J. J. Mayer

OMV (Austria)

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Stratigraphy and structure of the northern Rioni Basin, Georgia

EGUGA (2018)

Gábor Tari David Vakhania G. Tatishvili Vazha Mikeladze J. J. Mayer

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Citations (0)

Holocene source rock deposition in the Black Sea, insights from a dropcore study offshore Bulgaria

Geological Society London Special Publications (2017)

Mohammad Fallah J. J. Mayer Gábor Tari J. Baur

Abstract One of the main issues in source rock evaluation has always been the availability of thermally immature samples, which would represent the same source rock quality and facies as the mature source rock within the deeper parts of the basin. Forty dropcore sample locations from shallow depths beneath the present-day seafloor were selected and analysed for mineral composition and bulk geochemical parameters. The water depths of the samples range from shelfal to bathyal environments. The quartz content of the samples clearly decreases with increasing distance from sedimentary input sources (e.g. river deltas), whereas clay content increases towards the distal areas. Mass movements (e.g. slides and debris flows) along the present-day shelf are recognizable on the bathymetry, as well as in the mineral content. Bulk geochemical parameters show that currently only poor to fair gas-prone source rocks are deposited within the study area. This lack of source rock quality, as well as organic content, is attributed to the fine-grained sedimentary input from the Danube river. These fine-grained sediments decrease the organic productivity due to dulling (decrease in the thickness of the photic zone) of the water column, and dilute the currently deposited source rock with low TOC sediments. These effects decrease with distance from the Danube delta, as indicated by published data from outside the study area. Additionally mass movements along the present-day shelf rework possible source rocks. The results of this study clearly show that anoxic conditions alone are not sufficient for source rock deposition. Distance from major sedimentary input and basin geometry are of major importance, and should be considered in basin modelling.

Deposition

Black Sea

10.1144/sp464.11

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Citations (3)

Discussion on Transgressive and progradational beach and nearshore facies in the late Archaean Turffontein Subgroup of the Witwatersrand Supergroup, Vredefort area, South Africa; discussion and reply

South African Journal of Geology (1993)

P.G. Eriksson U.M. Schreiber C.P. Snyman B.F.F. Reczko B. G.

Transgressive

Supergroup

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Citations (1)

Shallow hydrocarbons in Lower Austria: A drilling hazard and a valuable exploration tool

Mitteilungen der Österreichischen Geologischen Gesellschaft/Austrian journal of earth sciences (2013)

J. J. Mayer Reinhard F. Sachsenhofer

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Citations (2)

The tectono-sedimentary setting of the area of the Vredefort structure during deposition of the upper quartzite member of the Hospital Hill subgroup

South African Journal of Geology (1988)

J. J. Mayer J. A. Albat

Deposition

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Citations (2)

Biostratigraphy and paleoenvironments of the Oligocene succession(İhsaniye Formation) at Karaburun (NW Turkey)

TURKISH JOURNAL OF EARTH SCIENCES (2019)

Michael D. Simmons Mike Bidgood Paul G. CONNELL Stjepan Ćorić Aral İ. Okay

The biostratigraphy and paleoenvironments of the İhsaniye Formation exposed at Karaburun in northwest Turkey is described based upon the study of abundant and well-preserved foraminifera, calcareous nannofossils and palynomorphs. The studied succession is Early Oligocene in age, with calcareous nannofossil zones upper NP21 (Subzone CNO1) to lower NP23 (Subzone CNO3) and planktonic foraminifera zones O1 (~P18) and O2 (~P19) represented, and palynological assemblages suggestive of zones D13 to D14a. Based on these new data, a revised interpretation of the stratigraphic succession is presented. Deposition was controlled by a now inverted normal fault, with deposition of older stratigraphy (upper NP21 to NP22) restricted to the original hanging wall. During NP23, deposition commenced on the footwall, resulting in progressive onlap of an exposed Eocene reefal limestone (Soğucak Formation). Three primary sedimentary facies are present: marls with thin calcareous siltstones, marls with synsedimentary slumps and debris flows, and coarse pebbly sandstones. The coarse pebbly sandstones were deposited in a fan-delta/shoreface paleoenvironment and represent the initial phase of onlap during biozone NP23 onto a rocky shoreline on the footwall side of the fault. The marl-dominated facies represent deposition in outer shelf?upper bathyal environments. The succession demonstrates evidence for a near-end Eocene relative sea-level fall. Changes in the abundance of planktonic foraminifera and the onlap onto the footwall demonstrate maximum subsequent transgression within NP23. This reflects eustasy rather than Paratethyan relative sea-level. No interpretation of sea-water salinity reduction can be made for the sediments deposited during biozone NP23 in the studied sections, although this is noted in coeval sediments in parts of Paratethys (the "Solenovian Event"). Together with the open marine nature of the diverse and abundant fossil assemblages, it is suggested that deposition of the Karaburun section was strongly influenced by a connection to the global ocean, via the Çatalca Gap, as suggested in a recent study.

Onlap

Marl

Biozone

Marine transgression

Paleogene

10.3906/yer-1907-7

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Citations (4)

COARSE CLASTIC TIDAL AND FLUVIAL SEDIMENTATION DURING A LARGE LATE ARCHEAN SEA-LEVEL RISE: THE TURFFONTEIN SUBGROUP IN THE VREDEFORT STRUCTURE, SOUTH AFRICA

SEPM (Society for Sedimentary Geology) eBooks (1998)

Бубличенко А.Г.J. J. Mayer

Sedimentation

10.2110/pec.98.61.0155

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Citations (13)

The Ventersdorp contact reef; final phase of the Witwatersrand Basin, independent formation, or precursor to the Ventersdorp Supergroup?

South African Journal of Geology (1997)

R. C. Hall B. G.J. J. Mayer

The Ventersdorp Contact Reef (VCR) is an Archaean conglomeratic gold placer, mined in the Carletonville, West Rand, and Klerksdorp goldfields of the Republic of South Africa. It belongs to a lithostratigraphic formation, the Venterspost Conglomerate Formation (VCF), which is considered to be stratigraphically independent of the underlying Witwatersrand Supergroup sediments and overlying Ventersdorp Supergroup volcanics. In this paper, the present formal stratigraphic placement of the Formation is compared with its alternative stratigraphic assignment to either of the underlying Witwatersrand or overlying Ventersdorp Supergroups. Evidence for a basin-wide, angular unconformity separating the VCF from Witwatersrand rocks, which were regionally lithified prior to deposition of the Formation, indicates that it is stratigraphically divorced from the Witwatersrand Supergroup. While similar angular, internal unconformities are present within the Witwatersrand Supergroup, a significant difference between these and the VCF unconformity is that the internal Witwatersrand unconformities are asserted to have basinward extents only to the tectonic hinge between continuous deposition and contemporaneous (Witwatersrand) foreland basin destruction. A genetic difference between the VCR and typical Witwatersrand placers is reflected by their differing mineralogical content and metamorphic grade. These differences, by implication, also reflect a substantial time gap separating their deposition. The fact that the conglomerates and sandstones of the VCF are locally interbedded with lava flows that are geochemically similar to the lava of the basal Westonaria Formation of the Ventersdorp Supergroup, indicates lithologic and genetic links to this Supergroup. These relationships are further supported by the presence of tuffaceous sandstone beds within the VCF. The occurrence of deformational load structures at the contact between the formation and the basal lava flows of the overlying Ventersdorp Supergroup indicates an unconsolidated, probably water-saturated state of the VCF sediments at the time of their envelopment by the lava, and implies a conformable relationship with the lower formations of the Supergroup. In conclusion, it is proposed that the VCF be stratigraphically assigned to the Ventersdrop Supergroup.

Supergroup

Conglomerate

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Citations (16)

Shatter cones in Vredefort rocks; imagination or reality?

South African Journal of Geology (1990)

H. M. Albat J. J. Mayer

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Citations (2)

Interpretation of heavy-mineral patterns in sandy soils of the region drained by the upper reaches of the Harts River

South African Journal of Geology (1985)

J. J. Mayer

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Citations (3)