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31.
Biomass, carbonate standing stock and production of the mediterranean coralCladocora caespitosa (L.) 总被引:1,自引:0,他引:1
Summary The Mediterranean coralCladocora caespitosa often occurs in large beds, i.e. populations of hemispherical clonies with stock densities varying between 1.9 and 4 coloneis
·m−2. Laboratory measurements of volume, skeleton weight, surface and number of corallites per colony, coupled with mean annual
growth rates evaluated through sclerochronology, allowed for the estimation of biomass, skeleton bulk density, calcimass (carbonate
standing stock) and secondary production (both organic and inorganic) of twoC. caespitosa beds at 4 and 9 m depth. The mean colony biomass varied between 0.73 and 0.99 kg dw ·m−2, corresponding to a calcimass between 2 and 5 kg CaCO3·m−2. Organic secondary production was 215.5–305.4 g dw of polyps ·m−2·y−1, while the potential (mineral) production was 1.1–1.7 kg CaCO3·m−2·y−1, for the year 1996–1997.
These values show thatC. caespitosa is one of the major carbonate producers within the Mediterranean and one of the major epibenthic species originating stable
carbonate frameworks both in recent and past times. 相似文献
32.
Franz T. Fürsich Markus Wilmsen Kazem Seyed-Emami Gerhard Schairer Mahmoud R. Majidifard 《Facies》2003,48(1):171-198
Summary Following a phase of predominantly siliciclastic sedimentation in the Early and Middle Jurassic, a large-scale, low-latitude
carbonate depositional system was established in the northern part of the Tabas Block, part of the central-east Iranian microplate,
during the Callovian and persisted until the latest Oxfordian/Early Kimmeridgian. Running parallel to the present eastern
block margin, a NNW/SSE-trending carbonate platform developed in an area characterized by reduced subsidence rates (Shotori
Swell). The growth of this rimmed, flat-topped barrier platform strongly influenced the Upper Jurassic facies pattern and
sedimentary history of the Tabas Block. The platform sediments, represented by the predominantly fine-grained carbonates of
the Esfandiar Limestone Formation, pass eastward into slope to basin sediments of the Qal'eh Dokhtar Limestone Formation (platform-derived
allochthonites, microbialites, and peri-platform muds). Towards the west, they interfinger with bedded limestones and marlstones
(Kamar-e-Mehdi Formation), which were deposited in an extensive shelf lagoon. In a N−S direction, the Esfandiar Platform can
be traced for about 170 km, in an E-W direction, the platform extended for at least 35–40 km. The width of the eastern slope
of the platform is estimated at 10–15 km, the width of the western shelf lagoon varied considerably (>20–80 km). During the
Late Callovian to Middle Oxfordian, the Esfandiar Platform flourished under arid climatic conditions and supplied the slope
and basinal areas with large amounts of carbonates (suspended peri-platform muds and gravitational sediments). Export pulses
of platform material, e.g. ooids and aggregate grains, into the slope and basinal system are interpreted as highstand shedding
related to relative sealevel variations. The high-productivity phase was terminated in the Late Oxfordian when the eastern
platform areas drowned and homogeneous deep water marls of the Upper Oxfordian to Kimmeridgian Korond Formation onlapped both
the Qal'eh Dokhtar Limestone Formation and the drowned Esfandiar Limestone Formation. Tectonic instability, probably caused
by faulting at the margins of the Tabas Block in connection with rotational movements of the east-central Iranian block assemblage,
was responsible for the partial drowning of the eastern platform areas. In some areas, relicts of the platform persisted to
produce shallow-water sediments into the Kimmeridgian. 相似文献
33.
Pavel Kabanov 《Facies》2003,49(1):243-270
Summary The type upper Moscovian-basal Kasimovian argillaceous-carbonate succession of central European Russia contains regionally
traced cyclothem-bounded subaerial exposure horizons (geosols) represented mainly by rendzina-type palaeosols. Palaeokarst
profiles occurrarely and grade laterally to palaeosols. Composite subaerial profiles divided by one or two thin marine beds
are called ‘multiple geosols’. The biofaces structure of the studied succession is defined by brachiopod and fusulinoid biofaces.
The heterogeneous Choristites biofacies characterizes openmarine intervals, which constitute the bulk of the succession, and
is defined by presence of Choristites. The Meekella biofacies with monospecific concentrations of Meekella shells and extreme rarity of other brachiopods characterises restricted peritidal intervals which commonly constitute the
terminal regressive parts of major cyclothems. Three fusulinoid biofacies defined by Baranova and Kabanov (2003) include restricted
peritidal Biofacies 1 with only small fusulinoids Fusiella and Schubertella present, open shoal-to-subtidal Biofacies 2 with the richest fusulinoid assemblages, and the most offshore Biofacies 3 with
less diverse, sometimes Hemifusulina-dominated, fusulinoid assemblages. Bioturbation patterns and ichnofossils allow recognition of deeper subtidal Zoophycos
and shallower non-Zoophycos ichnofacies. Among the latter, shallowest subtidal facies are characterized by presence of thalassinoid
burrows. Intertidal laminated lithofacies with suppressed bioturbation contain Skolithos burrows. Seventeen lithofacies are recognized. Terrestrial lithofacies include topclays (upper clayey palaeosol horizons)
and aeolian grainstones. Restricted peritidal lithofacies include cross-stratified skeletal-peloidal grainstones, fine-grained
laminated grainstones-mudstones, and lagoonal mudstones. Open shoal lithofacies include ooidal grainstones (rare, only in
Podolskian) and coarse skeletal-peloidal grainstones. The open subtidal lithofacies include skeletal packstones-rudstones,
shallow subtidal packstones-wackestones, deeper subtidal packstones-wackestones, Ivanovia boundstones (only in Podolskian), proximal tempestites, distal tempestites, and skeletal wackestones-mudstones. The fossiliferous
shale lithofacies is a miscellaneous group of marine shales lacking distinct features of the above-listed lithofacies. Conglomerates
of cyclothem bases that are regarded as early transgressive lithofacies are variable in their palaeoenvironmental position
and are characterized by concentrated pebbles derived from palaeosol reworking. The shallowest subtidal lithofacies of fine
packstones-grainstones is considered as transitional between open subtidal and restricted peritidal lithofacies. The origin
of stratiform dolostones is shown to be early diagenetic in the subsurface. The depositional model involves a shallow and
broad epicontinental ramp, where through water circulation prevented stratification of the water column and allowed large
skeletal benthos to colonize the entire spectrum of depositional environments. Storms are thought to be the principal water-mixing
agent. The anti-estuarine circulation carrying oxygenated waters down-ward may explain the lack of anoxic features in the
deepest facies that may have formed below storm wave base. 相似文献
34.
A computer-based parsimony analysis of the brachiopod genus Orbirhynchia (Late Albian–Middle Campanian) is described. The resulting cladogram indicates that the genus divided into two distinct lineages soon after its appearance in the Late Albian. One group is known only from marly and sandy facies of Cenomanian age, while the second, more diverse, group appeared later in the Cenomanian but persisted into the Campanian. These two groups exhibit distinct morphological trends which may be related to different ecological niches, perhaps with respect to local sedimentary environment. K ey words : brachiopod, Orbirhynchia , Cretaceous, phylogeny, palaeoecology. 相似文献
35.
In the current study, fifteen halophilic and halotolerant bacteria were isolated from salt-affected soil of ?anl?urfa, Turkey. The isolates were characterized by conventional and molecular techniques (16S rDNA sequence analyses) as belonging to seven different genus including Bacillus (5 isolates), Halobacillus (1 isolate), Oceanobacillus (2 isolates), Halomonas (3 isolate), Nesterenkonia (1 isolate), Chromohalobacter (2 isolates) and Jeotgalibacillus (2 isolates). According to the results obtained, the investigated bacterial strains have high salt tolerance and significant enzyme activities which can improve soil nutrient cycling and fertility. Furthermore, these bacterial strains have been investigated for their ability to dissolve common salts available in salt-affected soils. Salt dissolving experiments showed that two Chromohalobacter isolates were able to dissolve CaCO3 and one of the Halomonas isolate was able to dissolve both CaCO3 and MgCO3. As these bacterial isolates can dissolve CaCO3 and MgCO3, the availability of Ca2+ and Mg2+ ions may increase which can enhance the removal of the excess Na+ in soil profile. 相似文献
36.
Mikael Calner 《Facies》2005,51(1-4):584-591
Recent and ancient carbonate platforms are major marine ecosystems, built by various carbonate-secreting organisms with different sensitivity for environmental change. For this reason, carbonate platforms are excellent sensors for changes in contemporaneous marine environments. A variety of ecosystem changes in carbonate platforms have previously been recognised in the aftermath of mass extinction events. This paper addresses how two Silurian extinction events among graptolites, conodonts, and pentamerid brachiopods can be related to changes in the style of carbonate production and general evolution of low latitude carbonate platforms in a similar way as previously reported from the major five mass extinctions of the Phanerozoic. Strata formed on Gotland during the Mulde and Lau events share remarkably many similarities but are strikingly different in composition compared to other strata on the island. The event-related strata is characterised by the sudden appearance of widespread oolites, deviating reef composition, flat-pebble conglomerates, abundant micro- and macro-oncoids, stromatolites, and other microbial facies suggesting decreased bioturbation levels in contemporaneous shelf seas. Importantly, these changes can be tied to high-resolution biostratigraphic frameworks and global stable isotope excursions. The anomalous intervals may therefore be searched for elsewhere in order to test their regional or global significance. 相似文献
37.
Luca Basilone 《Facies》2009,55(1):115-135
The Rocca Busambra ridge in western Sicily is a shallow to pelagic Meso-Cenozoic carbonate structural unit of the Sicilian
Chain with a variety of tectono-sedimentary features. Palaeofaults, unconformities (buttress unconformity, onlap, downlap),
a network of neptunian dykes with several infilling generations, several large hiatuses, different facies and lateral facies
changes, and erosional submarine and subaerial surfaces are observed. Detailed fieldwork and structural analyses have indicated
the occurrence of fault planes with different orientations. These data, combined with facies studies and physical-stratigraphy
analyses, allow for the distinction of different depositional regions. A lateral change from an open-marine carbonate platform
with a stepped fault margin (located in the westernmost sector) to a deeper basinal depositional setting in the east, in the
context of an upper slope scalloped margin and base-of-slope systems with talus breccias, is envisaged here. Extensional to
transtensional tectonic pulses punctuated the sedimentary evolution during Early Toarcian, Late Jurassic, Early Cretaceous,
Late Cretaceous, and Early Miocene times. The collected data show that most fault planes have preserved their original orientations
throughout the reactivation processes. The reconstructed Meso-Cenozoic tectono-sedimentary evolution is closely related to
the late syn-rift and post-rift tectonic evolution of the Tethyan continental margin. 相似文献
38.
M. Azizur Rahman Tamotsu Oomori Gert W?rheide 《The Journal of biological chemistry》2011,286(36):31638-31649
Calcium carbonate exists in two main forms, calcite and aragonite, in the skeletons of marine organisms. The primary mineralogy of marine carbonates has changed over the history of the earth depending on the magnesium/calcium ratio in seawater during the periods of the so-called “calcite and aragonite seas.” Organisms that prefer certain mineralogy appear to flourish when their preferred mineralogy is favored by seawater chemistry. However, this rule is not without exceptions. For example, some octocorals produce calcite despite living in an aragonite sea. Here, we address the unresolved question of how organisms such as soft corals are able to form calcitic skeletal elements in an aragonite sea. We show that an extracellular protein called ECMP-67 isolated from soft coral sclerites induces calcite formation in vitro even when the composition of the calcifying solution favors aragonite precipitation. Structural details of both the surface and the interior of single crystals generated upon interaction with ECMP-67 were analyzed with an apertureless-type near-field IR microscope with high spatial resolution. The results show that this protein is the main determining factor for driving the production of calcite instead of aragonite in the biocalcification process and that –OH, secondary structures (e.g. α-helices and amides), and other necessary chemical groups are distributed over the center of the calcite crystals. Using an atomic force microscope, we also explored how this extracellular protein significantly affects the molecular-scale kinetics of crystal formation. We anticipate that a more thorough investigation of the proteinaceous skeleton content of different calcite-producing marine organisms will reveal similar components that determine the mineralogy of the organisms. These findings have significant implications for future models of the crystal structure of calcite in nature. 相似文献
39.
The degree to which organisms retain their environmental preferences is of utmost importance in predicting their fate in a world of rapid climate change. Notably, marine invertebrates frequently show strong affinities for either carbonate or terrigenous clastic environments. This affinity is due to characteristics of the sediments as well as correlated environmental factors. We assessed the conservatism of substrate affinities of marine invertebrates over geological timescales, and found that niche conservatism is prevalent in the oceans, and largely determined by the strength of initial habitat preference. There is substantial variation in niche conservatism among major clades with corals and sponges being among the most conservative. Time‐series analysis suggests that niche conservatism is enhanced during times of elevated nutrient flux, whereas niche evolution tends to occur after mass extinctions. Niche evolution is not necessarily elevated in genera exhibiting higher turnover in species composition. 相似文献
40.
Pohlsepia mazonensis gen. et sp. nov. from the Mazon Creek Konservat Lagersta¨tte (Carboniferous) of Illinois is an exceptionally preserved soft-bodied fossil coleoid, with well-defined body and arms. Lacking an internal shell and possessing eight subequal and two modified arms, Pohlsepia can be compared with both the living cirrate octopods and the decabrachian sepiardarids, both of which lack a well-developed internal skeleton. Given its sac-like body, lack of a well-defined head and presence of fins, Pohlsepia can be safely compared with modern cirrate octopods. It is the oldest known completely soft-bodied coleoid and as such has great significance with respect to the phylogeny of the group, given that both the octobrachian and decabrachian clades have previously been thought to have evolved in the Jurassic. K ey words : Coleoidea, Octobrachia, Konservat Lagersta¨tte , Mazon Creek, Carboniferous. 相似文献