Passive Continental Margin Basin Research Articles

Structural characteristics and main controlling factors on petroleum accumulation in Zagros Basin, Middle East

Zagros Basin is one of the essential basins in the Middle East with the giant oil and gas reserves. It is indicated by regional tectonic and sedimentary evolution, basin structural division, petroleum distribution characteristics and main controlling factors of petroleum accumulation. It has experienced four significant phases which are early Paleozoic intra-Cratonic pull apart basin and platform margin basin, late Paleozoic platform margin basin, Mesozoic passive continental margin basin, and Cenozoic foreland basin. The Zagros Mountain Front Fault and High Zagros Fault divided the basin into foredeep zone, simply folded zone, and Zagros thrust fault zone from southwest to northeast. The oil fields are mainly located in the foredeep zone, while the gas fields are mostly in the simply folded zone and few fields are in the Zagros thrust fault zone. The Lower Cretaceous Kazhdumi Formation mudstone is the main source rock for the Mesozoic, and Cenozoic reservoirs and the Silurian Gahkum Formation mudstone is the main source rock for the Paleozoic reservoirs. The Cenozoic carbonate is main reservoir followed by the Cretaceous Sarvak and upper Permian Dalan carbonate. The evaporite and mudstone are the main seal in the foredeep zone, while the mudstone in the simple anticline zone. The anticline structure and the seal type is the main controlling factor for the petroleum accumulation.

Geochemical Characteristics and Developmental Models of the Eocene Source Rocks in the Qiongdongnan Basin, Northern South China Sea

Seismic data show that a set of Eocene lacustrine source rocks exists in the Qiongdongnan (QDN) Basin, northern South China Sea (SCS). The high content of C30 4-methylsteranes detected in the crude oil suggests the existence and the effectiveness of the lacustrine source rocks, and these compounds were not found in the Oligocene and Miocene source rocks. The above date indicates that the Eocene source rocks are effective and oil-prone. Lacustrine source rocks in faulted period have high organic matter abundance and better organic matter types in the SCS and other typical passive continental margin basins in the world. Lacustrine source rocks in the Eocene source rocks (E2w) from the Baiyun Sag of the Pearl River Mouth Basin have relatively high total organic content (TOC) values, which can be explained by moderate to high paleoproductivity and anoxic environment. Therefore, it can be speculated that the Eocene source rocks have good hydrocarbon potential in the QDN Basin. The developmental pattern of Eoce...

Passive continental margin basins and the controls on the formation of evaporites: a case study of the Gulf of Mexico Basin

Passive continental margin basins are the most important type of oil- and gas-bearing basins and are significant in the formation of oil and gas. The development of evaporites in passive continental margin basins commonly controls the formation and storage of oil and gas. Therefore, it is important to study the factors that control the formation of evaporites in this type of basin. Taking the Gulf of Mexico Basin as an example, this paper discusses the factors that control the formation and development of evaporites during the development of a passive continental margin. These factors include stratigraphy, lithofacies paleogeography, paleocontinental position, paleoclimate, provenance and sea level changes, Based on this analysis, we conclude that the evolution of the passive continental basin was favorable for the formation of evaporites.

Provenance change from the Middle to Late Triassic of the southwestern Sichuan basin, Southwest China: Constraints from the sedimentary record and its tectonic significance

The formation of the Sanjiang and Qinling orogens caused by closure of Paleo-Tethys Ocean along the western and northern margins of the Yangtze block during the early Mesozoic created a unique basin-mountain system. Petrology, geochemistry, geochronology, sedimentary facies and paleocurrent data are integrated in order to investigate the changing provenance of Middle-Late Triassic successions from the southwestern Sichuan region, SW China. The detrital compositions from the Middle Triassic successions indicate low mature sediments of mafic and intermediate rocks origin, which derivation mainly from recycled orogenic and secondarily from the Emeishan Large Igneous Province (ELIP). The detrital zircon U-Pb age distribution pattern of the Middle Triassic sandstone samples exhibits four major age Groups at ~257Ma, 650–500Ma, 880–710Ma, and 1000–900Ma. Combined with the geochemical characteristics, an interior Yangtze block source including the Khamdian uplift and ELIP is suggested. The Late Triassic sedimentary rocks yield seven U-Pb age Groups at 245–210Ma, 290–260Ma, 460–410Ma, 650Ma, 880–710Ma, 1900–1600Ma, and 2600–2400Ma, which are consistent with the data reported from the Sichuan basin, Songpan Ganzi basin and the southern Yidun terrane, and are partly similar to those of the south Qinling orogen, Jiangnan Xuefeng thrust belt. In contrast to the Middle Triassic successions, the sandstone composition modals and whole-rock geochemistry of the Late Triassic samples denote mature deposits and of intermediate and acid rocks origin. Therefore, during the Late Triassic, the southwestern Sichuan basin received materials from the Songpan Ganzi folded belt and Yidun arc complex dominantly, and from the Qinling orogen and Jiangnan Xuefeng thrust belt subsidiarily. The Sanjiang orogen and the Songpan Ganzi folded belt should have controlled the formation of the southwestern Sichuan basin, while the development of the Qinling orogen and the western Jiangnan-Xuefeng orogen may also influenced the formation of the southwestern Sichuan basin. The southwestern Sichuan region evolved from the passive continental margin basin in the Middle Triassic into a foreland basin in the Norian age of the Late Triassic.

Classification and hydrocarbon distribution of passive continental margin basins

Abstract Sixty-six passive continental margin basins around the world were compared comprehensively from the aspect of seismogeology on the basis of plate tectonics. According to their textural and structural differences, passive continental margin basins were classified into seven subdivisions, i.e., rifted basin, non-saline faulted depression basin, saline faulted depression basin, non-saline depression basin, saline depression basin, delta reformed basin and positive reverse deformed basin. The passive continental margin basins around the world have been generated with the formation of Mesozoic and Cenozoic Atlantic and Indian Oceans and they have experienced superimposition of three prototypes, including intra-continental rift in rifting period, intercontinental rift in transitional period and passive continental margin in drifting period. In rifted basins, the petroleum systems are mainly located in the lower lacustrine/marine rift series of strata and the thinner depression series of strata at the upper part are only regional cap-rocks. Large oil and gas fields are mainly concentrated in structural traps of rift series of strata. In non-saline faulted depression basins, hydrocarbon generation and expulsion peaks occur in both upper thicker marine depression series of strata and lower rift series of strata. Reservoirs are formed in the structures of rift series of strata, and oil and gas are highly concentrated at slope fans in depression series of strata. In saline faulted depression basins, large oil and gas fields are mainly distributed in the lagoon carbonate rocks of subsalt series of strata and the deepwater slope fans of suprasalt depression series of strata. In saline depression basins, only petroleum systems in depression series of strata are active, and various traps are developed, such as slope fan, salt structure and bioherm. In non-saline depression basins, large oil and gas fields are mainly located in submarine fan groups of depression series of strata because this type of basins are of narrow continental shelf and steep continental slope. In delta reformed basins, four major ring-like structure belts (i.e., growth faulting-mud diapir-thrust nappe-foredeep gentle slope) are formed from the shore to the deepwater and large oil and gas fields can be formed in each belt. Positive reverse reformed basins are the passive continental margin basins which are influenced by global orogenesis since the Miocene. In this type of basins, oil and gas are concentrated in compressional anticlines of reverse series of strata.

Structural architecture differences and petroleum exploration of passive continental margin basins in east Africa

Abstract Based on the plate tectonic theory, and by studying seismic, geologic data and related documents, this study restored the proto-type basins and lithofacies paleogeography of East African passive margin basins in the major geological periods, and carried out analysis on the basin architecture characteristics and sedimentary filling variance. Based on the dissection of fifteen reservoirs, three hydrocarbon accumulation models were identified to find out favorable plays and the further exploration direction in this region. The East African passive continental margin basins experienced three prototype stages, Late Carboniferous-Triassic Karoo intercontinental failed rifts, Jurassic intercontinental-intracontinental rifts, and passive continental margins since the Cretaceous. The rift sequences are developed in all the basins, forming the “rift type”, “rift depression type” and “delta reconstruction type” passive continental margin basins in line with the different thicknesses of the sediment fillings during the depression period. In the “rift type” basins, the sediment thickness during the depression period was less than 3 000 m, forming “single source – structure type” hydrocarbon accumulation model, where the exploration direction will mainly focus on giant structural traps on the top of the rift sequences. In the “fault-depression type” basins, the sediment thickness during the depression period was more than 5 000 m, forming “double sources – double combinations type” hydrocarbon accumulation model, where the exploration direction will mainly focus on giant slip-collapse-debris flow deposits on the top and middle of the slope. In the “delta-reconstruction type” sediment basins, the thickness is more than 6 000 m, forming constructional delta deposits with four structural belts from onshore to offshore, unique growth faults, mud diapirs, thrust faults and fore deep gentle slope, which are named as “three sources – multi-combinations type” hydrocarbon accumulation model, and all the four structural belts can form giant oil and gas fields.

Meso-Neoproterozoic petroleum systems of the Eastern Siberian sedimentary basins

The elements of the petroleum systems of the Siberian platform have been formed in the course of geological evolution in Meso- and Neoproterozoic time and correspond to the supercontinent stage from assembly of Paleo-Mesoproterozoic Columbia to break-up of Neoproteorzoic Rodinia. Several large sedimentary basins were established within the Siberian craton during the Riphean. A number of passive continental margin basins (the Turukhansk, Cis-Patom basins and others) developed on the southern, western, and, probably, northern craton peripheries. Several other basins, such as the Irkineeva-Vanavara, Kotuy, Anabar-Kureika, and Udzha basins, were entirely intracratonic. The structural patterns of these basins and their petroleum systems were essentially affected by Baikalian orogeny events with intensive dislocations and erosion of Riphean series, especially along the margins of the continent. As a result, hydrocarbon accumulations formed by the source rocks, which have realized their potential in Riphean within the margin basins, were, most likely, completely destroyed. Vendian and Lower Cambrian deposits were the main source for present day oil fields of the central and northern parts of the Nepa-Botuoba Anteclise and the Turukhansk Uplift. The Upper Riphean source rocks of the intracratonic basins, on the contrary, are unlikely to be affected by the significant pre-Vendian erosion and, thus, could be a source for the oil fields of the Yurubchen-Tokhomo Zone and the Katanga Saddle. Such difference in petroleum system evolution for different basins is also supported by results of oil–source rock correlations based on biomarker studies.A new mega-cycle of formation of the sedimentary cover started on the Siberian platform in the Vendian (Ediacaran). The initial fabric of all the main structural elements of the platform was established at this time. The large Vendian depressions (the “prototypes” of Paleozoic Kureika and Cis-Sayan-Yenisei syneclises and Cis-Patom Trough) were areas of mainly marine sedimentation where the high potential hydrocarbon source series could be deposited. Large elevated areas served as a terrigenous provenance in the Early Vendian resulting in a large amount of clastic material deposited along their flanks. The most promising areas for new discoveries of hydrocarbon fields are in the slopes of the Baikit, Nepa-Botuoba and Anabar anticlises faced towards the Kureika Syneclise.

Petroleum Exploration Potential of Xisha Trough Basin in SCS

Nowadays oil-gas exploration make a great contribution to the world oil-gas reserve increase. A series of deepwater passive continental margin basins are found in Northern Continental Slope of South China Sea. These basins consisted of thick Mesozoic and Cenozoic sedimentary strata with the characteristics of the major world deepwater oil-gas basins. As one of Cenozoic sedimentary basins in deepwater area of Northern Slope of South China Sea, Xisha Trough Basin developed 1500-8000m thick sedimentary strata, which are north-south zoning characteristics of thicker in the center and thinner both in the north and south sides of basin. In its evolutionary history there are two stages: One is Paleocene-Oligocene Rift with Continental River-Lake Facies sedimentary and the other is Miocene-Quaternary Depression with shallow sea-hemiplegic sedimentary. It has good petroleum geological conditions that source rocks consist of lacustrine mudstones, paralic mudstone, and marine mudstone, Tertiary high porosity and permeability deepwater fan reservoirs are the main reservoir, and structural traps and lithologic traps developed. In a word, it has good oil-gas exploration potential.

O Grupo Canastra em sua área-tipo, região de Tapira, sudoeste do estado de Minas Gerais

This work aimed at describing the Neoproterozoic evolution of a Southern Brasilia Fold Belt segment, in Tapira area (southwest of Minas Gerais state, Brazil), using detailed geologic mapping. This area, the Canastra Group type-area, has showed great tectonic and stratigraphic complexities unlike the simplicity suggested in previous works. From recognizing the main tectonic discontinuities, it was possible to subdivide the area into some domains. In the west domain, they were individualized in tectonic sheet I, marked by pelitic rocks and pelitic-graphite rocks with psammitic intercalations, and II, pelitic rocks with psammitic and mafic-ultramafic intercalations overlapped by gneisses. In the east domain, a group of three tectonic sheets was defined, in which, in the two lower tectonic sheets, pelitic and pelitic-graphite rocks with psammitic rock intercalations prevailed, which is different in metamorphic conditions. The lower tectonic sheet is marked by mineralogical associations with muscovite + chlorite + quartz ± graphite ± albite, without biotite; however, the superior one is with muscovite + quartz + garnet ± chlorite ± biotite ± chloritoid ± graphite ± albite. In the upper tectonic sheet, pelitic rocks with local contributions of psammitic and ultramafics rocks occur. In the south domain, psammitic rocks basically occur with contributions of pelitics and rudaceous rocks, where the preservation of textures and sedimentary structures is common. Rocks of the several domains are interpreted as part of a passive continental margin basin, located in the western margin of the Sao Francisco paleocontinent. Thus, the south domain rocks would represent the facies of proximal platform; rocks of the lower and middle tectonic sheets (east domain) and of the tectonic sheet I (west domain) are of facies distal platform; and the ones from the upper tectonic sheet (east domain) and tectonic sheet II (west domain) were acknowledged as deposited in an environment of continental shelf and/or oceanic seafloor.

Rhyacian (2.23–2.20Ga) juvenile accretion in the southern São Francisco craton, Brazil: Geochemical and isotopic evidence from the Serrinha magmatic suite, Mineiro belt

Abstract The Serrinha magmatic suite (Mineiro belt) crops out in the southern edge of the Sao Francisco craton, comprising the Brito quartz-diorite, Brumado de Cima and Brumado de Baixo granodiorites, granophyres and felsic sub-volcanic and volcanic rocks, part of which intruded into the Nazareno greenstone belt. The suite rocks have petrographic features that are consistent with magma supercooling due to the low water content combined with volatile loss, leading to crystallization of quartz and alkaline feldspar at the rims of plagioclase phenocrysts (granophyric intergrowth). The investigated rocks are sub-alkaline, calc-alkaline and show low content in rare earth elements. The U–Pb zircon crystallization ages for the Brumado de Cima granodiorite [2227 ± 22 (23) Ma] and a coeval granophyre [2211 ± 22 (23) Ma], coupled with available single-zircon Pb evaporation ages for the Brito and Brumado de Baixo plutons, are significantly older than the “Minas orogeny” (ca. 2100–2050 Ga) of Quadrilatero Ferrifero area, eastward from the Serrinha suite. Our data establish an early Rhyacian event tectonically linked with the evolution of the Mineiro belt. The bulk Nd isotopic signature [low negative to positive eNd(t) values] of the Serrinha samples are consistent with the important role of Paleoproterozoic mantle components in the magma genesis. The integrated geologic, geochemical and isotopic information suggests that Paleoproterozoic evolution of the Mineiro belt initiated in a passive continental margin basin with deposition of the Minas Supergroup at ca. 2500 Ma. This stage was succeeded by outboard rupture of the oceanic lithosphere with development and coalescence of progressively younger magmatic arcs during Rhyacian time. One of the earliest arcs formed the Serrinha suite. The tectonic collage of the Serrinha and Ritapolis (2190–2120 Ma) arcs produced the NE–SW Lenheiro shear zone, resulting in mylonitization and recrystallization of both the granitoid intrusions and host rocks. As a matter of fact juxtaposition of distinct magmatic units in age and origin took place along the Lenheiros structure in this sector of the Mineiro belt.

Rifting process and formation mechanisms of syn-rift stage prolongation in the deepwater basin, northern South China Sea

Based on the latest seismic and geological data, tectonic subsidence of three seismic lines in the deepwater area of Pearl River Mouth Basin (PRMB), the northern South China Sea (SCS), is calculated. The result shows that the rifting process of study area is different from the typical passive continental margin basin. Although the seafloor spreading of SCS initiated at 32 Ma, the tectonic subsidence rate does not decrease but increases instead, and then decreases at about 23 Ma, which indicates that the rifting continued after the onset of seafloor spreading until about 23 Ma. The formation thickness exhibits the same phenomenon, that is the syn-rift stage prolonged and the post-rift thermal subsidence delayed. The formation mechanisms are supposed to be three: (1) the lithospheric rigidity of the northern SCS is weak and its ductility is relatively strong, which delayed the strain relaxation resulting from the seafloor spreading; (2) the differential layered independent extension of the lithosphere may be one reason for the delay of post-rift stage; and (3) the southward transition of SCS spreading ridge during 24 to 21 Ma and the corresponding acceleration of seafloor spreading rate then triggered the initiation of large-scale thermal subsidence in the study area at about 23 Ma.

The Vendian-Early Palaeozoic sedimentary basins of the East European Craton

abstract Vendian-Early Palaeozoic sedimentation on the East European Craton (EEC) was confined to the cratonic margins with limited intracratonic subsidence. Generally, there are two geodynamic stages involved: in stage 1, basins formed in response to continental break-up processes; in stage 2, basins formed in response to the reassembly of continental lithosphere fragments and associated continental accretionary processes. The establishment of the Peri-Tornquist passive margin was a polyphase process that commenced in the Early Vendian in the SW and ended in the Cambrian in the NW. Neoproterozoic rifting along the Scandinavian margin was essentially a long process (250 Ma), whereas the fragmentation of the continent along the earlier Timanian orogen in the east and establishment of Peri-Uralian basins took place in a rather short time span. A similar scenario is suggested for the basement of the Peri-Caspian Basin. The rift-to-drift transition is expressed differently on the various EEC margins and this could be a reflection of the relative strengths of the underlying lithosphere. The change to a convergent margin setting is recorded in Peri-Tornquist basins in the Late Ordovician, climaxing with high rates of subsidence during Late Silurian time. Subsidence rates on the cratonic margins were governed by the emplacement of orogenic loads. Where there was a short time span between Stages 1 and 2, continuing thermal subsidence from the former was superimposed onto the flexural subsidence of the latter, such as on the Dnestr margin. Other processes, such as dynamic loading related to mantle flow, are implied for the anomalously broad Stage 2 Baltic Basin. Peri-Uralian basins developed as passive continental margin basins throughout the Early Palaeozoic. Stress regime changes generated at the craton margins are reflected in the structure and subsidence patterns recorded in the intracratonic Moscow Basin.

On the Carboniferous Sequence Stratigraphy in the Tazhong Area, Xinjiang — A Model of the Sequence Stratigraphy Framework of Intracratonic Depressional Basins

AbstractThe Carboniferous prototype sedimentary basin in the Tazhong (Central Tarim basin) area is recognized as a compressive intracratonic depressional one. Three type I sequence boundaries and three type II sequence boundaries can be identified in the Carboniferous System, which can accordingly be divided into five sedimentary sequences. These sequences possess stratigraphic characters of the standard sequence and correspond to the depositional stratigraphic unit of a third–order eustatic cycle. They can be regionally or globally correlated with each other. The framework of sequence stratigraphy of the intracratonict basin in the study area distinctly differs from that of the passive continental–margin basin in the lack of depositional systems of early–middle lowstand, poor development of the deeply incised valley and condensed section of the maximum sea—flood, good development of type II sequence boundaries and coastal plain depositional systems coexisting with shelf–type fan deltas under wet climatic conditions, which consequently led to the formation of a paralic lithofacies framework.

Petroleum Geology of Campos Basin, Brazil: A Successful Case History of Deep Water Exploration: ABSTRACT

Campos Basin, the most prolific Brazilian basin, produces almost 400,000 bbl of oil per day and contains 70% of the national reserves. The basin is located on the southeastern coast of Brazil, covering a prospectable area of 100,000 km{sup 2} Campos is a passive continental margin basin originated by the breakup of Pangea and the rifting of the South American and African plates in the Early Cretaceous. The basin's sedimentary section encompasses three megasequences: nonmarine, transitional, and marine, ranging in age from Neocomian to Holocene. Hydrocarbon generation is related to nonmarine organic-rich shales and marls, and hydrocarbon entrapment assumes ascendent migration along fault planes and through salt gaps toward reservoirs ranging in age from Neocomian to Tertiary (mainly turbiditic sandstones). The first onshore stratigraphic well was drilled based on gravity surveys in 1958. The acquisition of new geophysical data, mainly seismic reflection data, followed after 1968. The first offshore well was drilled in 1971, and in 1974, the first oil field, Garopua, was discovered. Giant hydrocarbon accumulations have been discovered in water depths ranging from 400 to 1,800 m since 1984. As of mid-1989, 35 offshore oil fields have been discovered, 760 million bbl of oil, and 490 bcf ofmore » gas have been produced. The basin oil and equivalent gas reserves are estimated in 6.0 billion bbl, 60% of which is located in the deep-water giant oil fields.« less