Radiolarians and stratigraphy of Cenomanian-Coniacian deposits in the Crimean and West Sakhalin Mountains, Pt. 1: Biostratigraphic subdivision and correlation

Radiolarian biostratigraphy suggested in this work for the Cenomanian-Coniacian deposits in the Crimean and West Sakhalin Mountains is enhanced to be of a higher resolution. The Cenomanian-Coniacian succession of the West Sakhalin Mountains is subdivided into nine instead of five biostratigraphic units formerly known in this region. Deposits of the Crimean Mountains are subdivided based on radiolarians within the lower Cenomanian-lower Coniacian stratigraphic interval (the original biostratigraphic chart corresponded here to the upper Cenomanian-middle Turonian interval only). The established biostratigraphic subdivisions are correlated with those of the Tethyan and Pacific scales.     

Radiolarians and stratigraphy of Cenomanian-Coniacian deposits in the Crimean and West Sakhalin Mountains, Pt. 2: Comparative analysis

The work is aimed at summarizing data on Late Cretaceous radiolarians from the Crimean and West Sakhalin mountains. The Cenomanian-lower Coniacian stratigraphic interval of the Crimean Mountains yields 215 radiolarian species, and 80 concurrent species are known from the West Sakhalin Maintains. According to results of comparative analysis, there are 62 species in common from two regions, i.e., most of the species occurring in the West Sakhalin Mountains are also known from southerly regions, which is a good premise for correlation.     

Sedimentary formations of the Cretaceous Sakhalin Basin (Far East Asia)

The marine sedimentary formations of the Middle Albian to Maastrichtian in the Cretaceous Sakhalin Basin (CSB) were investigated. These successions of strata consist of interbedded sandy, clayey and calcareous rocks which are underlain by heterogeneous metamorphosed (up to greenschist facies) Paleozoic to Mesozoic (pre-Aptian) rocks. The studied sections display several different facies reflecting geological settings ranging from an inner shelf to a continental slope. Three depositional complexes bound by regional subaerial unconformities are recognized within the marine successions. Since the Albian, the CSB has been a rapidly subsiding marginal part of the Okhotsk Sea plate. The Naiba Valley succession, corresponding to a sublittoral zone, shows extremely high sedimentation rates up to 190 m/Ma. The stratigraphic distribution of lithofacies indicates that the CSB became shallower from the Middle Albian to the Maastrichtian.     

Early cretaceous radiolarian assemblages from the East Sakhalin Mountains

Three-dimensional radiolarian skeletons isolated from rock matrix in HF solution and then studied under scanning electron microscope substantiate the Early Cretaceous age of volcanogenic-cherty deposits sampled from fragmentary rock successions of the East Sakhalin Mountains. Accordingly the Berriasian age is established for jasper packets formerly attributed to the Upper Paleozoic-Mesozoic Daldagan Group; the Valanginian radiolarians are identified in cherty rock intercalations in the Upper Paleozoic (?) Ivashkino Formation; the Berriasian-Barremian assemblage is macerated from cherty tuffites of the Jurassic-Cretaceous Ostraya Formation; and the Aptian-early Albian radiolarians are characteristic of tuffaceous cherty rocks sampled from the Cretaceous Khoe Formation of the Nabil Group. Photographic documentation of radiolarian skeletons specifies taxonomic composition and age of the Berriasian, Valanginian, Berriasian-Valanginian, Barremian, and Aptian-Albian radiolarian assemblages from the East Sakhalin Mountains, and their evolution as related to abiotic events is considered. Coexistence of Tethyan and Pacific species in the same rock samples evidence origin of radiolarian assemblages in an ecotone. Consequently, the assemblages are applicable for intra- and interregional correlations and paleogeographic reconstructions.     

The radiolarian assemblages of the Bonarelli Horizon in the Umbria-Marche Apennines and Southern Alps, Italy

The Bonarelli Horizon is an important regional marker level in the Umbria-Marche Apennines. It is characterized by consisting of black bituminous shales that yield a distinctive radiolarian fauna. Black shales referable to the Bonarelli Horizon are also present in the Southern Alps. The horizon is of uniform lithology and contains radiolarian assemblages of late Cenomanian-early Turonian age throughout both the Umbria-Marche Apennines and Southern Alps. Several new radiolarian taxa have been recognised and described from the Bonarelli Horizon of both areas. Two new species are defined in this paper, namelySethocapsa bossoensisandXitus picenus.     

First finds of Late Tithonian and middle-late Albian radiolarian assemblages in volcanogenic-siliceous rocks of the Amur River right lower reaches and their tectonic significance

The lithological-stratigraphic study of volcanogenic-siliceous rocks developed on the left side of the Machtovaya River, a right tributary of the Amur River, yielded the first radiolarian assemblages of the late Late Tithonian, the late Late Tithonian-early Valanginian, and the middle-late Albian age. It is established that the stratigraphic succession of volcanogenic-siliceous rocks in this area is composed of upper Tithonian-Valanginian dark red to red-brown cherts with basalts in the lower part of the section and Albian dark gray clayey cherts, olive-gray siliceous-tuffaceous argillites, and tufaceous siltstones in its upper part. The replacement of cherts by their clayey varieties likely occurred in the Aptian. The composition, structure, and age of these strata and the rocks constituting the Kiselevka-Manoma accretionary complex are different, which indicates their different tectonic origin.     

Cenomanian Turrilitidae (Cretaceous heteromorph ammonites) from the Koppeh Dagh,northeast Iran: Taxonomy and stratigraphic implications

Early and early middle Cenomanian turrilitid ammonoids from the upper part of the Albian–Cenomanian Aitamir Formation of the Koppeh Dagh (northeast Iran) are described, illustrated and placed in an integrated stratigraphic context. The Aitamir Formation represents a graded siliciclastic shelf system and the turrilitid faunas comprise eight different species. Representatives of Mariella and Hypoturrilites have been recorded from a lower Cenomanian horizon in the Ghorghoreh section, corresponding to the Mantelliceras mantelli ammonite biozone. Mariella bicarinata (Kner, 1852) and H. wiedmanni Collignon, 1964 are recorded for the first time from Iran and the larger palaeobiogeographical area, respectively. The horizons with Turrilites costatus and T. scheuchzerianus at Taherabad can be dated as early middle Cenomanian Acanthoceras rhotomagense Zone, T. costatus Subzone. Concentrations of ammonoids commonly occur above regressive sandstone units, at the transition into overlying deeper marine shale units and in their lower parts, respectively. Such intervals represent the early transgressive systems tract of depositional sequences and may thus be regarded as early transgressive, slightly condensed shell accumulations. The uppermost lower to lower middle Cenomanian succession at Taherabad is of striking bio-, event- and sequence stratigraphic similarity to contemporaneous sections in northwest Europe. It reflects deposition during falling and low sea-level associated with the latest early Cenomanian unconformity SB Ce 3 as well as the pulsating transgressive development during the early middle Cenomanian, including levels correlative to the arlesiensis, primus and Mid-Cenomanian events in northwest Europe.     

Berriasian (Lower Cretaceous) brachiopods from the Crimea

Four successive assemblages of Berriasian brachiopods distinguished for the first time in the Crimea are correlated with concurrent subdivisions of the ammonoid scale. Berriasian brachiopods are represented by 44 species of 27 genera and 14 families, which are most complete in terms of taxonomic composition as compared to other concurrent brachiopod faunas known elsewhere. The assemblages are dominated by local species. As is proved, the Berriasian brachiopods studied are appropriate for age determination, subdivision and correlation of their host deposits. Their geographic distribution that has been analyzed elucidates connections of the Berriasian sea basins within the Mediterranean paleozoogeographic region.     

Stratigraphy and radiolarians of upper cretaceous sedimentary cover of the Arakapas ophiolite massif (Cyprus)

In the basal interval, sedimentary cover of the Arakapas ophiolite massif (southern Cyprus) is composed of metalliferous sediments of the Perapedhi Formation that is divided into three sequences based on diverse radiolarian assemblages. These are basal umbers of the Cenomanian age presumably (2–20 m), interlayering cherts and umbers of the Turonian-Coniacian (6–10 m), and opoka-like cherts of the Coniacian-Santonian. Higher in the succession, there are olistostrome deposits of the Moni Formation, which unconformably rest on the eroded underlying strata. In this formation also divisible into three sequences, the lower one 200 to 300 m thick is composed of variegated, presumably Campanian silty clays containing olistoliths of basic, presumably Upper Triassic volcanics, Lower Cretaceous sandstones, and opoka-like cherts and cherty limestones of the Albian-lower Cenomanian. Next sequence (100–200 m) is represented by alternation of variegated silty and green bentonitic clays of the Campaian, which enclose frequent olistoliths and horizons of fine-clastic olistostrome breccias. The upper sequence of upper Campanian-lower Maastrichtian bentonitic clays (50–100 m) contains interlayers of ash tuffs and clayey cherty sediments. Carbonate deposits of the upper Maastrichtian-Paleogene, conformably overlie the Moni Formation.     

Unusual eruption of the Main Pugachevo gas-water-lithoclastic (Mud) volcano in Sakhalin during the Winter of 2005

The examination of the Main Pugachevo gas-water-lithoclastic volcano during the summer of 2005 and GPS-controlled large-scale (1: 1000) mapping revealed its regular but rather peculiar eruption. It was the largest among the eruptions investigated since 1911 and produced a very unusual lithoclastic field with an area of about 100 000 m² and a volume of about 100 000 m³. The eruption occurred from three distinct active centers and began with a vigorous explosion-like gas burst from one center followed by the noncontemporaneous discharge of a gas-and water-saturated liquid lithoclastic mass from the three centers, which produced a number of flows of different directions and sizes. The flows almost completely covered the smoothed flat open area of the volcano and even invaded the larch forest surrounding the volcano, where they bent, overturned, broke, and occasionally uprooted and dragged over some distance some large trees. The analysis and comparison with all the previously documented eruptions of the Main Pugachevo gas-water-lithoclastic volcano revealed their fairly diverse, sometimes strongly variable character with respect to many parameters: the amount of ejected lithoclastic material; the number of eruption centers; and the proportions of the erupted gaseous, liquid, and solid components. In general, the eruptions show a distinctly multirank periodic character: relatively minor or small low-rank eruptions take place once every 1–2 yr, and large eruptions of a higher rank are much less frequent (supposedly, once in 70 years).     

A new genus of Tanyderidae (Insecta: Diptera) from Myanmar amber,Upper Cretaceous

A new genus and species, Similinannotanyderus lii gen. et sp. nov., is described from Myanmar amber. It differs from other genera of Tanyderidae based on special characters of wing venation and male genitalia. This new taxon broadens the diversity of Tanyderidae in the Cretaceous, and its morphological characters enhance our understanding of the development and evolution of the primitive crane flies.     

Sequence stratigraphy in the upper cretaceous of the Basco-Cantabrian Basin (northern Spain)

The sedimentary cycles of the Cenomanian to Maastrichtian were investigated in the Basco-Cantabrian Basin (BCB) in northern Spain (Provinces of Alava, Vizcaya and Burgos). The depositional area was a distally steepened carbonate ramp which extended from Catalonia northwestwards to the Basque country. The investigated sediments range from calciturbidites and pelagic marls to marl-limestone alternations deposited on a distal carbonate ramp. Shallow marine limestones, marls and intertidal clastics and carbonates were deposited on the proximal part of the carbonate ramp. The establishment of a regional sequence analysis is based on the investigation of seismic profiles, well logs and outcrop sections. Examples of outcrop sections are interpreted in terms of sequence stratigraphy (unconformities of third- and second-order cycles, depositional geometries, systems tracts). The sequence stratigraphic interpretation of outcrop sections is based on facies analysis, interpretation of observed depositional geometries and correlation of unconformities and marine flooding surfaces through the basin. A biostratigraphic framework is established based on ammonites, inoceramids, planktonic and benthic foraminifera. As a result, a regional sequence stratigraphic cycle chart is presented and compared with published global cycle charts. The correlation of the regional cycle chart with published cycle charts is good. In the Cenomanian and Turonian, several sequence boundaries in the BCB are shifted by up to one biozone compared with the global chart. Some type 1 boundaries of the standard chart are only type 2 in the BCB. Important type 1 boundaries in the BCB are: top Geslinianum Zone with a 100 m lowstand wedge at the basis of the sequence (sequence boundary 92.2) ; base Petrocoriense Zone with a 250 m shallowing-upwards lowstand wedge at the basis (sequence boundary 89.2); and within the Syrtale Zone (sequence boundary 85.0).The Campanian-Maastrichtian sequence record is strongly disturbed by local compressive tectonics. Several sequences are recognizable and can be correlated with the global cycle chart. Correlation is hampered by the low biostratigraphic resolution in the western basin part. Subsidence analysis of several sections of the Upper Cretaceous of the BCB and its interpretation in the regional tectonic context leads to a discussion of the causes of the observed cyclicity. A regional eustatic curve is presented for the Upper Cretaceous of the BCB. Stage and substage names were used according Code-Committee (1977). Correspondence to: K.-U. Gräfe     

Tertiary geodynamics of Sakhalin (NW Pacific) from anisotropy of magnetic susceptibility fabrics and paleomagnetic data

Sakhalin has been affected by several phases of Cretaceous and Tertiary deformation due to the complex interaction of plates in the northwest Pacific region. A detailed understanding of the strain is important because it will provide constraints on plate-scale processes that control the formation and deformation of marginal sedimentary basins. Anisotropy of magnetic susceptibility (AMS) data were obtained from fine-grained mudstones and siltstones from 22 localities in Sakhalin in order to provide information concerning tectonic strain. AMS data reliably record ancient strain tensor orientations before significant deformation of the sediments occurred. Paleomagnetically determined vertical-axis rotations of crustal rocks allow rotation of the fabrics back to their original orientation. Results from southwest Sakhalin indicate a N035°E-directed net tectonic transport from the mid-Paleocene to the early Miocene, which is consistent with the present-day relative motion between the Okhotsk Sea and Eurasian plates. Reconstruction of early–late Miocene AMS fabrics in east Sakhalin indicates a tectonic transport direction of N040°E. In west Sakhalin, the transport direction appears to have remained relatively consistent from the Oligocene to the late Miocene, but it has a different attitude of N080°E. This suggests local deflection of the stress and strain fields, which was probably associated with opening of the northern Tatar Strait. A northward-directed tectonic transport is observed in Miocene sediments in southeast Sakhalin, mid-Eocene sediments in east Sakhalin, and in Late Cretaceous rocks of west and northern Sakhalin, which may be associated with northwestward motion and subduction of the Pacific Plate in the Tertiary period. The boundaries of the separate regions defined by the AMS data are consistent with present-day plate models and, therefore, provide meaningful constraints on the tectonic evolution of Sakhalin.     

Late Middle Jurassic (Late Bathonian-early Callovian) radiolarian cherts from the Neotethyan Bornova flysch zone, Spil Mountains, Western Turkey

Alternating radiolarian cherts and mudstones associated with basaltic lavas occur in a olistolith within the Late Cretaceous Bornova Flysch in W Anatolia. Cherts yielded diverse and moderately preserved, Nassellaria-dominated radiolarian faunas of late Bathonian-early Callovian age. Associated volcanic rocks are geochemically classified as remnants of oceanic seamounts. This is so far the first late Middle Jurassic age from the crust of the Neotethyan Izmir-Ankara Ocean in W Anatolia, and suggests that its spreading started earlier. Similar ages were reported from the Vardar and Meliata-Hallstadt Tethyan oceanic branches in Greece and Serbia, which also opened in Late Triassic but closed earlier. Published in Russian in Stratigrafiya. Geologicheskaya Korrelyatsiya, 2009, Vol. 17, No. 3, pp. 70–80. The article is published in the original.     

Cretaceous moths (Lepidoptera: Micropterigidae) with preserved scales from Myanmar amber

Two new species of Micropterigidae, Sabatinca cretacea sp. nov. and Sabatinca limula sp. nov. are described from the Upper Cretaceous Myanmar (Burmese) amber (99 Ma). Based on exquisitely preserved specimens with clear morphological characters and detailed structure of scales, the diagnosis of Sabatinca perveta is emended. Our new findings support that scales have developed various types and shapes by the Cretaceous. The extinct Sabatinca species represent a separate group that may be a transitional group from Australian lineage to extant Sabatinca.     

Sequence architecture and carbonate platform configuration (Late Cenomanian–Santonian), Sinai, Egypt

Abstract Relative sea‐level changes on the mixed carbonate–siliciclastic platform of Sinai are manifested in shifts of distinct facies belts (deep‐water facies, high‐energy subtidal, shallow subtidal, lagoon, shallow shoreface siliciclastics, supratidal) and are interpreted in terms of sequence stratigraphy. Eight sedimentary sequences are recognized for the Upper Cenomanian to Santonian. Their correlation along a north–south transect reveals distinct changes in lithofacies and progradation/retrogradation patterns within the individual systems tracts. The number and stratigraphy of the sequence boundaries of Sinai correlate well with those from adjacent areas. Patterns of increased subsidence are documented for the Central Sinai Basin since the Late Cenomanian by increased thickness of the stratal packages (post‐CeSin 7 HST, post‐TuSin 1 LST and HST, post‐TuSin 2 LST) and are balanced by varying accumulation rates. Based on new sedimentological and biostratigraphic data, large‐scale palaeogeographic maps and cross‐sections show the: (1) temporal and spatial evolution of the Central Sinai Basin, e.g. its latest Cenomanian initial formation, Lower Turonian deep‐water facies, Middle Turonian to Coniacian synsedimentary subsidence; (2) drowning of the Cenomanian platform coinciding with the latest Cenomanian to Early Turonian relative sea‐level rise; (3) re‐establishment of the platform in Middle–Late Turonian times; and (4) a Coniacian basin and swell morphology.     

Quaternary palaeoceanographic changes in the northern South China Sea (ODP Site 1146): radiolarian evidence

The abundance and accumulation rates of siliceous microfossils in the northern South China Sea, including radiolarians, diatoms and sponge spicules, increased during most glacial intervals within the past 1100 kyr. Similar trends are observed in the index of thermocline surface radiolarians (TSR), diatom accumulation rates (DAR), charcoal accumulation rates (CAR) and the abundance of radiolarian species Cycladophora davisiana davisiana. Decreasing sea‐surface temperature accompanied by increased seasonality since 900 ka is indicated by a decline in the tropical radiolarian assemblage, including Tetrapyle octacantha and Octopyle stenozona, and by an increase in the subtropical assemblage, including Pterocorys zancleus, Peromelissa phalacra and Ommatartuts tetrathalamus tetrathalamus. Rapid increases at about 800 to 700 ka of siliceous microfossils, charcoal, subsurface and intermediate radiolarians, as well as the TSR index and the DAR, imply a fundamental shift in climate and a shoaling thermocline. Although these fundamental changes in the silicious fauna and flora of the South China Sea take place within the context of a developing 100‐kyr cycle, they do not change in step with changing sea‐level as indicated by marine δ¹⁸O. This is most clearly illustrated by the step‐like increase in silica accumulation (radiolaria, diatoms and sponge spicules) at 680 ka. Rather, these fundamental changes probably reflect intensified surface productivity associated with enhanced East Asian winter‐monsoon circulation. Copyright © 2003 John Wiley & Sons, Ltd.     

冲绳海槽表层沉积物放射虫属种空间分布特征及其影响因素

为探究冲绳海槽放射虫属种的空间分布特征及其海洋学意义,对采自冲绳海槽北部、中部和南部3个海域的34个表层沉积物中的放射虫群落组成特征进行了系统研究。总体看来,冲绳海槽表层沉积物放射虫丰度较高,群落组成以热带-亚热带暖水放射虫属种为主,其中优势种为Tetrapyle octacantha group、Spongodiscus resurgens和Euchitonia furcata。结果表明冲绳海槽放射虫属种存在明显的区域差异性,除T.octacantha group以外,其余暖水指示种含量总体上均呈现南高北低的变化趋势。冲绳海槽北部陆架-陆坡区受长江冲淡水的影响,温度和盐度变化较为剧烈,因此可能不利于大多数放射虫暖水指示种的发育,但T.octacantha group却因自身适宜生存的温度范围较大,进而得以在冲绳海槽北部陆坡区呈现出高值。较高的中层水温度可能是抑制亚北极中层水指示种Cycladophora davisiana在冲绳海槽分布的主要因素,而冲绳海槽的高海槛则限制了太平洋深层水种Carpocanistrum papillosum和Cornutella profunda的入侵。冲绳海槽放射虫的空间分布对区域海洋环境特征有着很好的响应,因此可以为古环境重建研究提供重要依据。     

First pachycephalosaurid (Dinosauria: Ornithischia) from the Frenchman Formation (upper Maastrichtian) of Saskatchewan,Canada

Compared to earlier representatives of the family, pachycephalosaurids are less well known from upper Maastrichtian deposits around the world. Here, we report on a nearly complete left postorbital attributable to the pachycephalosaurid Sphaerotholus cf. Sphaerotholus buchholtzae from the upper Maastrichtian Frenchman Formation of Saskatchewan. This marks a probable northern range extension for the species into Canada, and the first occurrence of a pachycephalosaurid from this formation. We further demonstrate the taxonomic distinction between Stegoceras edmontonense and S. buchholtzae, which has been debated, based on postorbital sutural proportions. The northerly occurrence of Sphaerotholus cf. S. buchholtzae is consistent with the hypothesis of low beta diversity during the late Maastrichtian of North America, and its high stratigraphic incidence documents the persistence of non-pachycephalosaurin pachycephalosaurines in a critical interval for understanding the end-Cretaceous mass extinction event.