphic, lithologic, and seismic reflection data to identify and correlate Miocene hardgrounds on the Queensland Plateau to third-order eustatic sea-level lowstands on the Haq et al. [Haq, B.U., Hardenbol, J., Vail, P.R., 1987. Chronology of fluctuating sea levels since the Triassic. Science, Vol. 235, pp. 1156–1167] curve. This enables us to estimate ages where biostratigraphic information is poor. We have used sediment backstripping to compute tectonic subsidence histories for sites on the Queensland Plateau (811/825, 812, and 814), the Marion Plateau (815) and the Queensland Trough (823) in order to determine regional subsidence patterns. Results of these calculations show that, although the Leg 133 sites are located on a passive margin approximately 1000 km south of the Pacific–Australian plate boundary, they record a greater amount of subsidence than can be predicted from simple elastic models (post 9 Ma subsidence of 1300±200 m in the Queensland Trough, 650±200 m on the western margin of the Queensland Plateau, post 5 Ma subsidence of 500±30 m on its southern margin, and 660±50 m on the northern margin of the Marion Plateau). These models show that it is difficult to account for observed subsidence, either by means of thrust loading in Papua New Guinea, or by a combination of the latter and in-plane stresses originating from collision along the Australian–Pacific plate boundary. Alternatively, shear wave tomography [van der Hilst, R.D., Kennett, B.L.N., Shibutani, T., 1998. Upper mantle structure beneath Australia from portable array deployments. In: Brown, J., Dooley, J., Goleby, B., van der Hilst, R., Klootwijk, C. (Eds.), Structure and Evolution of the Australian Continent. Geodynamics Series 26, pp. 39–57.] displays a NNW–SSE trending band of anomalously high velocities in the upper mantle stretching from the Queensland Plateau to Indonesia. These anomalies likely reflect subducted slab material originating from late Eocene–late Oligocene subduction north of Papua New Guinea. Thus, we suggest that the observed post 9 Ma tectonic subsidence of the Queensland and Marion plateaus and Queensland Trough is largely caused by dynamic surface topography due to Australia's northeastern margin overriding a slab burial ground, modulated by flexural deformation resulting from collision tectonics north of Australia. The observed rates of tectonic subsidence are much slower than those of third-order sea-level changes, and can thus be differentiated from glacial-eustasy.

The study of the Gulf of Cadiz on the basis of multichannel seismic profiles and wells illustrates the stratigraphy and tectonics. The evolution of the southern Iberian margins was more complex than in most North Atlantic margins since it entailed several phases of rifting, convergence and strike-slip motions. Three main tectonic provinces surround the internal zones of the Gibraltar Arc orogenic belt. These include in the Iberian margin of the Gulf of Cadiz the flysch units of the Campo de Gibraltar complex, the Betic External Zones, and the Neogene basins of the Guadalquivir Valley. Fault-bounded blocks of flysch and Subbetic units crops out over large areas of the southeastern Iberian shelf. The basement of the northwestern area, in contrast, is represented by the Paleozoic rocks of the Hercynian massif of Iberia. Half-graben structures determined the main structural trends of the margin during the Mesozoic, which were affected by inversion structures during the Neogene compressional stages. The Mesozoic and lower Cenozoic units are best observed in wells and seismic profiles from the northern area. These units are either obscure below a thick olistostrome deposit or are absent in most of the rest of the Gulf of Cadiz. Seven lithoseismic units from Triassic to Upper Oligocene and another seven Neogene and Quaternary units are identified based on the relationship to the depositional sequence and the emplacement of the olistostrome. The first tectonic phase was characterized by a passive margin, which was controlled by the development of half-graben extensional structures and carbonate platforms. This evolution comprises the Mesozoic and early Cenozoic. Ocean-spreading in the North Atlantic induced extensional tectonics, which deformed the Cretaceous syn-tectonic post-Aptian deposits. Increased amounts of terrigenous materials were supplied to the margin from Aptian to Albian times, controlling depositional patterns, while terrigenous siliciclastic facies replaced the Jurassic carbonate platforms. From Middle Eocene to Early Miocene the margin was influenced by the relative motions of Iberia and Africa and the development of the Alpine orogeny. The Iberian–African boundary in the Gulf of Cadiz experienced transpression and the Mesozoic basins probably underwent subduction. The emplacement of an olistostrome took place in the Gulf of Cadiz towards the Central Atlantic basin plains during the Tortonian. The end of the olistostrome emplacement during the Late Miocene coincides with accelerated tectonic subsidence, while thick progradational and aggradational depositional sequences were developed. The occurrence of closely juxtaposed regions of compression and extension during the Miocene may reflect the westwards progression of the Gibraltar Arc mountain front over a subducting thinned Tethys crust. When the motion between Iberian and Africa was N–S to NNW–SSE oriented, the migration of the arcuate mountain front into the eastern Gulf of Cadiz is attributed to a mechanism of collision induced delamination of the mantle lithosphere. In contrast to the Betic–Rif belts, however, there is no geophysical evidence to postulate that continental collision took place in the Gulf of Cadiz during the Cenozoic.

Seismic facies and Quaternary depositional systems of the Gulf of Cadiz have been characterized by means of high-resolution seismic profiles (airguns, Geopulse and ORE 3.5 kHz). A total of 11 Pleistocene and two Holocene sequences separated by type-1 or type-2 discontinuities were identified. The age of the depositional sequences was determined based on foraminifera ages from boreholes and by correlation with seismic profiles of the slope areas with uniform deposition and without significant discontinuities. These seismic units have been mapped throughout the margin, allowing to establish the correlation with eustatic sea-level curves and global climatic trends. The distribution and geometry of the units reveals that most of the sedimentary record was developed during episodes of forced regression. Ten regressive periods, corresponding to 5th-order cycles arranged into 4th-order, were distinguished. Absolute water depths for the development of coastal deposits in each unit were calculated using depth from present-day sea-level, corrected for tectonic subsidence in the area. The model for the evolution of the depositional system of the Gulf of Cadiz continental margin highlights the strong influence of tectonism in the development of depositional bodies, controlling the distribution of deposits generally produced during episodes of sea-level fall.

The Romanche transverse ridge (equatorial Atlantic) is located in the northern flank of the fracture zone, opposite the eastern ridge-transform intersection (RTI). It constitutes a major positive topographic anomaly that reaches a height of over 4 km above the level predicted by the thermal subsidence curve. A series of E–W aligned peaks, located on the crest of the transverse ridge, were at sea level during early and middle Miocene times; they are presently capped by a ~300 m thick, shallow-water carbonate platform that grew on a subsiding oceanic crust basement surface flattened by erosion at sea level. These structures are now about 1 km below sea level. High resolution seismic reflection surveys and multibeam morphobathymetry as well as study of samples recovered from the carbonate platform allowed a reconstruction of the paleoenvironment and of the vertical movements of the peaks starting from the lower Miocene. Ages derived from microfossils suggest that the base of the carbonate platform dates from 17–25 m.y. ago and the sinking of the platform started between 18 and 13 m.y. ago. These data were included in a numerical simulation model that takes into account thermal and tectonic subsidence, growth potential of the carbonates, subaerial and submarine erosion rates and Mio-Pliocene absolute sea level fluctuations. The results outline the subsidence history of the Romanche transverse ridge and suggest post-Miocene subsidence faster than that predicted by the thermal cooling model.

Cook Strait, the central seaway through the axial ranges of New Zealand, has many inferred origins. A compilation of marine geological and geophysical datasets suggests that Cook Strait developed when five sedimentary basins at a rapidly changing, obliquely convergent, plate boundary were moved into line and were linked by strong tidal scour in middle Pleistocene times. The basins relate partly to oblique subduction north of Cook Strait and partly to intercontinental transform to the south. Prior to opening, muddy, subduction pull-down and foreland basins in the northwest were separated from equally quiet water, rotating, forearc to transform basins in the southeast. The land barrier between them narrowed and was finally breached as subduction-related basins migrated southwards and transform-related basins extended northwards in response to rotation and divergent branching of a major transcurrent fault. Following breaching, a history of alternating scour and quiet water deposition is recorded by a series of deep, irregular unconformities in muddy basin fill. Scour is correlated with interglacial periods of high sea level when land barriers were submerged and strong tides, caused by a 140° phase difference at either end of the strait, eroded muddy sediments deposited in glacial periods when an emergent landbridge limited tidal exchange.

The Late Tertiary seismic facies and structures of the Levant passive margin off central Israel in the eastern Mediterranean Sea were studied by the interpretation of more than 3000 km of seismic reflection profiles, most of them previously unpublished single-channel profiles. The Neogene growth and evolution of this margin was influenced by the interaction of three main processes: (1) the outbuilding and loading of the margin by the Nile sediments since the Pliocene, (2) uplift and tectonic subsidence related to the tectonic activity along the Dead Sea Transform, and (3) the effect of the above processes on the thick Messinian evaporites which caused many salt-tectonic features including flowage, piercement diapirs, slumps, and en-echelon listric normal faults in the supra-salt sediments. We suggest that the study area may be divided into two segments, north and south of Caesarea. These segments vary in their depositional environment, the amount of sediment supply and load, salt-related features and tectonic activity. We propose that the northern segment is affected by low sediment supply and by the continued uplift of the Carmel structure, and that this segment may even be a part of this structure. The southern segment has been affected by the deposition and loading in the Nile-derived sediments since the Pliocene. Three main depositional sequences were observed in the southern segment: (1) sequence I (Early Pliocene) onlaps the top of the Messinian evaporites representing a rise of sea-level and renewed subsidence, (2) sequence II (Early Pleistocene) is lens-shaped, thinning to the north, west and east and was derived during a relatively short time interval from the Pre-Nile, and (3) sequence III (since the Pleistocene) represents a major episode of continental shelf construction.

Abundant subsurface data for Mesozoic and Cenozoic sections of the US Gulf Coast and the Middle East make it possible to track the relationship of shelf carbonates and evaporites (associated with minor amounts of clastics) to eustasy. Our contention is that because the sedimentary deposition for both regions was in part controlled by gentle tectonic subsidence punctuated by eustatic variations, the major hydrocarbon fields which occur here can be related to sea-level behaviur at the time of deposition of the reservoir sections and their early diagenesis. With the exception of chalks, most of these carbonate hydrocarbon fields can be related to highstand system tracts and include the following: 1. (1) Keep-up reservoirs with sheet-like geometry formed when carbonate accumulation matched sea-level rise, aggrading to form shoaling-upward cycles during sea-level highstands. 2. (2) Give-up and catch-up reservoirs with lense-like carbonate geometry formed on drowned shelves during and following rapid sea-level rises, often downslope from carbonate margins. Give-up reservoirs occur when carbonate accumulation was unable to match sea-level rise and catch-up reservoirs form where carbonate accumulation was initially unable to keep pace with the sea-level rise but then aggraded to sea-level. 3. (3) Reservoirs with the prograded discontinuous clinoform geometry of the platform margin, formed during stillstands by carbonate accumulation that not only kept up with the sea-level rise, but also advanced in a seaward direction. Source rocks for these carbonate reservoirs are often formed during rapid sea-level rises, while the reservoir seals are usually transgressive shales, dense transgressive limestones and/or highstand evaporites.

The 100 km long Boso Canyon is located on a plate boundary in the Sagami Trough, off Boso Peninsula (central Japan). Large volumes of sediment from the Izu Collision Zone and adjacent volcanoes have been transported to the Sagami Trough and the Izu-Ogasawara Trench through the Boso Canyon. Boso Canyon displays a channel morphology ranging from low- (straight) to high-sinuosity (meandering) in the midstream. An abandoned channel is preserved on the bench along the downstream high-sinuosity channel. Quantitative analyses of the canyon morphology demonstrate that the Boso Canyon has definite similarities with meandering subaerial rivers, especially with entrenched meanders. Three morphological parameters, sinuosity, channel gradients and canyon gradients, suggest that the canyon slope appears to be compensated by an increase in sinuosity to maintain an optimum channel profile. Three morphological stages for the canyon development can be recognized, pre-abandonment, channel abandonment and post-abandonment. Assuming that the tectonic framework of the region, in transtension, has not changed significantly since 0.5 Ma, these stages would be formed corresponding to sea-level changes. During the preabandonment stage (low sea-level phase), the Boso Canyon was straight and large amounts of detritus flowed down as turbidity currents to the Katsuura Basin slope and the Mogi Trench Fan on the Izu-Ogasawara Trench floor. The sediment supply rates were sufficient to mask the tectonic modification in channel morphology. Sediment supply rates to the Boso Canyon decreased abruptly as sea level rose, and the channel sinuosity increased to maintain optimum channel slope gradient. The building of the small confined Boso submarine fan probably began at the mouth of Boso Canyon which masked the basin topography of the Katsuura Basin. At highstand, the channel became least active, and differential tectonic subsidence led to enhanced channel entrenchment. The Boso Canyon is a good example suggesting that tectonic and sea-level changes are important in the origin and development of deep-sea channels on an active plate margin.

In the geologic record some of the most accurate gauges of changes in sea level are the sediment type, geometry and diagenesis of carbonate shelves and platforms. This is because carbonates frequently occur at or very near sea level and are usually less compacted than siliciclastics. World-wide changes in relative sea level (the sum of eustatic sea-level changes, sedimentation and crustal movements) have occurred repeatedly and cyclicly through geologic time, producing characteristic responses in carbonates. 1. (1) Relative rises in sea level (usually caused by the cumulative effect of tectonic subsidence and eustatic rise) may result in the following: 1.1. (A) Drowned carbonate reefs or platforms. Here carbonate growth potential is exceeded by relative sea-level rise, and is characterized by shallow-water sediments, overlain by hardgrounds and/or deep-water sediments, some of which may be condensed sequences. 1.2. (B) Platforms where only the fast growing rim and patches of the interior are able to match sea-level rise while the remainder of the platform is drowned (temporarily). 1.3. (C) Platforms which keep up and maintain a flat top at sea level and contain shallow-water sediments whose thickness at the least matches the height of the sea-level rise. If terrigenous supply is limited, prograding sheets of shelf carbonate occur (frequently capped by supratidal evaporites), with prograding shelf-margin carbonate clinoforms and turbidites. If terrigenous supply is high, the shelf carbonates encroach on deltaics. 2. (2) Relative drops in sea level (caused by crustal uplift or by subsidence being outpaced by a eustatic drop in sea level) cause karst and soil development over shelves and platforms, deposition of “deep-water” evaporites in adjacent semi-enclosed basins and in open marine basins the deposition of deltaic and aeolian clastics that bypassed the shelf. Falls are accompanied by platform-wide fresh-water diagenesis. During relative sea-level rises marine diagenesis is common in the subtidal portions of the shoaling-upward carbonates, and fresh-water diagenesis and dolomitization and sulphate deposition is common in their intertidal and supratidal portions. The stratigraphic significance of these reponses to relative sea-level change is that many are tied to eustatic events and so are predictable within a basin of deposition.

Nine discrete deep-sea basins (seven from the Calabrian and Mediterranean ridges and two from the Strabo Trench) were explored geologically during several cruises carried out from 1978 to 1984 in the Eastern Mediterranean. The seven basins, displaying similar geological features (Calabrian and Mediterranean ridges), may be divided into three groups on the basis of their size: (1) very small basins (Botticelli and Raffaello basins) whose area ranges from 1.1 to 4.3 km 2 ; (2) small basins (Ares, Aphrodite and Katia basins), from 7 to 13 km 2 ; and (3) large basins (Bannock and Cleft basins), from 22 to 74 km 2 . The two basins from the Strabo Trench (Tyro and Kretheus basins), whose areas range from 16 to 20 km 2 , are considered separately. Tectonics is the most important element affecting basin formation processes: progressive folding and faulting of Messinian, Pliocene and Quaternary sediments in the Calabrian and Mediterranean ridges allows the infiltration of water into the subbottom and dissolution of Messinian evaporites, so that collapse of the overlying unconsolidated Plio-Quaternary cover creates local distensive tectonics superimposed on the regional compressive tectonic setting. The size of the basins reflects different steps in this process. Very small basins are related to the fracturing occurring at the top of anticlines; small basins originate when anticlines are faulted and large amounts of water are able to reach the evaporites and increase the intensity of leaching. Finally, large basins are related to regional tectonic lineaments both compressive (large reverse faults, overthrusts) and strike-slip. Salt diapirism may be associated with some of these situations. The process responsible for the Tyro and Kretheus basins formation is the “pull-apart” mechanism connected with the strike-slip motion occurring in that area. The geometric position of subaqueously dissolved evaporites seems to influence the environment on the basin floor: brines originating from the dissolution of buried evaporites are thought to disperse in the subbottom, whereas brines originating from dissolution of evaporites cropping out on the basin walls can flow to the floor and cause stagnation only if the shape of the basin prevents the action of bottom currents.

A detailed geophysical survey of the Sunda Trench lower slope reveals the structure and stratigraphy of trench slope basins west of Nias Island. Structural ridges bound the basins and generally strike parallel to the trend of the arc. The ridges on the lower part of the trench slope are formed of folded trench strata and are bounded on their seaward margins by landward-dipping thrust faults. The basins near the toe of the slope are narrower and contain less sediment than basins higher on the slope. Deformation occurs across the entire slope; near-surface strata in the shallowest basin are tilted landward and are cut by a recent thrust fault. A progressive increase in the intensity of deformation with depth is evident. The landward dips and numerous onlapping relationships at the seaward edges of the basins indicate that the seaward margins of the basins are being relatively uplifted with respect to the basin strata. Basins near the outer-arc ridge receive terrigenous turbidites that are delivered down submarine canyons from Nias Island. A small submarine fan has developed at the mouth of a canyon in the shallowest basin. Local slumping of hemipelagic slope sediment forms a minor contribution to the overall sediment fill. Slumping is more important near the toe of the slope, because basins there are isolated from terrigenous sediment input.

Air-gun and 3.5-kHz seismic profiles from the eastern Aegean Sea off Turkey show that the continental shelf of outer Izmir and Candarli bays is formed by several superimposed deltaic sequences. During times of lowered sea level associated with late Quaternary glaciations, deltas prograded seaward more than 60 km from their present positions. Foreset progradation ceased with the rise of sea level in interglacial and post-glacial times and deltas were reestablished far inland in drowned river valleys. These major transgressions resulted in unconformities within the superimposed prograded delta sequences. The most recent three unconformities are correlated with the beginning of oxygen isotope stages 5, 3 and 1, and provide chronostratigraphic markers for a detailed analysis of sedimentation patterns in the late Quaternary. The coastal shelf and basins are subsiding at an average rate of about 1 m per 1000 years. This tectonic subsidence manifests itself as widespread normal block faulting which can be related to the pre-Miocene structural framework of the region.

A set of seismic and field data from the Corsica-Sardinian Straits allowed us to define three well-separated Oligocene deep basins: the Castelsardo and Porto Torres basins, forming the northern end of the Sardinian graben, and the Bonifacio Basin on the continental shelf of the Bonifacio Straits. A seismostratigraphic investigation of these three basins revealed two major tectonic events. A first Oligocene to Middle Aquitanian rifting phase, followed by oceanic spreading in the Western Mediterranean, and then a second rifting event between Corsica and Sardinia in Lower Burdigalian time. The first rifting is noticed in the three basins, but the second one only in the Porto Torres and Castelsardo basins.

Several multichannel, common depth point (CDP) seismic reflection profiles concentrated in the area of the entrance to Delaware Bay provide a tie between the known onshore geology of the Coastal Plain of Delaware and the offshore geology of the Baltimore Canyon Trough. The data provide a basis for understanding the geologic framework and petroleum resource potential of the area immediately offshore Delaware. Our research has focused on buried early Mesozoic rift basins and their geologic history. Assuming that the buried basins are analogous to the exposed Newark Supergroup basins of Late Triassic-Early Jurassic age, the most likely possibility for occurrence of hydrocarbon source beds in the area of the landward margin of the Baltimore Canyon Trough is presumed to be lacustrine, organic-rich shales probably present in the basins. Although buried basins mapped offshore Delaware are within reach of drilling, no holes have been drilled to date; therefore, direct knowledge of source, reservoir, and sealing beds is absent. Buried rift basins offshore Delaware show axial trends ranging from NW-SE to NNE-SSW. Seismic reflection profiles are too widely spaced to delineate basin boundaries accurately. Isopleths of two-way travel time representing basin fill suggest that, structurally, the basins are grabens and half-grabens. As shown on seismic reflection profiles, bounding faults of the basins intersect or merge with low-angle fault surfaces that cut the pre-Mesozoic basement. The rift basins appear to have formed by Mesozoic extension that resulted in reverse motion on reactivated basement thrust faults that originated from compressional tectonics during the Paleozoic. Computer-plotted structure contour maps derived from analysis of seismic reflection profiles provide information on the burial history of the rift basins. The postrift unconformity bevels the rift basins and, in the offshore area mapped, ranges from 2000 to 12,000 m below present sea level. The oldest postrift sediments that cover the more deeply buried rift basins are estimated to be of Middle Jurassic age (Bajocian-Bathonian), the probable time of opening of the Atlantic Ocean basin and onset of continental drift about 175–180 m.y. ago. By late Oxfordian-early Kimmeridgian time, the less deeply buried basins nearshore Delaware had been covered. A time-temperature index of maturity plot of one of the basins indicates that only dry gas would be present in reservoirs in synrift rocks buried by more than 6000 m of postrift sediments and in the oldest (Bathonian?-Callovian?) postrift rocks. Less deeply buried synrift rocks landward of the basin modeled might still be within the oil generation window.