Sedimentary Response Research Articles

Characteristics and Geological Significance of High-Frequency Cycles in Salinized Lake Basins: The Paleogene Kumugeliemu Group in the Xinhe Area, Northern Tarim Basin

Salinized lake basins have distinctive sedimentary response characteristics, similar to marine shallow-water carbonate platforms. High-frequency cycles can also be used to reveal more sedimentological information, such as relative lake-level fluctuations, lithofacies sequence combinations, and paleogeographic evolution. In this article, a comprehensive study on the stratigraphic shelf delineation and high-frequency cycles of the Paleozoic Kumugeliemu Group in Xinhe area, northern Tarim Basin, was performed using drilling cores, logging curves, and seismic analyses. As a result of the study, the following data were obtained: the three sets of marker beds in the Kumugeliemu Group in the study area could be divided into a bottom sandstone component (E1-2 km1), a lower gypsum mudstone component (E1-2 km2), a salt rock component (E1-2 km3), and an upper gypsum mudstone component (E1-2 km4) by petrology vertical overlay combination and isochronous tracking correlation, which constituted two third-order cycles (ESQ1, ESQ2). They were further divided into seven fourth-order cycles (Esq1–Esq7). Due to the droughty and saline lacustrine depositional system background, the internal rock fabric changed frequently and showed a periodic vertical overlay pattern. Stratified gypsum salt, gypsum mud (sand) rock, and gypsum rock were used as the cycle interface. A single cycle was mainly characterized by an upward shallower depositional sequence of rapid lake transgression followed by a slow lake regression, composed of massive sandstone–lamellar mudstone–lime dolomite–gypsum rock, massive sandstone–lamellar mudstone–gypsum rock (gypsum salt), massive sandstone–massive gypsum mud (sand) rock–gypsum rock, and other cycle structure types. The complete sedimentary cycle was superposed by a single cycle and compared by the inter-well thickness difference, indicating that the study area had a paleogeomorphology pattern of “West-Low–East-High”. The thickness of the cycles decreased gradually from bottom to top vertically, and five sedimentary stages were determined, i.e., freshwater, brackish, brackish water, salt lake, and semi-saltwater, reflecting the evolutionary process of increasing salinity, lake basin filling, and gradual salinization and shrinkage.

Basement membrane proteins in extracellular matrix characterize NF1 neurofibroma development and response to MEK inhibitor.

Neurofibromatosis Type 1 (NF1) is one of the most common tumor-predisposing genetic disorders. Neurofibromas are NF1-associated benign tumors. A hallmark feature of neurofibromas is an abundant collagen-rich extracellular matrix (ECM) that constitutes >50% of the tumor dry weight. However, little is known about the mechanism underlying ECM deposition during neurofibroma development and treatment response. We performed a systematic investigation of ECM enrichment during plexiform neurofibroma (pNF) development, and identified basement membrane (BM) proteins, rather than major collagen isoforms, as the most upregulated ECM component. Following MEK inhibitor treatment, the ECM profile displayed an overall down-regulation signature, suggesting ECM reduction as a therapeutic benefit of MEK inhibition. Through these proteomic studies, TGF-β1 signaling was identified as playing a role in ECM dynamics. Indeed, TGF-β1 overexpression promoted pNF progression in vivo. Furthermore, by integrating single-cell RNA-sequencing, we found that immune cells including macrophages and T cells produce TGF-β1 to induce Schwann cells to produce and deposit BM proteins for ECM remodeling. Following Nf1 loss, neoplastic Schwann cells further increased BM protein deposition in response to TGF-β1. Our data delineate the regulation governing ECM dynamics in pNF and suggest that BM proteins could serve as markers for disease diagnosis and treatment response.

Sulfate reduction promotes the release of organic phosphorus and iron-bound phosphorus in black-odor sediments in response to increased temperatures

Sulfate reduction promotes the release of organic phosphorus and iron-bound phosphorus in black-odor sediments in response to increased temperatures

Facies character and evolution of a mixed carbonate–siliciclastic shelf: Upper Triassic–Lower Jurassic succession in the eastern Northern Calcareous Alps (Stumpfmauer, Austria)

Western Tethys sedimentary successions constitute fundamental archives of Late Triassic–Early Jurassic environmental, carbonate production and tectonic changes. During the Late Triassic, the Northern Calcareous Alps (Austria) belonged to the Western Tethys passive margin, characterised by the deposition of the early-dolomitized peritidal Hauptdolomit (Norian) adjacent basinward to the Dachstein carbonate shelf and passing upward to the mixed carbonate–siliciclastic Kössen Formation (Upper Norian–Rhaetian). The Kössen Fm. was subdivided into the lower shallow-water Hochalm Member and the upper Eiberg Member, accumulated in an intraplatform basin coeval to shallow-water carbonates (Upper Rhaetian Limestone). The Eiberg Mb. and overlying Jurassic strata were extensively studied as a continuous marine record across the Triassic/Jurassic boundary. In contrast, shallow-water successions, time-equivalent to the Eiberg Mb. and Upper Rhaetian Limestone, located North of the Eiberg Basin, are poorly investigated. This study focusses on the approximately 350 m thick Norian to Lower Jurassic succession cropping out in the eastern Northern Calcareous Alps (Stumpfmauer). The 32 distinguished lithofacies compose seven, vertically superimposed, sedimentary units (A–G), belonging to the Hochalm Mb. of the Kössen Fm. (Unit A peritidal cyclothems, Unit B claystone/marlstone with fossiliferous beds, Unit C coral boundstone to floatstone), Upper Rhaetian Limestone (Unit D subtidal cyclothems with claystone), shallow-water carbonate strata transitional to Lower Jurassic (Unit E ooidal coated grain peloidal grainstone with basal transgressive lag, Unit F bivalve-rich, microbialite and oncoidal lithofacies, previously attributed to the Upper Rhaetian Limestone) and Hettangian–Sinemurian Kalksburg Fm. (Unit G cross-laminated coated grain peloidal grainstone with quartz and chert). The detailed lithofacies characterisation presented in this study contributes to the knowledge on the Northern Calcareous Alps stratigraphy and depositional environments across the Triassic/Jurassic boundary. The identified sedimentary units can be framed in the evolution of Western Tethys and share similarities with depositional systems from the Western Carpathians, Transdanubian Range, Southern Alps and Dinarides suggesting coherent sedimentary response and environmental, climate and tectonic controls in different palaeogeographic domains.

Analysis of the fluvial stratigraphic response to the Paleocene–Eocene Thermal Maximum in the Bighorn Basin, U.S.A.

ABSTRACT Geological deposits can reveal how environments of the past have responded to climate change, enabling important insights into how environments may respond to our current anthropogenically induced warming. The Paleocene–Eocene Thermal Maximum (PETM) occurred ca. 56 Ma and was a short-lived (approximately 200,000 years) global warming event (5–8°C rise). The PETM has been investigated at several terrestrial and marine localities across the globe. However, many studies are based on single successions, with very few sites being placed within a well-defined spatial and temporal context and with comparisons limited to deposits that lie immediately above and below the event. Due to the inherent variability of sedimentary systems, it is imperative that the appropriate context is provided to fully understand the impacts of climate change on landscapes and subsequent deposits. This study examines 28 locations, totaling over 4 km of recorded stratigraphy, within a newly defined quantified sedimentary basin context (Bighorn Basin, USA) to evaluate variability of fluvial response to the PETM. We show that channel-body and story thicknesses across the PETM are not statistically significantly different from deposits outside the climate event, implying that there is not a consistent sedimentary response to the climate event across the basin. Based on our large dataset we calculate that precipitation would have had to double for statistically significant changes in deposit thickness to be generated. We discuss how climatic signals may be lost due to the self-organization, spatial–temporal varied response and preservation potential in large fluvial systems. This study gives a new quantified perspective to climate events in the geologic record.

Sedimentary response to the early Silurian (Rhuddanian-Aeronian) post-glacial transgression and Kwangsian Orogeny in the Upper Yangtze region, South China

Unlike the lowermost Silurian ‘hot’ shales deposited in many other regions of the world, the early Silurian (Rhuddanian-Aeronian) succession in South China exhibits a distinctive lithofacies transition from organic-rich black siliceous mudstone in the early Rhuddanian, to interlaminated siltstone and mudstone with relatively low total organic carbon content in the late Rhuddanian, and finally to organic-lean argillaceous mudstone or calcareous mudstone in the late Aeronian. The interlaminated siltstone and mudstone interval has been the subject of a long-standing dispute over its nature, whether it belongs to turbidite or contourite. In this study, we employed a range of approaches, including petrographic analyses, UPb dating of detrital zircons, and measurements of paleocurrent directions to generate a dataset that reveals: (1) four typical fine-grained facies developed within the interlaminated siltstone and mudstone interval, (2) detrital zircon UPb ages yielding a wide age range from Archean (∼2.50 Ga) to early Paleozoic (0.42 Ga), with a predominant peak of ca. 447 Ma based on 516 detrital zircon UPb analyses, and (3) paleocurrent directions indicate the presence of current circulation in the Upper Yangtze region. The results of this study demonstrated that the detritus of the interlaminated siltstone and mudstone interval originated from concurrent explosive volcanic eruptions along the southeastern margin of the South China Craton. It was deposited and reworked by bottom currents under the background of the early Silurian post-glacial transgression. We suggest that the occurrence of the interlaminated siltstone and mudstone interval is indicative of a far-field sedimentary response to the onset and progradation of the Kwangsian Orogeny in the Upper Yangtze region.

Drainage and sedimentary response of the Northern Andes and the Pebas system to Miocene strike‐slip tectonics: A source to sink study of the Magdalena Basin

AbstractMiocene strike‐slip tectonics was responsible for creating and closing short‐lived (ca. 6 Ma) passages and the emergence of isolated topography in the Northern Andes. These geological events likely influenced the migration and/or isolation of biological populations. To better understand the paleogeography of the Miocene hinterland and foreland regions in the Northern Andes, we conducted a source‐to‐sink approach in the Magdalena Basin. This basin is located between the Central and Eastern Cordilleras of Colombia and contains an ample Miocene record, which includes Lower Miocene fine‐grained strata and Middle Miocene to Pliocene coarsening‐up strata. Our study presents a new data set that includes detrital U–Pb zircon ages (15 samples), sandstone petrography (45 samples) and low‐temperature thermochronology from the Southern Central Cordillera (19 dates); which together with previously published data were used to construct a paleogeographical model of the Miocene hinterland and foreland regions in the Northern Andes. The evolution of the Magdalena Basin during the Miocene was characterized by playa and permanent lake systems at ca. 17.5 Ma, which may be related to a marine incursion into NW South America and western Amazonia. The appearance of Eocene to Miocene volcanic sources in the Honda Group after ca. 16 Ma suggests the development of fluvial passages, which connected the Pacific with the western Amazonia and Caribbean regions. These passages were synchronous with a time of Miocene exhumation and topographic growth (ca. 16 to 10 Ma) in the Central Cordillera and the transition from lacustrine to fluvial deposition in the Magdalena Basin. Middle to Late Miocene strike‐slip deformation promoted by oblique plate convergence and the oblique collision of the Panamá‐Chocó Block likely explains the synchronous along‐strike fragmentation and exhumation in the Central Cordillera.

Biome responses to a hydroclimatic crisis in an Early Cretaceous (Barremian–Aptian) subtropical inland lake ecosystem, Northwest China

The Early Cretaceous palaeoclimate was characterized by arid–humid alternation and accompanied by a series of short-term extreme environmental events, resulting in significant disturbances to the terrestrial ecosystem. However, the discontinuity of terrestrial geological records leads to a lack of detailed research on the coevolution mechanism of organisms and the environment. This study aims to investigate the response of the late Barremian–early Aptian subtropical lake biome structure to the hydroclimate crisis in the Yin'e Basin based on palynology, macropalaeontology, and geochemistry (i.e., major and trace elements, organic carbon isotopes, and biomarkers). The warm and semihumid climate promoted an increase in the abundance and degree of divergence in the vegetation, and the brackish–oxic conditions of the water column were conducive to the prosperity of aquatic organisms. The early aridification of the climate led to a decline in the lake level and a salinity crisis. The saline–suboxic conditions of the water column triggered the first aquatic crisis, while bacterial populations increased gradually. Cooling and continuous aridification led to a significant reduction in the types and amount of vegetation. The insufficient supply of nutrients and the continuous shrinking of the lake caused a second aquatic crisis, and several macroscopic organisms disappeared. The multivariate correlation analysis based on geochemical parameters showed that the palaeoclimate was the key driving factor for the evolution of palaeolakes and their conditions in the water column, and there was a close relationship among the ecological environmental indicators. The petrological and geochemical parameters suggest the existence of lacustrine hydrothermal activity, which could also have a direct impact on the ecological environment of the lake. This study of the Bayingebi Formation palaeolake in the Yin'e Basin provides a strong example of the close coupling changes in the palaeoclimate and lake ecosystem to understand the continental sedimentary response to Early Cretaceous palaeoclimate warming events.

Managing at source and at scale: The use of geomorphic river stories to support rehabilitation of Anthropocene riverscapes in the East Coast Region of Aotearoa New Zealand

Recently uplifted, highly erodible rocks, and recurrent high intensity storms, generate exceedingly high erosion and sedimentation rates in the East Coast Region (Tairāwhiti) of Aotearoa New Zealand. Despite the recent nature of the Anthropocene record in global terms (∼650 years since Māori arrival, 250 years of colonial impacts), human disturbance has profoundly altered evolutionary trajectories of river systems across the region. Here we document catchment-by-catchment variability in anthropogenic signature as geomorphic river stories for five catchments (Waiapu, Hikuwai, Waimatā, Waipaoa, Mōtū). We show how targeted, fit-for-purpose process-based rehabilitation programmes that manage at source and at scale are required to facilitate river recovery in each of these catchments. The largest rivers in the region, Waiapu and Waipaoa, comprise steep, highly dissected terrains that are subject to recurrent hillslope failures, including systemic shallow landslides, occasional deep-seated rotational slumps and earthflows. Localised sediment input from large (>10 ha) gully mass movement complexes overwhelms valley floors. Targeted revegetation programmes are required to reduce extreme sediment inputs from these sources. Although there are fewer gully complexes in the Hikuwai, multiple landslips supply vast volumes of fine-grained sediment that aggrade and are recurrently reworked along channel margins in lowland reaches. Waimatā has no gully complexes and a smaller number of landslips, but large areas are subject to sediment input from earthflows. The terrace-constrained flume-like nature of this system efficiently flushes materials ‘from the mountains to the sea’, recurrently reworking materials along channel banks in a similar manner to the lower Hikuwai. Systematic reforestation in the middle-upper catchment and revegetation of riparian corridors is required to reduce sedimentation rates in these catchments. In contrast, terraces buffer sediment delivery from hillslopes in the upper Mōtū catchment, where a bedrock gorge separates large sediment stores along upper reaches from the lower catchment. As reworking of valley floor sediments in response to bed incision and reworking (expansion) of channel margins is the primary contemporary sediment source in this system, bed control structures and revegetation of riparian corridors are required as part of targeted sediment management plans. We contend that geomorphic river stories provide a coherent platform for Anthropocene rehabilitation strategies that work with the character, behaviour and evolutionary trajectories of river systems. Although this generic lens can be applied anywhere in the world, we highlight particular meanings and implications in Aotearoa New Zealand where such thinking aligns directly with Māori values that respect the mana (authority), mauri (lifeforce) and ora (wellbeing) of each and every river.

Sedimentary features and sequence stratigraphy of the successions around the Carboniferous–Permian boundary in the Ordos Basin: links to glacial and volcanic impacts

The sedimentary successions around the Carboniferous–Permian boundary (CPB) in the Ordos Basin were investigated using extensive outcrop, borehole, well logging, thin section, and geochemistry data to study sedimentary and sequence stratigraphic responses to glaciation and volcanism in paleotropical transitional strata. Within the studied interval, five distinct lithofacies have been identified, including bauxite, coal, and carbonaceous shale (No. 8 + 9 coal seams), sandstone (Qiaotou), limestone (Baode), and mudstone, which can be classified into three lithofacies associations. The most complete lithofacies association is composed of bauxite, coal, carbonaceous shale, sandstone, limestone/mudstone or their combinations from the bottom to the top, while coal and carbonaceous shale, as well as sandstone, are absent locally, resulting in the formation of the other two types of lithofacies associations. The occurrence of bauxite indicates shelf exposure and weathering, the occurrence of coal and carbonaceous shale indicates swampiness of the shelf, and the occurrence of sandstone reveals river rejuvenation; all of these are thought to be sedimentary responses to the transcontinental glacier expansion in Gondwana around the CPB. The presence of limestone and mudstone indicates carbonate platform and lagoon deposition, respectively, in the context of the earliest Asselian transgression caused by volcanism-induced glacier melting. The lithofacies associations record the regressive–transgressive cycles that occurred because of glaciation and volcanism near the CPB. The top surface of bauxite can be used as a sequence boundary, while the lowstand systems tract consists of the No. 8 + 9 coal seams and the Qiaotou sandstone, and the transgressive systems tract consists of the overlying Baode limestone and laterally equivalent mudstone. The lowstand systems tract, which contains source rock and hydrocarbon reservoirs, and the overlying transgressive systems tract, which serves as cap rock, form an excellent source-reservoir-seal combination.

Diverse scale deposition in response to the change in chemical properties of geothermal water at the Dieng geothermal power plant, Indonesia

The geothermal water discharged from the production well at the Dieng geothermal power plant experiences various drastic changes depending on the specific structure. As a result, various siliceous scales were found along the movement of the geothermal water at the Dieng geothermal power plant. To elucidate the geochemical property relationship between siliceous scales and geothermal waters at different locations, both the scale and the geothermal water samples were collected from (1) the inside of the two-phase pipeline, (2) the inside of the brine pipeline, and (3) at the open canal. The saturation index of the minerals was calculated based on the properties of the geothermal waters at each location to predict minerals that are possible to form. By comparing the properties of the scale and the mineral saturation index, quantitative mineral assemblage at each location was calculated, and the scale formation can be explained as follows. (1) Scale in the two-phase pipeline was composed of (Al, K)- and Fe-rich silicate, amorphous silica, and sulfide minerals formed at high temperature and near-neutral pH. The (Al, K)-rich and the Fe2+-rich silicates were controlled by the oversaturation of clinoptilolite and minnesotaite, and the amorphous silica was formed. The sulfide minerals were formed due to the high sulfur fugacity (fs2). (2) Scale in the brine pipeline was mainly composed of amorphous silica containing a small amount of (Al, K)-rich silicate formed under low pH (4∼5) and high-temperature conditions. (Al, K)-rich silicates were still precipitated even after acidification, likely due to the oversaturation of clinoptilolite above pH ∼4, and then the amorphous silica was formed. (3) Scale at the open canal was mainly composed of amorphous silica with small particles of hydrous ferric oxide (HFO), formed under an oxidizing condition at low temperature and low pH (4∼5). HFO reacted with silicic acid in geothermal water to form Fe3+-rich silicate that chemically resembles nontronite. The mineral with the highest proportion was amorphous silica in all three siliceous scales. Although the saturation index of amorphous silica was small, precipitation of amorphous silica may be induced and accelerated due to the adsorption of silicic acid on the (Al, K)-rich silicate and the Fe2+-rich silicate at high temperature and on the Fe3+-rich silicate at low temperature because of high surface area. The adsorbed silicic acid polymerizes on the silicate minerals.

Modification of large microbial mat deformation structures before burial: A modern case study

The presence of microorganisms gives remarkable plasticity and flexibility to wet sediments. Under these circumstances, a coherent microbial mat is developed, which is loosely attached to the underlying sediment layer. These thick microbial mats are capable of being lifted from the underlying sediments in response to high-energy events, such as currents and waves forming several types of synsedimentary microbial mat deformation structures. This study analyses excellent examples of these structures developed in Paso Seco (Argentina), a modern coastal flat colonized by microbial mats frequently inundated during storms, and the modifications that affect them before burial. To achieve this, the hydrodynamic conditions in the coastal flat over time were interpreted from water level records obtained with HOBO loggers. Field photographs were obtained to document the microbial structures (such as flipped-overs, tear mats, roll-ups, mat chips, and folds) covering the area after a high-energy event and over the course of the following two years. Specifically, emphasise was put in roll-up structures because of their large size. Sediment samples were extracted to make thin sections for petrography analysis. Once the microbial structures are formed, they show gradual changes caused by the hydrodynamic conditions that control the sedimentary environment, and on several occasions, these changes are preserved in the sedimentary profile. Our observations and measurement of modern sedimentary structures and the in-situ documentation of their evolution may be helpful for the identification and interpretation of analogous sedimentary structures in the fossil record, which could have undergone similar modifications prior to their burial.

Typical misinterpretations and scientific concepts in well-logging geologic studies

The method and theoretical system of well logging geology have been widely used in the fields of basic geology, petroleum geology and engineering geology, but the different response sensitivity of different well logging series to geological information and the mismatching between geophysical properties of multiple well logs and geological genesis of rocks frequently result in misunderstandings in the research process of well logging geology. Therefore, it is in an urgent need to analyze the typical misunderstanding cases in the research of well logging geology and explore the corresponding scientific ideas and countermeasures. After analyzing the typical misunderstandings in the research of well logging geology, this paper investigates vertical resolution scale of various logging series and its contradiction with detection depth and illustrates the importance of the integration of different scales of data. In addition, the factor inducing “fake logging data” and its influence on interpretation evaluation are clarified and a set of ideas for well logging evaluation of geological interpretation is put forward. And the following research results are obtained. First, the typical misunderstandings in the research of well logging geology can be classified into two categories, namely geological body interpretation misunderstanding and reservoir property parameter calculation misunderstanding. Second, special geological phenomena, such as high-density and high-resistivity mudstone can lead to logging data ambiguity, so attention shall be paid to petrophysical response mechanisms during geological logging interpretation. Third, to carry out well logging evaluation of unconventional oil and gas, it is necessary to integrate new technologies of electric imaging logging, dipole acoustic logging and nuclear magnetic resonance logging, and the calibration of core data and the integration of geological ideas can improve the interpretation accuracy. Fourth, In the process of borehole structural logging analysis, sedimentary response, geostress evaluation and fracture identification, geological ideas shall be integrated to avoid the logging interpretation misunderstanding caused by the same response of different geological phenomena in well logs. In conclusion, the dialectical and systematic thinking from geology to logging and then to geology, from practice to recognition and then to practice and from “a narrow view” to “a broad view” can provide a scientific ideas for the comprehensive research of well logging geology.

Sedimentary response and restoration of paleoshoreline of Taiyuan-Shanxi Formations in North China basin

The Permian Taiyuan-Shanxi Formations in the North China Basin are a series of terrestrial-marine strata whose depositional evolution exhibits unique particularities. Current studies involving the paleoenvironment of the Taiyuan and Shanxi Formations are mainly supported by sedimentary facies or geochemical analysis, yet studies on the sedimentary and geochemical responses of the paleoshoreline remain inadequate, which leads to the inconsistency of the concluded paleoshoreline distribution. Based on outcrop data, well data and major and trace element analysis, sedimentary and geochemical features of the paleoshoreline in both formations are identified. Combining sedimentary facies and geochemical analysis, this study aims to restore the distribution of the paleoshoreline in the Taiyuan and Shanxi Formations as well as its migrations.The outcrop and well data show that the paleoshoreline of the Taiyuan and Shanxi Formations features 3 types of sedimentary responses: (1) distributary channel deposits of the delta plain + argillaceous deposits of the delta front; (2) peat mire of the delta plain + argillaceous deposits of the delta front; and (3) distributary channel deposits of the delta plain + tidal flat-lagoon deposits. Based on major and trace element results, Sr/Ba, m = 100 × (MgO/Al2O3), Mn/Fe, f = (Rb/K)/(Zr/Al), CIA, Sr/Cu, V/(V + Ni), and V/Cr are selected as proxies for paleosalinity, paleowater depth, paleoclimate and paleo-redox conditions. The results show that transitional-brackish water was dominant during the transgression period of the Taiyuan Formation with mild changes in paleowater depth, while fresh water primarily covered the North China Basin during regression during the Shanxi Period, which was a time when paleo-water depth exhibited evident fluctuation in the northern region. Generally, the paleoclimate during the Taiyuan-Shanxi Period was warm and moist to hot and humid, and the paleo-redox conditions were anoxic to reductive.Under the influence of transgression during the Taiyuan Period, the boundary of the freshwater zone closely matches the maximum range of marine deposition, indicating a generally steady transgression background; additionally, the paleoshoreline was distributed in the vicinity of Yulin - Shijiazhuang - Baoding. During the regression event of the Shanxi Period, the paleoshoreline migrated southeast to the south of ZK03-2 and southeast of Yu88, extending southward along Sanmenxia - Luoyang - Zhengzhou - Yuzhou, and the freshwater zone extended southward and covered a considerable range of marine deposition, indicating a strong flux of terrestrial freshwater with periodic transgression. The analysis and conclusions in this paper would hopefully provide insights and a reference for the paleoenvironmental evolution and shoreline changes in the Taiyuan - Shanxi Formations of the North China Basin.

Middle-Late Eocene Climate in the Pearl River Mouth Basin: Evidence from a Palynological and Geological Element Record in the Xijiang Main Subsag

The temperature changes in the middle-late Eocene had a profound impact on various ecosystems around the world. This has been confirmed not only in marine sediments but also in lake ecosystems, which have provided more detailed isochronous continental sedimentary records. Based on systematic palynological and element analyses of fine-grained lacustrine sediments from the Xijiang main subsag in the Pearl River Mouth Basin, southern China, we reconstructed the climate evolution of the middle-late Eocene. A total of 73 genera and 115 species of sporopollen fossils were identified from the middle-late Eocene in the study area. Three pollen zones comprising Quercoidites–Polypodiaceaesporites–Pinuspollenites, Pinuspollenites–Ulmipollenites–Cedripites, and Pinuspollenites–Abietineaepollenites–Juglanspollenites were established from bottom to top. The analysis of the vegetation types, climatic zones, and dry–humid types of the sporopollen showed that, in the study area, the Eocene was dominated by a subtropical–warm temperate climate: the early-late Eocene was dominated by a temperate climate, and the late Eocene was characterized by the prevalence of a warm temperate climate, which was consistent with the palaeoclimate reconstruction results for element geochemical indices (Fe/Mn, Sr/Cu, CIA, PIA, etc.). In addition, the comparative study showed that the middle-late Eocene in the study area was characterized by a warm and humid climate, which transitioned to a warm and cool semihumid–semiarid climate and then a warm and cool semihumid climate. These findings demonstrated a good coupling relationship with the trend for the changes in the global palaeotemperature and can be used as an isochronous continental sedimentary response.

Modeling anthropogenic affected sediment transport in a mid-sized European river catchment–extension of the sediment rating curve equation

Land use and water resource management influence the suspended sediment concentration (SSC) in rivers. Fine sediments are an important driver for river development, even in coarse-material-rich rivers. In this study, the sediment rating curve approach is modified to predict SSC several river-km downstream of a sampling site. Further, the prediction is improved by adding sediment input, storage, and dilution effects through relevant anthropogenic measures through a model identification approach. Thus, the impact of the most severe anthropogenic measures, damming and changes in the length of a channel section for the Rur River, could be identified. Further, the impact of describing parameter changes for those measures on the SSC can be computed and considered in future water resource management. In this approach, particle swarm optimization was used to fit parameters in permutable test- and training data sets to identify linear extensions to the sediment rating curve. The input data consists of (1) SSC, which was obtained by sampling along the river section four times a year over approximately two years, (2) discharge data from river gauges supplemented by rainfall-runoff modeling between stations, (3) rainfall data from meteorological stations, and (4) sub-catchment characteristics like river section length and erosivity obtained with GIS. Via incorporating the river section length and sediment deposition in response to damming, we reduced the RMSE (root mean squared error) from 152.27 to 131.83% with a p-value of 0.073 in the Wilcoxon Signed Rank Test. Further integration of sub-catchment parameters like erosivity led to overfitting and decreased prediction accuracy. A catchment-wide prediction was achieved, but sub-catchments operate on different spatial scales with different connectivity behavior, which restricts the transferability of the equation. SSC-Q hystereses provide the first indications of characteristic sediment sources and were used to discuss connectivity behavior within the study area. They are recommended as part of a (sub-) catchment characterization for further studies.

Sedimentary architecture and glacial hydrodynamic significance of the stratified Oak Ridges Moraine, southern Ontario, Canada

High‐quality subsurface data provide new insights into the formation of Oak Ridges Moraine (ORM), an ~80 km3 sequence of stratified meltwater deposits resting >200 m above adjacent Lake Ontario. The ORM sedimentary succession comprises a three‐part regional architecture: (i) ~north–south channel sand–gravel; (ii) channel‐capping rhythmites; and (iii) east–west ridge sediments. The ORM depositional sequence overlies a regional unconformity with a cross‐cutting channel network resulting from ~north–south meltwater floods that transitioned progressively (falling stage) from a ~NNE to ENE flow direction (parallels Lake Ontario depression). Seismic profiles delineate the channels and channel fill characteristics of bank‐to‐bank channel sedimentation of thick gradational gravel–sand–mud sequences. Channel‐capping mud (~100–236 rhythmites) within multiple channels beneath the ORM landform mark a widespread interval of low‐energy, seasonally controlled subglacial pond deposition. During this quiescent period ice‐sheet thickness adjusted to flood‐induced stretching/thinning and re‐profiled slopes. New ice gradients led to east–west flow and deposition of the overlying third element, a sequence of high‐energy confined esker–fan sediments along ORM ridge. Close, sequential timing (~329 varve years) of channel, basin and ridge‐forming architectural elements supports naming this assemblage the ORM formation. Proposed ORM floods are analogous to Icelandic jökulhlaups based on the size, geometry and sedimentology. The observed rhythmite interval between flood events represents a short period (~236 years) of regional meltwater storage prior to east–west ORM flooding. The ORM channel and overlying esker‐fan sediment ridge represent two closely timed meltwater drainage events rather than formation by coalescing ice streams. The scale and timing of the ORM flood events are linked to rapid sea‐level rise, ~13.5 ka BP. This high‐resolution ORM sedimentological record may provide insights into depositional and glaciogenic controls of other large, stratified moraines. The ORM data indicate deposition in response to hydrodynamic events (outbreak floods, re‐profiled ice) rather than direct climate forcing.

The Hambergfjellet Formation on Bjørnøya – sedimentary response to early Permian tectonics on the Stappen High

The Hambergfjellet Formation on Bjørnøya – sedimentary response to early Permian tectonics on the Stappen High

The Hambergfjellet Formation on Bjørnøya – sedimentary response to early Permian tectonics on the Stappen High

The Hambergfjellet Formation on Bjørnøya – sedimentary response to early Permian tectonics on the Stappen High

Triassic Nappe in the Central Part of the Southern Central Asian Orogenic Belt (Ejinaq, NW China): Evidence from Structural Analysis and Geothermochronology

AbstractThe thrust nappe played an important role in the Mesozoic tectonic evolution of the middle part of the Central Asian Orogenic Belt (CAOB). However, the timing, structural style and kinematic processes of the thrust nappe remain controversial, particularly the detail of the thrust nappe in the Guaizihu region (110 km east of Ejinaq). In this study, we investigate new field mapping, seismic sections, geochronology and low‐temperature thermochronometric dating to provide constraints on the history of this thrust nappe in the Chaheilingashun area (northwestern Guaizihu region). The field mapping, seismic sections and structural analysis reveal that the autochthonous system had developed a series of strong fold structures in the upper Permian strata. The allochthonous system mainly contains Devonian monzogranite (U‐Pb age, ranges from 386.7 to 389.0 Ma) and Meso–Neoproterozoic schists (the maximum depositional age, ∼880 Ma), which were thrust upon the upper Permian strata during Middle to Late Triassic. Based on similar rocks, geochronological dating and the Yagan thrust, we suggest that the postulated root zone of this allochthon might have originated from the Huhetaoergai area (40–60 km northwest of the study area). The geochronological results reveal that the lower age limit of this thrust nappe is constrained by the Lower–Middle Triassic syntectonic sediments (tuffaceous sandstone, ∼247 Ma), which is the sedimentary response of the fold structure., The timing of the termination of this thrust nappe is defined by the cooling age (40Ar/39Ar data, 217–211 Ma) of the Devonian monzogranite and Meso–Neoproterozoic schists. Thus, we consider this thrust event in the study area to potentially have occurred in the period from 247 Ma to 211 Ma, which may represent the tectonic response to the closure of the Paleo‐Asian Ocean.