scholarly journals Lower Cretaceous carbonate gravity-flow deposits from the Bohinj area (NW Slovenia): evidence of a lost carbonate platform in the Internal Dinarides

2012 ◽  
Vol 183 (4) ◽  
pp. 383-392 ◽  
Author(s):  
Duje Kukoč ◽  
Špela Goričan ◽  
Adrijan Košir
Keyword(s):  
Early Cretaceous ◽  
Continental Margin ◽  
Lower Cretaceous ◽  
Carbonate Platform ◽  
Gravity Flow ◽  
Carbonate Platforms ◽  
Shallow Marine ◽  
Marine Benthos ◽  
Plassen Carbonate Platform ◽  
Internal Dinarides

Abstract In the Bohinj area (NW Slovenia), a distinctive interval of carbonate gravity-flow deposits overlying the pelagic Biancone limestone was analyzed for microfacies and dated with radiolarians. This interval, newly described as the Bohinj Formation, consists of a 3 m thick carbonate breccia capped by a 4 m thick massive calcarenite. The breccia is composed of clasts of carbonate platform facies, isolated ooids and oncoids, and bioclasts of shallow-marine benthos. Intraclasts of pelagic calpionellid wackestone and rare chert clasts are also present. Radiolarians from the pelagic limestone below indicate a latest Tithonian to earliest Berriasian age, and those above indicate a Berriasian to Early Valanginian age. Paleogeographically, the area was part of the Bled basin, which had a relatively distal position on the Adriatic continental margin. This position is suggested by flysch-type deposits in the area that are Early Cretaceous in age and thus correlate with the Bosnian Flysch in the central Dinarides. The Bohinj Formation provides evidence of a carbonate platform that must have been located more internally but is now not preserved. This inferred platform (named the Bohinj Carbonate Platform) may have developed on top of a nappe stack, which formed during the early emplacement of the internal Dinaric units onto the continental margin. The platform correlates regionally with genetically similar isolated carbonate platforms of the Alpine – Dinaride – Carpathian orogenic system, e.g., with the Plassen Carbonate Platform in the Northern Calcareous Alps and the Kurbnesh Carbonate Platform in Albania.

Mesozoic palaeogeography and tectono-stratigraphic features of the northern Amerini Mts. (Central Apennines, Italy): new constraints on their Jurassic and Cretaceous evolution

2020 ◽  
Author(s):  
Costantino Zuccari ◽  
Angelo Cipriani ◽  
Massimo Santantonio
Keyword(s):  
Early Cretaceous ◽  
Lower Cretaceous ◽  
Carbonate Platform ◽  
Indirect Evidence ◽  
Lower Jurassic ◽  
Geological Mapping ◽  
Carbonate Platforms ◽  
Central Apennines ◽  
Sedimentary Evolution ◽  
Structural High

<p>A geological mapping project was performed on the 1:10,000 scale in the northern Amerini Mts. (Narni–Amelia Ridge, Central Apennines), coupled with facies analysis and multidisciplinary outcrop characterisation. This project was focused on the Jurassic-Lower Cretaceous succession, in order to reconstruct the Mesozoic palaeogeography and tectono-sedimentary evolution of the study area. This sector of the Apenninic Chain (i.e. Umbria-Marche-Sabina palaeogeographic domain) experienced the Early Jurassic rifting phase, which dismembered the vast Calcare Massiccio carbonate platform. The development of a rugged submarine topography, coupled with drowning of the benthic factories, were the main effects of this normal faulting. The complex submarine physiography, made of structural highs and lows, is highlighted by facies and thickness variations of the Jurassic and Lower Cretaceous deposits. The hangingwall blocks hosted thick (hundreds of metres) pelagic successions, with variable volumes of admixed gravity-flow deposits. These successions onlapped the horst blocks along escarpments, rooted in the rift faults, where the pre-rift Calcare Massiccio was exposed. The tops of footwall blocks (Pelagic Carbonate Platforms or PCPs) were capped by thin (few tens of metres or less), fossil-rich and chert-free, condensed pelagic successions. This rift architecture was evened out at a domain scale in the Early Cretaceous. Successively, Miocene orogenic and Plio-Pleistocene extensional faulting caused uplift and exhumation of the Mesozoic rocks.</p><p>In the study area, geothematic mapping associated with the analysis of basin-margin unconformities and successions revealed a narrow and elongated Jurassic structural high (Mt. Croce di Serra - Mt. Alsicci structural high), surrounded by Jurassic basinal pelagites. The PCP-top condensed succession is not preserved. The chert-rich basinal units rest on the horst-block Calcare Massiccio through unconformity surfaces (palaeoescarpments), as marked by the silicification of the (otherwise chert-free) shallow-water limestone. The onlap successions embed megablocks of Calcare Massiccio (hundreds of metres across), detached from their parent palaeoescarpments. Very thin, condensed deposits form discontinuous veneers on the olistoliths of Calcare Massiccio (epi-olistolith deposits) and are onlapped by younger basin-fill pelagites. The beds surrounding the olistoliths are characteristically bent due to differential compaction, as their (newly acquired) strikes mimic the outline of the stiff objects they were burying.</p><p>Indirect evidence for a Toarcian, post-rift, tectonic pulse can be locally mapped, and is documented by angular unconformities between the Pliensbachian and Toarcian pelagites, as well as by mass-transport deposits found in the Rosso Ammonitico (Toarcian).</p><p>The same goes for millimetric to centimetric neptunian dykes made of Maiolica pelagites cross-cutting the Corniola Fm. (Sinemurian-Pliensbachian). These dykes, coupled with the occurrence of unconformities between Aptian-Albian pelagites (Marne a Fucoidi Fm.) and Lower Jurassic rocks (Calcare Massiccio and Corniola formations), provide evidence for a further Early Cretaceous tectonic phase, recently reported from the southern sectors of Narni-Amelia ridge.</p>

Deciphering the geodynamic evolution of the Dinaric orogen through the study of the ‘overstepping’ Cretaceous successions

2020 ◽  
Vol 157 (8) ◽  
pp. 1238-1264
Author(s):  
Giuseppe Nirta ◽  
Martin Aberhan ◽  
Valerio Bortolotti ◽  
Nicolaos Carras ◽  
Francesco Menna ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Continental Margin ◽  
Late Jurassic ◽  
Carbonate Platform ◽  
Depositional Environments ◽  
Small Scale ◽  
Large Area ◽  
Geodynamic Evolution ◽  
Sedimentary Evolution ◽  
Platform System

AbstractAlong the Dinaric–Hellenic orogen, the Late Jurassic – Early Cretaceous ophiolite obduction over the Adria continental margin was sealed by sedimentation of clastic terrestrial deposits rapidly followed by a widespread carbonate platform system since the Early Cretaceous period. These Cretaceous sediments presently crop out over areas of varying extension, from several hundred kilometre wide undeformed continuous covers to small-scale tectonic slivers involved in the tectonic stack following the latest Cretaceous–Palaeogene collision. These deposits are unconformably sedimented above the units formed by the Late Jurassic to Early Cretaceous nappe stacking above the eastern Adria continental margin. We studied these deposits in a large area between western Serbia and eastern Bosnia. In the studied area, these deposits are divided into three lithostratigraphic groups according to their age, depositional environment and type of underlying basement. The Mokra Gora Group sediments (upper Aptian–Maastrichtian) were deposited on top of previously obducted and weathered ophiolites, the Kosjerić Group (Cenomanian–Campanian) overlies composite tectonic units comprising obducted ophiolites and their underlying continental basement portions, while the Guča Group (Campanian–Maastrichtian) exclusively rests on top of continental basement. The reconstructed sedimentary evolution of these groups, together with the comparison with the syn- and post-obduction deposits at the front of the ophiolitic nappe(s) in a wider area of the internal Dinarides (e.g. Pogari Group and Bosnian flysch), allowed us to clarify the obduction mechanisms, including their tectonic context, the changes in depositional environments and the timing of depositional and tectonic events, and, in a wider view, shed light on the geodynamic evolution of the Dinaric belt.

scholarly journals THE LATE EARLY CRETACEOUS TRANSGRESSION ON THE LATERITES IN VOURINOS AND VERMION MASSIFS (WESTERN MACEDONIA, GREECE)

2018 ◽  
Vol 40 (1) ◽  
pp. 182 ◽  
Author(s):  
A. Photiades ◽  
N. Carras ◽  
V. Bortolotti ◽  
M. Fazzuoli ◽  
G. Principi
Keyword(s):  
Early Cretaceous ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Carbonate Platform ◽  
Upper Jurassic ◽  
Ophiolite Complex ◽  
Marine Transgression ◽  
The Third ◽  
Normal Salinity

Three stratigraphical sections from eastern Vourinos (Rhodiani area) to eastern Vermion massifs revealed the same age of the latérite events affecting the serpentinized ophiolite complex after its emplacement on the Pelagonian domain. All of them consist from their base upwards of serpentinized harzburgite slivers with lateritic unconformities on the top, followed by transgressive upper Lower Cretaceous neritic limestones. At Kteni locality (Rhodiani area), a laterite horizon, lying on top of serpentinites, is covered by transgressive neritic limestones with Salpingoporella urladanasi, assigning a Barremian - Albian age, followed by Orbitolinidae limestones. At Tsimodia locality (NNW to the previous), the latente horizon, lying on karstified Upper Jurassic reef limestones (which are the top member of a carbonate platform body tectonically lying on the ophiolites), is trans gres s ively overlain by iron-rich pisolith levels and Aptian limestones of the wackes tone-muds tone type, also containing Salpingoporella urladanasi, followed by Cenomanian Orbitolina limestones. Finally, the third examined locality, further north-eastward to the previous, is situated at the eastern slopes of Vermion massif and more precisely at the NWpart of Koumaria village. There, it can again be observed that the lateritized serpentinite slivers are overlain transgress ively by neritic limestones with Salpingoporella urladanasi, passing upwards into Upper Cretaceous recrystallized limestones with Orbitolinidae and rudist fragments and, finally, toflysch deposition. These features allow to recognize that the emersion and the consecutive lateritization of the thrust-emplaced ophiolites in Vourinos and Vermion massifs in the northern Pelagonian domain, starting from the Latest Jurassic, was followed by a marine transgression beginning from the Barremian - Albian, firstly under restricted and brackish carbonate platform conditions, marked by the presence of the dasycladalean alga Salpingoporella urladanasi, followed by normal salinity carbonate platform conditions. The neritic sedimentation was stable until the Early Cenomanian. Subsequently, a deepening, earlier at Vourinos and later at Vermion, resulted in deposition of pelagic and turbiditic carbonates and then offlysch.

New insights into the depositional environment and stratigraphic position of the Gugu Breccia (Pădurea Craiului Mountains, Romania)

2021 ◽  
Vol 21 (11) ◽  
pp. 215-233
Author(s):  
Traian Suciu ◽  
George Pleş ◽  
Tudor Tămaş ◽  
Ioan I. Bucur ◽  
Emanoil Săsăran ◽  
...  
Keyword(s):  
Lower Cretaceous ◽  
Depositional Environment ◽  
Carbonate Platform ◽  
Type Locality ◽  
Carbonate Platforms ◽  
Terrigenous Input ◽  
New Information ◽  
The Matrix ◽  
Stratigraphic Position ◽  
Sedimentary Formation

The study of the carbonate clasts and matrix of a problematic sedimentary formation (the Gugu Breccia) from the Pădurea Craiului Mountains reveals new information concerning its depositional environment and stratigraphic position. The identified microfacies and micropaleontological assemblages demonstrate that all the sampled limestone clasts from the Gugu Breccia represent remnants of a fragmented Urgonian-type carbonate platform. The Barremian age of the clasts suggests that the stratigraphic position of the Gugu Breccia at its type locality could be uppermost Barremian-lowermost Aptian, a fact demonstrated also by the absence of elements from Lower Cretaceous carbonate platforms higher in the stratigraphic column (e.g., Aptian or Albian) of the Bihor Unit. The sedimentological observations together with the matrix mineralogy bring new arguments for the recognition of terrigenous input during the formation of the Gugu Breccia.

Seismic Facies, Stratigraphy, Geomorphology, and Seismic Modelling of a Lower Cretaceous Carbonate Platform

2020 ◽  
pp. SP509-2020-18
Author(s):  
Jean-Christophe Embry ◽  
David Hunt ◽  
Arnout Colpaert ◽  
Anders Dræge ◽  
Laura Zahm
Keyword(s):  
Lower Cretaceous ◽  
Spatial Organization ◽  
Carbonate Platform ◽  
Rock Physics ◽  
Seismic Facies ◽  
Carbonate Platforms ◽  
Seismic Modelling ◽  
Seismic Sequences ◽  
Seismic Geomorphology ◽  
Platform Margin

AbstractGlobally, Lower Cretaceous carbonate platforms form important hydrocarbon reservoirs. An exceptional seismic dataset allowed us to examine controls on the stratigraphy, seismic geomorphology, facies architecture, and along-strike variability of a Lower Cretaceous platform. Within the platform succession, a partitioning of facies is developed between Transgressive, Highstand and Forced Regressive seismic sequences. Spectacular seismic geomorphologic images of the platform using spectral decomposition techniques reveal spatial organization within both depositional and diagenetic (i.e. paleokarst) patterns. The study was undertaken in order to optimise a well location. Pre-drill seismic facies interpretations were interpreted with the aid of offset well data and drill cores. Core data encompass a range of slope, platform margin and platform interior facies with inferred paleoenvironments that are matched to the seismic geomorphology of the platform. 2D Seismic forward modelling was integrated in our workflow to investigate the extent of potential sealing lithologies and the reservoir potential of the individual seismic sequences. Nearby wells were used to calibrate a modified rock physics model for the different lithofacies. Multiple seismic model realisations were generated to assess reservoir quality in alternative well locations and the continuity and quality of sealing strata. Results of the pre-drill forward-modelled poro-perm prediction are presented, showing a good fit with the final well observations after drilling.

Challenges of carbonate platform identification and characterisation from seismic data in frontier exploration – evaluating a possible Miocene example from the SE Caribbean

2020 ◽  
pp. SP509-2019-200
Author(s):  
Álvaro Jiménez Berrocoso ◽  
Massimiliano Masini ◽  
Josgre Salazar ◽  
Antonio Olaiz Campos ◽  
Jean C. C. Hsieh
Keyword(s):  
Seismic Data ◽  
Carbonate Platform ◽  
Sources Of Information ◽  
Carbonate Platforms ◽  
Shallow Marine ◽  
Southern Caribbean ◽  
Marine Carbonate ◽  
Marine Carbonates ◽  
Intensive Approach ◽  
3D Seismic Data

AbstractThe purpose of this study is to demonstrate that the identification of carbonate platforms in frontier exploration using seismic data remains challenging despite the variety of attributes that can be extracted from the data and their integration with other sources of information. A Miocene example from offshore Tobago (Southern Caribbean) is evaluated using 3D seismic data integrated with regional geology, potential fields, analogues, and structural restoration. The data are compatible with interpreting the target as shallow-marine carbonates, and a conceptual model is presented. However, far fewer of the seismic characteristics are diagnostic of a carbonate platform, and despite the intensive approach and the use of published criteria for subsurface carbonate interpretation, it was impossible to conclusively identify the target as a shallow-marine carbonate. Alternative explanations such as volcaniclastics, eroded remnants of siliciclastics and basement highs are considered. The study illustrates that it is common to find situations where the origin of a prospective geobody cannot be determined beyond significant levels of uncertainty unless it is drilled. If other elements of the petroleum system are favourable, this irreducible risk has to be accepted to avoid overlooking attractive carbonate reservoirs, provided all available data are used and all possible alternative interpretations considered.

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