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Molasse

Molasse refers to a thick sequence of clastic sedimentary rocks, primarily consisting of sandstones, conglomerates, and shales, deposited in foreland basins adjacent to rising mountain ranges during or after major orogenic (mountain-building) events.^[1] These sediments represent post-orogenic erosion products from the eroding orogen, accumulating as alluvial fans, fluvial systems, or shallow-marine deposits that thin and fine away from the mountain front.^[2] In contrast to the pre-orogenic flysch deposits, which form in deep geosynclinal settings, molasse signifies the transition to shallower, continental or marginal-marine environments as tectonic compression wanes.^[1] The term "molasse" originated in the context of the European Alps, where it describes the Oligo-Miocene sedimentary sequences in the North Alpine Foreland Basin, a wedge-shaped depression formed by flexural subsidence of the European plate under the load of advancing Alpine thrust sheets.^[3] This basin, spanning approximately 1,000 km from western Switzerland to eastern Austria, preserves up to 5,000 meters of sediments derived from the eroding Alps, with key formations including the Oligocene to Miocene Puchkirchen Formation (turbidites and mass-transport deposits) and coarser Upper Marine Molasse conglomerates.^[4] The Alpine molasse basin evolved in three main phases: initial deep-water turbidite deposition in the late Eocene to Oligocene, followed by organized channel systems in the early Miocene, and culminating in non-marine fluvial and lacustrine fills by the middle Miocene.^[4] Geologically, molasse basins are diagnostic of collisional tectonics, such as those in continent-continent collisions like the India-Asia event or the earlier Alpine orogeny between the African/Apulian and European plates.^[2] These basins migrate cratonward over time as thrust loading propagates, with subsidence ceasing when orogenic activity diminishes, as seen in the Swiss Molasse where deposition ended by the uppermost Serravallian stage around 11 million years ago.^[3] Economically, molasse sequences are significant for hydrocarbon exploration, hosting reservoir sands and source rocks in regions like the Alpine foreland, while their fossil-rich shales provide paleoenvironmental insights into post-orogenic landscapes.^[4]

Definition and Terminology

Definition

Molasse refers to a type of clastic sedimentary deposit consisting primarily of sandstones, shales, and conglomerates that accumulate in terrestrial or shallow marine environments adjacent to rising mountain chains during late-stage orogeny.^[5]^[6] These sediments form as erosional debris from uplifting orogenic belts is transported and deposited in proximal settings such as piedmont fans, alluvial plains, and paralic margins.^[5] In geological terms, molasse is closely associated with foreland basins, where it develops as a syntectonic to post-tectonic clastic wedge that thickens progressively toward the mountain front due to rapid sediment influx and flexural subsidence, while thinning toward the stable craton interior.^[5]^[7] This wedge-shaped accumulation records the waning phases of tectonic activity, with detritus derived from the erosion of thrust sheets and elevated terrains within the orogen.^[1]^[6] Molasse is distinguished from flysch, its pre-orogenic counterpart, by representing post-flysch deposits in shallower water or continental settings that follow the primary phase of thrust loading and deep-marine sedimentation.^[1]^[6] Whereas flysch comprises deep-marine turbidites formed in geosynclinal foredeeps prior to major collisional deformation, molasse signifies a shift to coarser, proximal clastics in foreland contexts after collision.^[1]^[5]

Historical Development

The term "molasse" derives from the Swiss German dialect, where it refers to soft, unconsolidated or poorly cemented sedimentary rocks, and was initially applied in the early 19th century to describe the friable clastic deposits in the northern Alpine foreland basin.^[5] This usage reflected the local observation of these sediments' softness and ease of erosion compared to the harder crystalline rocks of the rising Alps. The term entered formal geological literature through the work of Swiss geologist Bernhard Studer, who published Beyträge zu einer Monographie der Molasse in 1825, providing the first detailed monograph on these deposits as a distinct lithological unit in the Swiss Molasse Basin. In the mid- to late 19th century, pioneering geologists expanded on Studer's foundation by integrating molasse into broader descriptions of Alpine stratigraphy. Similarly, Austrian geologist Édouard Suess formalized molasse as a key facies in his multi-volume Das Antlitz der Erde (1883–1909), linking it to the subsidence and filling of foreland basins during the final phases of orogeny and contrasting it briefly with the deeper-water flysch facies as complementary elements in mountain-building cycles.^[8] These efforts established molasse not just as a local rock type but as a stratigraphic marker of tectonic evolution. By the mid-20th century, the term's application evolved from its Alpine origins to a global concept, applied to similar late-orogenic clastic wedges in various mountain belts worldwide, particularly following the widespread adoption of plate tectonics theory in the 1960s and 1970s. This shift emphasized molasse's role in recording flexural subsidence and sediment dispersal in foreland settings driven by lithospheric loading from collisional tectonics, transforming it into a tectofacies indicative of orogenic maturation rather than merely a regional lithology.^[5]

Geological Formation

Foreland Basin Context

Foreland basins, where molasse deposits accumulate, form primarily through flexural subsidence of the continental lithosphere induced by the loading of an advancing orogenic wedge along convergent plate margins.^[9] This process creates peripheral foreland basins adjacent to the thrust belt, characterized by a wedge-shaped subsidence profile that accommodates sediment infill, with maximum depth occurring near the orogenic front due to the distributed load of thrust sheets and associated topography.^[9] The evolution of these basins progresses through distinct stages driven by ongoing tectonic convergence. Initially, in the underfilled stage, deeper marine conditions prevail, leading to the deposition of fine-grained flysch sediments in the foredeep as the basin accommodates limited sediment supply relative to subsidence rates.^[10] As convergence continues and the orogenic wedge propagates forward, the basin transitions to an overfilled stage, where uplift in the hinterland exposes coarser sediments, increasing supply and shifting deposition to shallower marine or continental molasse facies that prograde across the basin.^[10] Thrust belt propagation exerts primary control on basin geometry by migrating the locus of maximum subsidence outward, while isostatic rebound from erosion and unloading modulates subsidence rates, often resulting in decelerating patterns that influence the overall accommodation space.^[11] These dynamics ensure that foreland basin architecture reflects the balance between orogenic loading and lithospheric response, with propagation rates determining the lateral extent and rebound contributing to episodic variations in subsidence.^[11]

Sedimentation Mechanisms

Sedimentation in molasse basins primarily involves the erosion of sediments from actively rising mountain fronts, where tectonic uplift exposes crystalline and sedimentary rocks to rapid denudation. These eroded materials, predominantly coarse clastics such as gravels and sands, are then transported into the adjacent foreland basin through a network of fluvial, alluvial, and deltaic systems. Fluvial systems dominate in the proximal zones, channeling high-energy discharges from the orogen, while alluvial fans form at the mountain-basin interface, distributing debris via sheetfloods and braided streams; further basinward, deltaic systems prograde into marine or lacustrine environments, sorting and depositing sediments in lobate patterns.^[12]^[4] This transport culminates in progradational sedimentation, where sediments advance basinward, building thick clastic wedges that thicken toward the orogen. Proximal facies near the mountain front consist of coarse-grained conglomerates and sandstones deposited in high-gradient, unstable environments, often exhibiting growth strata that record syntectonic deformation. Distally, finer-grained sands, silts, and muds accumulate in lower-energy settings, such as floodplains or shallow marine shelves, forming a lateral transition that reflects decreasing transport energy and increasing subsidence influence. In the Alpine Molasse Basin, for instance, the Puchkirchen Formation exemplifies this wedge geometry, with turbidite channels and mass transport deposits prograding from the Eastern Alps over thicknesses exceeding 2,500 meters.^[12]^[4] Deposition rates in molasse basins are modulated by eustatic sea-level fluctuations and climatic variations, which interact to produce cyclic sequences in shallow marine realms. During sea-level highstands, increased accommodation space allows finer sediments to dominate distal areas, fostering transgressive deposits like offshore sands; conversely, lowstands enhance progradation of coarse clastics via exposed shelves. Climatic shifts, such as aridification or pluvial episodes, alter rainfall and vegetation cover, thereby influencing erosion efficiency and sediment yield— for example, reduced flux during humid phases can lead to underfilled basins and marine incursions. In the Swiss Molasse, the Burdigalian transgression around 20 Ma illustrates this, where eustatic rise combined with tectonic subsidence generated wave- and tide-dominated cycles, with sediment supply dropping from 25,000 km³/Ma to 15,000 km³/Ma due to drainage reorganization.^[13]^[12]

Characteristics

Lithological Composition

Molasse deposits are predominantly composed of immature, poorly sorted clastic sediments, including sandstones, conglomerates, and shales, derived from proximal orogenic sources such as rising mountain belts.^[4]^[14] These sediments reflect rapid erosion and short transport distances, resulting in angular grains and a mix of grain sizes within individual beds. Conglomerates often feature matrix-supported pebbles from metamorphic and igneous terrains, while shales and mudstones form finer-grained intervals interspersed among coarser units.^[4] The composition of sandstones in molasse sequences varies depending on the provenance of the orogen but often includes significant feldspar and lithic fragments alongside quartz grains, indicating derivation from granitic, metamorphic, and sedimentary basement rocks. In the Alpine molasse, sandstones are typically arkosic, characterized by high contents of feldspar (often exceeding 25%).^[15] Framework compositions vary spatially and temporally but consistently show first-cycle detritus with unstable minerals like potassium feldspar and rock fragments from low- to high-grade metamorphics. For example, in the Himalayan Siwalik Group, sandstones are more commonly sublitharenites or lithic arenites with lower feldspar content.^[16]^[17] Cementation is variable, with calcareous cements common in marine-influenced facies and siliceous cements dominating in more continental settings, influencing porosity and diagenetic evolution.^[15]^[14] Fossil content in molasse deposits often includes terrestrial fauna such as mammals, reptiles, and plants in continental facies, alongside shallow marine assemblages like foraminifera, mollusks, and echinoids in coastal or sublittoral environments, providing evidence of the depositional settings.^[18] These biotic remains are typically sparse and fragmented due to the high-energy, proximal depositional regimes. Facies variations in lithology underscore transitions between fluvial, deltaic, and marine influences, as detailed in stratigraphic analyses.^[18]

Stratigraphic Architecture

Molasse sequences in foreland basins typically exhibit a characteristic vertical organization characterized by coarsening- and thickening-upward successions, transitioning from fine-grained distal deposits such as shales and sandstones to coarse-grained proximal conglomerates and sandstones derived from the adjacent orogenic belt.^[19] These sequences reflect progressive progradation of alluvial fans and fluvial systems into the basin during the post-orogenic phase, with sediment supply increasing as tectonic uplift exposes coarser source rocks.^[21] Laterally, the architecture forms wedge-shaped geometries that thicken toward the orogen, achieving thicknesses of several kilometers in proximal zones, as seen in the North Alpine Foreland Basin where molasse deposits reach up to 3.6 km.^[21] Unconformities within molasse stratigraphy often delineate distinct tectonic pulses, representing episodes of uplift, erosion, and renewed subsidence linked to orogenic thrusting.^[19] These surfaces commonly show onlap relationships onto underlying flysch deposits or older basement rocks, such as Mesozoic carbonates in the Alpine system, indicating basinward migration of the depocenter and flexural subsidence.^[21]^[12] In the proximal foredeep, such unconformities may exhibit angular discordance due to thrust-related deformation, while distal onlap patterns record the passage of the forebulge.^[12] Post-depositional diagenetic processes significantly alter the stratigraphic units of molasse, particularly through mechanical and chemical compaction, which reduce intergranular porosity from initial values of around 40% to as low as 2-8% at depths exceeding 3 km.^[22] Cementation, often involving saddle dolomite or calcite precipitates from burial fluids, further occludes pore spaces, enhancing lithological heterogeneity and influencing fluid flow properties within the sequences.^[22] These features are prominent in dolostone intervals, where progressive burial drives pressure solution and stylolitization.^[22]

Types

Marine Molasse

Marine molasse deposits form in shallow marine environments within foreland basins, particularly in coastal and deltaic settings where tidal processes play a dominant role in sediment distribution. These settings include estuarine incised valley fills, tidal inlets, delta mouth bars, and tidal flat channels, often exhibiting progradational or aggradational stacking patterns with thicknesses ranging from tens to hundreds of meters. Tidal influences are evident in sedimentary structures such as reactivation surfaces, clay drapes, and bipolar paleocurrents, reflecting high-energy deposition in macrotidal to mesotidal regimes.^[23] Characteristic lithologies include cross-bedded sandstones, featuring trough cross-bedding, herringbone structures, and epsilon cross-stratification formed by tidal dunes and lateral accretion in channels and bars. Shelly limestones occur as bioclastic grainstones, wackestones, and shell coquinas, often concentrated in offshore or estuary mouth barriers, with examples including bivalve- and echinoid-rich beds up to 1 meter thick. These features indicate dynamic shallow marine conditions with wave-ripple lamination and bioturbation by traces like Thalassinoides and Ophiomorpha. In the Upper Marine Molasse, transgressive-regressive cycles organize these deposits into sequences, with five base-level cycles forming two major transgressive-regressive units during the Burdigalian-Ottnangian, leading to parasequences (0.5-15 meters thick) bounded by flooding surfaces and marked by fining- or coarsening-upward trends.^[24]^[23]^[25]^[26] Compared to continental molasse, marine variants display higher sediment sorting due to prolonged tidal and wave reworking, resulting in well-sorted sands in deltaic and estuarine facies. Abundant marine fossils, such as selachian teeth (Carcharias, Dasyatis), bivalves (Ostrea sp., Pecten sp.), and foraminifera, distinguish these deposits, reflecting diverse shallow marine ecosystems. In restricted basins connected to the Paratethys, intercalated evaporites like gypsum and halite layers occur, formed during episodes of reduced marine connectivity and increased aridity, contrasting with the fluvial-alluvial dominance and terrestrial biota in continental equivalents.^[23]^[24]^[27]

Continental Molasse

Continental molasse refers to the non-marine counterpart of molasse deposits, formed in terrestrial environments such as foreland basins and intermontane depressions adjacent to rising orogenic belts. These sediments primarily accumulate through the action of alluvial fans, rivers, and lakes, which transport and deposit coarse conglomerates derived from nearby mountain erosion—with clasts ranging from angular in proximal settings to rounded in distal fluvial environments—alongside finer beds consisting of sandstones and mudstones, often colored by iron oxides in some regions. In the North Alpine Foreland Basin, for instance, the Upper Freshwater Molasse (OSM) exhibits a southward progression from distal braided rivers and lakes to proximal alluvial fans, with conglomerates featuring well-rounded clasts from Alpine sources like greenstones and radiolarites.^[25]^[28] Paleosols within these continental sequences serve as key indicators of paleoclimate, reflecting shifts from arid to humid conditions through features like leaching, mottling, and pseudogley development, which suggest moderate to high precipitation rates and groundwater influence during the Miocene. Coal seams, often interbedded in finer-grained, organic-rich layers of lacustrine and palustrine settings, further point to periods of wetter, swampy environments conducive to peat accumulation, as seen in the OSM of the Jura region where thin lignite horizons occur amid siltstones and marls. These paleoenvironmental signals highlight cyclical wet-dry variations, with stable isotope data from paleosols indicating warm-season temperatures exceeding 24°C and annual rainfall up to 1350 mm during the Miocene Climatic Optimum.^[29]^[25]^[30] Compared to marine molasse equivalents, continental deposits form thicker, more proximal accumulations near the orogen, with rapid lateral facies changes from coarse conglomeratic fans to finer fluvial and lacustrine sands and muds over short distances, often exceeding 200 m in thickness in basin margins like the Esparron syncline. These variations result from high sediment supply and localized subsidence, leading to wedge-shaped stratigraphic geometries that thin northward.^[28]^[31]

Examples

Alpine Molasse Basin

The Alpine Molasse Basin, situated north of the European Alps and extending across parts of Switzerland, Germany, Austria, and eastern France, serves as the archetypal foreland basin for molasse sedimentation, formed in response to the collisional tectonics of the Alpine orogeny. Oligocene to Miocene deposits within this basin accumulate to thicknesses exceeding 5 km, primarily recording the flexural response of the underlying European lithosphere to loading by southward-advancing Alpine thrust sheets. These sediments, largely clastic in nature, were predominantly sourced from the progressive erosion of the uplifting Alpine orogen, with detrital contributions reflecting the exhumation of metamorphic and sedimentary units from the central and eastern Alps.^[32]^[33] The stratigraphic succession is classically divided into the Lower Marine Molasse (UMM), Lower Freshwater Molasse (USM), Upper Marine Molasse (OMM), and Upper Freshwater Molasse (OSM), marking repeated marine incursions and continental overfills as the basin evolved from deep-marine to shallow-marine and finally terrestrial depositional environments. The UMM, spanning the late Oligocene (Chattian) to early Miocene (Aquitanian), comprises fine-grained marine sandstones, marls, and shales deposited in a subsiding piggyback basin setting during initial flexural deepening. The USM (early Miocene, Aquitanian to Burdigalian) represents an initial continental phase with fluvial and lacustrine deposits. The OMM, deposited during the early to middle Miocene (Burdigalian to Langhian), features coarser-grained sediments including cross-bedded, quartz-rich sandstones indicating deltaic and shallow-marine progradation driven by heightened erosion in the Alps. Transitioning upward, the OSM (middle to late Miocene, Serravallian to Tortonian) records the final continental phase, dominated by fluvial conglomerates, sandstones, and overbank mudstones; a key unit is the Nagelfluh Conglomerate, composed of rounded, calcite-cemented pebbles derived from Alpine ortho- and paragneisses, signifying alluvial fan and river systems draining the orogen.^[33]^[24]^[34] Basin evolution was intrinsically coupled to the dynamics of the Alpine orogeny, with phases of rapid thrust propagation and nappe emplacement inducing episodic flexural subsidence that accommodated the influx of erosional debris. Subsidence rates in proximal sectors reached up to 0.5 mm/year during Miocene peak activity, varying spatially with distance from the orogenic wedge and temporally with changes in plate convergence. This subsidence pattern, combined with eustatic sea-level fluctuations, controlled the marine-to-continental shift, culminating in basin inversion and partial erosion by the late Miocene as orogenic loading waned.^[35]^[36]

Other Global Occurrences

Molasse deposits occur widely beyond the Alpine orogen, providing comparative insights into post-collisional sedimentation in diverse tectonic settings. In the Himalayan foreland basin, the Siwalik Group exemplifies Miocene-Pliocene continental molasse, comprising fluvial sandstones, siltstones, mudstones, and conglomerates deposited in channels, floodplains, and piedmont environments.^[37] These sediments, spanning approximately 13 to 2.5 million years ago, were primarily sourced from the eroding Himalayan highlands via ancient precursors to the Indus and Ganges river systems, recording progressive tectonic uplift and denudation.^[38] The group exhibits a tripartite division into Lower (older, finer-grained), Middle, and Upper (younger, coarser) Siwalik subunits, with northward-thickening wedges reflecting flexural loading of the Indian plate.^[39] Post-orogenic Permo-Carboniferous basins in the Appalachian orogen host molasse equivalents, particularly in the Maritimes Basin of Atlantic Canada, where coal-bearing measures fill fault-bounded depocenters. These Late Carboniferous to Early Permian deposits include alluvial redbeds, fluvial sandstones, and coal seams formed in terrestrial to marginal-marine settings following the Acadian orogeny.^[40] In the central Appalachian Basin, Late Pennsylvanian clastic wedges from the eroding highlands transition to alluvial plains, dominated by coarsening-upward siliciclastics and thin coal layers, marking the final infilling of the geosyncline.^[41] In the Indo-Australian collision zone, the Celebes Molasse of Sulawesi, Indonesia, represents Neogene post-orogenic sedimentation initiated by Early Miocene microcontinental collisions. This sequence, spanning the Miocene to Pliocene with unconformities at circa 23 Ma, 15 Ma, and 5.3 Ma, consists of conglomerates, sandstones, marls, shales, and limestones derived from ophiolitic and volcanic sources.^[42] Depositional environments range from shallow marine reefs and shelves to deep-water turbidites and submarine fans, reflecting episodic uplift, extension, and subsidence at the Eurasian-Australian plate boundary.^[43]

Significance

Tectonic and Paleoenvironmental Insights

Molasse deposits serve as critical archives for understanding orogenic dynamics through provenance analysis, which elucidates the uplift and erosion history of adjacent mountain belts. Detrital zircon geochronology, employing U-Pb dating via laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), identifies age populations in zircon grains to trace sediment sources from the eroding hinterland. In the North Alpine Foreland Basin, Eocene to Oligocene sediments (35–22.5 Ma) predominantly feature zircon ages of 300–370 Ma, 380–490 Ma, and 500–710 Ma, reflecting unroofing of Austroalpine and Penninic units, while Early Miocene samples (21–13.5 Ma) show a dominance of 252–300 Ma ages indicative of exhumation in the Variscan-aged Lepontine dome.^[44] This provenance shift around 21 Ma signals tectonic extension and accelerated uplift-erosion in the Central Alps, with sediment flux responding to orogenic wedge growth.^[44] Comparable studies in the Western Alps Molasse Basin reveal zircon age spectra with peaks at 525–650 Ma (late Neoproterozoic–early Cambrian), 375–525 Ma (pre-Variscan), 299–375 Ma (Variscan), and 252–299 Ma (Permian), sourcing from External Massifs, Austroalpine units, and minor Valaisan contributions.^[45] Rare Cretaceous zircons (e.g., 100–130 Ma) further highlight middle Miocene exhumation of subalpine fold-thrust belts.^[45] Such analyses, often integrated with Hf isotopes and heavy mineral assemblages, demonstrate how molasse provenance records progressive unroofing, with increasing sediment grain size and flux correlating to enhanced tectonic denudation rates in the hinterland.^[44] Paleoclimate reconstructions from molasse sedimentary structures and lithofacies provide insights into depositional environments influenced by orogenic climate feedbacks. Red beds, prevalent in continental molasse sequences, form through pedogenic processes under oxidizing conditions, where hematite pigmentation arises from iron oxidation in well-drained soils with limited organic matter.^[46] These deposits, including fine-grained overbank silts and calcretes, indicate semi-arid to arid climates with seasonal precipitation, as limited weathering preserves primary Fe-bearing silicates for post-depositional reddening. In post-Variscan molasse basins like the Pennsylvanian–Permian Mulargia–Escalaplano Basin (Sardinia), red bed facies with fluvial channels and playa evaporites reflect a hot-arid regime during orogenic collapse, marked by weak unconformities and low-energy depositional structures.^[47] The timing of tectonic events is constrained by unconformities in molasse stratigraphy, which mark episodes of uplift, erosion, and basin subsidence shifts. These hiatuses, dated through biostratigraphy, magnetostratigraphy, and Sr chemostratigraphy, correlate with thrust front propagation in the orogen. In the Miocene molasse of the western Alps, angular unconformities (e.g., at ~17.35 Ma) delineate eastward-to-westward thrust migration across fault zones from ~18 Ma to 12 Ma, with depocenter relocation reflecting ~6.3–6.7 km of shortening at rates of 1.2 km/Myr and propagation speeds of ~2.9 km/Myr.^[48] Growth strata overlying these unconformities document syntectonic sedimentation during Burdigalian to Serravallian compression. In the Subalpine Molasse thrust belt, regional unconformities separate megasequences from the Oligocene to Miocene, with major activity from 21 Ma (Eggenburgian) to 12 Ma (Badenian), involving break-back thrusting and southward migration at variable rates tied to ~45 km total shortening.^[49] These records quantify orogenic advance velocities and link foreland basin evolution to critical wedge mechanics.

Economic and Scientific Value

Molasse basins hold economic importance primarily through their hydrocarbon potential, serving as reservoirs and source rocks in foreland settings. In the Alpine foreland, such as the Bavarian Molasse Basin, Tertiary sands and Jurassic formations host oil and gas accumulations, with discoveries like the Monchsrot oil field demonstrating viable production from Middle Jurassic reservoirs beneath Tertiary sequences.^[50] Basin inversion processes in these settings can form structural traps essential for petroleum accumulation.^[51] Scientifically, molasse sequences contribute to assessments of seismic hazards, particularly in regions with ongoing tectonic activity or induced seismicity from resource extraction. Studies of the crustal stress field in the Molasse Basin aid in modeling induced seismic risks, as seen in the Bavarian sector where stress orientations inform hazard evaluation.^[52] Additionally, their stratigraphic records support broader research into tectonic evolution and paleoenvironmental changes.

References

[1]
Flysch and molasse | U.S. Geological Survey - USGS.gov
The waste products that accumulate as a deposit flanking mountains and built in part of the deformed flysch make up the molasse. In field practice the groups ...
[2]
[PDF] Chapter 11 SEDIMENTARY BASINS
1.1 The official definition of a sedimentary basin is: a ... The classic molasse facies, thick nonmarine conglomerates, is deposited in foreland basins.<|control11|><|separator|>
[3]
Alpine Geology
molasse: 1.a sedimentary sequence deposited during the Miocene period in southern Germany, subsequent to the rising of the Alps; composed primarily of soft, ...
[4]
[PDF] THE EARLY EVOLUTION OF THE MOLASSE FORELAND BASIN ...
The present Molasse basin is a narrow remnant of the original basin, and up to 5000 m of sediments are folded and thrusted as parts of the Alpine fold-and- ...
[5]
Meaning of Molasse | GSA Bulletin - GeoScienceWorld
Jun 1, 2017 · Discussion of the evolution of mountain belts is facilitated by use of the term “molasse” for recurring late orogenic clastic wedges ...
[6]
Classic swiss clastics (flysch and molasse) The alpine connection
Flysch and molasse are orogenic clastics related to Alpine mountain building. Flysch is pre-collision, while molasse is post-collision, and flysch is often ...Missing: definition distinction
[7]
Molasse of Foreland Basins: The Elusive Model: Abstract
Molasse is typically defined as a syntectonic to post-tectonic wedge of nonmarine to shallow marine sediment filling a foreland basin that is floored by ...
[8]
The voyage of the 'Guyot Stone' from the Swiss Alps to Neuchâtel ...
Jul 30, 2021 · In 1890, former students of Arnold Guyot at the University of Neuchàtel dedicated a 'large glacial boulder from Neuchâtel' to his memory.
[9]
[PDF] Eduard Suess and Global Tectonics: An Illustrated 'Short Guide'
Eduard Suess (1831-1914) is one of the most widely misunderstood and miscited authors in the history of tectonics mainly because of the nature of his writings ...
[10]
None
### Summary of Foreland Basin Formation and Molasse Context
[11]
Flysch to molasse transition in peripheral foreland basins
Jun 2, 2017 · During progressive plate convergence, peripheral foreland basins develop from an underfilled flysch stage to a filled or overfilled molasse ...
[12]
Foreland basin subsidence driven by topographic growth versus ...
Mar 1, 2012 · Our analysis combines three elements: (1) a growing thrust wedge, modeled as a distributed load with a self-similar triangular cross section ...
[13]
[PDF] Foreland basin systems revisited: variations in response to tectonic ...
ics, orogenic loading, and flexural subsidence in foreland basins. Flexural loading of an ideal elastic plate results in a rapidly damped sinusoidal profile.
[14]
Tectonic processes, variations in sediment flux, and eustatic sea ...
Nov 19, 2019 · ... Molasse basin through the buckling of the foreland plate at a smaller scale. We suggest that this influenced the water depths within the basin ...
[15]
[PDF] Classic swiss clastics (flysch and molasse) The alpine connection
Mar 24, 2015 · ABSTRACT. - Flysch and molasse are discussed in the light of alpine geodynamics. They are pre-collision and post-collision orogenic.Missing: definition | Show results with:definition
[16]
Petrography and chemistry of sandstones from the Swiss Molasse ...
Jul 16, 2003 · The aim of this study is (1) to provide a comprehensive view of the compositional evolution of proximal sandstones from the Swiss Molasse Basin ...
[17]
[PDF] Stratigraphy and facies of the Upper Marine Molasse (OMM ... - CORE
examined for their mineralogical composition, fossil content and structural character. ... interpretation as terrestrial deposits (USM) by VOLLMEYER & ZIEGLER ( ...
[18]
[PDF] Two-phase stratigraphie model of foreland-basin sequences
This two-phase model of foreland sedimentation predicts that coarsening-upward sequences in the proximal and distal parts of the basin have reciprocal ...Missing: architecture | Show results with:architecture
[19]
The Swiss Alps and their peripheral foreland basin: Stratigraphic ...
Apr 30, 2002 · [25] A comparison of the events in the east and west reveals similar ages for the Flysch and Molasse stages of the foreland basin evolution.
[20]
Effects of progressive burial on matrix porosity and permeability of ...
To provide more insight into compaction processes, the present study examines the effects of progressive burial on two dolomitized mudstone units belonging to ...Research Paper · 5. Results · 6. Discussion
[21]
[PDF] SEDIMENTOLOGY AND SEQUENCE STRATIGRAPHY OF TIDAL ...
Sandstone bodies of the Marine Molasse include: (i) estuarine incised valley fills; (ii) tidal inlets; (iii) delta mouth bars, and (iv) tidal flat channels. ...
[22]
Stratigraphy and palaeoecology of the Upper Marine Molasse (OMM ...
Aug 26, 2016 · The coarse clastic debris originated from the Napf fan delta in the southwest, which drained the central Swiss Alps during the Early Miocene ( ...
[23]
Sedimentology of the Jura Molasse: Miocene tidal clastics and ...
Jul 28, 2023 · The bioturbated sands seen above this from 190 to 95 m could be found in a range of shallow marine environments, but in this case are ...
[24]
Sequence stratigraphy of an alluvial fan-delta in the Upper Marine ...
Aug 7, 2025 · We suggest five base level cycles forming two transgressive-regressive sequences for the Upper Marine Molasse. The lower sequence (base level ...
[25]
The legacy of the Tethys Ocean: Anoxic seas, evaporitic basins, and ...
At the end of the Eocene, the demise of the Tethys Ocean led to the formation of one of the largest anoxic seas in the last 50 million years of Earth history.Missing: differences | Show results with:differences
[26]
The peri-Alpine Paleogene Red Molasse of southeastern France
Oct 17, 2025 · Here, MR1 deposits are represented by fluvial fan deposits prograding to the west, but have a more proximal character than at Esparron. In this ...
[27]
Paleosol-catena of the fluvial environment of the Upper Freshwater...
Leaching, bleaching, and mottling of paleosols indicate moderate to high precipitation rates. Pseudogley-paleosols additionally point to an intensive ...Missing: climate | Show results with:climate
[28]
Middle Miocene long-term continental temperature change in and ...
May 14, 2020 · The NAFB paleosol T(Δ47) shows two warming peaks (>30 °C) that are bracketing the MCO with warm season temperatures typically >24 °C. The onset ...
[29]
Controls of erosional denudation in the orogen on foreland basin ...
Oct 1, 1997 · Crustal thickening in this part of the orogen is reflected in the proximal Molasse by sedimentary cycles characterized by an increase in the ...
[30]
Foreland basin evolution around the western Alpine Are
Younger basin stratigraphy (Oligocene-Miocene) is over 5kin thick and relatively undeformed. (plateau molasse) except within the imbricated. Subalpine Molasse ...
[31]
Molasse & North Alpine Foreland Basin - Palaeontology - LMU Munich
Kuhlemann, J., Kempf, O. (2002). Post-Eocene evolution of the North Alpine Foreland Basin and its response to Alpine tectonics. – Sediment Geol 152, 45–78.<|control11|><|separator|>
[32]
The Development of the Rhine - jstor
which now form the conglomerate 'Nagelfluh' and give rise to mountains in ... molasse' (Burdigalian and Helvetian) as the deepening continued, and the.<|control11|><|separator|>
[33]
Possible environmental effects on the evolution of the Alps-Molasse ...
As a result, the Molasse basin subsided at high rates causing the topographic axis to shift to the proxi- mal basin border and alluvial fans to establish at the ...<|control11|><|separator|>
[34]
The last erosional stage of the Molasse Basin and the Alps
Aug 6, 2025 · We consider that erosion of the Molasse Basin occurred in response to a shift in the drainage direction rather than because of a change in ...
[35]
Siwalik plant megafossil diversity in the Eastern Himalayas: A review
In the Southeastern Himalaya, the Siwalik Group was deposited between 13 and 2.5 Ma, with the transition between the lower and middle Siwaliks dated at about ...
[36]
Isotopic Preservation of Himalayan/Tibetan Uplift, Denudation, and ...
The Siwalik Group (predominantly fluvial sandstones and siltstones), is widespread throughout the foothills of the Himalaya from Pakistan to eastern India.
[37]
[PDF] Dynamic fluvial systems and gravel progradation in the Himalayan ...
Mar 1, 2000 · The Siwalik strata tradi- tionally have a tripartite division into the progres- sively younger Lower, Middle, and Upper Siwalik. Formations ( ...
[38]
(PDF) Chapter 6 The Maritimes Basin of Atlantic Canada
Aug 10, 2025 · The topmost three formations are alluvial redbeds. Fault-bounded basins with coal measures of similar age cover large areas below Prince ...
[39]
[PDF] Carboniferous Geology and Biostratigraphy of the Appalachian Basin
This document covers the Carboniferous geology and biostratigraphy of the Appalachian Basin, including the Black Warrior Basin, and the Pennsylvanian of the ...
[40]
The Celebes Molasse: A revised Neogene stratigraphy for Sulawesi ...
post-dating ophiolite emplacement in SE Sulawesi following collision. The Lower Miocene megasequence includes shallow to deep marine. sediments that were ...
[41]
[PDF] 4. Neogene Tectonic Evolution of the Celebes-Sulu Basins
At the end of early Miocene time the southern margin of the Celebes-Sulu block collided with the Banda block in central Sulawesi. This collision induced rapid ...
[42]
Tectonic exhumation of the Central Alps recorded by detrital zircon ...
Nov 23, 2020 · Eocene to Miocene sedimentary strata of the Northern Alpine Molasse Basin in Switzerland are well studied, yet they lack robust ...Missing: etymology | Show results with:etymology
[43]
https://www-odp.tamu.edu/publications/124_SR/VOLUME/CHAPTERS/sr124_04.pdf
[44]
Pedogenic continental red beds: How, why and when red? Redox ...
Nov 15, 2024 · Continental red beds are coloured by secondary Fe(III)-oxy-hydroxides (mainly hematite) which makes them excellent archives of ancient ...
[45]
Sedimentary evolution of the Pennsylvanian–Permian Mulargia ...
Jun 15, 2022 · It includes red bed coarse- to fine-grained sediments deposited under a dry to hot climate (microflora, Pittau et al. Reference Pittau, Del Rio ...
[46]
Chronology of thrust propagation from an updated tectono-sedimentary framework of the Miocene molasse (western Alps)
Summary of each segment:
[47]
Geometry, amount, and sequence of thrusting in the Subalpine ...
Dec 5, 2014 · In this paper we review the structure of the most external thrust belt of the Alps between the Rhein valley and Salzburg based on a new tectonic map.