Turonian Radiolarians from Karnezeika,Argolis Peninsula,Peloponnesus (Greece)

Near Karnezeika a roughly 140 m thick Upper Cretaceous section consists of interbedded pelagic limestones, cherts and coarse polymict breccias including ophiolites and shallow water limestones. At the base, pink pelagic limestones rest on deeply altered and fractured Lower Jurassic Pantokrator Limestone. This first pelagic facies is dated as middle Turonian, based on planktonic Foraminifera. Over 100 m of coarse ophiolite-carbonate breccias, interpreted as a channel or canyon fill in a pelagic environment, document the erosion of the Late Jurassic nappe edifice along the Cretaceous Pelagonian margin. Above these breccias, we mesured 16 m of principally pink and red pelagic limestones and radiolarian cherts, in which we recovered well-preserved radiolarians discussed here. In this interval, the presence of planktonic Foraminfera allows to state a late Turonian to Coniacian age. More than 40 radiolarian species are described and figured in this work. The radiolarian chronostratigraphy established by 10 different authors in 11 publications was compared for this study and used to establish radiolarian ranges. This exercise shows major discrepancies between authors for the radiolarian ranges of the studied assemblage. Nevertheless, a Turonian age can be stated based on a synthesis of cited radiolarian ranges. This age is consistent with the age based on planktonic foraminifera. In combining the ages of both Radiolaria and planktonic Foraminifera, the studied samples can be restricted to the late Turonian. However, the discrepancies of published radiolarian ranges call for an urgent, major revision of the Late Cretaceous radiolarian biochronology. The integration of planktonic foraminifera with radiolarians may greatly enhance biochronologic resolution in sections where both groups occur.     

Geochemistry of Cenomanian/Turonian boundary sediments in the mountainous part of Crimea and the northwestern Caucasus

Detailed data obtained on the chemistry of sedimentary rocks from the mountainous part of Crimea and the northwestern Caucasus that were dated at the Cenomanian/Turonian boundary and were formed during Oceanic Anoxic Event 2 (OAE 2) make it possible to calculate the dissolved oxygen concentration in the bottom waters of the sedimentation basin. The enrichment coefficients of trace elements in the black shales are revised and an explanation is suggested for the genesis of the rocks with regard for unusual climatic changes.     

Radiolarians of the upper Cenomanian and lower Turonian from deposits of the Ananuri Formation, the western Caucasus (Lazarevskoe area)

Diverse radiolarians (over 70 species) are detected in cherty rocks above the bituminous shale horizon, the marker of anoxic event OAE-2 recorded across the Cenomanian-Turonian boundary in the upper part of the Ananuri Formation of flyschoid deposits, the Lazarevskoe area of the western Caucasus. The radiolarian assemblages studied are comparable in composition with radiolarians from concurrent Cenomanian-Turonian boundary strata in other Mediterranean regions (e.g., in the Crimea and Turkey). The lower radiolarian assemblage includes index species Dactyliosphaera silviae of synonymous Cenomanian zone. Alievium superbum present in the upper assemblage is index species of the relevant Turonian zone. Within the studied flyschoid sequence, sediments indicative of the above event (bituminous shales and cherts) are confined to upper elements of flysch rhythms.     

Stable isotope analysis of the Cenomanian–Turonian (Late Cretaceous) oceanic anoxic event in the Crimea

Carbon and oxygen isotope data from Cenomanian–Turonian sediments from the southwest of the Crimea are presented. The sediments consist of limestones, marls and organic-rich claystones, the latter with total organic carbon values up to 2.6 wt. %, representing Oceanic Anoxic Event 2. A shift to more negative δ¹⁸O values through the uppermost Cenomanian into the lowermost Turonian may be the result of warming; however, petrographic analysis shows that the samples have undergone a degree of diagenetic alteration. The carbon isotope data reveal a positive excursion from 2.7‰ to a peak of 4.3‰ at the Cenomanian/Turonian boundary; values then decrease in the early Turonian. This excursion is comparable to those of other Cenomanian–Turonian sections, such as those seen in the Anglo-Paris Basin, and is thought to be due to global changes in the oceanic carbon reservoir. On this curve are a number of negative δ¹³C excursions, just below the Cenomanian/Turonian boundary. It is suggested that these negative excursions are associated with the uptake of light carbon derived from the oxidation and deterioration of organic material during localised exposure of the sediments to oxic or meteoric diagenetic conditions, possibly during sea-level fluctuations.     

The sedimentary conditions of Middle-Upper Tithonian Limestones of the Demerdzhi Plateau (Mountain Crimea)

As a result of a microfacies analysis of the section of Middle-Upper Tithonian Limestones of the Demerdzhi Plateau (Mountainous Crimea), 12 microfacies types of rocks were distinguished. It has been established that these microfacies types formed in the facies zones of an inner carbonate platform: the littoral, restricted and open marine and sand shoals of the margins of a carbonate platform. The sequence of the microfacies types in the vertical section corresponds to a transgressive trend with minor sea-level fluctuations of the second order. In addition, the communities of microencrusters, which played an active role in sediment stabilization and formation of small bioherms, have been studied. These communities are considered to be evidence of the shallowness of the paleobasin     

Radiolarians from the Pohang Basin,Southeast Korea and Paleoceanographic Implications

We identified a total of 101 species and two subspecies of radiolarians belonging to 56 genera from 95 samples collected from the Hagjeon and Duho Formations in the Pohang Basin of the southeastern Korean Peninsula. On the basis of the biostratigraphic range of Cyrtocapsella cornuta and Theocorys redondoensis, the depositional period of the upper Hagjeon and lowest Duho Formations was determined to be early to late Middle Miocene. The occurrence of deep-dwelling radiolarians indicates that the paleobathymetry seems to become gradually progressing toward an upper bathyal environment in the middle part of the Hagjeon Formation. However, we prefer to accept another interpretation for the occurrence of deep-sea indicators in the Hagjeon and the lowest part of the Duho Formations, and consider the presence of a region of upwelling cold water that might have simulated a deep-water environment in relatively shallow water. This interpretation is based on the present upwelling of a cold-water mass off the southeast coast of Korea, the occurrence of upwelling microfossils from the Pohang Basin, and the effect of the closing of the Korea Strait approximately 15 Ma. We also considered that the uppermost part of the studied section represents a shallow-water environment.     

Permo-Carboniferous Radiolarians from the Wupata''''erkan Group,Western South Tianshan, Xinjiang, China

1 IntroductionThe Wupata'erkan Group, also called Wupata'erkanFormation (Wang et al., 1990), in the western SouthTianshan, China (Fig. 1), mainly comprises gray and darkgray fine-grained clastic rocks, interlayered with medium-acidic volcanic rocks (andesite and quartz porphyry),carbonates, cherts and variegated tuffaceousconglomerates. The chert in the formation was firstly foundin our field trip along sections of the Qiqi'erjianakesu Riverand Kekebiele Daban. Deformation of the group is…     

Permo-Carboniferous Radiolarians from the Wupata''erkan Group,Western South Tianshan, Xinjiang, China

1 IntroductionThe Wupata'erkan Group, also called Wupata'erkanFormation (Wang et al., 1990), in the western SouthTianshan, China (Fig. 1), mainly comprises gray and darkgray fine-grained clastic rocks, interlayered with medium-acidic volcanic rocks (andesite and quartz porphyry),carbonates, cherts and variegated tuffaceousconglomerates. The chert in the formation was firstly foundin our field trip along sections of the Qiqi'erjianakesu Riverand Kekebiele Daban. Deformation of the group is…     

泰国北部难河构造带二叠纪放射虫、硅质岩和玄武岩

在泰国北部难河构造带Pha Som变质杂岩中发现保存很好的放射虫硅质岩、玄武岩地层层序.层状硅质岩含放射虫化石Follicucullus porrectus, 地质时代为中二叠世晚期至晚二叠世早期.其硅质岩SiO₂含量均在92.5%以上, Al/ (Al+Fe+Mn) 平均比值为0.51, Ce/Ce*比值为1.14, 为大陆边缘型硅质岩.玄武岩具有富集大离子亲石元素与高场强元素以及轻稀土富集等洋岛玄武岩的特点.说明难河构造带中-晚二叠世之交存在洋岛型火山岩和靠近大陆边缘的深海盆地硅质岩, 代表了小洋盆的沉积组合.该构造带闭合时间应在晚二叠世与晚三叠世之间.      

Jurassic magmatic bodies of mountainous Crimea in the Bodrak River catchment (Southwestern Crimea)

The synthetic (geological and petrochemical) study of Jurassic magmatic bodies in the catchment of the Bodrak River (mountainous Crimea) is conducted. Their structural position and a Middle Jurassic age were determined. The magmatic bodies of mountainous Crimea were compared to those of the Lozovskaya zone. The study considers the geodynamic settings of the Middle Jurassic magmatism in mountainous Crimea.     

泰国东南部Rayong省Klaeng地区的中-晚泥盆世放射虫

Tectonic subdivision of mainland Thailand has been discussed by means of Paleozoic and Mesozoic stratigraphy, micropaleontology represented by fo-raminiferal and radiolarian biostratigraphy and paleo-biogeography, tectonic settings of granitoids, and ul-tramafic rocks that are distinctive of suture lines. Re-cently, Ueno (2002) and Ueno and Charoentitilat (2011) proposed a new tectonic scheme of mainland Thailand and divided it into three geotectonic units: the Sibu-masu Block, Sukhothai Zone, and Indochina Block from west to east, which are separated by the Mae Yuan Fault, the Chiang Rai Tectonic Line, and the Nan–Uttaradit Suture, respectively. In Northern Thai-land, moreover, the peculiar Inthanon Zone is recog-nized in the eastern part of the Sibumasu Block, where Paleo-Tethyan oceanic rocks are widely distributed as tectonic slices. These geotectonic subdivisions in Northern Thailand are relatively clear. However, the tectonic subdivisions of Central and Southeast Thai-land have not been well documented and are still con-troversial because there is short of information about basement rocks in those areas. In this circumstance, we have examined Paleozoic to Mesozoic stratigraphy, lithology, and radiolarian ages of siliceous rocks dis-tributed in Southeast Thailand to clarify the geotec-tonic belongings of this area and the southern exten-sions of geotectonic units consisting of Northern Thailand. In the course of this research, we could ob-tain Middle to Late Devonian radiolarians from well-bedded siliceous rocks distributed in southwest of Klaeng, Rayong Province. In this study, we report lithology and age of the radiolaria-bearing rocks and discuss their stratigraphy and geological correlation nearby the Klaeng region.     

Carbonate dikes in lava (Karadag,Crimea)

The dikes are obviously injections synchronous with their host lavas. They were produced at the floor of a marine basin where the thin sheet of lava was easily cooled and fissured on its contact with water and by seismic oscillations of the ground. reviewed by: V.P. Sokoloff.     

Palynofacies evidence of dysoxia and upwelling in the Turonian of the Sergipe Basin,Brazil

This paper presents the integrated results of palynofacies and geochemical analyses in Turonian carbonate strata from the Sergipe Basin, Brazil. Forty-three outcrop samples were analyzed from sections of the Cotinguiba Formation in the Votorantim and Rita Cacete quarries. Our results allow for the characterization of the organic matter and interpretation of the environments of deposition. Together with the existing geochemical data, the results allow for recognition of oxic and dysoxic intervals and inferences pertaining to local oceanographic conditions to explain these environmental changes. The palynofacies groups are dominated by marine palynomorphs and amorphous organic matter (AOM), with minor amounts of terrigenous palynomorphs and phytoclasts. The total organic carbon (TOC) and δ¹³C ratio are directly correlated with the dominant palynofacies elements, particularly AOM. The upper section in Rita Cacete quarry has the most complete data set, and the TOC, δ¹³C and marine-derived AOM in this section tend to decrease upsection and serve to differentiate the oxic and dysoxic intervals. The sections also contain abundant, low-diversity dinoflagellate assemblages composed primarily of Trichodinium boltenhagenii, Cribroperidinium? muderongense, Canningia reticulata and Xenascus plotei. The palynofacies and dinoflagellate assemblages indicate deposition in shallow marine to outer neritic environments. The dysoxic events are recognized by an increase in TOC and δ¹³C, high amounts of AOM, an abundance of the low-diversity dinoflagellate assemblages and the lowest amounts of terrestrial components. The changes in marine productivity seem to be related to periods of low-intensity upwelling, which likely decreased the levels of dissolved oxygen in the basin.     

新疆阿拉套山西段察哈乌苏二长花岗岩成因及构造意义

察哈乌苏岩体位于新疆西天山阿拉套山南缘的西段,大地构造位置属阿拉套山南缘泥盆纪—石炭纪弧后盆地,岩体主要由灰白色中粒二长花岗岩、灰白色中-细粒二云二长花岗岩组成。岩石地球化学数据显示,岩石中SiO2、Al2O3、碱含量较高,A/CNK=1.08～1.14,属过铝质高钾钙碱性花岗岩系列;轻稀土元素相对富集,重稀土元素相对亏损,稀土元素配分模式呈轻稀土富集的缓右倾型,具有明显的Eu负异常;强烈富集大离子亲石元素（LILE） Rb、Th、U、K、Hf,亏损高场强元素（HFSE） Ba、Nb、Ta、Sr、P、Ti;岩石具有较低的ISr值（0.701 5～0.702 6）。综合研究,表明察哈乌苏二长花岗岩为低Sr高分异S型花岗岩,兼具A型花岗岩的特征,是长石分离结晶的产物。二长花岗岩具有较高的正εNd （t）值（+0.37～+1.18）;高的Th、Ta含量及Th/Ta值（6.12～8.54）指示岩浆源区为亏损地幔,但受到古老地壳物质同化混染的影响。构造判别图解中所有样品落入火山弧花岗岩和同碰撞花岗岩的交界部位,更靠近同碰撞花岗岩区域。察哈乌苏岩体的侵位时代为313 Ma,结合区域地质背景,笔者认为伊犁微板块在310 Ma前已与准噶尔微板块碰合,北天山洋盆闭合时限早于晚石炭世末,310 Ma以后,阿拉套山地区逐渐进入后碰撞伸展阶段。因此,察哈乌苏二长花岗岩应为后碰撞花岗岩,岩体形成于同碰撞挤压向后碰撞伸展转换过渡阶段的张性环境,是幔源玄武质岩浆底侵和发生ACF作用的结果,其构造背景可能为活动大陆边缘。     

Cretaceous foraminifera from the Turonian succession at Beer, southeastern Devon, England

During Winter 2000/2001 a major cliff fall occurred at the back of the bay in Beer, southeastern Devon. In the subsequent remedial works the cliff was cleared of loose material prior to stabilisation works. This process provided a suite of samples from previously inaccessible parts of the cliff succession. By adding these samples to earlier suites of samples collected over the last 30 years it has been possible to improve our knowledge of the foraminifera of Turonian age in southwestern England.The planktic foraminifera are, perhaps, the most significant component of the assemblages as many of the taxa recorded in Devon are of southern aspect and are relatively rare in others parts of the U.K. The planktic zonation recognised in this section is, therefore, almost identical with that recorded in Tethyan areas and a precise correlation can be generated. There are relatively large numbers of important taxa such as Helvetoglobotruncana helvetica, Dicarinella imbricata, Marginotruncana sigali, M. pseudolinneiana, M. coronata and M. schneegansi. The benthic foraminifera, by comparison, are relatively rare and are represented by a low diversity assemblage. This is typical of northwestern European chalk successions of Turonian age and is coincident with the highest sea levels of the Cretaceous. In the middle to late Turonian there is a dramatic shallowing event that is recorded world-wide at this level. The assemblage changes towards the top of the accessible succession at Beer record this significant, world-wide event.     

太行山北段阜平幔枝构造成矿作用研究

阜平幔枝构造北东倾伏端,是轴部乌龙沟-上黄旗韧脆性剪切带与外围主拆离滑脱带的交汇部位,断裂构造发育,岩浆活动强烈,成矿控矿有利,矿床类型多样.笔者以上明峪主拆离滑脱带型金矿、镰巴岭上盘盖层裂隙型铜铅锌矿和支家地上叠断陷盆地中次火山岩裂隙型银矿为例,讨论了幔枝构造外围主拆离滑脱带、上盘盖层密集裂隙带和上叠断陷盆地次火山岩构造的成矿控矿作用,总结成矿规律,归纳成矿模式.     

太行山北段阜平幔枝构造成矿作用研究

阜平幔枝构造北东倾伏端,是轴部乌龙沟-上黄旗韧脆性剪切带与外围主拆离滑脱带的交汇部位,断裂构造发育,岩浆活动强烈,成矿控矿有利,矿床类型多样.笔者以上明峪主拆离滑脱带型金矿、镰巴岭上盘盖层裂隙型铜铅锌矿和支家地上叠断陷盆地中次火山岩裂隙型银矿为例,讨论了幔枝构造外围主拆离滑脱带、上盘盖层密集裂隙带和上叠断陷盆地次火山岩构造的成矿控矿作用,总结成矿规律,归纳成矿模式.     

Chernobyl radiocaesium in a karst system,Marble Cave,Crimea

 Surface contamination with radioactive caesium introduced into the environment after the accident at the Chernobyl nuclear plant was high enough in the Crimean Mountains to allow using radiocaesium as an indicator of penetration of radioactive contamination into a karst system. Caesium concentrations have been studied in soils above Marble Cave, Tchatyrdag Plateau, in percolation waters and in sediments transported by percolation waters within the cave. Contamination of the daylight surface with ¹³⁷Cs is about 30 kqB m^–2 which is approximately 13 times higher than the density of global fallouts. Besides ¹³⁷Cs, almost all samples showed presence of ¹³⁴Cs with the ¹³⁷Cs/¹³⁴Cs ratio close to that of Chernobyl contaminations. Concentrations of ¹³⁷Cs range from 9 to 15 mBq l^–1 in the present percolation waters in the cave. In sediments related to percolation waters ¹³⁴Cs is detected in some samples besides ¹³⁷Cs, although the effect of ²²⁸Ac is not ruled out. Surprisingly, the highest concentrations of radiocaesium were measured in "old" sediments in the cave's lower series. These sediments are not associated with modern percolation and are represented by a clay/moonmilk alternating sequence deposited in an old dried cave lake. Moonmilk layers have higher caesium content than clay. It is assumed that Chernobyl caesium was transported into the cave with aerosols which were then deposited mainly in areas where condensation occurs. The sampling site is located just in the boundary between two microclimatic zones with a temperature gradient of 0.5  °C. Active condensation processes occur in this area. Caesium was not detected in another similar sampling site (old lake deposits) located within homogeneous microclimatic conditions. If the above interpretation is correct, these results show the geochemical significance of the aerosol-condensation mechanism of mass transport and localisation. Received: 1 June 1995 · Accepted: 4 December 1995     

太行山北段阜平幔枝构造成矿作用研究

阜平幔枝构造北东倾伏端 ,是轴部乌龙沟 -上黄旗韧脆性剪切带与外围主拆离滑脱带的交汇部位 ,断裂构造发育 ,岩浆活动强烈 ,成矿控矿有利 ,矿床类型多样。笔者以上明峪主拆离滑脱带型金矿、镰巴岭上盘盖层裂隙型铜铅锌矿和支家地上叠断陷盆地中次火山岩裂隙型银矿为例 ,讨论了幔枝构造外围主拆离滑脱带、上盘盖层密集裂隙带和上叠断陷盆地次火山岩构造的成矿控矿作用 ,总结成矿规律 ,归纳成矿模式。     

Radiolaria,planktonic foraminifera,and stratigraphy of Turonian-lower Coniacian in the Biyuk-Karasu section,Crimea

The first data on the distribution of Radiolaria and planktonic Foraminifera in the section at Biyuk-Karasu River in central part of the Crimean Mountains, are presented. Based on the study of radiolarian findings, the upper Cretaceous deposits of Biyuk-Karasu section are subdivided into the following biostratigraphic units: Alievium superbum-Phaseliforma turovi (middle Turonian), Dactylodiscus longispinus-Patulibracchium (?) quadroastrum (upper Turonian), and Orbiculiforma quadrata-Patellula sp. B (Turonian-Coniacian boundary deposits). The stratigraphic interval of Alievium superbum-Phaseliforma turovi has been previously characterized by the complex of Alievium superbum-Phaseliforma sp. A (middle Turonian, Mt. Chuku section, SW of the Crimean Mountains, and middle Turonian, Mt. Ak, central part of the Crimean Mountains). Based on the study of Foraminifera findings, the following biostratigraphic subdivisions were identified: Whiteinella paradubia (lower-lower part of the middle Turonian), Marginotruncana pseudolinneiana (uppermost middle Turonian), and Marginotruncana coronata (upper Turonian). The complex of beds with Marginotruncana pseudolinneiana and Marginotruncana coronata are comparable to the deposits of zones of same name in the Crimean-Caucasian region.