共查询到20条相似文献,搜索用时 0 毫秒
2.
The Seslerio-Caricetum sempervirentis and the Caricetum ferrugineae from the Northern Calcareous Alps show considerable ecological and regional variation. 412 relevés representing both communities were classified by cluster analysis. Several subassociations and variants were distinguished and interpreted principally in terms of ecology and geographical distribution. 相似文献
3.
New data from the Berchtesgaden Alps result in a reconstruction of the Mesozoic-Cenozoic geodynamic history of the Northern Calcareous Alps. The closure of the western part of the Neotethys Ocean started in the late Early Jurassic and is evidenced by the onset of thick clay-rich sediments in the outer shelf area (=Hallstatt realm). The Middle to early Late Jurassic contraction is documented by the migration of trench-like basins formed in front of a propagating thrust belt. Due to ophiolite obduction, these basins propagated from the outer shelf area, forming there the Bajocian to Oxfordian Hallstatt Mélange, to the Hauptdolomit/Dachstein platform area, where the Oxfordian Rofan and Tauglboden Mélanges were formed. The basins were separated by nappe fronts forming structural highs. This scenario mirrors syn-orogenic erosion and deposition in an evolving thrust belt. Active basin formation and nappe thrusting ended around the Oxfordian/Kimmeridgian boundary, which was followed by the onset of carbonate platforms on structural highs prograding towards the former basins in latest Oxfordian to Early Tithonian time. Underfilled basins remained between the platforms. Rapid deepening around the Early/Late Tithonian boundary was induced by extension due to mountain uplift and resulted in the reconfiguration of the platforms and basins related to normal and probably strike-slip faults. Erosion of the uplifted nappe stack including obducted ophiolites caused final drowning and demise of the platforms in the Berriasian. The remaining Early Cretaceous basins were filled up with molasse sediments including siliciclastics until Aptian. Around the Early/Late Cretaceous boundary again extension and strike-slip movements started, followed by Eocene thrusting and Miocene strike-slip movements with block rotations. These younger tectonic movements destroyed the Triassic to Early Cretaceous palaeogeography and arranged the modern block configuration. The described Jurassic to Early Cretaceous history corresponds with that of the Western Carpathians, the Dinarides, and the Albanides, where (1) age dating of the metamorphic soles prove late Early to Middle Jurassic inneroceanic thrusting followed by late Middle to early Late Jurassic ophiolite obduction, (2) Kimmeridgian to Tithonian shallow-water platforms formed on top of the obducted ophiolites, and (3) latest Jurassic to Early Cretaceous sediments show postorogenic character. Therefore, we correlate the Jurassic geodynamic evolution of the Northern Calcareous Alps with the closure of the western part of the Neotethys Ocean. 相似文献
4.
The sedimentation of the Late Cretaceous Gosau Group of the Northern Calcareous Alps records the complex geodynamic evolution of the northern part of the Austroalpine microplate. The tectonically controlled sedimentation and facies distribution were mainly governed by the oblique subduction of the Pennic-Ligurian ocean below the Austroalpine margin. Most of the Gosau successions comprise two distinct sedimentary complexes. The Lower Gosau Subgroup (upper Turonian-Campanian) is characterized by terrestrial to shallow-marine facies associations: alluvial fan and fan delta deposits, shallow-marine sandstones and sandy limestones, and storm-influenced nearshore and shelf deposits. During the early Santonian sea-level highstand, a great part of the Northern Calcareous Alps was covered by a shallow shelf sea. Palaeotransport directions point to source areas situated both to the north and to the south of the Northern Calcareous Alps. The Upper Gosau Subgroup (upper Santonian-Eocene) comprises deep-water hemipelagic and turbiditic deposits. Rapid subsidence into bathyal to abyssal depths started diachronously from the northwest (Santonian) to the southeast (Maastrichtian) after a short phase of deformation and erosion. Abyssal deposits in the northern parts of the Northern Calcareus Alps and north-directed palaeotransport indicate a tilting of the slope towards the north. This subsidence pulse is attributed to an event of subcrustal tectonic erosion, probably triggered by the subduction of a topographic high of the South Penninic ocean. The relationships of the Gosau Group of the Austroalpine unit to Late Cretaceous deposits of the Carpathians and Southern Alps are discussed in the framework of a plate tectonic model. 相似文献
5.
In the Northern Calcareous Alps (NCA), meteoric cementation of Quaternary talus slopes was mainly sourced by dissolution of matrix and lithoclasts, by leaching of glacial till, and by groundwaters entered from underneath. Cement precipitation can take place within a few hundreds to a few thousands of years after talus deposition, but later diagenetic changes locally are indicated. Downslope along well-preserved talus successions, a change in prevalent diagenetic pathways is related to prolonged availability of pore waters from the apex to the toe of the slope. Talus slopes contain a significant proportion of carbonate mud probably produced by a combination of physical, chemical, and biological processes. 234U/ 230Th cementation ages of talus successions are scattered over a total range of 5–480 ka. The talus relicts of the NCA thus became cemented at highly different times during the late Quaternary. With the available data, we could not identify a specific palaeoclimatic significance of talus cementation. 相似文献
6.
Oncoidal limestones with different oncoid types are ubiquitous in back-reef open-lagoonal and, to a minor amount, in closed-lagoonal facies of the Late Jurassic Plassen Carbonate Platform of the Northern Calcareous Alps. A common feature of the oncoids from moderately to well-agitated open-lagoonal habitats are incorporated small trochospiral benthic foraminifers, tentatively assigned to trochamminids, switched between individual micritic layers. Their life style is discussed concluding a specialized feeding on cyanophytes on the outer side of the oncoids and later becoming biomurated by successive sheet formations due to oncoid growing. 相似文献
7.
Summary In the area of Haidach (Northern Calcareous Alps, Austria), coral-rudist mounds, rudist biostromes, and bioclastic limestones
and marls constitute an Upper Cretaceous shelf succession approximately 100 meters thick. The succession is part of the mixed
siliciclasticcarbonate Gosau Group that was deposited at the northern margin of the Austroalpine microplate.
In its lower part, the carbonate succession at Haidach comprises two stratal packages that each consists, from bottom to top,
of a coral-rudist mound capped by a rudist biostrome which, in turn, is overlain by bioclastic limestones and, locally, marls.
The coral-rudist mounds consist mainly of floatstones. The coral assemblage is dominated by Fungiina, Astreoina, Heterocoeniina
and Agathelia asperella (stylinina). From the rudists, elevators ( Vaccinites spp., radiolitids) and recumbents ( Plagioptychus) are present. Calcareous sponges, sclerosponges, and octocorals are subordinate. The elevator rudists commonly are small;
they settled on branched corals, coral heads, on rudists, and on biolastic debris. The rudists, in turn, provided settlement
sites for corals. Predominantly plocoid and thamnasteroid coral growth forms indicate soft substrata and high sedimentation
rates. The mounds were episodically smothered by carbonate mud. Many corals and rudists are coated by thick and diverse encrustations
that indicate high nutrient level and/or turbid waters.
The coral-rudist mounds are capped by Vaccinites biostromes up to 5 m thick. The establishment of these biostromes may result from unfavourable environmental conditions for
corals, coupled with the potential of the elevator rudists for effective substrate colonization. The Vaccinites biostromes are locally topped by a thin radiolitid biostrome. The biostromes, in turn, are overlain by bioclastic limestones;
these are arranged in stratal packages that were deposited from carbonate sand bodies. Approximately midsection, an interval
of marls with abundant Phelopteria is present. These marls were deposited in a quiet lagoonal area where meadows of sea grass or algae, coupled with an elevated
nutrient level, triggered the mass occurrence of Phelopteria.
The upper part of the Haidach section consists of stratal packages that each is composed of a rudist biostrome overlain by
bioclastic wackestones to packstones with diverse smaller benthic foraminifera and calcareous green algae. The biostromes
are either built by radiolitids, Vaccinites, and Pleurocora, or consist exclusively of radiolitids (mainly Radiolites). Both the biostromes and the bioclastic limestones were deposited in a low-energy lagoonal environment that was punctuated
by high-energy events. In situ-rudist fabrics typically have a matrix of mudstone to rudistclastic wackestone; other biogens (incl. smaller benthic foraminifera)
are absent or very rare. The matrix of rudist fabrics that indicate episodic destruction by high-energy events contain a fossil
assemblage similar to the vertically associated bioclastic limestones. Substrata colonized by rudists thus were unfavourable
at least for smaller benthic foraminifera.
The described succession was deposited on a gently inclined shelf segment, where coral-rudist mounds and hippuritid biostromes
were separated by a belt of bioclastic sand bodies from a lagoon with radiolitid biostromes. The mounds document that corals
and Late Cretaceous elevator rudists may co-occur in close association. On the scale of the entire succession, however, mainly
as a result of the wide ecologic range of the rudists relative to corals, the coral-dominated mounds and the rudist biostromes
are vertically separated. 相似文献
8.
Summary During the Middle and early Late Triassic carbonate ramps and rimmed platforms developed at the northwestern margin of the
Tethys ocean. In the Northern Calcareous Alps, Anisian stacked homoclinal ramps evolved through a transitional stage with
distally steepened ramps to huge rimmed platforms of Late Ladinian to Early Carnian age. Middle Triassic to early Late Triassic
facies and biota of basin, slope and platform depositional systems are described. Special emphasis is given to foraminifers,
sponges, microproblematic organisms and algae.
The Ladinian to early Carnian reef associations are characterized by the abundance of segmented sponges, microproblematica,
biogenic crusts and synsedimentary cements. Among the foraminifers, recifal forms like Hydrania dulloi and Cucurbita infundibuliformis (Carnian in age) are reported from the Northern Calcareous Alps for the first time. Some sphinctozoid sponges like Paravesicocaulis concentricus were known until now only from the Hungarian and Russian Triassic. 相似文献
10.
Summary The Turonian to Santonian terrestrial to neritic succession (Lower Gosau Subgroup) in the Northern Calcareous Alps of the
eastern part of the Tyrol, Austria, provides an example for deposition on a compartmentalized, narrow, microtidal to low-mesotidal,
wave-dominated, mixed siliciclastic-carbonate shelf. The shelf was situated in front of a mainland with a relatively high,
articulated relief, and underwent distinct changes in facies architecture mainly as a result of tectonism.
The investigated succession was deposited above a deeply incised, articulated truncation surface that formed when the Eo-Alpine
orogen, including the area of the future Northern Calcareous Alps, was uplifted and subaerially eroded. Distinct facies associations
were deposited from (1) alluvial fans and fan deltas, (2) rivers, (3) siliciclastic lagoonal to freshwater marsh environments,
(4) areally/temporally limited carbonate lagoons, (5) transgressive shores, (6) siliciclastic shelf environments, and (7)
an aggrading carbonate shelf. During the Turonian to Coniacian, the combination of high rates of both subsidence and sediment
accumulation, and a narrow shelf that was compartmentalized with respect to (a) morphology of the substratum, (b) fluviatile
input of siliciclastics and contemporaneous input of carbonate clasts from fan deltas, (c) deposition of shallow-water carbonates,
and (d) water energy and-depth gave rise to an exceptionally wide spectrum of facies as a distinguishing feature of the succession.
With the exception of facies association 7, which formed only once, depositional sequences in the Turonian to Coniacian interval
contain all of the facies associations 1 to 6. During Turonian to Coniacian times, the shelf was microtidal to low-mesotidal,
and was dominated by waves, storm waves and storm-induced currents. In vegetated marshes, schizohaline to freshwater marl
lakes existed. Transgressions occurred onto fan deltas and in association with estuaries, or in association with gravelly
to rocky shores. The transgressive successions, including successions deposited from transgressive rocky carbonate shores,
are overlain by regressive successions of shelf carbonates or shelf siliciclastics. Deposition of shallow-water carbonates
generally occurred within lagoons and over short intervals of time. A „catch-up” succession of shelf carbonates about 100
m thick accumulated only in an area protected from siliciclastic input.
In its preserved parts, the Turonian to Coniacian succession does not record deposition adjacent to major active faults. Lateral
changes in thickness result mainly from onlap onto the articulated basal truncation surface. Subsidence most probably was
controlled by major detachment faults outside the outcrop area, and/or was distributed over a wide area in association with
secondary faults above the major detachments.
During Coniacian to Early Santonian times, both the older substratum and the overlying Turonian-Coniacian succession were
subaerially exposed, faulted and deeply eroded. The following Early Santonian transgression ensued with rocky carbonate shores
ahead of a sandy, narrow shoreface-inner shelf environment and a deeper shelf with intermittentlydysaerobic mud. The transgression
was associated with the influx of cooler and/or nutrient-rich waters, and heralds an overall deepening. Still during the Early
Santonian, the deepening was interrupted by another phase of subaerial exposure. Subsequently, a short phase of shelf deposition
was terminated by deepening into bathyal depths. 相似文献
11.
Late Jurassic reefs are generally assumed to lack “cement crusts”. In the present paper, microencruster frameworks with variable amounts of cement are described from Late Jurassic to Earliest Cretaceous shallow-water carbonates of the Northern Calcareous Alps of Austria. The boundstones are characterized by a specialized and highly diverse community of microencrusters, partly occupying cryptic habitats. Volumetrically of minor importance compared to similar Permo-Triassic examples, Late Jurassic to Earliest Cretaceous microframeworks here reported compare well with cement reefs or cement-supported counterparts of other time intervals. The assumed depositional setting is that of a fore-reef slope environment. Generally, this peculiar microfacies can be integrated in current concepts of Late Jurassic reef classifications. Although more details are still needed for comparison, Late Jurassic microencruster-cement frameworks seem to be typical, but not restricted to the margins of Neotethyan isolated platforms. This work is dedicated to Erik Flügel, former professor of the University of Erlangen, for his fundamental pioneer research on various aspects of microfacies, including poorly known phenomena of ancient cement reefs. 相似文献
12.
Several boreal and alpine forests are depleted in nutrients due to acidification. Fertilization may be a remedy, but rapidly-soluble salts (N, P, K, Mg) may pose nitrate problems for the groundwater or decrease microbial activity.With the aim to investigate potential nitrogen leaching after fertilization we set up an experiment employing intact soil cores (11 cm diameter, 20–40 cm long) from a mixed forest and a Picea abies stand (soil type Rendsina) in the Northern Calcareous Alps of Austria. The cores were fertilized with a commercial NPK fertilizer or a methylene-urea-apatite-biotite (MuAB) fertilizer at a rate corresponding to 300 kg N ha -1 and incubated for 28 weeks together with unfertilized controls. Both soil water (retrieved 5 cm below the soil surface) and leachate were analyzed for nitrate and ammonium in regular intervals. After the incubation, soil microbial biomass and basal repiration were determined and a nitrogen mineralization assay was performed.For the control, in the soil water and leachate maximum NH 4
+ and NO 3
- concentrations of 5 and 11 mg N L -1, respectively, were found. Compared to that, MuAB fertilizer resulted in a slow increase of NH 4
+ and NO 3
- in the soil water (up to 11 and 35 mg N L -1 respectively) and in the leachate (4 mg NH 4
+-N L -1 and 44 mg NO 3
--N L -1). Highest nitrogen loads were found for the fast release NPK fertilizer, with NH 4
+ and NO 3
- concentrations up to 170 and 270 mg N L -1, respectively, in the soil water. NH 4
+-N levels in the leachate remained below 5, while NO 3-N levels were up to 190 mg L -1. Fast- release NPK caused a significant decrease of microbial biomass and basal respiration. These parameters were not affected by MuAB fertilizer.The results suggest that the MuAB fertilizer may be an ecologically appropriate alternative to fast-release mineral fertilizers for improving forest soils. 相似文献
13.
The Late Jurassic succession of Mount Rettenstein (central Northern Calcareous Alps, Austria) is unique in comparison to all
other sections known in the Northern Calcareous Alps because it provides the oldest coexistence of radiolarite basin sedimentation
with contemporaneous shallow-water carbonate intercalations. An up to 3.5-m-thick debris flow made up of shallow-water carbonate
detritus with a radiolaritic matrix is overlain by thin (calcareous) radiolarite, followed by several hundreds of meters of
shallow-water carbonates of the Plassen Formation. Benthic foraminifers ( Labyrinthia mirabilis Weynschenk and Alveosepta aff. jaccardi) and the radiolarian associations indicate a depositional age of both the debris flow and the basal Plassen Formation around
the boundary of Middle/Late Oxfordian resp. in the Late Oxfordian. This is as yet the first unambiguous evidence of Oxfordian
shallow-water sedimentation in the Northern Calcareous Alps. This early neritic stage with the settlement of ooid bars and
coral-stromatoporoid-reefs, evidenced by the debris flow resediments in siliceous basin sedimentation, is followed by the
definite, rapid progradation of the actual Late Oxfordian/Kimmeridgian–Berriasian Plassen Carbonate Platform with its steep
slope configuration. Assumably, this evolution was steered by a mixture of both global environmental and regional tectonic
constraints. 相似文献
14.
The uppermost Rhaetian Adnet reef is part of the Dachstein carbonate platform and is situated at the transition to the intrashelf Kössen Basin. Its diagenetic evolution is investigated focusing on dissolution cavities in the Tropfbruch quarry of Adnet (near Salzburg) stratigraphically situated immediately below the Triassic–Jurassic boundary. Sea-level changes due to global eustatic trends and regional tectonics are assumed to be the controlling factors in the development of a manifold diagenetic sequence characterized by phases of meteoric dissolution, marine and burial cementation, and internal sedimentation. Despite small-scale variations of the sequence, a superordinate pattern of diagenetic phases could be elaborated. Small-scale eustatic sea-level falls subordinate to a global regression trend caused subaerial exposures of the Adnet reef in the latest Rhaetian to earliest Hettangian. The result was karstification and meteoric dissolution of aragonitic coral skeletons ( Retiophyllia) leading to the formation of biomoldic porosity. Coral septa which escaped dissolution were transformed into neomorphic calcite spar under meteoric–phreatic conditions. A first generation of dog-tooth cements precipitated sporadically on the altered coral skeletons. Eustatic sea-level rise in Early to Mid-Hettangian times caused a renewed flooding of the pore space of the Adnet reef by marine water and the influx of a first generation of internal sediments (IS I), derived from the karstified host rock of the Upper Rhaetian reef limestone. These internal sediments are overgrown by radiaxial-fibrous calcites (RFCs) whose oxygen-isotopic signature (δ 18O = ?1.3 (±0.7)‰) indicates precipitation in deeper (colder) water (18–21°C) due to a first phase of drowning. An intermediate phase of eustatic sea-level lowstand in the Late Hettangian is expressed by dissolution and corrosion of RFCs. Rapid drowning of the Dachstein carbonate platform due to eustatic sea-level rise and tectonic movements took place in the Early Sinemurian and a second generation of internal sediments (IS II) derived from the Lower Sinemurian Adnet Formation is washed into the dissolution cavities. Where IS II is absent, RFCs are overgrown by a second generation of dog-tooth cements with a bright-luminescent outer rim indicating the transition to negative redox conditions in the pore water during shallow burial. Burial diagenesis is represented by blocky calcite cements which occlude the remaining pore space. Depleted oxygen-isotope values and significant Fe contents indicate precipitation under reducing redox conditions and elevated temperatures of 30–50°C at burial depths of 420–870 m. Locally, replacive saddle dolomite is the latest diagenetic phase in the Adnet reef indicating crystallization under hydrothermal influences related to compressional subduction regimes of the Penninic Ocean. 相似文献
15.
The ruderal communities of the orders Sisymbrietalia and Onopordetalia from the western part of Slovakia have been subjected to numerical classification and ordination. The ordination techniques proved to be a useful tool in the elucidation of the cluster pattern as well as in the detection of the main environmental variation underlying the floristic variation within the data. Results obtained with numerical techniques and traditional syntaxonomical classification have been compared. The similarity between these results is low at the level of the orders. This incompatability is explained by the differences in the weighting of the species in the course of the classification process and by the addition of non-floristical criteria that often occurs in syntaxonomical classification according to Braun-Blanquet. The highest value has been observed at the 3-clusters level (both orders and the Malvion neglectae). High similarity among the results of the numerical techniques have been observed, particularly in the group of space-dilating clusterings (Ward's method, Complete linkage clustering and MeQuitty's similarity analysis). Average linkage clustering produces the most diverse result. The Malvion neglectae appeared as a separate group in all numerical techniques adopted. This suggests the upranking of its syntaxonomical position. The Bromo-Hordeion murini turned out to be a very heterotoneous syntaxon. 相似文献
16.
Nitrogen relations of natural and disturbed tropical plant communities in northern Australia (Kakadu National Park) were
studied. Plant and soil N characteristics suggested that differences in N source utilisation occur at community and species
level. Leaf and xylem sap N concentrations of plants in different communities were correlated with the availability of inorganic
soil N (NH +
4 and NO −
3). In general, rates of leaf NO −
3 assimilation were low. Even in communities with a higher N status, including deciduous monsoon forest, disturbed wetland,
and a revegetated mine waste rock dump, levels of leaf nitrate reductase, xylem and leaf NO −
3 levels were considerably lower than those that have been reported for eutrophic communities. Although NO −
3 assimilation in escarpment and eucalypt woodlands, and wetland, was generally low, within these communities there was a suite
of species that exhibited a greater capacity for NO −
3 assimilation. These “high- NO −
3 species” were mainly annuals, resprouting herbs or deciduous trees that had leaves with high N contents. Ficus, a high-NO −
3 species, was associated with soil exhibiting higher rates of net mineralisation and net nitrification. “Low-NO −
3 species” were evergreen perennials with low leaf N concentrations. A third group of plants, which assimilated NO −
3 (albeit at lower rates than the high-NO −
3 species), and had high-N leaves, were leguminous species. Acacia species, common in woodlands, had the highest leaf N contents of all woody species. Acacia species appeared to have the greatest potential to utilise the entire spectrum of available N sources. This versatility in
N source utilisation may be important in relation to their high tissue N status and comparatively short life cycle. Differences
in N utilisation are discussed in the context of species life strategies and mycorrhizal associations.
Received: 5 July 1997 / Accepted: 13 July 1998 相似文献
17.
The macroinvertebrate communities of 16 karst springs in the Southern Limestone Alps (Slovenia, SE Europe), were studied from May to September 1999, together with the major chemical parameters of the water and selected physical characteristics of the springs. The springs are located in an area of 800 km 2, between 410 and 955 m a.s.l., and drain into two rivers whose catchments are separated by mountain ranges up to 2864 m. The Soča river drains into the Adriatic Sea and the Sava into the Black Sea. Springs showed relatively large fluctuations in discharge and small variations in temperature (normally about 1 °C) during the period of study. Seventy macroinvertebrate taxa were collected. Chironomidae (Diptera), Limnephilidae (Trichoptera), Enchytraeidae (Oligochaeta), Tricladida (Turbellaria) and Belgrandiella kuesteri (Gastropoda) were the most widespread taxa, collected from the majority of sampling sites. The environmental characteristics showed a great heterogeneity, and there was a large variation in the taxonomic composition and relative abundance of taxa between springs and during seasons. The coexistence of taxa with highly divergent ecological requirements is characteristic of the spring communities studied. They range from stygobionts and spring-restricted species to ubiquitous species. The differences observed in spring fauna in the two river catchments were probably dictated by differences in local environmental parameters and not by the geographical location in the different river catchments. 相似文献
18.
Lower Cambrian calcareous microfossils that preserved monospores and basal attachment organs with rhizoids have been discovered in jaspers of the Karakatty Formation of the Northern Tien Shan. A new genus, Koroleviphyton Kolosov, is established in the red algae division Rhodophyta with the type species K. attenuescens (Kolosov, 1983). 相似文献
19.
Short-lived plant communities of ruderal habitats in North Korea were studied using the Zürich-Montpellier approach. The Beckmannio eruciformis-Potentilletum costatae, the Daturo tatulae-Siegesbeckietum pubescentis, the Humulo japonicae-Chenopodietum albi and the Cosmo-Humulion japonicae were described as new. 相似文献
|