Hooked on salt: Rethinking Alpine tectonics in Hallstatt (Eastern Alps, Austria)

Geology ◽  
2020 ◽  
Author(s):  
Oscar Fernández ◽  
Mario Habermüller ◽  
Bernhard Grasemann
Keyword(s):  
Late Jurassic ◽  
Eastern Alps ◽  
Salt Tectonics ◽  
Alpine Tectonics ◽  
Carbonate Platforms ◽  
Gravity Driven ◽  
World Class ◽  
Permian Salt ◽  
Platform Carbonates ◽  
First Time

Permian salt in the Hallstatt and neighboring salt structures of the Eastern Alps (Austria) crops out along with Triassic deep-water deposits that are at odds with the surrounding Triassic platform carbonates. The traditional interpretation of this juxtaposition is that the salt bodies were emplaced in the Late Jurassic as gravity nappes onto the carbonate platforms, in what has been considered to be the earliest orogenic event in the Eastern Alps. Here we describe for the first time a world-class outcrop of halokinetic sequences in Triassic platform carbonates flanking the Hallstatt diapir. Combining this with other outcrop evidence, we prove that the Hallstatt diapir grew passively during the Triassic, surrounded by carbonate platforms, and extruded to the seabed during the Jurassic. The development of the Hallstatt diapir in a platform setting disproves its emplacement as a gravity-driven nappe, proves the relevance of salt tectonics in the Mesozoic development of the Eastern Alps, and challenges the existence of a Late Jurassic Alpine orogenic event.

Unlocking The Complex Geology & Petroleum Systems; Efforts to Awakening The Sleeping Giant – A Prospectivity Rejuvenation Case Study of West Sebuku Block, South Makassar Basin, Indonesia

2021 ◽  
Author(s):  
R. Utomo
Keyword(s):  
Essential Element ◽  
Petroleum System ◽  
Carbonate Platforms ◽  
Petroleum Systems ◽  
Exploration And Production ◽  
Seismic Acquisition ◽  
Platform Carbonates ◽  
Steep Slopes ◽  
First Time

Significant uplift in the seismic imaging quality from the latest wide coverage of the Multi-Client Broadband PSDM 3D (MC3D) acquisition and processing, as well as cost and operational efficiencies, is an essential element to unlock the exploration potential of the under-explored South Makassar Basin. Many of exploration wells are usually drilled based on limited data, and structural closures are defined by sparse 2D seismic data and inadequate petroleum system models. Additional 3D seismic acquisition over the same area may enhance the structural imaging and provide a better understanding of the petroleum system. However, imaging the stratigraphic and structural complexities beneath carbonate platforms and steep slopes can be challenging and continued de-risk the plays. In 2018, Mubadala Petroleum requested PGS to acquire the first Multi-Client Broadband PSDM 3D survey in the South Makassar Basin. This MC3D survey has, for the first time, enabled imaging of well developed Eocene Platform carbonates and the Basement. Historical exploration and production activities with in the Basin have focused largely on the Oligocene aged carbonate debris flow deposits, as seen at Ruby Field. These new Eocene Platform carbonate and Basement plays have enabled Mubadala Petroleum to develop a significant exploration portfolio, revitalizing exploration activity in the Basin.

scholarly journals ?Kimmeridgian-Tithonian shallow- water platform clasts from mass flows on top of the Vardar/Axios ophiolites

2016 ◽  
Vol 47 (1) ◽  
pp. 184
Author(s):  
G. Kostaki ◽  
A. Kilias ◽  
H. J. Gawlick ◽  
F. Schlagintweit
Keyword(s):  
Early Cretaceous ◽  
Late Jurassic ◽  
Eastern Alps ◽  
Sediment Supply ◽  
Carbonate Platforms ◽  
Northern Greece ◽  
Tectonic Event ◽  
Mass Flows ◽  
Sedimentary Succession ◽  
Ophiolite Emplacement

The Late Jurassic to Early Cretaceous sedimentary succession of the Neochorouda Unit lies unconformably on top of the Oreokastro ophiolites of the Vardar/Axios “suture zone” in northern Greece. This succession consists of turbidites and mass flows and provides an upper limit for ophiolite emplacement. New biostratigraphic and microfacies analysis from the clasts in the mass flows were carried out for a better understanding of the Late Jurassic to Early Cretaceous geodynamic history. Microfacies and organism content prove the onset of Late Jurassic carbonate platforms on top of a Middle to Late Jurassic nappe stack striking from the Eastern Alps to the Hellenides. Middle to Late Jurassic nappe stacking towards WNW to NW followed late Early to Middle Jurassic intra-oceanic thrusting in the Western Vardar/Axios (= Neotethys) Ocean and subsequent ophiolite obduction onto the Pelagonian Units forming a thin-skinned orogen on the lower plate. After ophiolite emplacement Kimmeridgian- Tithonian carbonate platforms sealed widespread this tectonic event. Tithonian extension due to mountain uplift resulted in partial erosion of these platforms and new extensional basins were formed. Late Tithonian to earliest Cretaceous erosion of the uplifted nappe stack including the obducted ophiolites resulted in sediment supply into the newly formed basins also east of the Pelagonian Units.

scholarly journals Ophiolite derived material as parent rocks for Late Jurassic bauxite: evidence for Tithonian unroofing in the Northern Calcareous Alps (Eastern Alps, Austria)

2021 ◽  
Author(s):  
Timotheus Martin Christoph Steiner ◽  
Hans-Jürgen Gawlick ◽  
Frank Melcher ◽  
Felix Schlagintweit
Keyword(s):  
Shallow Water ◽  
Late Jurassic ◽  
Xrd Analysis ◽  
Eastern Alps ◽  
Major And Trace Elements ◽  
Parent Material ◽  
Northern Calcareous Alps ◽  
Carbonate Platforms ◽  
Northern Calcareous ◽  
Platform Margin

AbstractIn shallow-water limestones of the Plassen Formation in the Tirolic nappe of the Northern Calcareous Alps, bauxite was formed on karstified and tilted platform margin grainstones to boundstones around the ?Kimmeridgian/Tithonian boundary, or in the Early Tithonian as proven by Protopeneroplis striata Weynschenk, Labyrinthina mirabilis Weynschenk, and Salpingoporella pygmaea Gümbel. The platform established on top of the obducted ophiolite nappe stack. The onset of unroofing at the Kimmeridgian/Tithonian boundary exposed ophiolites to weathering, forming laterites, and bauxites. The weathered ophiolitic material was shed on the tilted, emerged, and karstified platform, where the bauxite accumulated. Continued subsidence led to flooding, and a Tithonian transgressive carbonate sequence sealed the bauxites. XRD analysis of the bauxite yields a composition of mainly boehmite with hematite and some berthierine, kaolinite, and chromite. SEM analysis verified magnetite, hematite, rutile, chromite, zircon, ferropseudobrookite, ilmenite, monazite, xenotime, and garnet distributed in pisoids and within the matrix. The pisoids reach a millimeter in size and partly show cores of older, larger pisoids. The composition of the chromites indicates an ophiolitic origin. Geochemical examination using major- and trace elements points to a mafic andesitic to basaltic parent material contaminated with highly fractionated rocks from an island arc. Formation of Early Tithonian bauxites in shallow-water limestones confirms Middle to Early Late Jurassic ophiolite obduction. This was followed by uplift and unroofing of the orogen from the Kimmeridgian/Tithonian boundary onwards after a period of relative tectonic quiescence with an onset of carbonate platforms during the Kimmeridgian on top of the nappe stack and the obducted Neo-Tethys ophiolites.

scholarly journals Pre-salt rift morphology controls salt tectonics in the Campos Basin, offshore SE Brazil

2021 ◽  
Author(s):  
Francyne B. Amarante ◽  
Christopher A-L. Jackson ◽  
Leonardo M. Pichel ◽  
Claiton M. S. Scherer ◽  
Juliano Kuchle
Keyword(s):  
Hydrocarbon Exploration ◽  
Passive Margin ◽  
Salt Tectonics ◽  
Borehole Data ◽  
Temporal And Spatial Distribution ◽  
South Central ◽  
Campos Basin ◽  
Se Brazil ◽  
Gravity Driven ◽  
Base Salt

<p>Salt-bearing passive margin basins offshore SE Brazil have been and remain attractive for hydrocarbon exploration and production. In the Campos Basin, major reservoir types include post-salt turbidites, which are located in structural traps related to thin-skinned faulting above salt anticlines and rollers. Classic models of gravity-driven salt tectonics commonly depict kinematically linked zones of deformation, characterised by updip extension and downdip contraction, separated by a weakly deformed zone associated with downdip translation above a relatively smooth base-salt surface. We use 2D and 3D seismic reflection and borehole data from the south-central Campos Basin to show that this does not adequately capture the styles of salt-detached gravity-driven deformation above relict, rift-related relief. The base-salt surface is composed of elongated, broadly seaward-dipping ramps with structural relief reaching c. 2 km. These ramps define the boundary between the External High and the External Low, basement structures related to the rift tectonics. Local deformation associated with the base-salt ramps can overprint and/or influence regional, margin-scale patterns of deformation producing kinematically-variable and multiphase salt deformation. We define three domains of thin-skinned deformation: an updip extensional domain, subdivided into subdomains E1 and E2, an intermediate multiphase domain and a downdip contractional domain. The multiphase domain is composed of three types of salt structures with a hybrid extensional-contractional origin and evolution. These are: (i) contractional anticlines that were subjected to later extension and normal faulting; (ii) diapirs with passive and active growth later subjected to regional extension, developing landward-dipping normal faults on the landward flank; and, lastly, (iii) an extensional diapir that was subsequently squeezed. We argue that this multiphase style of deformation occurs as a consequence of base-salt geometry and relief creating local variations of salt flow that localize extension at the top and along the ramps, and contraction at the base. Translation and extension of salt and its overburden across major base-salt ramps resulted in three ramp syncline basins northeast of the study area, partially bounded by salt-detached listric faults. The temporal and spatial distribution and evolution of these and other key salt and overburden structures, and their relationship to base-salt relief, suggest 30 to 60 km of horizontal gravity-driven translation of salt and overburden.</p>

Controls on the evolution of passive-margin salt basins: Structure and evolution of the Salina del Bravo region, northeastern Mexico

2019 ◽  
Vol 132 (5-6) ◽  
pp. 997-1012 ◽  
Author(s):  
Michael R. Hudec ◽  
Tim P. Dooley ◽  
Frank J. Peel ◽  
Juan I. Soto
Keyword(s):  
Seismic Data ◽  
Passive Margin ◽  
Salt Tectonics ◽  
Structural Systems ◽  
Thrust Belt ◽  
Entire Region ◽  
Fold And Thrust Belt ◽  
Gravity Driven ◽  
Northeastern Mexico ◽  
Uplift History

Abstract Passive-margin salt basins tend to be much more deformed than their nonsalt equivalents, but they are by no means all the same. We used seismic data to study the Salina del Bravo region, northeast Mexico, to investigate the ways in which margin configuration and postsalt uplift history can influence passive-margin salt tectonics. The Salina del Bravo area contains four main structural systems, all of which trend NNE across the entire region. These structures are the Bravo trough, Sigsbee salt canopy, Perdido fold-and-thrust belt, and BAHA high. Gravity-driven deformation did not begin until more than 130 m.y. after salt deposition, because of buttressing against the BAHA high. We suggest that deformation was ultimately triggered in the Cenozoic by Cordilleran uplift that tilted the margin seaward and created a major sediment source terrane. Sediments shed from the uplift expelled salt seaward to form the Sigsbee canopy. At the same time, tilted and loaded sediments were translated seaward on the Louann salt until they were buttressed against the BAHA high, forming the Perdido fold-and-thrust belt. A physical model was built to test this hypothesis. The model was able to reproduce most of the major structures in the region, suggesting that the hypothesis is reasonable. The Salina del Bravo region shows how a downdip buttress can inhibit gravity-driven salt deformation in passive-margin salt basins. Furthermore, the area also shows the importance of postsalt uplift, which can destabilize a margin through a combination of tilting and sedimentation.

First records of Somalinautilus (Cephalopoda: Nautiloidea) from the Jurassic of Southern Germany – inferences for trans-provincial migrations

2020 ◽  
Vol 298 (2) ◽  
pp. 137-146
Author(s):  
Günter Schweigert
Keyword(s):  
Sea Level ◽  
Geographic Distribution ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Southern Germany ◽  
First Time ◽  
Lower Kimmeridgian ◽  
Lower Bathonian

The Late Jurassic nautiloid Somalinautilus antiquus (Dacqué, 1910), previously only known by the holotype from Lower Kimmeridgian strata of Ethiopia, is reported from the Lower Kimmeridgian (Platynota Zone) of Southern Germany. This unexpected record largely expands the known geographic distribution of this species. Another species of Somalinautilus, S. clavifer Tintant , 1994, is recorded for the first time from the Middle Jurassic (Lower Bathonian, Zigzag Zone) of Southern Germany. A short stratigraphic and palaeogeographic review of Somalinautilus occurrences is provided. Faunal migrations of nautiloids over large distances were probably triggered by sea- level highstands and/or palaeocurrents.

scholarly journals Middle and Late Jurassic radiolarians from the Neotethys suture in the Eastern Alps

2016 ◽  
Vol 91 (1) ◽  
pp. 25-72 ◽  
Author(s):  
Luis O’Dogherty ◽  
Špela Goričan ◽  
Hans-Jürgen Gawlick
Keyword(s):  
Mass Flow ◽  
Late Jurassic ◽  
Eastern Alps ◽  
Accretionary Wedge ◽  
Taxonomic Study ◽  
New Genera ◽  
Two New Species ◽  
Mass Flow Deposits ◽  
Thermal Overprint ◽  
Radiolarian Assemblages

AbstractCherty limestones, marls and radiolarites are widespread in the Hallstatt Mélange of the Northern Calcareous Alps. The mélange was formed during the Neotethyan orogeny in a series of deep-water basins that progressively developed in front of the advancing nappe front. The low thermal overprint of these rocks favors the good preservation of radiolarians (polycystines) that have been used for dating and reconstructing the Jurassic tectonostratigraphy of the area. This paper describes rich Middle–Late Jurassic radiolarian faunas from four localities in the Hallstatt Mélange near Bad Mitterndorf in Austria. Two different successions, both spanning from the Bathonian to the Oxfordian, are dated. In the first succession, the radiolarites are intercalated between or occur as matrix in mass-flow deposits originating from the accretionary wedge. The second succession is nearly 100 m thick but is devoid of mass-flow deposits and documents a continuous radiolarite deposition in greater distance from the nappe stack. Both successions are ascribed to the Sandlingalm Basin, which evolved on a relatively distal continental margin during early stages of the orogeny.The highly diverse and well-preserved radiolarian assemblages have been used for a detailed taxonomic study. Two new families are described: Minocapsidaen. fam. andXitomitridaen. fam.; six new genera are describedDoliocapsan. gen.,Crococapsan. gen.,Parvimitrellan. gen.,Xitomitran. gen.,Campanomitran. gen., andMizukidellan. gen. In addition, one new replacement name,Takemuraella(proTriversus), is introduced, the diagnoses of 6 genera are emended, and two new species are described:Hemicryptocapsa nonagintan. sp. andMizukidella mokaensisn. sp.

scholarly journals Analogue modelling of the interplay between gravity gliding and spreading across complex rift topography in the Santos Basin

2021 ◽  
Author(s):  
Leonardo Pichel ◽  
Oriol Ferrer ◽  
Christopher Jackson ◽  
Eduard Roca
Keyword(s):  
Physical Modelling ◽  
Sao Paulo ◽  
Salt Tectonics ◽  
São Paulo ◽  
Lateral Deformation ◽  
New Concepts ◽  
Gravity Driven ◽  
Competing Hypotheses ◽  
Base Salt ◽  
Structural High

The Santos Basin presents a complex and controversial evolution and distribution of salt tectonics domains. The controversies revolve mainly around the kinematically- linked Albian Gap and São Paulo Plateau. The Albian Gap is a ~450 km long and 60 km wide feature characterized by a post-Albian counter-regional rollover overlying depleted Aptian salt and in which the Albian is absent. The São Paulo Plateau is defined by a pre-salt structural high with significant base-salt topography and overlain by ~2.5 km thick salt. Another prominent feature is the Merluza Graben, a rift depocentre that underlies the southern portion of the Albian Gap and displays significant (3-4 km) of base-salt relief. Two competing hypotheses have been proposed to explain the origin and kinematics of these provinces. One invokes post- Albian extension within the Albian Gap and contraction in the Sao Paulo Plateau. The other invokes post-Albian salt expulsion in the Albian Gap and salt inflation in the São Paulo Plateau without significant lateral deformation. A recent study shows these processes contribute equally to the evolution of these domains, also demonstrating the importance of the previously neglected base-salt relief. We apply 3D physical modelling to test these new concepts and understand the interplay between laterally- variable base-salt relief, gliding and spreading on salt tectonics. Our results show a remarkably-similar salt and post-salt evolution and architecture to the Santos Basin as proposed in recent studies. They improve the understanding on the distribution and interaction of salt-related structural styles and gravity-driven processes, being also applicable to other salt-bearing margins.

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