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1.
Ståhls G Vujic A Pérez-Bañon C Radenkovic S Rojo S Petanidou T 《Molecular ecology resources》2009,9(6):1431-1438
DNA barcoding has become a useful system for linking different biological life stages, and for identification of species within a known taxonomic framework. In this study, we generated mitochondrial DNA COI barcodes using adult specimens of all 22 species of the hoverfly genus Merodon (Diptera, Syrphidae) occurring on Lesvos island (Greece). The generated COI barcodes could well discriminate between all Merodon taxa of Lesvos, except for M. loewi and M. papillus that shared the same haplotype, despite their clear morphological differences. In addition, the barcodes revealed two cases of hitherto unknown morphologically cryptic species close to M. avidus and M. nigritarsis, respectively. Because only few successful rearings of immature stages of Merodon hoverflies are available, the larval host plant remains unknown for these phytophagous taxa. The obtained COI barcode library for the Merodon spp. of Lesvos will constitute a tool to link any unknown immature stages with already known species, and thus provide important life-history information and promise for ecological studies. 相似文献
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3.
Dipl. Geol. Spyridon M. Bellas Dr. Dorothee Mertmann Dr. Emmanuil Manutsoglu cand. geol. Jan Bartholdy Prof. Dr. Dimitris Frydas 《Facies》1995,33(1):107-119
Summary The Argyrotopos profile of the Oligocene Ayii Pantes Formation in the NW Greece was studied using litho- and biofacies-analysis.
The exposed sequence is mainly composed of monotonous marls and sandy marls. A rich fossil content, e.g. calcareous nannoplankton,
is recorded. Some sandstone beds and two graded limestone beds with abundant lepidocyclinids and globigerinids are intercalated.
The nannofossil assemblages from the measured profile of the Ayii Pantes Formation are attributed to theSphenolithus distentus Zone (NP 24) which is equivalent to theCyclicargolithus floridanus Subzone (CP 19a) of the Chattian, Upper Oligocene. The deposition took place in an euphotic subtidal environment situated
on the eastern margin of the Apulian Platform. The lepidocyclinids were derived from this platform and were transported basinwards.
The formation of the marls is influenced by sediment flux from the west. 相似文献
4.
Summary A local intraplatform basin developed in the Gartnerkofel-Zielkofel area of the Carnic Alps (southern Carinthia, Austria) during the Middle Triassic (Ladinian). This basin was filled with a transgressive basinal sequence composed of the Uggowitz Formation and overlying Buchenstein Formation. At the northwestern slope of the Gartnerkofel, the platform carbonates of the Schlern Dolomite interfinger with the Buchenstein Formation, causing the formation of two depositional sequences. The Uggowitz Formation consists of the Uggowitz Breccia and the Kühweg Member. Sediments of the Uggowitz Breccia were formed by different types of gravity induced processes. The Kühweg Member is a thin sequence of silt-and fine-grained sandstones which were deposited in a slope to basin margin environment by turbidity currents. The overlying Buchenstein Formation consists of hemipelagic to pelagic limestones of Fassanian age with intercalated pyroclastic rocks (Pietra verde). Nodular limestones were deposited under slow rates of accumulation during a relative sea-level highstand. The uppermost Buchenstein Formation is composed of hemipelagic limestone beds with intercalated graded calcarenites and breccias of platform-derived debris, showing characteristics features of a fore-reef slope of the prograding Schlern Dolomite. Uggowitz Formation and basal Buchenstein Formation are interpreted as a transgressive systems tract, nodular limestones from the middle part of the Buchenstein Formation mark an early highstand systems tract, forereef slope sediments of the upper Buchenstein Formation formed during the beginning regression of a late highstand systems tract, the basal part of the overlying Schlern Dolomite probably reflects a lowstand systems tract. The intercalated bedded limestone facies within the Schlern Dolomite is characterized by large, platform derived blocks, slump structures, breccia beds, graded calcarenites and hemipelagic limestones indicating a forereef slope environent. This intercalated facies belongs to the Buchenstein Formation and interfingers with the Schlern Dolomite. Conodonts from this intercalated slope facies point to Late Fassanian age. Therefore, the two Middle Triassic depositional sequences of the Gartnerkofel area can be correlated with the depositional sequences ‘Ladinian 1’ and ‘Ladinian 2’ of the Dolomites, proposed byDe Zanche et al. (1993). A brief comparison with the basinal sequences of similar age of the karawanken Mountains and the Carnia is presented. 相似文献
5.
Jim I. Mead 《Geobios》2013
An abundant fossil record of the snake clade Scolecophidia exists in Europe; however, the minute snake is noticeably absent in reports about the North American Paleogene and Neogene. Presented here are four localities from Florida, USA, that contain scolecophidian remains older than the Pleistocene: Thomas Farm (late Early Miocene, Hemingfordian Land Mammal Age, LMA), Live Oak (Oligocene-Miocene transition, latest Arikareean LMA), White Springs 3B (late Arikareean LMA), and Brooksville 2 (Late Oligocene, middle Arikareean LMA). These remains extend their known existence by about 26 m.y. and are now the oldest reported scolecophidian remains in North America. Molecular evidence on extant scolecophidians concludes that these tiny snakes have a Gondwanan origin. Interestingly, the oldest record of a scolecophidian is from Europe (Belgium) and dates back to the middle Paleocene (MP 1–5). The earliest African record of the snake clade comes from the Paleocene-Eocene boundary in Morocco. The clade is apparently absent from Europe and Middle East deposits dating from the latest Eocene through to the latest Oligocene (MP 19–30) and to the Early Miocene (MN 4). A portion of this time is known as the booid ‘Dark Period’ which represents an apparent response to global aridization and cooling. Scolecophidians appear to re-emerge into the southern Eurasian record in the Early Miocene (MN 4) and become widely dispersed throughout Europe and Middle East. The fossil record of these minute snakes is largely absent in southern Asia and South America. It is possible that the current lack of a decent fossil scolecophidian record outside of Europe and Middle East is due mainly to a bias in the methodology to recover fossils; wet sieving sediments through < 1.0 mm mesh is needed to recover the minuscule vertebrae. 相似文献
6.
Dr. Adam El-Shahat 《Facies》1993,28(1):67-76
Summary An extensive carbonate platform of predominately Middle Miocene age (Marmarica Formation) occupies the larger part of the
northern plateau of the Western Desert of Egypt. The Marmarica Formation (up to 150m thick) exposed on the cliffs facing the
Mediterranean coast consists mainly of alternating limestones and dolostones. Deposition took place in a shallow and normal
marine environment. The limestones are dominated by algal boundstone, crossbedded packstone and bioturbated wackestone facies.
The occurrence of the crossbedded packstone facies throughout the Marmarica Formation indicates that a shallow marine environment
prevailed.
Lithification of the precursor carbonates took place mainly in a meteoric environment. Replacement dolomitization ranged from
fabric destructive to retentative and from fabric selective to pervasive. The presence of an abundant open marine fauna, the
lack of evaporites, coupled with the contents of Sr and Na suggests that dolomitization took place in solutions more dilute
than normal sea water.
The limestone and dolostone facies cannot be separated into distinct types based on their major or trace element chemistry.
Only Mn and Sr seem to be facially controlled. Both elements are particularly enriched in the lagoonal facies compared with
the organic buildup facies. The difference in the Mn content is attributed to their proximity to continental areas at the
time of deposition. The differences in Sr values are interpreted by an originally differing mineralogy (calcite versus aragonite)
and different rates of diagenesis. Dolomitization did not appear to influence the Mn content as substantially as the Sr content.
The amount of the acid insoluble residue is controlled by the distribution of Si, Ti, Al, Fe, k, Rb and Zr. 相似文献
7.
Summary Modern carbonate sedimentation in the Caribbean Sea commonly occurs on banks that are surrounded and isolated by deep oceanic water. This depositional regime also occurred during the Tertiary, and many islands, such as Cayman Brac, have sequences that evolved in such settings. Cayman Brac is a small (about 39 km2) island, located on the Cayman Ridge, that has an exposed Oligocene to Pliocene succession which encompasses three unconformity-bounded formations. The upper Lower Oligocene Brac Formation is formed ofLepidocyclina limestones and sucrosis dolostones that locally contain numerous bivalves and gastropods. The overlying Lower to Middle Miocene Cayman Formation is formed of pervasively dolomitized mudstones to grainstones that contain an abundant, diverse biota of corals, gastropods, bivalves, foraminifera, and algae. Rhodolites are locally common. The Pliocene Pedro Castle Formation is formed of limestones, dolostones, and dolomitic limestones that contain a biota which is similar to that in the Cayman Formation. The unconformities between the formations represent substantial periods of time during which the previously deposited carbonates were lithified and eroded to produce karst terrains. All facies in the Brac, Cayman, and Pedro Castle formations on Cayman Brac developed on a bank that was no more than 20 km long and 3 km wide. There is no evidence of reef development other than isolated thickets ofStylophora and/orPorites and no systematic stratigraphic or geographic changes in the facies patterns of the formations. Comparison with modern Caribbean banks shows that the depositional regime was primarily controlled by water depth and energy levels. Limestones of the Brac Formation probably accumulated in low-energy conditions in water less than 10 m deep. The overlying Cayman Formation contains facies that formed in water 15 to 30 m deep with good cross-bank circulation. The Pedro Castle Formation formed in slightly shallower water (5–25 m) and lower energy conditions. The disconformities between the packages correlate with world wide eustatic drops in sea level. 相似文献
8.
Tvrtko Korbar Ladislav Fuček Antun Husinec Igor Vlahović Nenad Oštrić Dubravko Matičec Vladimir Jelaska 《Facies》2001,45(1):39-58
Summary The island of Cres is located in the northern part of the Adriatic Sea. The island is built up of predominantly Cretaceous
carbonates deposited in north-western part of extensive and long-lasting Adriatic Carbonate Platform. Owing to the influence
of synsedimentary tectonics supported by eustatic changes during the latest Albian/Early Cenomanian, different sedimentary
environments were established: from shallow intraplatform basin and related slope, across basin margin to protected shallow-platform.
During the Early to Middle Cenomanian rudist communities (ichthyosarcolitid/caprinid/radiolitid)flourished along a relatively
high-energy intraplatform basin margin. Fair amounts of coarse-grained bioclasts, derived almost exclusively from broken rudist
shells, were deposited over a marginal depocenter. Contemporaneously, pithonellid wackestone-packstones containing microbioclasts
and planktonic foraminifera were deposited basinward while marginal bioclastic sediments and limestone blocks of the basin
margin origin were sporadically deposited within the basin. The opening of the Cres intraplatform basin was aborted and the
basin was finally filled up during the Late Cenomanian. Since the Cres intraplatform basin was established at the beginning
of the Cenomanian it probably represented the initiation phase in the north-western extension of the later Adriatic Trough
development. 相似文献
9.
Socrates J Roussiakis 《Geobios》2002,35(6):699
Some relatively rare carnivore remains from Pikermi are studied. The present specimens include Simocyon primigenius(ROTH and WAGNER, 1854), Promeles palaeatticus(WEITHOFER, 1888), Martes woodwardiPILGRIM, 1931, Felis atticaWAGNER, 1857 and Machairodus giganteus(WAGNER, 1848), as well as some postcranial remains that resemble Enhydriodon? latipesPILGRIM, 1931 and are assigned to Mustelidae gen. et spec. indet. Some of these species were not known until now but from their holotypes as M. woodwardi and E.? latipes. Other species such as F. attica and M. giganteus are better known but from relatively scant material. Since the material of the earlier mentioned species comes from Pikermi, their type locality, it is of especial importance and improves our knowledge for the Pikermi carnivores and their relationships to other species. In some cases where the material comes from ossiferous blocks, the accompanying faunal context is discussed. 相似文献
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11.
A new fossil species of Zelkova is described from the Oligocene Ningming Formation of Guangxi, South China. Zelkova ningmingensis sp. nov. is characterized by leaves with craspedodromous venation pattern and drupaceous fruit type. The new species possesses elliptical to ovate leaves, bearing 7–12 pairs of secondary and simple toothed margin, as well as epidermal cells with straight or rounded anticlinal walls. The species is compared with extant and other fossil species hitherto reported of the genus. It is most similar to the living Zelkova schneideriana in the leaf gross morphology and epidermal characters, which may be suggested to be the ancestral type of Zelkova schneideriana. The discovery of Zelkova ningmingensis sp. nov. in Guangxi indicates that Zelkova has already existed in southern China as early as the Oligocene. In combination with Zelkova material from the Oligocene of Europe, it can be inferred that Eurasian Zelkova had begun to diversify by at least the Oligocene. Because China is the biodiversity centre of modern Zelkova, the fossil herein provides new insights into Zelkova biogeography. 相似文献
12.
Dr. Susanne M. L. Pohler 《Facies》1998,39(1):1-34
Summary Biohermal and biostromal buildups were investigated in late Early and Middle Devonian carbonate complexes of the Tamworth
Belt. The buildup types and subtypes were studied in three regions (Yarramanbully, Sulcor and, Wyaralong') to clarify their
paleo-environmental position.
Two stages of development are recognized: Incipient bioherms and bioherms. Incipient bioherms are carbonate buildups with
organisms which commonly form true bioherms. They dominate the sediment with small growth forms but are not prolific enough
to build large bio-frameworks. Small nodular and globular stromatoporoids characterize the incipient bioherms and are interpreted
as stunted growth forms. In one location (‘Wyaralong’) the coarse stromatoporoid calcarenite represents a fore-reef facies,
at Sulcor a shallow subtidal setting with moderate water energy can be deduced. The bioherms can be sub-divided into stromatoporoid-,
stromatoporoid-Stachyodes-, and stromatoporoid-rugose coral bioherms. Their variable composition probably reflects growth and deposition in different
zones of a reef complex and/or different proximity to areas of denundation indicated by high siliciclastic input. In the Tamworth
region true bioherms occur only in the Moore Creek Limestone Member (Middle Devonian), and not in older carbonate successions.
Biostromes are sub-divided into (1) incipient biostromes with stromatoporoid-heliolitid biostromes and alveolitid biostromes;
(2) aggregate biostromes withAmphipora andStachyodes biostromes; (3) stratified biostromes; (4) mixed aggregate/stratified biostromes. The different types of biostromes are not
limited to specific time-intervals, but rather to environmental conditions.
Bioherms and aggregate biostromes with ramose stromatoporoids are interpreted as-shallow water deposits, whereas the biostromes
formed in deeper water. This differentation is crucial for reconstruction of the depositional history of the basin.
Association of biohermal limestone with aggregate biostromes (i.e.Amphipora- andStachyodes limestone) reflects differentiation of a carbonate platform into reef and quiet water off-reef depositional centres. The
sporadic development of deep-water buildups signals deposition over an increasing relief possibly caused by tectonism. 相似文献
(1) | Incipient biostromes are characterized by laminar stromatoporoids and tabulate corals. Their forms are interpreted as initial layers of skeletons which were hampered by adverse conditions in growth. The stromatoporoid-heliolitid incipient biostrome (Eifelian Moore Creek Ls. Mbr., Yarramanbully) is characterized by abundance of dislodged laminar, ragged and tabular colonies associated with small globular and nodular heliolitids. An unstable substrate may have caused the growth disruptions. Decreasing grain-size of skeletal debris and increasing mud-content suggests deposition on a bathymetric gradient with deepening to the south. The alveolitid incipient biostrome (Eifelian Moore Creek Ls. Mbr., ‘Wyaralong’) is composed of nodular limestone with laminar alveolitids, stromatoporoids andSphaerocodium. It grades eastwards into dark nodular limestone with siliceous sponges and westwards it interdigitates with mudrich calcarenite. Deepening from west to east is implied. The incipient biostromes are interpreted as foreslope facies deposited at depths ranging from shallow subtidal (coarse-grained calcarenite) to deeper subtidal (fine-grained mud-rich calcarenite). |
(2) | The term ?aggregate biostromes? is chosen to characterize large mono-or oligo-generic aggregations of sessile colonial animals with calcareous skeletons with ramose growth habit examplified byAmphipora- andStachyodes biostromes. Both genera of ramose stromatoporoids lived in quiet shallow subtidal environments, withAmphipora apparently enduring higher mud contents and possibly hypersalinity and/or oxygen deficiency. |
(3) | Stratified biostromes are built mainly by tabular and laminar stromatoporoids and tabulate corals. Only one example from the Sulcor Limestone Member can be recognized in the Tamworth region. These deep and quiet water buildups formed when sedimentation rate was low. Possibly they indicate drowning of the carbonate platform. |
(4) | Mixed stratified/aggregate biostromes are also deep water carbonate buildups. They exhibit an alternation of growth forms (ramose and stratified) at different levels. The mixed biostromes at yarramanbully (Emsian) show alternating growth habits varying in 50 m to 60 m-intervals from stratified growth form-dominated to aggregate growth form-dominated to mixed buildup facies. Sea level changes due to tectonism or orbital changes may be the cause. Small scale cyclic alternations of growth forms occur in irregular (decimeter) intervals in the Yarramanbully biostromes and in more regular intervals in Eifelian mixed stratified/aggregate biostromes. Possible control factors include sea-level or climatic changes and faunal interactions. |
13.
Summary The coastline of the Salento Peninsula (Apulia region, Southern Italy) is characterized by a rocky shore with spectacular
cliffs where the investigated fringing reef complex, the so called Castro Limestone, spectacularly outcrops for at least 40
km.
As reconstructed from several measured sections, the Castro Limestone, which is Middle Chattian in age from our own data,
disconformably mantles a tectonically deformed falaise of Cretaceous-Eocene rocks and is overlain by a remarkable erosional
surface characterized by a very peculiar rhodolite rudstone. The Castro Limestone unit can be considered as a classic unconformity
bounded depositional sequence representing, most probably, a shelf margin prograding complex, related to the major Middle
Oligocene sea level lowstand.
Stratigraphic and sedimentologic features, together with paleontological characters, allow recognition of a virtually complete
range of reef environments across the reef profile.
Several geomorphic zones and associated facies are described, from the most landward reef area (‘back reef’) across the reef
flat and reef from downward to the fore reef slope, contributing to a better knowledge of the evolution of Oligocene reefs
and reef communities in Italy and in the Mediterranean area. 相似文献
14.
Signatures of hydrocarbon venting in a Middle Devonian Carbonate Mound (Hollard Mound) at the Hamar Laghdad (Antiatlas, Morocco) 总被引:3,自引:0,他引:3
Dipl.-Geol. Jörn Peckmann Prof. Dr. Otto Heinrich Walliser Prof. Dr. Walter Riegel Prof. Dr. Joachim Reitner 《Facies》1999,40(1):281-296
Summary The Middle Devonian Hollard Mud Mound is situated in the eastern Hamar Laghdad, which is a small mountain range in the Tafilalt
in SE Morocco. In contrast to the well known Lower Devonian Kess-Kess mounds, the Hollard Mound is of Middle Devonian age.
The facies in the core of this mud mound differs from that of the other parts of the mound, and exhibits signatures of ancient
hydrocarbon venting. The carbonate phases of the core facies are derived from the oxidation of vent fluids and consist of
clotted micrite, a cryptocrystalline carbonate associated with spheres of uncertain origin, and a calcitic rim cement (rim
cement B). These vent carbonates show δ13C values in the range of −11 to −20% PDB indicating that some of their carbon is derived from isotopically light hydrocarbons.
Fossiliferous micrite has been affected by hydrocarbon venting in the proximity of the vent site, which is indicated by intermediate
δ13C values between vent carbonates and not affected sediments. Bivalves occur in dense populations within the core facies. They
form autochthonous shell accumulations and are almost exclusively articulated. it is likely that these bivalves were dependent
on chemosynthesis similar to their counterparts at modern vents. The vent deposits also exhibit an unusual prasinophyte assemblage,
which might have been linked to the specific nutrient availability at the vent site.
The ancient vent site is characterized by an enhanced carbonate precipitation and rapid lithification. The latter is corroborated
by the three-dimensional preservation of phytoplankton (prasinophytes and acritarchs) and the occurrence of stromatactoid
pores. An early phase of carbonate corrosion predating the formation of vent carbonates affected the fossiliferous micrite
of the core facies and is thought to be related to a phase of H2S-rich venting. 相似文献
15.
Summary The Steudnitz quarry (East Thuringia, Germany) exposes the entire Lower Muschelkalk (Middle Triassic, Anisian) with a thickness of 103 m. In this paper, a primarily palynofacies-based sequence-stratigraphical interpretation supported by lithological investigations is proposed. Palynofacies of the sampled carbonate rocks is dominated by land-derived phytoclasts and pollen grains. Spores are quite rare. Marine plankton reaches its maximum abundance in an interval around the ThuringianSpiriferina-bed and the Terebratel-beds. In accordance with lithological features, this interval may be interpreted as a third-order maximum-flooding zone. Two different third-order interpretations are presented and discussed. Third-order sequences and parasequence sets can be identified by use of palynofacies analysis. Furthermore, palynofacies analysis provides an additional possibility of recognizing partly eroded or originally incomplete cycles (‘missed beats’). In some cases, a resolution down to the level of parasequences is possible. High-resolution palynofacies analysis is a powerful new tool in sedimentology but should always be combined with lithofacies interpretation. It provides very useful, additional information for high-resolution sequence analysis and palaeoenvironmental interpretation. Being a rather young method, high-resolution palynofacies analysis still shows some calibration problems with classical methods. However, these should be solvable by further research. 相似文献
16.
The Late Miocene fossiliferous locality of Chomateri is located close to the classic locality of Pikermi, but unfortunately its faunal context is not sufficiently known. Some fossil remains of spiral-horned antelopes from Chomateri are assigned to Prostrepsiceros rotundicornis and Protragelaphus skouzesi. The co-existence of P. rotundicornis and P. skouzesi is relatively rare in the Late Miocene, but well-documented in Pikermi. Comparisons of the Chomateri material support a middle Turolian age for the Chomateri locality and suggest a close chronological relation to the Pikermi fauna. 相似文献
17.
Bacterial abundance and production in river sediments as related to the biochemical composition of particulate organic matter (POM) 总被引:4,自引:1,他引:4
The major proportion of heterotrophic activity in running waters islocalized on the solid surfaces of sediments in the benthic and hyporheic zoneand is dominated by microorganisms. However, this assertion is based on thestudies of small streams, and little is known about the microbial metabolism oforganic matter in river ecosystems. We therefore explored the relationshipsbetween bacterial abundance and production and the gradients of organic matterquality and quantity in sediments of a sixth-order lowland river (Spree,Germany). We found vertical gradients of detrital variables (particulateorganicmatter (POM), particulate organic carbon (POC), nitrogen (PN), and protein) andof bacterial variables (abundance, production, turnover time, and proportion ofbacterial carbon in total POC) in two different sediment types. These gradientswere steeper in stratified sediments than in the shifting sediments. Detritalvariables correlated strongly with bacterial abundance and production. The bestcorrelation was found for detrital variables indicating substrate quantity andquality (rS = 0.90 for PN with abundance). Although bacterialbiomasscomprised only 0.7% of the POC (1.9% of PN, 3.4% of the protein) in sediments,the turnover of sedimentary organic carbon was fast (median = 62d), especially in the shifting sediments. Our findings demonstratethat sediment dynamics significantly foster organic carbon metabolism in riversystems. Thus, these sediments, which are typical for lowland rivers, stronglyinfluence the metabolism of the whole ecosystem. 相似文献
18.
Six new complexes, [Cu4I4(PPh2Cy)4]·2H2O (1), [CuI(PPhCy2)2] (2), [CuCl(PPhCy2)2] (3), and [CuBr(PPh3)3]·CH3CN (4), [Ag(PPhCy2)2(NO3)] (5), [Ag(PCy3)(NO3)]2 (6) [where Ph = phenyl, Cy = cyclohexyl], have been synthesized and structurally characterized by X-ray diffraction, IR absorption spectra and NMR spectroscopic studies (except complex 4). The X-ray diffraction analysis of complex (1), pseudo polymorph of complex [Cu4I4(PPh2Cy)4], reveals a stella quadrangula structure. The four corners of the cube are occupied by copper(I) atoms and four I atoms are present at the alternative corners of the cube, further more the copper(I) atoms are coordinated to a monodentate tertiary phosphine. Complexes (2) and (3) are isostructural with trigonal planar geometry around the copper(I) atom. The crystal structure of complex (4) is a pseudo polymorph of complex [CuBr(PPh3)3] and the geometrical environment around the copper(I) centre is distorted tetrahedral. In the AgI complexes (5) and (6), the central metal atoms have pseudo tetrahedral and trigonal planar geometry, respectively. Spectroscopic and microanalysis results are consistent with the single crystal X-ray diffraction studies. 相似文献
19.
Priv.-Doz. Dr. Christoph Breitkreuz Priv.-Doz. Dr. Friedrich-Franz Helmdach Dipl. Geol. Rolf Kohring Dipl. Geol. Volker Mosbrugger 《Facies》1992,26(1):67-80
Summary Thick terrestrial Late Carboniferous to Triassic volcanosedimentary successions, a prominent feature of the Chilean and Argentinian
High Andes, were formed on the active continental margin of Gondwanaland. Their stratigraphic position and the paleogeographic
and paleoclimatic relations to neighbouring successions are poorly defined. A more precise age has been obtained for alluviolimnic
intra-arc sediments (Miembro Medio), which are intercalated in the Late Carboniferous-Triassic volcano-sedimentary successions
in the Salar de Atacama area of northern Chile.
The ostracodesCarbonita cf.pungens andParaparchites sp., which occur in the lower part of the Miembro Medio, are of Late Carboniferous, probably Westphalian age. The diverse
taphoflora, which occurs in a higher stratigraphic level than the ostracodes, includes sphenophytes, ferns, gymnosperms and
pteridophylls, for which we assume a late Westphalian-Early Permian age. Considering radiometric data of under-and overlying
volcanic rocks, a Westphalian-Stephanian (to? Early Permian) age is inferred for the Miembro Medio.
Fauna and flora indicate that warm-humid and seasonal climatic conditions existed during the deposition of the lower fossiliferous
part of the Miembro Medio. This coincides with the sedimentary paleoclimatic indicators of the Miembro Medio and the climate
which was assumed to have predominated in wide parts of the Central and Southern Andes during the Latest Carboniferous. 相似文献