Section 15 M. Seceda Upper Permian Italy: Permian, Italy

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
unclassified
Pretricolpipollenites bharadwaji microspore
Gigantosporites aletoides microspore
Gardenasporites leonardi microspore
Jugasporites delasaucei microspore
Pallidosporites minimus microspore
Paravesicaspora splendens microspore
Striatoabieites angulistriatus microspore
Scutasporites unicus microspore
Scheuringipollenites ovatus microspore
Perisaccus granulosus microspore
Leiosphaerids X marine palyn
Vesicaspora schemeli microspore
Lycopodiopsida - Selaginellales
Densoisporites holospongia microspore
unclassified
Strotersporites richteri microspore
Lunatisporites alatus microspore
Lunatisporites noviaulensis microspore
Falcisporites spp. microspore
Sulcatisporites interpositus microspore Leschik 1955
Coniferales - Podocarpaceae
Platysaccus sp. microspore Naumova 1954
unclassified
Nuskoisporites dulhuntyi microspore
Equisetopsida - Cupressales
Inaperturopollenites nebulosus microspore
unclassified
cf. Crucisaccites sp. microspore Lele and Maithy 1964
Circumstriatites spp. microspore
nomen nudum belonging to Plantae
Lueckisporites microgranulatus microspore
Lueckisporites virkkiae microspore
Lueckisporites sp. a microspore Potonié and Klaus
Lueckisporites parvus microspore
Corisaccites sp. microspore Venkatachala and Kar
Labiisporites granulatus microspore
Algae - Zygnemataceae
Tetraporina sp. microspore Naumova 1950
unclassified
cf. Sahnites turingiacus microspore
Acanthotriletes sp. microspore Potonié and Kremp 1954
Ginkgoopsida - Ephedrales
Ephedripites sp. microspore Bolkhovitina and Potonié 1958
unclassified
Vittatina costabilis microspore
Vittatina ovalis microspore
Guttulapollenites sp. microspore Goubin
Protohaploxypinus limpidus microspore
Protohaploxypinus sp. microspore Samoilovitch 1953
Protohaploxypinus microcorpus microspore
Klausipollenites schaubergeri microspore
Potonieisporites sp. microspore Bharadwaj
Fungi X
Cells and spores
see common names

Geography
Country:Italy
Coordinates: 43.0° North, 12.2° East (view map)
Paleocoordinates:3.6° South, 24.1° East
Basis of coordinate:based on nearby landmark
Time
Period:Permian
10 m.y. bin:Permian 1-4
*Period:Late/Upper Permian
Key time interval:Permian
Age range of interval:298.90000 - 251.90200 m.y. ago
* legacy (obsolete) database fields
Stratigraphy
Stratigraphy comments: The Upper Permian deposits of the eastern Southern Alps display the typical features of early rift successions: onset of sedimentation after a long period of subaerial erosion, and upward fining trend from red beds, trough evaporates to marine carbonates, with backstepping pattern of component sequences. These are though to be part of second order Upper Permian-Scythian rift-related sequence.
Lithology and environment
Lithology description: Val Gardena sandstone and the Bellerophon Formation ( Upper Permian ) in the Dolomites and Carnia show an overall transgressive trend and record the transition from continental red-bed to marine sedimentation in an extensional tectonic setting. The eastward progression of the Bellephron transgression resulted in the diachrony of the boundary between Val Gardena Sandstone and Bellephron Formation. The transgression was actually punctuated by a series of cyclical pulsations, which resulted in complex interfingering of terrigenous, evaporitic and carbonate deposits and in the subdivisions of the sedimentary succession into a number of sequences. The various vacies are essentially contempareous and follow one another along a paleoslope gently inclined towards the east, so that the red beds grade basinwards (i.e. eastwards ) through sabkha and lagoonal deposits into marine carbonates. In the area between the Adige Valley and the Karawanken Mountains the Bellephron Formation ranges in thickness from 0 ( westernmost area ) to 360 m. The Bellephron Formation consists of a very complex array of lithofacies, its depositional area may be subdivided from west to east into 1) Coastal belt characterized by sabkha-type sediments interfingering with terminal fan deposits. 2) Hypersaline lagoon or restricted inner shelf, characterized by evaporates and carbonate deposits. 3) An inner carbonate shelf. The transition from coastal to offshore environments was extremely gradual, suggesting a very gentle depositional gradient, and resulting in sedimentation particularly sensitive to environmental changes. The Bellephron Formation is sharply or transitional overlain by a regional widespread member between different sections, in the absence of outcrop continuity. The Upper Permian succession of the Southern Alps displays the typical features of early rift successions. The overall pattern is that of transgressive, backstepping and onlapping arrangements of deposits suggesting a background of regional subsidence. Sedimentation started in graben-like depressions, and was initially fed by local sources. Later as a result of regional subsidence and morphogenetic evolution of the basin, the original depositional areas joined, ultimately resulting in an unified and increasingly expanded depression with sedimentary fill progressively onlapping the margins of the basin. Basin opening is recorded by coarse scree and alluvial fan deposits. The thickness of Val Gardena Sandstone in the study area ranges from zero ( Trento area ) to more than 500 m ( Comelico area ). In the Dolomites and Carnia, the red beds grade into the evaporitic and carbonate deposits of the Bellerophon Formation. The transgression progressively encroached on western areas. A structural high between the Adige Valley and the Giudicarie Line prevented the westward progression of the transgression, so that the Bellerophron Formation appears on a broad scale as a sedimentary wedge pinching out westwards. The Bellephron Formation is overlain by the Lombardian Unit ( continental sediment ). Val Gardena Sandstone:Alluvial fan facies Val Gardena Sandstone:Very poorly sorted and structureless sandy-gravelly red brown mudstone. Shows diamitic like textures, in which a variable amounts of granules and small pebbles, and rarely sparse sub angular to sub rounded pebbles or cobbles, float in a matrix of very poorly sorted mixture of sand, silt and clay. Bed thickness averages 100 cm and ranges 25-210 cm. Internal bedding and clast imbrication are lacking. Normal grading sometimes occurs in the coarser-grained varieties. Individual beds usually have flat, non-erosional basal contacts. Beds are locally capped by fine clast-supported conglomerates, either one clast thick or displaying a crude planar lamination in the finer grained varieties. Crudely to distinctly parallel stratified gravel and gravely sand. This facies ranges from clast-supported gravel, in which a crude stratification is shown by variations in clast size and concentration, to gravely sand in which an internal stratification is highlighted by the interbedding, on a centimetre or decimetre scale, of medium to coarse sandstone bands and rows of granules or pebbles and rarely cobbles, or less commonly by the alternation of fine gravel bands and pebble rows. Average thickness 55 cm, range 10-200 cm. Clasts in conglomerates may show a distinct imbrication and may be in mutual contact or supported by a sand matrix. Outside clasts in the pebblecobble size range and mudstone clasts locally occur. Grading is generally absent, but fining upwards trends have been observed. Structureless or normally graded coarse to medium sandstone. Thickness averages 50 cm and ranges 6-160 cm. Normally graded varieties may grade upwards into finely sandy siltstone. The matrix of coarser varieties may contain a certain amount of silt. Clay chips locally present. Beds may be distinguished on the basis of geometry into sheet-like or lenticular, the latter with erosional base and planar top. Probably deposited by supercritical flows. Iregular upper profile may reflect the tendency of flows to branch into very shallow channels separated by low bars in the late flood stage. Trough cross-bedded sandstone, gravely sandstone and fine-grained conglomerate. It commonly shows lenticular geometry and an erosional base. In most cases it consists of medium to coarse-grained sandstone, occasionally with sparse granules and small pebbles; trough cross-bedded conglomerates were only observed in section 18. Thickness of through cross-bedded units average 65 cm and ranges 20-180 cm. Set height is usually less than 20 cm. Isolated units typically occur as shallow lenticular bodies fining upwards from coarse to medium or fine sandstone, and usually encased within siltstone or sandy/gravely mudstone; they commonly occur as composite units consisting of a number of mutually erosive sets, locally with mud drapes on the troughs, associated in places with planar lamination. Liquefraction pockets are locally observed. Multi-channel bedload rivers :Facies 1: Composite sandstone bodies resulting from stacking and cross-cutting of broad lenses 0.5-1.5 m thick with low relief erosional bases commonly floored by mudstone clasts. Broad lenses are associated with apparently unchannelized, planar-laminated intervals. Lithologies are coarse to microconglomeratic sandstone displaying planar lamination, low angle and possible antidune cross-lamination, locally with rows of small pebbles and or mud clasts. Major lenses, a few tens of metres wide with composite infill, may be identified as shallow channels, whereas small lenses are scour-and-fill structures, commonly consisting of low-angle cross-beds. These units are locally interbedded with mud lenses and are occasionally reworked at the top by small scour-and-fill structures or decimetre-scale trough cross bedding. No consistent vertical trends of grain size or physical structures occur. Facies 2 Trough cross-bedded sandstones bodies, resulting from the lateral and vertical amalgamation of channel units, less commonly by isolated lenticular channelized units up to 3 m thickness, mostly represent the second facies association. The dominant structure is trough cross bedding, in sets up to 1 m thick, associated with planar low-angle lamination. Planar cross-stratification, notably rare, occurs within lenticular channelized bodies as isolated sets up to 2 m high, resting upon a limited thickness of trough cross-strata confined in the lowest part of the channel. Cosets of troughs are bounded at the base by erosion surfaces locally overlain by pebbles lag of extra-and intraformational material. A few trough cosets show a decrease in scale and grainsize upwards, grading into planar-laminated or rippled fine-grained sandstone and locally mudstone. The dominant lithology is medium to coarse sandstone, locally microconglomeratic, clay chips and pebble rows are common both in the planar-laminated facies and the base of trough cross-bedded sets. Mud veneers locally drape the foresets or troughs of cross-bedded sands, and impersistant mud lenses with locally abundant plant debris many separate adjacent cosets. The sand-mud contact is locally loaded. The erosional upper contact of mudstone lenses and the abundance of mud clasts suggest that the mud was originally more abundant than preserved amounts suggest. Linguoid ripples migrating in the troughs of cross-bedded sands at about right angles to the dip direction of the foresets of trough cross-bedded sands are locally observed. Terminal fan facies :Generally single-storey ribbons and sheet like composite channelized bodies, generally of mixed load type, showing on average an upward increasing reduction in thickness and river bedload content; these are encased in an increasingly overbank of sediments, leading to low channel interconnections. This evolution is typically absent or very poorly developed in the marginal parts of the basin and in the less subsiding areas characterized by reduced thickness of sedimentary succession. Simple single-storey ribbons range from 0.9 to 4.3 m in thickness. The sediments involved range coarse sands, locally bearing granules and small pebbles, to fine sands and mudstone. Channel fills exhibit a sharp, fairly incised, irregular erosional base, sometimes with a remarkedly stepped appearance, floored by mudstone clasts and sometimes-reworked calcrete nodules. Vertically accreted ribbons commonly display a crudely developed fining-upward textural sequence, with trough cross bedding of upward decreasing scale, locally accompanied by planar lamination; small ribbons of this type may have been deposited by single flood events. Other ribbons show an inclined heterolithic stratification suggesting limited lateral migration, with muddy members of the couplets usually reaching the base of the channel. Thick muddy intercalations, sometimes pedogenically modified, may occur in the lateral accretionary units indicating that the fill was highly episodic in some channels. Burrow networks are relatively common in the upper part of the channel fills. Internal scouring surfaces, in place floored by mudstone clasts, are quite common, and several stages of scour and fill are characteristic, especially in channelized bodies of the inner more proximal zone of the system, and suggests highly fluctuating hydrodynamic conditions. Sheet like sandstones, mostsly resulting from lateral and to a limited extend also vertical amalgation of ribbons and small-storey internal organization can be found. Channel fills are interbedded with a great variety of interchannel sand and silt units deposited during flooding. Splay sandstones and commonly form a volumetrical large proportion of the total sand framework, especially near the transition into inferred sabkha sediments and may extend far into the interchannel areas, reflecting the extremely flashy and ephemeral nature of the associated streams. Splay deposits include both sheet sand layers showing virtual non-erosional basal contacts with the underlying sediments, and more discontinous and lenticular beds with broadly erosional bases. Sheet sandstone layers partly appear to be wings tapering away from channel sandstone bodies and sometimes coalescing to form extensive sheet-splays. The may be rich in vegetal debris and show small-scale flood sequences. Wave ripples draped by mud laminae are also locally observed. The upper surface of some play sandstone layers show evidence of a local shallow scouring. Splay sandstones and associated mudstones in places show root traces and or invertebrate burrows and are occasionally interbedded with dolomite and gypsum layers. Horizons with mud cracks in the mudstones. Spaly sandstones may appear organized into thickening and coarsening-upward sequences 6-10 m thick, displaying a clear upward increase in the sand/mud ratio. These consists of basal mudstone intervals with sparse, thin, sandstone interbeds passing up into thicker-bedded sheet-sandstones and eventually single channel fills. Mouth bar :Small-scale upward thickening and coarsening sequences 3-6 m thick are generally observed at the transition from lagoonal/marine to continental facies associations. Muddy layers alternate with thin-bedded sandstones in the lower part, and progressively disseappear, to grade upwards into a amalgated package of sandstone layers generally displaying unidirectional structures such as ripple-drift cross-lamination, trough cross bedding and planar-lamination; the sequence may be capped by erosive based channel sandstones. The facies association is thought to represents small mouth-bars encroaching on a shallow-water basin. Bellerophron Formation The Bellerophon Formation is charcterized by a complex array of facies and facies associations, all deposited in coastal to shallow shelf settings. The whole sedimentary body is typically zoned both laterally and vertically. Lateral zoning is highly by the eastward transition from thinner successions with marginal evaporites and repeated evidence of subaerial exposure into thicker successions characterized by fully marine facies associations and basinal evaporites. Vertical zoning is controlled by the overall transgressive trend affecting the VGS-Bellerophon Formation lithosome, and results in the VGS red beds grading upwards into a sulphate-evaporite/dolomite unit in turn overlain by a marine carbonate unit, usually very rich in fossils. A the whole succession is punctuated by a number of presumably third-order transgressive-regressive cycles ( depositional areas ), the vertical stacking of the facies associations does not actually follow a simple transgressive trend. Generally speaking, each depositional sequence records a more pronounced seaward shift of the entire system with respect to the underlying sequence. Coastal sabkha facies :The sabkha cycle consists of four main facies. A) Thin-bedded grey, fine-grained dolomite commonly with minor terrigenous content. Cm-thick dark grey to blackish peletic or marly interbeds generally occur. The depositional textures, partially obliterated by dolomitization, include: aphanitic dolomite and dolomitized wackestone with eurytopic microfossils, foraminifers, a few algae. In some cases microfossils have been replaced by gypsum. Macrofossils are quite rare. Environment: shallow subtidal setting, mud dominated lithologies suggest low hydrodynamic energy, while the poorly diversified faunas indicate some sort of ecological restriction. B) Bedded to massive grey to black marly-silty dolomite with displacive sulphate nodules; the microfacies recognized within the dolomite are mainly represented by former wackestone-packstone with skeletal components and silt- to sand-size terrigenous grains. The gypsum nodules range in size and abundance; they are typically displacive, deforming the surrounding sediment. Widespread bioturbation. C) Densely packed, layered, nodular gypsum, commonly with enterolithic folds, deriving from facies b through further increase in size and abundance of gypsum nodules; these begin the coalesce, but are still separated by significant amounts of marly dolomite. D) Chicken-wire gypsum: the dark mainly dolomitic partings between gypsum nodules are reduced to stylolitic undulate seams; the bulk of the rock consists of a mosaic of rounded to flattened cm-size sulphate nodules, commonly with compenetrating bouderies. The depositional environment of facies c en d is that of supratidal sabkha, where massive intrasediment growth of sulphate nodules occurs, continuously fed by solutions moving upward by capillarity from the water table through evaporative pumping. The whole facies sequence records progradation of the supratidal sabkha on the marginal lagoon setting.
Geology comments: Val Gardena Sandstone:Alluvial fan facies Val Gardena Sandstone:The coarser varieties may represent viscous subaerial debris flows, locally reworked in the late flood stage by dilute tractional flows. The finer-grained varieties , consisting of very poorly sorted mixtures of sand, silt and clay, may have been generated by rapid deposition from mud-laden sheet-flows of short duration, or graphy with little erosion, or spilled out of channels and spread over relatively flat surfaces. The finely conglomeratic top was probably deposited from waning aqueous “tail” following the debris flow slurry. The coarser units of this facies may represent the deposits of highly concentrated dispersion related to powerful sheet-floods with no approach to an organized system of banks, bars or channels, whereas the finer-grained units reflect the tractional reworking of mass-flows deposits during waning or fluctuating stages of a major flood, or the nuclei of low longitudinal bars within shallow distributaries, later modified in the falling stage limited lateral accretion or incision by minor channels. The finer grained varieties may have been emplaced by supercritical bedload flows, related to shallow, ephemeral, braided streams crossing the more distal areas of the fans. Outsize clasts may represent the coarser bed load abandoned as a result of loss of competence due to expansion of the flow at the transition point from the main channels of the fan to a network of very shallow, braided channels an low, longitudinal bars.

This facies may have been deposited by more or less concentrated sheet flows, lenticular geometries may reflect shallow scouring due to local turbulence.

Planar laminated to low angle cross-bedded fine to coarse sandstone, sometimes with rows of granules.

Subfacies may be due to migration of linguoid megaripples or dunes, probably not higher than 20 cm, and may either represent late tractional reworking by shallow channelled flows in the late flood stage at the expense of mass flow deposits in the relatively proximal areas of the fans, or the record of small, shallow, ephemeral braided river channels active in the distal fan. In most cases the smaller units may represent the record of migration of bedform trains during a single flood, whereas the large lenticular composite units, locally with mud drapes on the troughs, reflect a number of depositional events occurring in shallow, ephemeral channel.

Multi-channel bedload rivers :Facies 1:The cross-cutting channels forms represent a network of shallow broad channels cut in the early flood stage followed by infilling, essentially by vertical accretion, under supercritical flow conditions. The abundance of planar-laminated sands and the rarity of high-angle cross-lamination in the fills suggest high stage shallow flows, with little low-stage modification of bedforms. The facies association suggest the activity of an ephemeral braided river system, consisting of a network of shallow, interlacing, poorly defined channels.
Local mud lenses indicate formation of temporary ponds within abandoned channel segments.
This facies association may be considered typical of distal parts of major alluvial fans and mainly occurs in the Northern parts of the Dolomites.

Facies 2: Deeper fluvial channels, probably already represented trunk rivers.
The rarely observed sets of planar cross-strata may represent deposition in transverse bars.
The waning stage of flood flows is apparently recorded only by linguoid ripples migrating in the troughs of larger bedforms after crest emergence, mud drapes on floodstage bedforms, and mud lenses infilling abandoned channels. The latter were commonly removed by flood erosions as indicated by the abundance of mudstone clasts. The evidence for episodic flood-stage deposition followed by rapid withdrawel of floodwaters and subaerial emergence of bedforms with depositional of mud drapes strongly suggests flashy discharge conditions.
The facies association may represent the record of flashy bedload fluvial system with a regime characterized by rapid variations in discharge, as suggested the virtual lack of late stage modification of flood-related bedforms. The scale of bedforms suggests relatively deep channels, perhaps due to the confining influence of paleovalley flanks.
In the northwestern areas, where both facies associations are represented, the respective deposits occur in vertical succession with a clear trend fining upward, suggesting that they are the record of proximal and distal bedload fluvial systems. Paleocurrent directions in both are similar to those of overlying point bar sequences, but significantly diverge from paleocurrents of underlying alluvial fan facies associations, suggesting that sediment related to lateral influx were replaced by trunk river deposits.

Terminal fan facies :Rivers probably underwent a definite decrease in depth downstream and a sharp fall-off in their average discharge in the lower part of their courses, due to a number of factors including:
A) Loss of water by evapo-transpiration and lower precipitation.
B) Infiltration into a permeable alluvium.
The rivers were probably exotic, and reduced to a network of low-gradient, shallow, ephemeral wadi distributaries plugged during repetive flash-flooding events and subject to frequent avulsions.
Mouth bar.
Coastal Sabkha.


Taphonomy
Modes of preservation:body,adpression,original carbon,original sporopollenin,original cellulose
Size of fossils:microfossils
Temporal resolution:time-averaged
Spatial resolution:parautochthonous
Collection methods and comments
Collection excludes:all macrofossils
Collection methods:core,chemical,mechanical,field collection
Reason for describing collection:paleoecologic analysis
Metadata
Database number:32205
Authorizer:C. Looy Enterer:W. Puijk
Modifier:W. Puijk Research group:paleobotany
Created:2003-06-11 03:23:47 Last modified:2003-06-12 03:37:07
Access level:the public Released:2003-06-11 03:23:47
Creative Commons license:CC BY
Reference information

Primary reference:
8503. F. Massari, C. Neri, P. Pittau, D. Fontana, and C. Stefani. 1994. Sedimentology, palynostratigraphy and sequence stratigraphy of a continental to shallow-marine rift-related succession: Upper Permian of the eastern Southern Alps (Italy). Mem. Sci. Geol. 46:119-234 [C. Looy/W. Puijk/C. Looy]