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1.
The age ranges of Upper Cretaceous lithotectonic complexes of Western Kamchatka—terrigenous Kikhchik, volcanic Irunei, and terrigenous Omgon—are analyzed to reveal their almost simultaneous deposition. The pre-Cenozoic settings of these complexes are reconstructed. Based on analysis of the composition and structural features of Late Cretaceous lithotectonic complexes and on correlation of events, the Late Cretaceous paleogeography is reconstructed. It is found that the formation of the contemporary structure of the studied region would have required significant displacement of the volcanic Irunei complex from west to east and the terrigenous Omgon complex from north to south. It is concluded that the Western Kamchatka continental block (minor lithospheric plate) was independent in the Late Cretaceous.  相似文献   

2.
Planktonic foraminifer distributions in seventeen stratigraphic sections of Upper Cretaceous hemipelagic and pelagic sequences of northern Bey Da?lar? Autochthon (western Taurides) yield six biozones such as, Dicarinella concavata Interval Zone, Dicarinella asymetrica Range Zone, Radotruncana calcarata Range Zone, Globotruncana falsostuarti Partial Range Zone, Gansserina gansseri Interval Zone, and Abathomphalus mayaroensis Concurrent Range Zone. Two of the zones, Dicarinella concavata Zone and Dicarinella asymetrica Zone, are identified in the massive hemipelagic limestones of the Bey Da?lar? Formation, of Coniacian-Santonian age. They are characterized by scarce planktonic foraminifera and abundant calcisphaerulids. The other four biozones are determined from the cherty pelagic limestones of the Akda? Formation and indicate a late Campanian-late Maastrichtian time interval. The planktonic foraminifera observed in these four biozones are diverse, complex morphotypes (K-selection), suggesting open oceans. The assemblage of the Abathomphalus mayaroensis Zone shows that the latest Maastrichtian record is absent throughout the northern part of the autochthon. Two main sedimentary hiatuses are recognized within the Upper Cretaceous pelagic sequence. Early to middle Campanian and latest Maastrichtian-middle Paleocene planktonic foraminifera are absent in all measured stratigraphic sections. Hiatus durations differ between sections as a result of diachronism of onset of the hemipelagic and pelagic deposition and the post-Santonian and post-Maastrichtian erosional phases. Drowning event and the early-middle Campanian and latest Maastrichtian-middle Paleocene hiatuses in the pelagic sequence are attributed to regional tectonics during the Late Cretaceous.  相似文献   

3.
The stratigraphic division and sequence of the Upper Cretaceous sediments in eastern Heilongjiang Province,China,have been ambiguous and controversial,mainly due to a lack of biostratigraphically useful fossils and related radiometric dating.A new species of angiospermous fossil plant.Platanus heilongjiangensis sp.nov.,from Qitaihe in eastern Heilongjiang has been found in sediments conformably above which zircons from a rhyolitic tuff has been dated by U-Pb radiometric methods as 96.2± 1.7 Ma.indicating that the Upper Houshigou Formation is of Cenomanian age.This discovery not only provides new data to improve our stratigraphic understanding of the Houshigou Formation,but also shows that Platanus flourished in the early Late Cretaceous floras of the region.This new study also indicates active volcanism taking place in the eastern Heilongjiang region during the Cenomanian of the Late Cretaceous.  相似文献   

4.
A new Upper Cretaceous genus and species of soldier beetles, Archaeomalthodes rosetta gen. et sp. nov., is described and illustrated from an individual preserved in Upper Cretaceous (Cenomanian, ca. 99 Ma) amber from northern Myanmar. It is undoubtedly placed in extant subfamily Malthininae based on its small-sized body, somewhat abbreviated elytra and fusiform terminal maxillary palpomere, representing the oldest documented occurrence of Malthininae. It suggests that this subfamily is an ancient group, which originated at least in the earliest Late Cretaceous. Our discovery sheds light on the palaeodiversity of Cantharidae in the Late Mesozoic. Together with other previously reported fossil cantharids, it is likely that Malthininae has been fairly diverse during the early evolution of Cantharidae. On the other hand, a morphological similarity between Archaeomalthodes and Recent malthinines and the occurrence of flowering plants in the Burmese amber implies a potential flower-visiting behaviour of this fossil species.  相似文献   

5.
辽宁北部秀水盆地秀D1井孢粉组合及其地层意义   总被引：2，自引：1，他引：1  
孢粉化石采自辽宁省北部秀水盆地的秀D1井,分析、鉴定和系统研究结果表明,来自秀D1井井深62.1~1089.7m的孢粉化石自下而上划分为3个孢粉组合,下部孢粉组合(井深703.85~1089.7m)以Osmundacidites-Klukisporites-Podocarpidites为代表,地质时代为晚侏罗世堤塘期(Tithonian),中部孢粉组合(井深381.5~699.3m)以Densoisporites-Cicatricosisporites-Piceaepollenites为代表,地质时代为早白垩世贝里阿斯期(Berriassian),上部孢粉组合(井深62.1~339m)以Cicatricosisporites-Impardecispora-Pinuspollenites为代表,地质时代为早白垩世凡兰吟期—欧特里夫期(Valanginian-Hauterivian)。秀D1井钻遇地层所含孢粉组合特征在区域上可以与冀北地区大北沟组,辽宁西部地区下白垩统义县组、九佛堂组,松辽盆地东南缘下白垩统火石岭组、沙河子组所产的孢粉组合对比。含孢粉组合地层时代的确定解决了井柱地层的划分,以及与区域地层的对比关系,同时为区域地层古生物研究提供了翔实的基础资料。  相似文献   

6.
The isotopic and geochemical studies of the Upper Cretaceous-Cenozoic flysch sequences of the Kamchatka Peninsula and southern Koryak region revealed that they were formed at least from two sources: one depleted (T) with low 87Sr/86Sr and high positive SrNd(T) values and one enriched (T) with high 87Sr/86Sr and negative SrNd(T) values. The enriched source was likely represented by complexes of ancient upper continental crust. The subduction-related rocks and, to a lesser extent, basalts of mid-oceanic ridges or back-arc basins could serve as a juvenile source for most of the flysch sediments. The Upper Cretaceous flysch sediments differ from their Cenozoic analogues in composition. The Upper Cretaceous rocks are dominated by enriched upper crustal material. The Cenozoic sequences of the Ukelayat Trough and Paleocene-Eocene sequences of the Kumroch Range contain a substantial amount of island-arc volcanoclastic material; the Eocene flysch of Karaginskii Island is compositionally similar to the Upper Cretaceous flysch sequences.  相似文献   

7.
A new genus and species of tetrablemmid spider, Electroblemma bifida n. gen. et sp., is described, from two adult males found in Upper Cretaceous (Cenomanian) amber of Myanmar. The genus is distinguished by its enormous dorsal carapace projection and highly modified chelicerae. The new genus is referred to the tribe Tetrablemmini within the subfamily Tetrablemminae. The presence of a relatively derived tetrablemmid on the south-east Eurasian continent during the Late Cretaceous suggests that the family was already well diversified in tropical rainforests at this time.  相似文献   

8.
Lepisosteid fishes are well known from the Upper Cretaceous of Europe, but only by fragmentary remains from some Cenomanian and Campanian–Maastrichtian deposits. Here we report various cranial and postcranial remains of gars, discovered in the Upper Cretaceous (Santonian) Csehbánya Formation of Iharkút (Bakony Mountains, Hungary). These remains represent one of the most diverse assemblages of lepisosteid fish material from Upper Cretaceous continental deposits of Europe. Based on tooth morphology, scale-microstructure and the features of the supracleithrum we refer these remains to the genus Atractosteus. Besides some uncertain remains from the Cenomanian of France and Spain, the Santonian aged fossils from Iharkút represent the oldest undisputable occurrence of the family Lepisosteidae in the European continental Cretaceous. Using tooth crown morphology, the surface microstructure of the ganoid scales and the anatomy of the supracleithrum a review of the Late Cretaceous lepisosteid record suggests the occurrence of both Atractosteus and Lepisosteus in the European archipelago.  相似文献   

9.
This paper presents an updated review of the Upper Mesozoic and Cenozoic sedimentological and stratigraphic evolution of the Levant margin with a focus on the northern Lebanon. Facies and microfacies analysis of outcrop sections and onshore well cores (i.e., Kousba and Chekka) supported by nannofossil and planktonic foraminifers biostratigraphy, allowed to constrain the depositional environments prevailing in the Turonian to Late Miocene. The “Senonian” (a historical term used to define the Coniacian to Maastrichtian) source rock interval was subdivided into four sub-units with related outer-shelfal facies: (1) Upper Santonian, (2) Lower, (3) Upper Campanian, and (4) Lower Maastrichtian. This Upper Cretaceous rock unit marks the major drowning of the former Turonian rudist platform. This paper confirms the Late Lutetian to Late Burdigalian hiatus, which appears to be a direct consequence of major geodynamic events affecting the Levant region (i.e., the continued collision of Afro-Arabia with Eurasia), potentially enhanced by regressional cycles (e.g., Rupelian lowstand). The distribution of Late Burdigalian–Serravallian rhodalgal banks identified in northern Lebanon was controlled by pre-existing structures inherited from the pulsating onshore deformation. Reef barriers facies occur around the Qalhat anticline, separating an eastern, restricted back-reef setting from a western, coastal to open marine one. The acme of Mount Lebanon’s uplift and exposure is dated back to the Middle–Late Miocene; it led to important erosion of carbonates that were subsequently deposited in paleo-topographic lows. The Late Cretaceous to Cenozoic facies variations and hiatuses show that the northern Lebanon was in a higher structural position compared to the south since at least the Late Cretaceous.  相似文献   

10.
The Divrigi and Kuluncak ophiolitic mélanges are located in central Anatolia in the Tauride ophiolite belt. The stratigraphic sequence in the Divrigi ophiolitic mélange includes, from bottom to top, the Upper Jurassic-Lower Cretaceous Akdag limestone, Upper Cretaceous Çalti ultramafic rocks, and the Curek listwaenite. The Divrigi ophiolitic mélange is intruded by the Late Cretaceous-Eocene Murmano pluton. The above stratigraphic sequence is followed by the Eocene-Paleocene Ekinbasi metasomatite and the Quaternary Kilise Formation.

The oldest sequence of rocks in Kuluncak ophiolitic mélange in the GuvenÇ area is the Karadere serpentine/ultramafic body overlain successively by the Kurtali gabbro, Gundegcikdere radiolarite, the GuvenÇ listwaenites, and the Buldudere Formation. All of these units are Late Cretaceous in age. The Karamagra siderite deposit in the Hekimhan area probably was formed in the Lower Cretaceous at the contact between Çalti ultramafic rocks and the Buldudere Formation. The Kuluncak ophiolitic mélange was intruded by a subvolcanic trachyte in the Late Cretaceous. The Eocene-Paleocene Konukdere metasomatite, the Miocene Yamadag volcanic rocks, and Quaternary slope deposits are late in the stratigraphic sequence in the GuvenÇ area.

The Kuluncak ophiolitic mélange in the Karakuz area is similar to that at GuvenÇ; however, gabbro, radiolarite, and Miocene volcanic rocks are not present. The Miocene is represented by the Ciritbelen Formation at Karakuz and the Karakuz iron deposit is hosted by a Late Cretaceous subvolcanic trachyte.

The rareearth and trace-element concentration of serpentinite in the Divrigi and Kuluncak ophiolitic mélanges indicate that all of the ultramafics and their alteration products were derived from a MORB, which was depleted in certain elements and oxides. The results expressed in this study support the idea that the Divrigi and Kuluncak ophiolitic mélanges within the Tauride ophiolite belt originated from Northern Tauride oceanic lithosphere (Poisson, 1986), instead of a northern branch of Neo-Tethys (Sengor and Yilmaz, 1981).  相似文献   

11.
Outcrops of the Upper Cretaceous (Coniacian-Campanian) Chico Formation, exposed along the east flank of California's northern Great Valley, have yielded a highly diverse, well-preserved molluscan fauna. Previously uncollected deposits, as well as classic localities, have been stratigraphically collected to determine the Santonian-Campanian succession of important ammonites and inoceramid bivalves.Five megafossil zones are readily identifed in outcrops of the Chico Formation. These are, in ascending stratigraphic order, the zones of Hyphantoceras venustum, Baculites capensis, Bostrychoceras elongatum, Inoceramus schmidti and Baculites chicoensis.Two of the zones, Bostrychoceras elongatum and I. schmidti, are missing at the type locality of the Chico Formation because of a stratigraphic disconformity. As a result, previous conceptions about the ranges of some important ammonites and inoceramids in California are in error.Lowest exposures of the H. venustum Zone in the Chico Formation are probably latestConiacian in age. Recent palaeomagnetic sampling of Cretaceous strata of the Great Valley (Ward et al., 1983) has confirmed that the Baculites chicoensis Zone is indicative of the lowest Campanian. The age of the I. schmidti Zone in California is therefore latest Santonian.This molluscan sequence enables precise correlation of Chico strata with other Upper Cretaceous outcrop in the Great Valley; in addition, lowermost deposits of the Upper Cretaceous Nanaimo Group of British Columbia can now be firmly correlated with California strata.  相似文献   

12.
The stratigraphic distribution of the principal Upper Cretaceous facies in Sardinia ispresented, with special reference to the eastern part of the Island. Included are remarks on the mid-Cretaceous tectonic activity, which marks the base of the Upper Cretaceous depositional cycle. The presence of Upper Santonian and Lower Maastrichtian (the latter represented by marls with sparse turbidite interbeds) in the Lanaitto syncline (Oliena) is documented. Both contain outer-shelf assemblages rich in planktic Foraminifera. Recognition of rare detrital glaucophane in the Maastrichtian sandstones suggests a source area affected by high-pressure metamorphism, possibly corresponding to the southward extension of alpine Corsica.The Tertiary conglomerates exposed near Oliena include pebbles of facies (Campanienand Upper Maastrichtian rudistid limestones with larger Foraminifera) unknown in outcrop. A preliminary study of the rudists suggests a faunal exchange between different palaeobio-geographical provinces belonging, respectively, to the West European and Adriatic Plates.A palaeontological appendix contains remarks on some representatives of the family Heterohelicidae and on one species of Gunnarites found in the Lower Maastrichtian.  相似文献   

13.
The first specimen of Aturoidea to be recorded in East Asia has been found in the Upper Cretaceous Sada limestone in Shimanto City, Kochi Prefecture, Japan. The specimen is one of the few representatives from the Upper Cretaceous, along with species known from Libya, Angola, and India. The specimen is very similar to A. mathewsonni from the Paleocene deposits in California. However, we describe the specimen as A. cf. mathewsonni, as it slightly differs from A. mathewsonni in the shape of the lateral lobe of the suture. The finding reveals that Aturoidea had already lived in waters around East Asia in the Late Cretaceous.  相似文献   

14.
Metabasites (amphibolites, garnet amphibolites, and basic crystalline schists) compose numerous sheeted bodies (often highly boudined) from a few to 100 meters thick in the plagiogneisses and migmatites of the Kolpakov Group. Chemically, they are reconstructed as basalts and picrites that were metamorphosed, as host terrigenous rocks, under the kyanite-sillimanite subfacies of the amphibolite facies (t = 620–650°C, P s = 5.9–6.9 kbar). Metabasites are dominated by amphibolites and basic crystalline schists distributed throughout the entire section of the Kolpakov Group, whereas garnet amphibolites are more typical of the upper parts of the group, where they are intercalated with amphibolites, basic crystalline schists, plagiogneisses, and quartzites. Metaultrabasites (plagioclase-free amphibolites) occur much more rarely as small boudins up to few meters in size. According to U-Pb SHRIMP zircon dating, the plagiogneiss protolith age corresponds to the end of the Early-Late Cretaceous (90–100 Ma), which is similar in age to the weakly metamorphosed terrigenous deposits of the Kikhchik Group of the Sredinny Range. This allows us to consider the terrigenous rocks of these groups as isofacial sedimentary rocks. The same age (Early-Late Cretaceous boundary) was taken for protoliths of metabasites forming interbeds among metaterrigenous deposits of the Kolpakov Group. The interval of 100?90 Ma coincides with the beginning of the formation of the Okhotsk-Chukotka volcanogenic marginal-continental belt in East Asia. It is shown that the Kolpakov Group possesses the geochemical features of tholeiitic basalts of different geodynamic settings and comprises both typically island arc (low-Ti) and oceanic (moderate to high-Ti) tholeiites associated with ultrabasic volcanic rocks—picrites. Such a chemical peculiarity of basic rocks is typical of the marginal-continental extension zones (pull-apart basin) that were initiated on the sialic crust. It is obvious that similar geodynamic setting of the basite magmatism existed for the Sredinny Range of Kamchatka. The ascent of the mantle matter beneath the extension zone of the continental crust of the sedimentary basin and its intersection by faults that formed simultaneously with the Okhotsk-Chukotka volcanogenic belt served as the beginning of the basite volcanism in the sedimentary basin. They provided an intense fluid effect and a temperature increase in the crust with subsequent granitization and metamorphism of volcanogenic-terrigenous deposits and, finally, the development of the modern structure of the Sredinny Kamchatka Massif. The intense Late Cretaceous basite volcanism and associated granitoid magmatism in Kamchatka were presumably caused by the ascent of mantle plumes bearing hydrogen fluids.  相似文献   

15.
This article gives an account of the results of the U-Pb-SHRIMP study of zircons derived from gneissoid and equigranular granitoids of the Malka Uplift of the Sredynnyi Range in Kamchatka. It was established that intrusion and crystallization of granitoids occurred in the time interval from 76.2 ± 1.5 to 83.1 ± 2.0 Ma. The texture of zircon crystals suggests their magmatic origin. The obtained data reliably confirm that granite formation and emplacement of the recently formed continental crust in Kamchatka took place in the Late Cretaceous (Campanian).  相似文献   

16.
The Family Afrograptidae is a ‘conchostracan’ group with multiple radial costae reaching to the umbo on their carapaces. It comprises four described genera: Afrograpta, Camerunograpta, Congestheriella and Graptoestheriella with a total of thirteen described species which are occasionally reported from the Jurassic and the Cretaceous in Africa, Europe and South America (i.e. Afrograpta from the Upper Cretaceous of Cameroon; Camerunograpta from the Jurassic to Cretaceous of Cameroon; Congestheriella from the Jurassic to Upper Cretaceous of the Congo Basin, Brazil, Bulgaria, Venezuela and Argentina; and Graptoestheriella from the Upper Jurassic to Lower Cretaceous of Brazil). A new genus and a new species, Surreyestheria ockleyensis gen. et sp. nov., belonging to the Family Afrograptidae from the Lower Cretaceous (lower Barremian) Upper Weald Clay Formation of Ockley Village, Surrey County, southern England is described in this paper. The new genus mainly differs from the other four genera by the special reticulate ornamentation on its carapace. It indicates that the Family Afrograptidae was more diverse and more widely distributed in the late Mesozoic than previously supposed. Afrograptidae is a special branch of Estheriellina the latter originating in the late Palaeozoic and the former in the early Mesozoic. Afrograptids, as a whole had been widespread across Pangea in the Early Jurassic.  相似文献   

17.
The results of complex palynological and microfaunistic studies of Upper Cretaceous and Cenozoic deposits of the Bakchar iron ore deposit are presented. Geochronologically, the age of the deposits varies from Campanian to Quaternary. It was established that the Slavgorod, Gan’kino, and Jurki (?) formations contain four biostratons in the rank of beds with dinocysts and three biostratons in the rank of beds with spores and pollen. The Cenozoic continental deposits contain four biostratons in the rank of beds, containing spores and pollen. As a result of the study, a large stratigraphic gap in the Cretaceous–Paleogene boundary deposits, covering a significant part of the Maastrichtian, Paleocene, Ypresian, and Lutetian stages of the Eocene, was established. The remnants of a new morphotype of heteromorphic ammonites of genus Baculites were first described in deposits of the Slavgorod Formation (preliminarily, upper Campanian). The distribution features of the different palynomorph groups in the Upper Cretaceous–Cenozoic deposits in the area of study due to transgressive-regressive cycles and climate fluctuations were revealed.  相似文献   

18.
The Kocali Complex in SE Turkey includes pelagic sediments (pelagic limestones, cherts, etc.), basic volcanic rocks of oceanic crust origin together with platform-derived sediments. Its depositional age was previously assigned as Late Jurassic–Early Cretaceous. In order to study the radiolarian contents of volcano-sedimentary sequences in this complex, six stratigraphic sections have been measured mainly at the NE and NW Adiyaman city.Radiolarian faunas from these stratigraphic sections reveal that the age of these sequences ranges from middle Carnian to Rhaetian. Based on these data, the depositional age of the complex is older than the previously assigned. Lithological characteristics (widespread Triassic basic volcanic rocks associated with pelagic sediments) and radiolarian contents of these sequences have close similarities with the sequences of the Alakircay Nappe of the Antalya Nappes in western and central Taurides.Based on taxonomic studies, 99 taxa have been determined of which one genus (Adiyamanium) and four species (Monocapnuchosphaera kocaliensis, Paronaella speciosa, Ferresium okuyucui and Adiyamanium crassum) are described as new.  相似文献   

19.
The Upper Cretaceous succession of the Leonese Area (NW Spain) comprises mixed clastic and carbonate sediments. This succession is divided into two lithostratigraphic units, the Voznuevo Member and the Boñar Formation, which represent fluvial, shoreface, intertidal, subtidal and open‐shelf sedimentary environments. Regional seismic interpretation and sequence stratigraphic analysis have allowed the study of lateral and vertical changes in the sedimentary record and the definition of third‐order levels of stratigraphic cyclicity. On the basis of these data, the succession can be divided into two second‐order depositional sequences (DS‐1 and DS‐2), incorporating three system tracts in a lowstand to transgressive to highstand system tract succession (LST–TST–HST). These sequences are composed of fluvial systems at the base with palaeocurrents that flowed westward and south‐westward. The upper part of DS‐1 (Late Albian–Middle Turonian) shows evidence of intertidal to subtidal and offshore deposits. DS‐2 (Late Turonian–Campanian) comprises intertidal to subtidal, tidal flat, shallow marine and lacustrine deposits and interbedded fluvial deposits. Two regressive–transgressive cycles occurred in the area related to eustatic controls. The evolution of the basin can be explained by base‐level changes and associated shifts in depositional trends of successive retrogradational episodes. By using isobath and isopach maps, the main palaeogeographic features of DS‐1 and DS‐2 were constrained, namely coastline positions, the existence and orientation of corridors through which fluvial networks were channelled and the location of the main depocentres of the basin. Sedimentation on the Upper Cretaceous marine platform was mainly controlled by (i) oscillations of sea level and (ii) the orientation of Mesozoic faults, which induced sedimentation along depocentres. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

20.
The enigmatic staphylinid subfamily Dasycerinae consists of only 17 species within a single extant genus Dasycerus, but it is easily distinguished from other rove beetles by overall, latridiid beetle-like body and extremely slender, verticillate antennae. Direct fossil evidence is lacking for this group. Here, I describe the first fossil of this peculiar subfamily, Protodasycerus aenigmaticus gen. and sp. n., from the Upper Cretaceous Burmese amber. Despite considerable external similarities to extant dasycerine species, this new genus possesses several important morphological differences: a much smaller body size (ca. 1.1 mm), narrowly elongate antennomeres 1 and 2, not strongly transverse metaventrite, elytra striate but not tricostate, and truncate posterior margin of the elytra exposing four abdominal tergites dorsally. The new finding of a Cretaceous representative of the Dasycerinae helps elucidate the origin and early evolution of the omaliine group subfamilies, implying rather close similarities between the Dasycerinae and the monobasic subfamily Neophoninae. Discovery of P. aenigmaticus suggests a rather ancient origin of the subfamily by the Upper Cretaceous.  相似文献   

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