The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
A Zelilidis - One of the best experts on this subject based on the ideXlab platform.
-
potential source rocks organic geochemistry and thermal maturation in the southern Depocenter kipourio grevena of the mesohellenic basin central greece
International Journal of Coal Geology, 2007Co-Authors: Pavlos Avramidis, A ZelilidisAbstract:Abstract The study area is the southern Depocenter (depth > 4200 m) of the Mesohellenic Basin which extends between Kipourio and Grevena, central Greece. The Mesohellenic Basin is a Middle-Tertiary intramontane basin developed within the Hellenide orogen. Previous studies have focused on the depositional environments, configuration and hydrocarbon potential of the basin. In this paper we present additional geochemical and petrographic data from outcrop samples of the basin's southern Depocenter, which is considered the most promising area, in terms of hydrocarbon prospectivity. A total number of thirty six samples were analysed: Rock-Eval pyrolysis, maceral analysis, vitrinite reflectance and thermal alteration index, bitumens extraction, liquid chromatography, and GC-MS. The samples were collected from deltaic deposits and submarine fan sediments of Late Eocene to Late Oligocene age. The TOC values of the analysed samples range between rich and very rich and the organic matter consists mainly of type III kerogen and the organic matter consider to be predominately gas prone. The thermal maturity assessed from Tmax and vitrinite reflectance shows an immature stage of the organic matter along with the presence of layers having reached the very early mature stage. Vitrinite reflectance measurements and maturity calculations (applying the Lopatin modeling), reveal that the lower part of the Depocenter sediments falls within the ‘oil window’. The extractable organic matter (EOM) (mg bitumens/g TOC) indicate the existence of samples (from deltaic deposits) with high ratio of transformation (EOM) (> 100 mg bitumen/g TOC). The GC and GC-MS analyses of the biomarkers indicate mainly the occurrence of terrestrial organic matter reflecting oxidizing conditions and both immature and very early mature stages. The results of the Rock-Eval pyrolysis and the distribution of the isoprenoids support the assumption of the input of an organic matter mixture.
-
Potential source rocks, organic geochemistry and thermal maturation in the southern Depocenter (Kipourio–Grevena) of the Mesohellenic Basin, central Greece
International Journal of Coal Geology, 2007Co-Authors: Pavlos Avramidis, A ZelilidisAbstract:Abstract The study area is the southern Depocenter (depth > 4200 m) of the Mesohellenic Basin which extends between Kipourio and Grevena, central Greece. The Mesohellenic Basin is a Middle-Tertiary intramontane basin developed within the Hellenide orogen. Previous studies have focused on the depositional environments, configuration and hydrocarbon potential of the basin. In this paper we present additional geochemical and petrographic data from outcrop samples of the basin's southern Depocenter, which is considered the most promising area, in terms of hydrocarbon prospectivity. A total number of thirty six samples were analysed: Rock-Eval pyrolysis, maceral analysis, vitrinite reflectance and thermal alteration index, bitumens extraction, liquid chromatography, and GC-MS. The samples were collected from deltaic deposits and submarine fan sediments of Late Eocene to Late Oligocene age. The TOC values of the analysed samples range between rich and very rich and the organic matter consists mainly of type III kerogen and the organic matter consider to be predominately gas prone. The thermal maturity assessed from Tmax and vitrinite reflectance shows an immature stage of the organic matter along with the presence of layers having reached the very early mature stage. Vitrinite reflectance measurements and maturity calculations (applying the Lopatin modeling), reveal that the lower part of the Depocenter sediments falls within the ‘oil window’. The extractable organic matter (EOM) (mg bitumens/g TOC) indicate the existence of samples (from deltaic deposits) with high ratio of transformation (EOM) (> 100 mg bitumen/g TOC). The GC and GC-MS analyses of the biomarkers indicate mainly the occurrence of terrestrial organic matter reflecting oxidizing conditions and both immature and very early mature stages. The results of the Rock-Eval pyrolysis and the distribution of the isoprenoids support the assumption of the input of an organic matter mixture.
Michael J Quinn - One of the best experts on this subject based on the ideXlab platform.
-
upper miocene stevens sands in the maricopa Depocenter southern san joaquin valley california
AAPG Bulletin, 1991Co-Authors: Michael J QuinnAbstract:Abstract During the upper Miocene the southern San Joaquin Valley underwent rapid structural changes. Localized uplift shed coarse-grained quartz-rich sands into the subsiding Maricopa Depocenter, in the form of deep marine turbidites. These upper Miocene turbidites in the southern portion of the San Joaquin basin are collectively referred to as the “Stevens” sands. First encountered in a well drilled in 1936, the Stevens turbidite sands have become a major oil exploration target. A schematic model for the sand-rich Stevens turbidite deposition is used to examine four producing fields within the Maricopa Depocenter. Examples of sand-rich turbidite morphology, seismic signatures, depositional styles, and lateral migration of channel-lobe systems will be presented to demonstrate the effect of upper Miocene structural growth upon Stevens deposition within the Maricopa Depocenter.
Tomas Villamil - One of the best experts on this subject based on the ideXlab platform.
-
campanian miocene tectonostratigraphy Depocenter evolution and basin development of colombia and western venezuela
Palaeogeography Palaeoclimatology Palaeoecology, 1999Co-Authors: Tomas VillamilAbstract:Abstract The position of the central axis of deposition over Colombian and Venezuelan continental crust has varied markedly through time. The axis migrated from west to east from Late Cretaceous to Oligocene but at times, secondary drainage divides were established by local uplift events. In Oligocene times with initial inversion of the Eastern Cordillera the central axis of deposition was divided into two main axes, the proto-Magdalena and the proto-Orinoco systems. The west to east migration of the central axis of deposition had a tectonic origin and it occurred in combination with tectonically driven changes in accommodation space. Depocenter evolution can be divided as follows. (1) The axis of the Campanian and early Maastrichtian Depocenter was located few km east of the present position of the Central Cordillera of Colombia; it migrated east with gradual uplift of the Central Cordillera. (2) The central axis of late Maastrichtian deposition is positioned approximately over the present-day western foothills of the Eastern Cordillera, possibly crosses the Eastern Cordillera over the Santander Massif and continues into the Maracaibo Lake in western Venezuela. Accommodation space decreased from Campanian to Maastrichtian times. In Cretaceous–Tertiary boundary times parts of the eastern margin of the Eastern Cordillera were uplifted by an initial phase of inversion of deeply rooted Jurassic and Early Cretaceous normal faults. (3) In Paleocene times the central axis of deposition was located along the spine of the Eastern Cordillera and extended into the Maracaibo Basin, and accommodation space continued to decrease. (4) In latest Paleocene times the central axis of deposition shifted to eastern regions of the Eastern Cordillera and accommodation space decreased. (5) The Early Eocene central axis of deposition was located along the present-day eastern foothills of the Eastern Cordillera; accommodation space continued to decrease and the regional Middle Eocene unconformity began to develop. In Middle Eocene times a regional unconformity developed, marking the climax of the pre-Andean Orogeny. Deposition during these times was dominant in the Maracaibo Basin area where large amounts of sediment derived from vast exposed areas accumulated. (6) The Late Eocene central axis of deposition was confined to the present position of the Llanos foothills. Late Eocene deposition reflects a regional increase in accommodation space. In Oligocene times the initial uplift of the Eastern Cordillera divided the main Depocenter into two central axes. Accommodation space diminished in uplifted regions but continued to increase in the Depocenters allowing sporadic marine ingressions into the present position of the Llanos foothills. As uplift of the Eastern Cordillera continued, the eastern Depocenter axis (proto-Orinoco) migrated east and the western Depocenter axis (proto-Magdalena) migrated west. This process continued through the rest of the Cenozoic.
-
Campanian–Miocene tectonostratigraphy, Depocenter evolution and basin development of Colombia and western Venezuela
Palaeogeography Palaeoclimatology Palaeoecology, 1999Co-Authors: Tomas VillamilAbstract:Abstract The position of the central axis of deposition over Colombian and Venezuelan continental crust has varied markedly through time. The axis migrated from west to east from Late Cretaceous to Oligocene but at times, secondary drainage divides were established by local uplift events. In Oligocene times with initial inversion of the Eastern Cordillera the central axis of deposition was divided into two main axes, the proto-Magdalena and the proto-Orinoco systems. The west to east migration of the central axis of deposition had a tectonic origin and it occurred in combination with tectonically driven changes in accommodation space. Depocenter evolution can be divided as follows. (1) The axis of the Campanian and early Maastrichtian Depocenter was located few km east of the present position of the Central Cordillera of Colombia; it migrated east with gradual uplift of the Central Cordillera. (2) The central axis of late Maastrichtian deposition is positioned approximately over the present-day western foothills of the Eastern Cordillera, possibly crosses the Eastern Cordillera over the Santander Massif and continues into the Maracaibo Lake in western Venezuela. Accommodation space decreased from Campanian to Maastrichtian times. In Cretaceous–Tertiary boundary times parts of the eastern margin of the Eastern Cordillera were uplifted by an initial phase of inversion of deeply rooted Jurassic and Early Cretaceous normal faults. (3) In Paleocene times the central axis of deposition was located along the spine of the Eastern Cordillera and extended into the Maracaibo Basin, and accommodation space continued to decrease. (4) In latest Paleocene times the central axis of deposition shifted to eastern regions of the Eastern Cordillera and accommodation space decreased. (5) The Early Eocene central axis of deposition was located along the present-day eastern foothills of the Eastern Cordillera; accommodation space continued to decrease and the regional Middle Eocene unconformity began to develop. In Middle Eocene times a regional unconformity developed, marking the climax of the pre-Andean Orogeny. Deposition during these times was dominant in the Maracaibo Basin area where large amounts of sediment derived from vast exposed areas accumulated. (6) The Late Eocene central axis of deposition was confined to the present position of the Llanos foothills. Late Eocene deposition reflects a regional increase in accommodation space. In Oligocene times the initial uplift of the Eastern Cordillera divided the main Depocenter into two central axes. Accommodation space diminished in uplifted regions but continued to increase in the Depocenters allowing sporadic marine ingressions into the present position of the Llanos foothills. As uplift of the Eastern Cordillera continued, the eastern Depocenter axis (proto-Orinoco) migrated east and the western Depocenter axis (proto-Magdalena) migrated west. This process continued through the rest of the Cenozoic.
Bruno Savoye - One of the best experts on this subject based on the ideXlab platform.
-
The long-term evolution of the Congo deep-sea fan: A basin-wide view of the interaction between a giant submarine fan and a mature passive margin (ZaiAngo project)
Tectonophysics, 2009Co-Authors: Zahie Anka, Michel Séranne, Michel Lopez, Magdalena Scheck-wenderoth, Bruno SavoyeAbstract:We have integrated the relatively unknown distal domains of the Lower Congo basin, where the main Depocenters of the Congo submarine fan are located, with the better-constrained successions on the shelf and upper slope, through the analysis of thousands of km of 2D seismic reflection profiles off-shore the Congo-Angola passive margin. The basin architecture is depicted by two ca. 800-km-long regional cross sections through the northern (Congo) and southern (Angola) margin. A large unit deposited basinward of the Aptian salt limit is likely to be the abyssal-plain equivalent of the upper-Cretaceous carbonate shelf that characterized the first post-rift deposits in West-equatorial African margins. A latest-Turonian shelf-deepening event is recorded in the abyssal plain as a long period (Coniacian-Eocene) of condensed sedimentation and basin starvation. The onset of the giant Tertiary Congo deep-sea fan in early Oligocene following this event reactivates the abyssal plain as the main Depocenter of the basin. The time-space partitioning of sedimentation within the deep-sea fan results from the interplay among increasing sediment supply, margin uplift, rise of the Angola salt ridge, and canyon incision throughout the Neogene. Oligocene-early Miocene turbidite sedimentation occurs mainly in NW-SE grabens and ponded inter-diapir basins on the southern margin (Angola). Seaward tilting of the margin and downslope salt withdrawal activates the up-building of the Angola escarpment, which leads to a northward (Congo) shift of the transfer zones during late Miocene. Around the Miocene-Pliocene boundary, the incision of the Congo submarine canyon confines the turbidite flows and drives a general basinward progradation of the submarine fan into the abyssal plain The slope deposition is dominated by fine-grained hemipelagic deposits ever since. Results from this work contribute to better understand the signature in the ultra-deep deposits of processes acting on the continental margin as well as the basin-wide sediment redistribution in areas of high river input. © 2008 Elsevier B.V. All rights reserved.
Thomas Stachel - One of the best experts on this subject based on the ideXlab platform.
-
Carbonatite magmatism and fenitization of the epiclastic caldera-fill at Gross Brukkaros (Namibia)
Bulletin of Volcanology, 1995Co-Authors: Thomas Stachel, Volker Lorenz, Gerhard BreyAbstract:The Gross Brukkaros inselberg is a dome structure with a crater-shaped central depression within Precambrian/Cambrian country rocks which was active as a Depocenter during the Late Cretaceous. The formation of the structure was due to the intrusion and subsequent intermittent depletion of a shallow magma reservoir. Juvenile material has not been recognized hitherto. This is the first account of juvenile lapilli from within the epiclastic fill of the caldera structure. The lapilli are calciocarbonatites and magnesiocarbonatites in composition, but are characteristically low in elements such as P, Nb, Ba and Sr, otherwise typical of carbonatites. This signature, however, is also characteristic of carbonatites from surrounding volcanic centers and necks. The Brukkaros sediments suffered strong metasomatic-hydrothermal alteration, which introduced in a first stage fluids rich in Fe, Ti, Na, Nb, V, K (Ca?, CO_2?), and in a second stage the Brukkaros sediments were silicified on a large scale and locally enriched in P, Th and Cr. Si is derived from desilication of the wall rocks (basement?, Nama sediments) of the magma reservoir. Cr was probably mobilized during alteration of the abundant doleritic detritus within the Brukkaros Depocenter.
-
Gross Brukkaros (Namibia)—an enigmatic crater-fill reinterpreted as due to Cretaceous caldera evolution
Bulletin of Volcanology, 1994Co-Authors: Thomas Stachel, Volker Lorenz, I. G. StanistreetAbstract:At Gross Brukkaros a central depression has developed within domed Nama Group sediments and has functioned as a local Depocenter, with a primary fill deposited during the Cretaceous and a small secondary fill by alluvial fans during the Tertiary and Quaternary. The diameter of the entire structure is about 10 km and that of the central depression is about 3 km. Within this Depocenter the sedimentary sequence consists mainly of debris-flow and mudflow deposits, with minor intercalations of fluviatile (braided channel) sediments and fossiliferous lacustrine deposits. The sedimentary system represents a set of coalesced subaerial fans which formed a fringing sedimentary apron along the margin of the Depocenter. This sedimentary apron passed distally and centrally into a permanent lake, which was characterized by a fluctuating water level. Facies transitions observed are typical of those described from modern and ancient fan delta systems. Contact relationships show the Gross Brukkaros sediments to be about the same age (Upper Cretaceous) as the surrounding carbonatitic volcanism. An Upper Cretaceous age is also consistent with the plant fossil association recently recognized within the lacustrine beds of Gross Brukkaros.