The study of 13 modern basin plains ranging in size from the 200-km 2 Navidad Basin up to the giant (>100,000-km 2 ) Hatteras and Sohm Abyssal Plains has revealed that these features owe their existence to large-volume turbidity currents capable of covering the entire basin floor. Such convulsive events flatten out the topographic irregularities formed by the deposition of small flows between the big events. Giant events maintain the flat plain floor. The largest event measured to date in modern basin plains is the Black Shell Turbidite of the Hatteras Abyssal Plain, which is at least 100 km 3 in volume and perhaps double that. In some instances, a single giant flow may arrive on the basin simultaneously from geographically widespread basin entry points, indicating that the initiating mechanism, probably an earthquake, was regional in scope.

Deposition of shallow-water carbonates on the vast Yangtze Platform of south China spanned the late Proterozoic through Middle Triassic, accumulating as much as 4000 m during the Early and Middle Triassic. Deeper-water carbonates and silici-clastics accumulated to comparable thickness in the Nanpanjiang Basin southeast of the platform. After the demise of the platform, an additional 2500 m of mostly silici-clastics spread across the platform in Late Triassic. Deposition of platform carbonates was also widespread in the Permian of south China, but a transgression in perhaps the last 2 m.y. of the Permian combined with differential subsidence to reconfigure the Yangtze Platform in the Triassic. The margin retreated ∼100 km northward in the Guiyang (eastern) sector, and a low-relief ramp developed over the flat top of the Permian platform, whereas the Early Triassic margin mimicked the Permian location in the Zhenfeng sector to the southwest. Nevertheless, deposition was essentially continuous from the Permian into the Triassic in most localities in Guizhou. Triassic deposition began with widespread terrigenous mud bearing thin-shelled bivalves or ammonoids. Renewed carbonate deposition within the Induan produced thin-bedded, laminated, dark-gray lime mudstone with planktonic biota in the basin interspersed with carbonate breccias. Thin-bedded lime mudstones with prominent burrows formed farther updip to the north and west. Thick intervals of oolite and of shallow-water lime mudstone interbedded with terrigenous clastic wedges that thicken and merge to the west mark the updip limit of deposition on a carbonate ramp. Platform-interior carbonates are more than three times as thick as their basinal equivalents. The ramp configuration evolved into a flat-topped platform with a slight rim in the Olenekian, recorded by peritidal carbonate cycles at the platform margin and subtidal lagoonal muds and ultimately evaporites in the interior. Carbonate deposition spread farther westward to cover the terrigenous siliciclastics of the Induan. A major deepening event within the Olenekian is marked by black, ammonoid-bearing, nodular limestone and fissile shale. The patchy distribution of this facies indicates differential warping of the platform rather than purely eustatic causes. The basin received a starvation diet of siliciclastic and carbonate mud with minor silty turbidites and carbonate debris flows. At the end of Early Triassic, platform-interior deposits averaged 1175 m thick and basinal equivalents only 250 m. Acidic volcanic ash spread across the Yangtze Platform at the Olenekian-Anisian transition. Anisian deposits in the Nanpanjiang Basin are dominantly siliciclastics that thicken dramatically in southwestern Guizhou and adjacent Guangxi. Biogenic frame-stones constructed by organisms of questionable origins, Tubiphytes and Plexoramea , assisted by sponges, arborescent corals, skeletal stromatolites, and copious encrusters, rimmed the Anisian platform. This rim collapsed along most of the Guiyang sector to form a basin-margin wedge 175 km long deposited by turbidity currents, debris flows, and rock fall. Collapse led to retreat of the margin by ∼2.7 km; exceptionally by 10 km. In contrast the reef margin advanced slightly in parts of the Zhenfeng sector. Mud-dominated peritidal cycles formed in the lee of the reefs. Deposition in the platform interior was entirely subtidal with alternating episodes of normal marine water, hypersalinity, and siliciclastic influx. An increase in siliciclastic content eastward throughout the Middle Triassic signals the emergence of the Jiangnan Massif, which had been covered throughout the Permian and at least the Induan. Platform sedimentation in the Ladinian features peritidal cycles that extended far into the interior to define a flat-topped platform. High depositional energy is reflected in grainstones and packstones composed of grapestone, bioclasts, and ooids. Barriers other than sand shoals appear to have been absent. Biogenic facies are confined to small outcrops of Tubiphytes and coral boundstone, interpreted as patch reefs. Tepee structures cap many cycles or disrupt successive cycles, indicating extended subaerial exposure. At the beginning of the Ladinian, the platform margin of the Guiyang sector prograded at least 0.6 km. In the Zhenfeng sector the margin retreated slightly, further indication of more rapid subsidence of the western part of the platform. The Nanpanjiang Basin apparently starved early in the Ladinian, but filled to overflowing with siliciclastic turbidites and mud in the later Ladinian or the early Carnian. Transport direction of the very fine sand of the turbidites was from the east, pointing to the Jiangnan Massif as a continued source of sediment, both by land onto the platform and by sea into the basin. East and west sectors of the Yangtze Platform in Guizhou present stark contrasts during the Carnian and Norian. Shallow-water carbonate deposition continued into the Carnian in the Guiyang sector, but tongues of terrigenous mud and sand from the northeast reached to the platform margin and damped out carbonate deposition by the end of the Carnian. Erosion prevailed in the Norian, truncating formations toward the north down to the level of the Anisian. Shallow-water carbonate deposition ended dramatically with the beginning of the Carnian in the Zhenfeng sector. Nodular-bedded, dark-gray lime mudstone with ammonoids overlies peritidal deposits, documenting the drowning of the Yangtze Platform. A very condensed sequence of black shale with concentrations of manganese, reduced iron, and organic carbon followed. Siliciclastic flysch and shallow-water sandstone totaling 1265 m thick filled the accommodation space resulting from the drowning by the end of the Carnian. Norian deposits are cross-bedded sandstones and conglomerates that form thinning- and fining-upward cycles attributed to braided streams that encroached on coastal swamps represented by commercial coal and by mudrocks containing fresh-water, brackish, or marine fossils. The braided streams were rejuvenated and apparently reversed in the Rhaetian to form a coarse-grained clastic wedge that thins and fines toward the north and east across an erosion surface that cuts as deep as Anisian rocks in northern Guizhou. Jurassic and Lower Cretaceous rocks overlie the Rhaetian rocks concordantly, contradicting prevalent interpretations of a major orogeny (Indosinian) in the Late Triassic in Guizhou. The angular unconformity underlying Upper Cretaceous conglomerates dates major deformation in Guizhou as mid-Cretaceous.

ABSTRACT Oil and gas exploration started in the Santos Basin of Brazil during the 1970s. After almost 25 years of drilling 102 dry and subcommercial exploration wells, the exploration campaigns came to a near halt. With the opening of the Brazilian petroleum market in 1997, the National Agency of Petroleum, Natural Gas and Biofuels (ANP) was founded, and exploration in the basin resumed. The years between 1999 and 2004 saw an increase in the exploration effort of major oil companies, including ExxonMobil, Petrobras, Shell, British Gas, Galp, and Eni, among others. The new drilling campaign added 65 exploration wells in only six years. However, the oil discovery success ratio was below 5%. The lessons learned were significant, showing that the search for Tertiary and Upper Cretaceous turbidites of the Santos Basin would not be as successful as in the Campos Basin. Furthermore, the turbidite reservoir paradigm hindered the adoption of new and more productive paradigms—in particular, the directive to “Go Deep.” With the advancement of molecular geochemistry and deep-water seismic and 3-D petroleum system modeling technology, the incredible journey from near failure changed the fate of the Santos Basin to a huge success. In 2006, the Tupi oil field which targeted a new pre-salt play concept, encountered good-quality oil sourced by lacustrine calcareous black shales of the rift-upper Barremian Itapema Formation source rock system that accumulated in more than 400 m, thick-net-pay microbialite reservoir in the sag–mid-to-late Aptian system. In the following years, several giant oil fields, utilizing the same play concept, were discovered in the basin, including Sapinhoa, Búzios, and Mero. These fields showed similar reservoir performance to the Tupi Field, which had more than 30 wells producing more than 25,000 bbl/day, and some of them producing up to 45,000 bbl/day (e.g., 1-BRSA-1305-RJS). In December 2019, the Santos Basin pre-salt system contained more recoverable reserves than all other Brazilian sedimentary basins combined. This chapter describes how the petroleum system approach using rock and oil samples from the Santos Basin supports the dismantling of previous paradigms and the creation of new ones that resulted in the immense success of Santos Basin exploration. This work is based on the application of the petroleum system concept from source to trap, integrated with 3-D modeling and recent results of oil and gas production data from the largest oil fields found to date in the Santos Basin.

Abstract Variations in microfaunal abundance are a useful tool in recognizing basin evolutionary stages. The Western Black Sea basin, situated near a continental passive margin, has three evolutionary phases: flysch, filling, and shelf sedimentation. Flysch sediments accumulated after basin rifting and contain rare and sporadic microfossils. During the filling phase, mostly turbidite sediments accumulated. Their microfossil record shows mixed, rather poor assemblages in periods with increased terrigenous input, but the assemblages are rich in hemipelagic sediments at the tops of turbidite sequences. The most diverse and abundant assemblages occur in sediments of the shelf sedimentation phase. During a basin evolutionary stage, microfaunal abundance shows a gradual upward increase, reaching highest values at the top. A tentative correlation with the supercycles of the Haq et al. (1988) chart is made. This correlation shows that a microfaunal abundance peak is situated in the lower proximity of a supercycle top in the Haq et al. (1988) chart.

Abstract North Sea Central Graben salt diapirs grew by both passive downbuilding and active compressional reactivation during deposition of large Paleocene age turbidite fans derived from the uplifted Scottish platform. Once downbuilding diapirs were buried by more than approximately 200 m of overburden, including some Late Cretaceous chalk, very little bathymetric relief (<20 m) was present over the salt domes, and turbidites could flow across the crests of the salt diapirs. Diapirs having less, or no, overburden present during the Paleocene created more bathymetric relief (ranging between approximately 100 to 300 m), which diverted turbidite flows around the diapirs. Consequently, sandstones are absent on the crest of these salt domes, and high angle onlap reflectors are present on the diapir flanks. The turbidite sandstones close to the diapirs show large amounts of slumping and soft sediment deformation where the paleo-topographic relief was high during deposition (e.g. , South Pierce, Merganser diapirs). This can have a slightly detrimental effect on oil recovery, but apparently not productivity, if the affected sequence contains shales. Some diapirs (e.g. Jenny and Kyle, Fig. 1) are flanked by Paleocene debris flows containing lithified chalk fragments and occasionally reworked Zechstein evaporites indicating that the salt diapirs were emergent, or had high local sea bed relief. These flows can constitute high quality reservoirs due to the large amount of inter-clast porosity and later fracturing. Figure 1. Regional map of the Central North Sea, showing approximate limit of Paleocene sandstone (yellow), salt diapirs (pink) and oilfields (green on inset map). The inset scan with black background shows the Paleocene reflector amplitudes outlining the fans, with orange shading indicating the brightest amplitude reflectors. Compliled from Ahmadi et al. (2003) , Zanella and Coward (2003) , and PGS (2004). This study indicates the importance of analyzing the thickness and nature of the overburden present above salt crests, and the sediment onlap patterns, when turbidite deposition took place. These observations can be useful in predicting the presence, or absence, of turbidites over the crests of salt diapirs.