Non-marine Successions Research Articles

Coupling of X-ray fluorescence and Strontium isotopes to track brine influences in continental deposits: study of the Oligocene sediments in the Digne area (SE basin, France)

Deciphering past salt tectonics events is often difficult in orogenic domains. The southwestern Alpine foreland in France presents a long Mesozoic extensive salt tectonics history, inverted during the Cenozoic Alpine orogeny. Syn-orogenic Cenozoic salt-related deformations are rather difficult to identify because of the contemporaneous shortening experienced by the foreland. This study is based on sedimentologic and geochemical approaches (Sr concentration and 87 Sr/ 86 Sr ratio) of the Oligocene non-marine succession of St Geniez (Digne region, France. Oligocene salt influences are highlighted by (1) high strontium concentrations (>1000 ppm) in most of the series, (2) the occurrence of Halophyticgastropods and (3) the deposit of two gypsum beds. 87 Sr/ 86 Sr ratio measured in the limestones and the gypsum beds confirm a Triassic origin for the strontium, originating from the diapir of Sorine, located to the south-west for the first part of the series, and from the Authon Thrust, located to the north, for the upper part. Geochemical values also suggest the occurrence of two Triassic evaporite levels, one already known and attributed to the Carnian-Norian (Late Triassic) and one attributed to the Olenekian-Anisian (Ealy-Middle Triassic). These results support that combined use of field geology and geochemistry can provide information on erased past salt-tectonics.

Characteristics of sediments and regolith alterations in the Plio-Pleistocene succession, coastal cliff sections, St Vincent Basin, South Australia

Syn- and post-depositional alterations are distinguished in a detailed lithological and mineralogical study of the largely unconsolidated Plio-Pleistocene non-marine succession in coastal cliff sections in the St Vincent Basin south of Adelaide. At its base, the sequence interfingers with Late Pliocene estuarine marine sediments in places but mostly unconformably overlies older Cenozoic marine sediments or Neproterozoic bedrock. The fluvial and alluvial siliclastics have bioturbation, blocky-prismatic macro-peds and subtle Fe-mottling indicators of hiatuses in deposition, and imprints of soil and shallow groundwater environments. A relative abundance of kaolinite, illite and randomly interstratified illite-smectite reflects both sediment source and conditions in the local depositional environment. A thick deposit of aeolian calcareous silt with associated pedogenic calcretes blankets the succession. Conspicuous bleached Fe mega-mottled intervals and zones of alunite-halloysite within the sequence record post-depositional, groundwater-related alterations in regolith environments. These formed during incision and erosion of the sedimentary fill in the basin in response to regional falls in base level. Each marks a different time and specific geomorphic environment according to the chemistry of the discharge of local groundwaters from aquifers that were intersected by incision and scarp retreat.

Toward a chronostratigraphy of the Paleocene-Eocene sedimentary record in northwestern Argentina

The Santa Bárbara Subgroup of the Salta Group in northwestern Argentina represents a key sedimentary record to understand the geological, biological, and climatological changes that occurred in South America during the Paleogene. However, the lack of absolute ages in these non-marine successions have prevented conclusive interpretations and correlations at a regional-scale. In this contribution, we present an integrative study based on sedimentological and stratigraphic approaches, a paleontological review, and, for the first time, an absolute age from a tuff level in the upper section of the Mealla Formation. We propose the following scenario: 1) Cycles of low and high accommodation stages that can be tracked at basin-scale providing a criterion to regional correlations; 2) An U–Pb zircon age of 58 Ma, which combined with previously estimated ages for Santa Bárbara Subgroup indicate that this unit is constrained between 61 and 49? Ma; 3) On view of this new age the fossil-bearing levels of the Mealla Formation fill a hiatus of more than 4 Myr in the South American vertebrate record for the middle to late Paleocene, reshaping our understanding of the early evolutionary stages of this fauna. Our results represent a robust first step to achieve reliable regional correlations and an integrative comprehension of the evolution of the Salta Basin and its fossil biota.

Tracing marine flooding surface equivalents across freshwater peats and other wetland deposits by integrated sedimentological and pollen data

Large volumes of peatland deposits characterise the Holocene stratigraphy of the Po Plain. A combination of sedimentological and pollen-based paleoenvironmental analyses enables recognition and stratigraphic correlation of small-scale (2–5 m thick) packages of peat-bearing strata, stacked rhythmically in a retrogradational to progradational set and bounded by chronostratigraphically significant surfaces. Across these repetitive lithofacies successions, the proportion of facies-controlled palynomorphs is used as a diagnostic signature to characterise marine flooding surface equivalents (helophytes and hydrophytes) and shoaling-upward (terrestrialization) trends (trees and mesophilous herbs) that record systematic variations in groundwater table associated with increasing/decreasing accommodation. Paludification surfaces at the base of peats delineate the updip (freshwater) equivalents of brackish/marine flooding surfaces recognized at seaward locations atop peat layers (give-up transgressive surfaces). Peat beds exhibit maximum thickness in aggradational strata of the lowermost highstand systems tract, above the maximum flooding surface (MFS). An extrinsic control due to eustatic rise can be inferred for peat development in transgressive deposits: peats, in particular, reveal warmer climates at flooding surfaces (specifically around the MFS) that invariably coincide with rapid shifts to deeper depositional environments. Under highstand conditions, autogenic mechanisms affected base-level changes in the paralic swamps. At this stratigraphic level, peat-bearing strata primarily reflect subtle changes in accommodation due to distributary-channel avulsion, subsidence, and peat autocompaction. Detailed patterns of Holocene peat distribution on millennial timescales can help decipher multiple high-resolution accommodation cycles developed in the rock record on sub-seismic scales, resulting in an improved stratigraphic analysis and prediction of chronologically less constrained non-marine successions.

Geochemical analysis and tectonic evaluation of the Miocene–Pliocene sequence at Al Rehaili area, Northern Jeddah, Saudi Arabia

Geochemical data and approach play a vital role in constraining and evaluating provenance of sedimentary rocks and tectonic settings. It provides valuable information on both the rock compositions of the provenance and the depositional setting. This study is aimed to predict provenance, source rocks, and tectonic settings of the non-marine successions of Bathan Formation (Miocene–Pliocene siliciclastic sequence) exposed along the road cuts at Al Rehaili area, north of Jeddah. The non-marine successions of Bathan Formation were divided into three main sedimentary units (units I, II, and III). From these units, 17 sandstone samples were selected and used to carry out the geochemical analysis using major oxides and trace elements. The examined samples are interpreted as quartz-rich sandstones, which are mainly sourced from intermediate rocks of igneous, sedimentary, and meta-sedimentary rocks of the Arabian Shield. Furthermore, the provenance of the studied sandstones is interpreted as that of mixed granite, granodiorite, rhyolite, and basaltic source rocks. Most of the tectonic discrimination plots indicate that the tectonic settings of the study area are defined as an active continental margin, which approves the interpretation of previous studies.

SEM Morphological Study of the Paratype of the Spinicaudatan <i>Feiyunella zhedongensis</i> (Chen and Shen, 1977) from Cretaceous of Linhai, Zhejiang, South-East China

Spinicaudatans, a suborder of the abandoned taxonomic group “Conchostraca”, are very useful for biostratigraphic subdivision and correlation of the non-marine successions, remarkably in otherwise fossil-scarce red beds. Feiyunella, a monospecies spinicaudatan genus, was established based on specimens from sediments of Upper Cretaceous red beds in different localities of Zhejiang Province. The morphological examination under a scanning electron microscope of the type specimens of Feiyunella zhedongensis (Chen and Shen, 1977) has found that the paratype from the Fangyan Formation at Xiaoling of Linhai City, Zhejiang Province, is not Feiyunella, but a younger individual of Linhaiella.

Solving a tuff problem: Defining a chronostratigraphic framework for Middle to Upper Jurassic nonmarine strata in eastern Australia using uranium–lead chemical abrasion–thermal ionization mass spectrometry zircon dates

To better predict the architecture of reservoirs and the location of undiscovered resources in fluvial-dominated strata, a sound chronostratigraphic framework is needed. This study reassesses the stratigraphic framework of petroleum-bearing Jurassic fluviolacustrine successions in the Eromanga, Surat, and Clarence–Moreton Basins of eastern Australia. Correlation of the strata is challenging because of the heterolithic facies, the absence of conventional stratigraphic marker beds, and the longevity of palynostratigraphic zones. The abundance of laterally discontinuous volcanic air–fall tuffs and volcanogenic sandstones across the Jurassic of eastern Australia allows for the construction of a new, regional chronostratigraphic framework. High-precision U-Pb zircon chemical abrasion–thermal ionization mass spectrometry (CA-TIMS) dates ranging from 168.07 ± 0.07 Ma to 149.08 ± 0.06 Ma were obtained from 31 samples from 13 wells across 3 basins. Five chronostratigraphic datums were defined and extrapolated to 677 wells within a time interval of 420 ka or less over hundreds of kilometers across eastern Australia. The new chronostratigraphic framework reveals inaccuracies in picking lithostratigraphic units based on lithology and wire-line log characteristics and shows coal-bearing facies of the Walloon Coal Measures to be two episodes of coal (peat) accumulation separated by an unconformity. The study also demonstrates the feasibility of extending chronostratigraphic datums to neighboring basins without tuff beds by dating the youngest zircon in volcanogenic sandstones by U-Pb CA-TIMS following laser ablation–inductively coupled plasma mass spectrometry analysis. The dates provide a substantial revision to the Middle to Upper Jurassic stratigraphy of eastern Australia. The use of precise U-Pb CA-TIMS dates should help elucidate the lithofacies architecture of nonmarine successions in other basins and assist in petroleum development.

First record of Reduviasporonites from the Permian–Triassic transition (Gondwana Supergroup) of India

Kar, R. & Ghosh, A.K., May 2018. First record of Reduviasporonites from the Permian–Triassic transition (Gondwana Supergroup) of India. Alcheringa XX, XXX–XXX. ISSN 0311-5518.We have performed a palynological study from an outcrop succession within the Gondwana Supergroup in India, spanning the end-Permian event. The sampled succession is located within the Tatapani-Ramkola Coalfield, in the Balrampur District of Chhattisgarh State, India. Diverse and well-preserved palynological assemblages representing non-marine successions were identified and four assemblage zones were distinguished: the upper Permian Zone I: Striatopodocarpites–Densipollenites, and Zone II: Striatopodocarpites–Crescentipollenites; the Lower Triassic Zone III: Falcisporites–Klausipollenites and Zone IV: Densipollenites–Lunatisporites. Importantly, the fossil genus Reduviasporonites Wilson is recorded across the Permian–Triassic transition in this study. Although the affinity of Reduviasporonites has been disputed (both fungal and algal affinities have been proposed), the genus is an important constituent of the palynological assemblages from the upper Permian and Lower Triassic deposits in different parts of the world. Here we report the first record of Reduviasporonites from the Permian–Triassic continental sediments in India, adding another significant data point for their presence at the Permian–Triassic boundary (PTB). We further discuss the affinity and palaeoecological perspectives of the taxon.Ratan Kar [ratankar@yahoo.com] and Amit K. Ghosh [akghosh_in@yahoo.com] Birbal Sahni Institute of Palaeosciences, 53 University Road, Lucknow 226 007, Uttar Pradesh, India. Received X.X.2017; revised X.X.2017; accepted X.X.2018.

From arid to humid – The Jurassic–Cretaceous boundary interval in northern Germany

The Jurassic–Cretaceous boundary interval in northwest Europe is characterised by a distinctive climatic change from pronounced aridity toward more humid conditions. In order to better understand the timing and evolution of the environmental dynamics related to this climatic change, terrestrial and aquatic palynomorphs (spores, pollen, dinoflagellate cysts, freshwater algae) have been studied from two recently drilled cores. The cores, which are both located in the Lower Saxony Basin (northern Germany), provide two 139 m and 134 m thick non-marine successions embedded in a high-resolution biostratigraphic framework. The lower part of the cores can be attributed to the Münder Formation (upper Tithonian–middle Berriasian), the upper part to the Bückeberg Group (middle–upper Berriasian). For reconstructing the arid to humid climate transition 110 samples have been analysed for their palynological content.In the Lower Saxony Basin, the late Jurassic–earliest Berriasian vegetation was dominated by cheirolepidiacean conifer forests growing under arid conditions along a coastal belt. A marked decline in cheirolepidiacean pollen and the spread of pioneering plants records an increase in seasonal humidity in the early–mid Berriasian. In the mid–late Berriasian the presence of highly diverse floras reflects even more humid and warm conditions. Fluvio-deltaic mixed swamp forests, which grew landwards behind the coastal belt were composed of conifers, ferns, lycopods, horsetails, bryophytes, ginkgos, cycads and Bennettitales. Cheirolepidiaceans, probably forming part of mangrove-type plant communities, remained an important component of the coastal flora. The climatic shift correlates to the upper Subcraspedites lamplughi–middle Heteroceras kochi ammonite zones of the marine Boreal zonation scheme and is synchronous to the early–mid Berriasian shift from arid to humid recorded from southern England.

U-Pb ages of detrital zircons in Lower Cretaceous non-marine successions of the Gyeongsang Basin, Northeast Asia: Implications for sediment provenance

The Cretaceous Gyeongsang Basin is the largest non-marine Mesozoic sedimentary basin of the Korean Peninsula. The Lower Cretaceous successions of the Gyeongsang Basin are coevally correlated to those of the Cretaceous Gunsan Basin in the Yellow Sea which is located far to the west of the Gyeongsang Basin. This study presents U-Pb ages of detrital zircons to evaluate the sediment provenances of the Gyeongsang Basin. The detrital zircon ages clearly show the different distributions between the northern (Uiseong area) and southern (Jinju area) areas of the Gyeongsang Basin. The detrital zircons of the northern area have an age cluster in the Jurassic or Triassic, whereas the detrital zircons of the southern area show a wide range of ages from early Cretaceous to Neoarchean. In the Gunsan Basin, detrital zircons from a core also yield ages ranging from early Cretaceous to Neoarchean. The age distribution from the Gunsan Basin is similar to those of the southern Gyeongsang Basin, except for the absence of Jurassic detrital zircons. The petrographic modal analysis of sandstones in the Gyeongsang Basin suggests a mixed provenance. This study indicates that possible sediment provenances of the Gyeongsang Basin were shared with those of the Gunsan Basin. We suggest that the sediment provenance of the northern Gyeongsang Basin was adjacent basement highs, whereas sediments to the southern Gyeongsang Basin were probably derived from relatively distant source areas that possibly were located in the vicinity of the Gunsan Basin during the early Cretaceous (ca. 113Ma).

Upper Cretaceous to Neogene Palynology of the Rawat Basin, White Nile State, Sudan

The palynology of the Upper Cretaceous to Neogene non-marine succession in the Rawat Basin, White Nile State Sudan was investigated. An attempt was made to determine the relative age, and depositional environment of the studied interval. Based on the stratigraphic distribution of selected pollen and spores from two exploration wells, seven informal palynozones from the Campanian to the Neogene are proposed. The zones, in stratigraphically ascending order, are as follows: Assemblage Zone I, Campanian (Gelhak Formation); Assemblage Zone II, Maastrichtian (Melut Formation); Assemblage Zone III, Eocene (Yabus Formation); Assemblage Zone IV, Oligocene (Adar Formation); Assemblage Zone V, Oligocene/Miocene (Jimidi Formation); Assemblage Zone VI, Miocene (Miadol Formation); Assemblage Zone VII, Miocene/Pliocene (Daga and Agor formations). The ages are based on stratigraphic ranges of marker species in contemporaneous basins in Africa and South America and a series of assemblage species such as Ladakhipollenites lehmanii, Triorites sp (Zone I), Proteacidites sigalii (Zone II), Proxapertites operculatus (Zone III), Deltoidospora cf. africana (Zone IV), Magnastriatites howardii (Zone V), Cyathidites minor (Zone VI), Verrucatosporites usmensis (Zone VII). The paleo-environment of deposition were determined to range from fluvial to lacustrine environments.

Revision of the Maastrichtian-Palaeocene charophyte biostratigraphy of the Fontllonga reference section (southern Pyrenees, Catalonia, Spain)

The Fontllonga section is one of the best-known stratigraphic sections wordwide for the study of charophyte biostratigraphy of the Maastrichtian and lower Palaeocene. An updated proposal for the charophyte biostratigraphy of this section is presented after summarizing previous knowledge. The zone of Peckichara cancellata allows the upper Campanian–lowermost Maastrichtian to be characterised in the base of the section (La Macana Formation). The Microchara punctata biozone represents most of the Maastrichtian (Figuerola Formation). Within this biozone, a Clavator ultimus subzone is proposed to improve characterisation of the lower and middle Maastrichtian. Both the upper and lower boundaries of the Microchara punctata biozone proposed in previous studies are modified based on new occurrences of the index species. A charophyte assemblage belonging to the Dughiella bacillaris biozone is reported for the first time from the middle of the section (Perauba Complex) and provides an age for this unit ranging from the upper Danian to lower Thanetian. A foraminifer assemblage found in the basal marine deposits above the non-marine succession of the Fontllonga section provides new biostratigraphic data to locate the upper boundary of the non-marine succession at least within the upper Thanetian.

Formation-Evaluation Log-Off Results for Coalbed-Methane-Field Development

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 176823, “Formation-Evaluation Log-Off Results Comparing New- Generation Mining-Style Logging Tools With Conventional Oil-and-Gas Logging Tools for Application in Coalbed-Methane-Field Development,” by T. Gan, B. Balmain, A. Sibgatullin, M. Ward, and F. Liu, Arrow Energy, and E. Murphy and L. Cook, Shell, prepared for the 2015 SPE Asia Pacific Unconventional Resources Conference and Exhibition, Brisbane, Australia, 9–11 November. The paper has not been peer reviewed. An operator’s coalbed-methane (CBM) -development projects in Queensland, Australia, are designed with a large volume of wells that will need to be drilled and evaluated over the next decade. At present, the cost of logging is forcing the operator to choose between early data coverage vs. restricted logging. To resolve this issue, the operator has embarked on a series of technology trials to investigate various cost-effective formation-evaluation solutions. This paper presents the results of a comparison of state-of-the-art mining logging technology and conventional oil-and- gas logging technology. Introduction The Surat basin is a broad intracratonic downward that covers an area of approximately 300 000 km2 in southeastern Queensland and northeastern New South Wales. The operator’s interests are solely in Queensland. The basin comprises a primarily nonmarine Jurassic succession overlain by a mixed nonmarine and marine Early Cretaceous succession. (For detailed geological information, please see the complete paper.) The operator’s proposed Surat CBM project is located in the eastern part of the basin, in Queensland only, with an area of 22 000 km2. It is important to use geophysical logs as part of the data-acquisition program, especially during the early development phase. The geophysical logs are used for coal identification, derivation of coal properties, and coal ranking. Current mining logging technology consists of a basic logging suite such as gamma ray, density/photoelectric factor, and neutron and resistivity tools. For advanced logging operations in exploration and appraisal wells, these must be replaced by conventional oil-and-gas logging tools to ensure holistic subsurface characterizations and front-end engineering work for future project- development decision making. Logging-Technology-Trial Results for CBM Data Acquisition Trials proved the availability of a cost-saving proposal for logging vertical development wells, which can meet formation-evaluation objectives while minimizing the costs of openhole logging. This is primarily achieved by running a basic logging suite of density, gamma, caliper, and deviation. An important distinction to consider is that, in conventional oil and gas, density sensitivity is usually down to approximately 2.0 g/c m3 because of the use of weighted muds. In CBM, formation water or very lightweight muds are used and coal densities can be as low as 1.2 g/cm3, pushing the boundaries of density-tool measurements to obtain such low readings. Mining-Drillpipe-Push (MDP) Logging Tools. This logging-conveyance method involves the addition of a composite collar within the drilling bottomhole assembly before the production section is drilled. Once total depth (TD) is reached, the drillpipe is broken open at surface and the logging tools are pumped down and latched into the composite collar. The pipe is then tripped out of the well, and the logging occurs through the composite collar in memory mode. The logging tools for this trial included density, gamma, dual-neutron, and resistivity.

Perspectives on Cretaceous Gondwana break-up from detrital zircon provenance of southern Zealandia sandstones

AbstractDetrital zircon U–Pb ages in 37 sandstones from late Early – Late Cretaceous marine and non-marine successions across southern Zealandia indicate a provenance from local basement within present-day Zealandia. Samples from Taranaki Basin were derived from Median and Karamea batholith granitoids with transport directions from west to east. Samples from West Coast, Western Southland and Great South basins contain components derived more locally and more variably from Median Batholith and Rahu Suite granitoids and/or the Palaeozoic Buller Terrane. West Coast Basin samples have more plutonic contributions and Great South Basin localities have more Albian-aged (c. 110–100 Ma) zircons. Samples from Canterbury Basin were sourced from Torlesse Composite Terrane basement. The provenance variations are present in both marine and non-marine sandstones and suggest localized watersheds. This fits an interpretation of Late Cretaceous deposition in rift-controlled basins across southern Zealandia during pre-Gondwana break-up regional extension. More speculatively, some additional source areas may have been created at the rifted margins of Zealandia during this break-up.

Palynology of the Kazanian stratotype section (Permian, Russia): palaeoenvironmental and palaeoclimatic implications

Palynomorph assemblages reflect changes in land plant communities and are thus significant proxies to interpret palaeoenvironmental and palaeoclimatic changes. The Middle Permian of the East European Platform is crucial to the understanding of marine and non-marine palaeoclimate archives and interregional correlations of marine and non-marine successions, utilising palaeoclimate signatures documented in the palynological record. New palynological data from the Kazanian stratotype section are presented and interpreted with respect to palaeoenvironment and palaeoclimate. This dataset will serve as a basis for ongoing studies on the type area of the Kazanian and the mid-Permian biodiversity patterns, preceding the end-Guadalupian crisis and the changes of the end-Permian biotic diversification followed by the most severe extinction event in Earth’s history at the Permian-Triassic boundary.

Geology of the late Miocene south-eastern Volterra Basin (Northern Apennines, Italy)

We present a 1:10,000 scale geological map for the south-eastern sector of the Volterra Basin (Northern Apennines, Italy), together with supporting stratigraphic-structural data. The Volterra Basin consists of a major structural depression within the Northern Apennines hinterland, NNW-SSE-oriented and filled with more than 2000 m of late Miocene-Quaternary deposits. Its south-eastern sector is classically considered as a type area for late Tortonian non-marine strata, here mapped and refined in terms of internal stratigraphy adopting a scheme of depositional and lithostratigraphic units. Stratigraphic assessments helped in redefining the character of the lower boundary of the non-marine succession, as well as in mapping a newly recognized angular unconformity. Deformation structures affecting the basin fill include blind normal faults rooted to a deep detachment, outcrop-scale transtensional faults and clusters of gentle folds. Faults and folds appear to be kinematically linked. Our structural observations largely agree with those present in the literature, supporting a model of post-orogenic crustal stretching.

The Emptiness of the Stratigraphic Record: A Preliminary Evaluation of Missing Time In the Mesaverde Group, Book Cliffs, Utah, U.S.A

Abstract Observations of modern sedimentation rates in nonmarine and shallow-marine clastic environments indicate that deposits formed in comparable settings in the ancient record could accumulate in a fraction of the time that would appear to be available according to conventional chronostratigraphic dating methods. Typically as little as 10% of elapsed time is represented by sediment, the remainder by breaks in sedimentation, many of which are inconspicuous. An examination of the chronostratigraphy and sedimentary history of the Mesaverde Group of the Book Cliffs, Utah, U.S.A., confirms this pattern. Shoreface, deltaic, and nonmarine successions are considered to be particularly fragmentary. Ravinement surfaces may each account for up to 105 years of missing time. In the sedimentary record of shallow-marine and nonmarine deposits stratigraphic continuity is not to be expected, and calculation of time-related issues, such as mass-balance transport rates and the trajectories of shoreline transgression and regression, must take this into account.

Controls on clay minerals assemblages in an early paleogene nonmarine succession: Implications for the volcanic and paleoclimatic record of extra-andean patagonia, Argentina

The distribution of the clay minerals of the Banco Negro Inferior-Río Chico Group succession (BNI-RC), a middle Danian–middle Eocene mainly continental epiclastic–pyroclastic succession exposed in the Golfo San Jorge Basin, extra-Andean Patagonia (∼46° LS), is assessed in order to determine the possible origin of clay and specific non-clay minerals using X-ray diffraction and scanning electron microscopy analyses. The control over the clay mineralogy of the sedimentary settings, contemporary volcanism, paleoclimate and weathering conditions is considered. A paleoclimatic reconstruction is provided and correlated with the main global warming events that occurred during the early Paleogene.Mineralogical analyses of BNI-RC demonstrate that smectite and kaolin minerals (kaolinite, halloysite and kaolinite/smectite mixed layers) are the main clay minerals, whereas silica polymorphs (volcanic glass and opal) are common non-clay minerals. Throughout the succession, smectite and kaolin minerals are arranged in different proportions in the three clay–mineral assemblages. These show a general vertical trend in which the smectite-dominated assemblage (S1) is replaced by the smectite-dominated assemblage associated with other clays (S2) and the kaolinite-dominated assemblage (K), and finally by S2 up-section. The detailed micromorphological analysis of the clay and non-clay minerals allows us to establish that the origins of these are by volcanic ash weathering, authigenic and pedogenic, and that different stages in the evolution of mineral transformations have occurred.The supply of labile pyroclastic material from an active volcanic area located to the northwest of the study area could have acted as precursor of the authigenic and volcanogenic minerals of the analyzed succession. Diverse fine-grained lithological facies (muddy and tuffaceous facies) and sedimentary settings (coastal swamp and transitional environments, and different fluvial systems) together with variable climate and weathering conditions controlled the mineralogical transformations and the arrangement of clay–mineral assemblages. The paleoclimatic reconstruction suggests a general warm and humid climate. However, the temporal trend of the clay–mineral assemblages, the ratios between smectite and kaolinite and the micromorphological analysis of clay minerals contrasted with evidence from sedimentological analyses suggest a warm and seasonal climate for the basal part of the unit, a warm and humid climate with a relatively more perennial rainfall regime in the middle part of the unit, and a warm and less humid, probably subhumid, climate up-section. Such a reconstruction makes it possible to establish a correlation with some of the hyperthermal events of the Early Paleogene Global Warming (EPGW) and, consequently, constitute one of the most complete time records of the EPGW in South America.

Geochemistry of fine-grained sediments of the upper Cretaceous to Paleogene Gosau Group (Austria, Slovakia): Implications for paleoenvironmental and provenance studies

Bulk rock geochemistry of 169 fine-grained sediment samples of the upper Cretaceous to Paleogene Gosau Group (Northern Calcareous Alps, Austria and Slovakia) from borehole and outcrop localities was performed to separate non-marine and marine deposits. Geochemical characteristics of different Gosau depositional systems, basins and sediment provenance using major-, trace-, and rare earth elements were also investigated. Geochemical proxies such as boron concentrations were tested for seeking the possibilities of paleosalinity indicators. Due to the fact that several pelagic sections are represented by extremely low boron contents, B/Al* ratios are recognized as more robust and differentiate reliably between marine (mean: 160 ± 34) and non-marine (mean: 133 ± 33) samples. Using statistical factor analysis, hemipelagic to pelagic samples from the Gießhübl Syncline and Slovakian equivalents can be differentiated from marginal-marine to non-marine samples from the Grünbach and Glinzendorf Syncline related to terrigenous (SiO2, Al2O3, K2O, Th, Rb, Zr and others) and pelagic indicative elements (CaO, Sr, TOT/C and B/Al*). A clear indication for ophiolitic provenance is traced by high amounts of chromium and nickel. Only non-marine successions of the Glinzendorf Syncline show higher Cr and Ni concentrations (up to 250 and 400 ppm, respectively) and enriched Cr/V and Y/Ni ratios trending to an ultramafic source.

Radiometric Zircon Ages of a Tuff Sample from the Baishantou Member of Wuyun Formation, Jiayin: A Contribution to the Search for the K‐T Boundary in Heilongjian River Area, China

Abstract:The existence of the Cretaceous‐Tertiary (K/T) boundary in the non‐marine succession is expected at Jiayin in the Heilongjiang River area, China. Zircons from a tuff sample from the Baishantou Member of Wuyun Formation in Jiayin were analyzed by the laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) U‐Pb dating and fission‐track dating methods. Ages of 64.1±0.7 Ma (U‐Pb) and 61.7±1.8 Ma (fission‐track dating) were obtained, which allow re‐evaluation of a previously reported late Maastrichian age for the tuff layer that was in conflict with the paleontological evidence. These results confirm the Danian age of the section in agreement with the paleontological evidence.