History Of Basin Research Articles

The Effect of Size Distribution on the Geochemistry and Mineralogy of Tropical River Sediments and Its Implications regarding Chemical Weathering and Fractionation of Alkali Elements

Abstract The mineralogical and geochemical compositions of the sediments deposited by rivers have been used extensively to evaluate past chemical weathering and the physical erosion history of drainage basins at different time scales. However, the role of sediment sorting in the mineralogical and geochemical compositions of river sediment needs to be better constrained because it could significantly modify proxies used to evaluate weathering intensity in the past. In this study, major and trace element concentrations and mineralogical compositions were determined on seven different grain-size fractions of riverbed samples taken from the Pahang and Kelantan Rivers in the Malay Peninsula. The main aims are to assess chemical weathering and the fractionation of alkali elements during sediment transportation under tropical climate conditions. Fine sediments (from <2 μm to 4-8 μm) were characterized by higher concentrations of Al2O3, P2O5, V, Sc, and Cs than coarse sediments (from 8-16 μm to 32-63 μm). The presence of heavy minerals, such as zircon and monazite, was found to have critical effects on the concentration of several elements (e.g., Zr and Th), leading to extremely high elemental concentrations in the coarse-sediment fractions. Variations in elemental concentrations with particle sizes are mainly attributed to changes in the mineralogical composition during mineral sorting and weathering. In both rivers, the intensity of chemical weathering increased with decreasing grain sizes. However, the relationship between grain size and chemical weathering trends in the Pahang and Kelantan River basins was different in each case due to differences in plagioclase and K-feldspar concentrations, especially in the coarse-sediment fractions (16-32 μm and 32-63 μm). Kaolinite percentage, illite chemistry index, and illite crystallinity were directly proportional to the chemical index of alteration (CIA), suggesting that these mineralogical parameters are suitable proxies for determining chemical weathering intensity in sediments that have undergone significant changes due to mineral sorting during transportation. The comparison of Rb/K and Cs/K ratios and the CIA suggested that K and Rb mainly derive from primary minerals during the process of chemical weathering, whereas Cs is mainly present in fine weathered particles due to the reabsorption of Cs on clay minerals. Overall, our results highlight the relationship of grain size and mineral assemblages to different states of chemical weathering (and alkali fractionation) in tropical river basin sediments. These relationships need to be considered when using mineralogical and geochemical compositions to reconstruct weathering history in a “source to sink” approach.

Neogene history of fluvial to shallow marine successions in the Kendari Basin, SE Sulawesi, Indonesia

AbstractCollision between Australia and SE Asia began in Sulawesi, the world's eleventh‐largest island, in the Early Miocene and subsequently Neogene sediments were deposited largely in coastal to shelf environments throughout the island. These sediments have been assigned to the Celebes Molasse, previously considered as a single post‐orogenic unit deposited unconformably on pre‐Neogene sedimentary, metamorphic and ophiolitic rocks. The most complete and extensive sequences of Neogene sediments are in the Kendari Basin, situated at the southern end of the SE Arm of Sulawesi, where an outcrop‐based sedimentological study was undertaken to interpret depositional environments, palaeogeography and stratigraphy. The oldest Neogene sediments are shallow marine carbonates and deltaic siliciclastics of the Bungku Formation. They are unconformably overlain by the Upper Miocene Pandua Formation which consists of sediments deposited in a variety of environments including braided river channels, fluvio‐tidal channels, tidal flats, mouth bar complex and shoreface deposits. A Mio‐Pliocene subaerial unconformity separates the marginal marine serpentinite‐rich sediments of the Pandua Formation from the overlying fluviatile quartz‐rich Langkowala Formation. The sediments of the lower part of the Langkowala Formation include conglomeratic channel fill, while the sediments of the upper part are transgressive deposits decreasing in maximum grain‐size, marked by a reduction in channel/overbank ratio and increasing tidal influence. The transgressive Pliocene Eemoiko Formation is characterised by transgressive lags or onlap shell beds and deposits of a landwards‐backstepping carbonate platform. The improved understanding of the Kendari Basin will aid the interpretation of the sedimentation history of frontier basins surrounding SE Sulawesi, many of which have not yet been drilled.

A mid-Permian mafic intrusion into wet marine sediments of the lower Shoalhaven Group and its significance in the volcanic history of the southern Sydney Basin

A mid-Permian (late Kungurian) micro-dolerite dyke/sill complex located at Kinghorn Point intruded into the then unconsolidated upper Wandrawandian Siltstone of the lower Shoalhaven Group, southeastern Sydney Basin. The dark grey siltstone was deposited in the deeper part of a coastal seaway characterised by northward-directed paleocurrents, with a Cruziana ichnofacies, crinoid stem fossils and abundant glendonites indicating a cold climate. Thin periodic storm deposits, or tempestites, of fine-grained sandstone of volcanogenic origin are scattered through the siltstone. These paler sandy beds were probably derived from island volcanoes to the south or southeast, indicating that regional volcanism was pervasive during this glacial episode. Evidence for penecontemporaneous igneous emplacement into mid-Permian wet unconsolidated shallow marine sediments includes: destruction of primary sedimentary structures caused by extensive interaction and intermingling between the sedimentary and igneous materials, the presence of brecciated contacts and peperite, angular and rounded dolerite fragments in the siltstone, fluidisation and entrainment of the sediments into cooling and flow fractures in the magma, and the presence of tube-like flow features. There are also hyaloclastite and baked sediments along the contact margins, fumaroles and vesicles within both the sediment and magma. High vesiculation is characteristic of intrusion near the surface, and possibly extrusion at the sediment–water interface. The geochemistry of the intrusion, especially key element ratios of the high-field-strength, major and trace elements, is very different from that of the shoshonites of the nearby Permian (mid Wordian to Capitanian) Gerringong Volcanics, having much lower Zr/TiO2, Nb/Y, Nb/Zr, K2O, P2O5, Rb, Th, U, Y, Zr and Nb, and higher MgO, suggesting they are unrelated. This indicates that the Kinghorn Point intrusion was associated with an earlier intermediate pre-Gerringong Volcanics phase, or it may be distinctive and unrelated. Magmatic geochemical comparisons further afield along the northern Sydney Basin and Tamworth Fold Belt boundary coasts show that volcanism was pervasive during the Wandrawandian glacial episode and that regional mid-Permian mafic volcanism was well evolved in the southern Sydney Basin during sedimentation. KEY POINTS A mid-Permian syndepositional dolerite intrusion at Kinghorn Point shows classical peperite and soft-sediment deformation features. Previously unreported mafic tuffaceous sandstone beds within the Wandrawandian Siltstone were probably derived from island volcanoes to the south or southeast. Geochemistry of the intrusion shows that it is not related to the mid Wordian to Capitanian Gerringong Volcanics. Regional volcanism was pervasive during the Wandrawandian glacial episode along the southeast Panthalassan margin of Gondwana.

Concurrent 14. Presentation for: Major geological surfaces of the Exmouth Plateau from the new Broadband PreSDM reprocessed 3D seismic data with full waveform inversion

Presented on Wednesday 18 May: Session 14 The Barrow Sub-basin and Exmouth Plateau, of Australia’s North West Shelf, contain Australia’s largest gas reserves, underpinning the three major LNG facilities, including Gorgon, Wheatstone and Pluto. In addition, there remains significant near-field exploration potential such as the Sasanof prospect. While there is full 3D seismic coverage in the basin, the existing 3D surveys are of different vintages covering only parts of the basin with diverse acquisition and processing parameters. Multi-Client Resources has produced an extensive 3D seismic reprocessing project (BEX-MC3D) incorporating 23 legacy 3D surveys to provide a seamless 25 570 km2 3D dataset. The BEX-MC3D was processed from field tape through DUG Technology’s advanced Broadband PreSDM processing sequence with Full Waveform Inversion (FWI) imaging. The BEX-MC3D provides one continuous superlative 3D dataset covering almost the entire Barrow Sub-basin and the Exmouth Plateau. Major geological surfaces corresponding to key tectonic events from overburden to reservoirs have been interpreted from the BEX-MC3D Priority area in the current study. These high-fidelity imaged surfaces form a basin-wide framework for: (1) rapid exploration lead and prospect identification through the creation of trap and reservoir visualisations; (2) improved reservoir connectivity analysis and modelling of producing and discovered fields to support better reservoir management and field development decisions; and (3) improved understanding of basin-burial history for reservoir quality and geo-mechanical property prediction. This paper will present and discuss major geological surfaces in the context of future exploration lead/prospect identification, reservoir characterisation for field development and management, and improving overall understanding of the basin history. To access the presentation click the link on the right. To read the full paper click here

Tectonic evolution and subsidence history of the Cretaceous basins in southern Egypt: The Komombo Basin

AbstractThe structure and tectonic evolution of the Cretaceous rift basins of southern Egypt are poorly understood. In this study, the tectonostratigraphy of the Komombo Basin has been determined using seismic, well and biostratigraphic data. The tectonostratigraphy of the basin is compared to the Kharit, Nuqra and Beni Suef basins in Egypt as well as Muglad Basin in Sudan. The Komombo Basin is a 58 km long, 28 km wide NW–SE trending half‐graben infilled with 2200 m of Berriasian‐Maastrichtian sediments and overlain by 400 m of Pliocene sediments. Four Berriasian to Maastrichtian syn‐rift and post‐rift sequences and three Pliocene channel systems of Nile sediments have been identified. Moreover, a series of normal faults, negative flower structures, reverse faults and folds are mapped in the basin. Backstripping reveals two rift phases during the Berriasian‐Barremian and Turonian‐Santonian, respectively. Additionally, the tectonic subsidence curves indicate that two major unconformities have occurred during the Aptian‐Albian and Maastrichtian‐Pliocene, which are correlated with a basement uplift during the Albian‐Cenomanian and the Oligocene‐Miocene flank uplift related to the opening of the Red Sea, respectively. The rift episodes are attributed to far‐field stress changes resulting from the initial opening of the South Atlantic and followed by the NW part of the African plate colliding and anticlockwise rotating into Europe. The highest β factors (1.20–1.11) for both rift phases are found at the centre of the basin. The rift phases thinned the crust from 32.5 to 28.2 km and 31.9 km in the depocenter and the western flank of the basin. The Komombo Basin has a similar rift history, stratigraphy and structural style to the Kharit, Nuqra and Mugland basins. All of these basins witnessed two major rift phases in the Early and Late Cretaceous, whereas the Beni Suef Basin encountered strike‐slip tectonic events in the Late Cretaceous.

Research on Diagenetic Evolution and Hydrocarbon Accumulation Periods of Chang 8 Reservoir in Zhenjing Area of Ordos Basin

The Mesozoic Chang 8 Section in the Zhenjing area is a typical low permeability-tight sand reservoir and is regarded as the most important set of paybeds in the study area. Guided by the principles of basic geological theory, the diagenetic evolution process and hydrocarbon accumulation periods of the Chang 8 reservoir in the study area were determined through various techniques. More specifically, core observation, scanning electron microscopy (SEM), X-ray diffraction (XRD), and vitrinite reflectance experiments were performed in combination with systematic studies on rock pyrolysis and the thermal evolutionary history of basins, the illite-dating method, and so on. The Chang 8 reservoir is dominated by feldspar lithic and lithic feldspar sandstones. Quartz, feldspar, and lithic fragments are the major clastic constituents. In clay minerals, the chlorite content is the highest, followed by illite/smectite formation and kaolinite, while the illite content is the lowest. The major diagenesis effect of the Chang 8 reservoir includes compaction, cementation, dissolution, metasomatism, and rupturing. The assumed diagenetic sequence is the following: mechanical composition → early sedimentation of chlorite clay mineral membrane → early cementation of sparry calcite → authigenic kaolinite precipitation → secondary production and amplification of quartz → dissolution of carbonate cement → dissolution of feldspar → late cementation of minerals such as ferrocalcite. Now, the study area is in Stage A in the middle diagenetic period. Through the inclusion of temperature measurements, in conjunction with illite dating and thermal evolutionary history analysis technology in basins, the Chang 8 reservoir of this study was determined as the phase-I continuous accumulation process and the reservoir formation epoch was 105~125 Ma, which was assigned to the Middle Early Cretaceous Epoch.

New Insight into the Depositional Age of No. 6 Coal in Heidaigou Mine, Late Paleozoic Jungar Coalfield, Inner Mongolia, China

Coal deposits can provide novel stratigraphic markers for reconstructing the evolution history of a sedimentary basin and correlating sedimentary successions. Age dating was conducted on zircons harvested from the No. 6 coal seam within the Heidaigou Mine, Inner Mongolia. Two-kilogram samples were taken, and the recovered zircons were analyzed for U–Pb isotopic and rare earth elements (REE). The REE results of the zircon grains showed that all the zircon grains were enriched in heavy rare earth elements (HREE) but depleted in light rare earth elements (LREE). In addition, zircons from the No. 6 coal seam had strongly positive Ce (Ce/Ce* = 2.4–224.6) and strongly negative Eu anomalies (Eu/Eu* = 0.1–0.6). Combined with the clear oscillatory zones in the cathodoluminescence images, all the zircon grains of the No. 6 coal were characteristic of zircons with magmatic origins. The 206Pb/238U ages of 34 zircon grains produced a narrow age population of 303–286 Ma, with a weighted average age of 293.0 ± 1.5 Ma (mean-squared weighted deviation = 1.5). Therefore, we infer that the No. 6 coal in the Heidaigou Mine was deposited during the Early Permian, and the Carboniferous–Permian boundary should be located stratigraphically lower than the No. 6 coal. The zircon U–Pb geochronology is a useful tool to determine the depositional ages of non-marine-influenced coal.

Discovery of Late Triassic bivalves from Jurassic deep-water deposits in Riganpeicuo area, Tibet and their geological significance

The Jurassic sequences in the South Qiangtang Basin of Tibet are essential for understanding the paleogeography and tectonic evolution of this basin and the Bangong-Nujiang Meso-Tethys Ocean (BNMO). However, the partial absence of fossils hinders the study of the stratigraphic distribution and tectonic paleogeography of the basin. Late Triassic bivalves, including nine species in nine genera, were identified for the first time in olistostromes from the Sêwa Formation in the Riganpeicuo area. Based on detailed geological field surveys and sedimentary facies analysis, the lower-middle part of the Rigenco section is a deep-water turbidite fan deposit and the upper part is a shallow sea mixed shelf deposit, which differs distinctively from the carbonate platform facies of the Jiebuqu Formation. Therefore, the strata formerly assigned to the Jiebuqu Formation (Rigenco section) is formally reassigned to the Lower-Middle Jurassic Sêwa Formation and Middle Jurassic Shaqiaomu Formation. These results not only provide further understanding of the sedimentary infill history of the South Qiangtang Basin, but also further support that the BNMO was already open in the Late Triassic and formed a mature ocean in the Early-Middle Jurassic, with subsequent rapid subduction. Both the opening and subduction processes were completed in a relatively short time interval with a large number of attendant olistostromes.

Major geological surfaces of the Exmouth Plateau from the new Broadband PreSDM reprocessed 3D seismic data with full waveform inversion

The Barrow Sub-basin and Exmouth Plateau, of Australia’s North West Shelf, contain Australia’s largest gas reserves, underpinning the three major LNG facilities, including Gorgon, Wheatstone and Pluto. In addition, there remains significant near-field exploration potential such as the Sasanof prospect. While there is full 3D seismic coverage in the basin, the existing 3D surveys are of different vintages covering only parts of the basin with diverse acquisition and processing parameters. Multi-Client Resources has produced an extensive 3D seismic reprocessing project (BEX-MC3D) incorporating 23 legacy 3D surveys to provide a seamless 25 570 km2 3D dataset. The BEX-MC3D was processed from field tape through DUG Technology’s advanced Broadband PreSDM processing sequence with Full Waveform Inversion (FWI) imaging. The BEX-MC3D provides one continuous superlative 3D dataset covering almost the entire Barrow Sub-basin and the Exmouth Plateau. Major geological surfaces corresponding to key tectonic events from overburden to reservoirs have been interpreted from the BEX-MC3D Priority area in the current study. These high-fidelity imaged surfaces form a basin-wide framework for: (1) rapid exploration lead and prospect identification through the creation of trap and reservoir visualisations; (2) improved reservoir connectivity analysis and modelling of producing and discovered fields to support better reservoir management and field development decisions; and (3) improved understanding of basin-burial history for reservoir quality and geo-mechanical property prediction. This paper will present and discuss major geological surfaces in the context of future exploration lead/prospect identification, reservoir characterisation for field development and management, and improving overall understanding of the basin history.

Detrital zircon U–Pb ages of Tertiary sequences (Palaeocene‐Miocene): Inner Fold Belt and Belt of Schuppen, Indo‐Myanmar Ranges, India

The along‐strike heterogeneity in the tectonics of Himalaya is well recognized; however, the eastern segment of Himalaya is less studied compared to the other segments. This study combines the comprehensive field data, as well as the U–Pb geochronology of sandstone samples from the Indo‐Burma Range (east India). The study shows that the Lower Disang Formation was deposited in an open marine environment with a steep gradient during the Late Cretaceous to Mid‐Eocene, accommodating the detritus solely from an Indian source. Furthermore, during the Early to Late Eocene interval, the sedimentary basin changed to a shallow marine shelf when the sediments from Himalayan as well as trans‐Himalaya were deposited. The Upper Disang Formation must have been deposited just before or during the collision process between the Indian and Asian plates. After the India‐Asian collision, there was a remnant ocean, in which the sediments of the Barail and Surma groups were deposited in the shallow marine to deltaic environments. The Tethys Ocean completely dried out in the Late Miocene resulting in a change from marine to fluvial environments, which facilitated the deposition of the sandstones of the Tipam Formation. Based on the U–Pb ages, the Palaeogene basin history in the Indo‐Burma Range was unlike the central Himalaya, that is, the detritus were mainly sourced from the Burmese Plate and adjoining magmatic rocks.

Pore pressure prediction using 2D Basin modeling technique

Overpressure and underpressure in the basin are mainly developed due to the disequilibrium compaction between the pore fluids and overburden pressure, and the heat flow/geothermal gradient in the rocks, leading to serious hazards in drilling operations due to the catastrophic well blowouts. Although some techniques have been used to explain the pore pressure mechanisms, there are still some missing gaps in the prediction. Basin modeling software is a very powerful tool as it incorporates various physical phenomena and can simulate the geological history of a sedimentary basin. Thus, a two-dimensional basin modeling software – TemisFlow, was used in the study. The present study was conducted at the Pelotas Basin, Brazil with the aims of (1) to build and run scenario test for pore pressure prediction of the Pelotas Basin, Brazil, (2) to identify the factors that control the pressure development, (3) to test the sensitivity of the parameters that control the pressure distribution, and (4) to evaluate the pressure distribution and pattern in the study area. The temperature model simulated by the software is calibrated with the field data provided in the well log as field pressure data is not provided. Nevertheless, calibration still can be done as the temperature at present and during the basin evolution is one of the parameters to pressure calculation in the model. Generally, the results show abnormal pressure zones are developed only in lower permeability of lithology – shale. Based on the simulations scenarios tested, the presence and generation of hydrocarbon in the Pelotas Basin also contribute a little to the development of overpressure in the basin. Based on the basin modeling results, the main overpressure mechanism in Pelotas Basin is still mainly due to compaction disequilibrium.

The Great Preglacial “Bell River” of North America: Detrital Zircon Evidence for Oligocene–Miocene Fluvial Connections Between the Colorado Plateau and Labrador Sea

The idea of a great pre-glacial river that drained much of North America into the Arctic waters of modern Canada was first suggested in 1895 by Robert A. Bell. In the 1970s, petroleum exploration in Hudson Strait and the Labrador Sea located the massive, submerged delta of what is now known as the Bell River. Reconstructions suggest that three main branches of the Bell River joined up near modern Hudson Bay. The eastern branch largely drained the Canadian Shield, but the central and western branches had headwaters in the Cordilleran orogenic belt and its foreland in the present-day U.S. and northwestern Canada, respectively. We present new detrital zircon U–Pb data from Lower Oligocene and Lower Miocene sand from an exploration well in the Saglek delta of the northern Labrador Sea. In conjunction with other detrital zircon results from the Labrador Sea (and elsewhere) these data record the configuration and history of this continental-scale drainage basin in more detail. Mesozoic and younger detrital zircon grains (< 250 Ma) are subordinate to Precambrian age groupings, but Cenozoic populations become more abundant during the Oligocene, suggesting that the basin had expanded into areas now occupied by the Colorado Plateau and the Basin-and-Range Province. Proterozoic and Phanerozoic detrital zircon grain populations in Saglek delta sediments are similar to those of the Pliocene Colorado River. The results support an earlier idea that initial incision of the Grand Canyon and denudation of the Colorado Plateau were associated with a north-flowing paleo-river that fed into the Bell River basin. This contribution continued until the Pliocene capture of this ancestral river by the Gulf of California basin, after which the excavation of the modern Grand Canyon was completed. The Bell River drainage basin was later blocked by the expansion of Pleistocene ice sheets.

Joint consistent static correction of PP- and PS-waves: A case history of Basin A

The shallow S-wave velocity model is difficult to accurately obtain in seismic exploration, resulting in poor imaging quality when traditional static correction methods are applied to PS-waves. Moreover, unlike for PP-waves, identifying an interface near the water table to use as the datum for PS-waves is almost impossible in many cases. We have developed a case history of joint consistent static correction for PP- and PS-waves of Basin A in Sichuan province, China. In our workflow, crosscorrelation calculation is performed on PP-wave common shotpoint and common receiver-point stacked sections and PS-wave common receiver-point stacked sections to jointly obtain stable shot and receiver statics of PP- and PS-waves. Based on the similarity between the PP-wave and the PS-wave events from the same interface, P-wave statics are used to constrain the calculation of S-wave statics. For comparison, conventional refraction static correction is implemented on the research data. Results show that both approaches produce comparable results for PP-waves, but the PS-wave results from the conventional approach indicate apparent residual statics. This case history demonstrates that joint consistent static correction can effectively solve the static correction problems of multicomponent seismic data and significantly improve the imaging quality.

Waterway to Go! Excavations at Lochrin Basin, Edinburgh

Regeneration of the former industrial areas surrounding Tollcross, Edinburgh, has provided opportunities to rediscover some of the important elements of the area's industrial past. Constructed as a private enterprise that linked into the newly constructed canal network, Lochrin Basin was a significant example of an ambitious family enterprise of the 19th century. Due to its private status and abandonment in the late 19th century, it was infilled and was unfortunately not given the same protected status as the rest of the canal network. However, excavations at the site of the former canal basin revealed that it survived mainly intact, with some surprising elements encountered. As part of the post-excavation process, a programme of documentary research was undertaken to provide a more comprehensive history of Lochrin Basin's inception, construction, and use.

The rejuvenation of hydrocarbon exploration in the Eastern Mediterranean

The exploration history of the large Eastern Mediterranean Basin, which encompasses the Nile Delta, Levantine, Herodotus and Eratosthenes provinces, has seen several phases of rejuvenation since exploration started in the 1950s, with new plays opened repeatedly after the basin was considered mature by the industry. The 584 exploration wells drilled to date have discovered more than 23 Bboe recoverable reserves/resources, mostly gas. The first discovery was the Abu Madi Field, in 1967, which opened the Messinian clastic play. Over time, other plays and sub-plays were opened, including the Serravallian–Tortonian, the Plio–Pleistocene, the Oligo–Miocene in the Levantine, the intra-Oligocene and the Cretaceous carbonates. The exceptional variety of plays, with different trapping styles, reservoir and seal facies patterns has few equivalents worldwide and makes the region a valuable training ground for explorers. The geological variety is not the only reason for such a complex and episodic exploration history: commercial (gas market) and geopolitical issues have also had an impact on the activity in parts of the basin. The largest discoveries have been made in the last 10 years (Tamar, Leviathan, Zohr) and, despite the intense exploration activity, parts of the basin remain underexplored. The company with the longest and most successful play opening history in the basin is Eni. Today, most major oil companies are active in the basin, which even after 70 years is still considered one of the world's exploration hotspots.

Sedimentology and geomorphology of Lake Yamma Yamma - A long-lived structurally controlled playa lake of the Lake Eyre Basin, Australia

ABSTRACT Intraplate tectonism and continental climate change have important roles in the evolution of the arid Lake Eyre Basin, one of the world’s largest interior basins, and a place with economic, environmental, and cultural significance for many Australians. Just off one of the main rivers of the Basin, Cooper Creek, Lake Yamma Yamma – a 20 km by 40 km ephemeral feature – traps sediment ~750 km upstream and ~90 m higher than the ultimate base level of the Basin – Kati Thanda-Lake Eyre. This paper is the first to report on the sedimentology and geomorphic evolution of this modern ephemeral playa lake. Field-based sedimentology, laboratory-based grain size analysis, satellite image interpretation, inundation frequency maps, hydrological data, and digital elevation data, were used to interpret sedimentary processes and the evolution of the lake. Results suggest Lake Yamma Yamma is a long-lived feature. Evolution is primarily structurally controlled, with the main lake delta migrating north-west over time. Quaternary fluvial, lacustrine and aeolian deposition is likely controlled by intraplate tectonism, and palaeo-shorelines may be remnant features of a prior climate regime. Age dating of this sedimentary archive could provide important information on the history, palaeoclimate, and evolution of the Lake Eyre Basin, and the Australian continent.

Settlement Names Referring to Eastern Slavic Settlers in Medieval Hungary

Hungarians arrived at the Carpathian Basin at around 895–900 and after a long journey from the east they occupied the interior plains, mostly the river valleys (in Hungarian history, this event is referred to as the Conquest). The previous tribal alliance had slowly disintegrated by the time of king Stephen I (1001–1038) when pagan beliefs were replaced by Christianity. The peripheral areas of the Kingdom of Hungary, however, were typically uninhabited until the 12th century when the ethnic landscape started changing with the arrival of Saxon settlers, Slavs, Romanians, and Pechenegs. We have no Hungarian written sources from the time preceding the Conquest. The early Latin (less frequently Greek) written sources contain Hungarian words and expressions only sporadically and they are mostly proper names designating places. However, due to their early appearance and low number, these have proved to be truly valuable for linguistics and historical studies exploring the early history of Hungarians and the ethnic and population history of the contemporary Carpathian Basin. In this respect, the settlement names rooted in ethnonyms have a key role as they also shed light on relations between Hungarians and other peoples. This paper studies settlement names that may refer to Eastern Slavic settlers designated by the ethnonym orosz in the medieval Hungarian language. The ethnic groups designated by this name were first registered in the 11th–12th century, however, groups of Slavs could have joined the Hungarian populace before the Conquest. The study shows that the highest proportion of settlement names derived from this ethnonym are found in the northeastern, northern, as well as eastern regions of early medieval Hungary, mostly along the border of the country. The author describes the most frequent name formation patterns that can also be used for relative dating of oikonyms, and discusses the extension to which these data may be useful for the reconstruction of the ethnic landscape of medieval Hungary.

The formation history of the Arctic Basin and the Arctic Ocean according to seismic and geological data

The formation history of the Arctic Basin and the Arctic Ocean according to seismic and geological data

Using ToF-SIMS analyses for analysing individual oil inclusions of different fluorescence colours in a single quartz crystal from the Barrandian (Czech Republic)

The fluorescence colour and molecular signature of oil inclusions can provide precious information on the thermal maturity of inclusion oils and the fluid migration history of basins. Here we show how molecular mass spectrometric analyses in combination with fluorescence microscopy can be used to reveal heterogeneities in the chemical compositions of oil inclusions within a micrometer sized quartz crystal. We used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to extract and directly analyse the molecular content of two yellow and two white-blue fluorescing oil inclusions in a single quartz crystal from the Barrandian Basin (Czech Republic). The cyclic ion species detected primarily in the yellow fluorescing oil inclusions likely originate from steranes, hopanes, and other tricyclic and tetracyclic terpanes, whereas these are less abundant in the white-blue fluorescing oil inclusions. Depth profiles of the fluid inclusions indicate that the white-blue fluorescing oil inclusions are emptied faster in the ToF-SIMS instrument, presumably due to a higher content of more volatile components than in the yellow fluorescing oil inclusions. The phenanthrene to dibenzothiophene ratio derived from ToF-SIMS of the four inclusion oils from the Barrandian Basin indicates marine clastic sediments as the source rocks for all the inclusion oils. The phenanthrene to alkylphenanthrene ratio derived from ToF-SIMS indicates no major difference in thermal maturity of the oil in the white-blue and yellow fluorescing oil inclusions. Instead, variation in the chemical content of the trapped oil induced by trapping fractionation may be the key control.

Depositional age, provenance, and palaeoenvironment of the Lower Permian mudstones in the Qiangtang Basin, Tibet: Evidence from geochronology and geochemistry

The geochronology of tuffaceous sandstone and elemental geochemistry of mudstones in the Lower Permian Zhanjin Formation (well QZ‐5) in the Central Qiangtang Basin were studied to determine their depositional age, provenance, tectonic setting, and depositional conditions. Twenty‐six synchronous igneous zircons from tuffaceous sandstone at 596.5 m have a weighted average U–Pb age of 292.5 ± 2.5 Ma, tentatively constraining the sedimentary age of the Zhanjin Formation to the Early Permian. Low SiO2/Al2O3 and Th/Sc ratios indicate a low sedimentary recycling and compositional maturity for the source area of the Zhanjin Formation mudstones. The low Al2O3/TiO2, moderate‐high Fe2O3/Al2O3, high TiO2/Fe2O3, low‐moderate TiO2/Zr, and moderate Co/Th ratios combined with post‐Archean Australian shale‐normalized rare earth element distributions imply that the provenance of the Zhanjin Formation mudstones was mainly from the mixed mafic and felsic sources that is composed of basalt and rhyolite exposed in the Central Qiangtang Basin. The tectonic discrimination plots, low Fe2O3/TiO2, (La/Ce)N, and high Al2O3/(Al2O3 + Fe2O3) ratios reveal that the studied mudstones mostly formed in rift settings, consistent with the geologic evolutionary history of the Early Permian Qiangtang Basin. Trace element ratios (V/Cr and Cu/Zn), enrichment factors (MoEF), and δCe values combined with sedimentary features indicate that almost all the studied mudstones were deposited in an open marine environment along the continental margin, and were associated with oxic and dysoxic water columns.