Pub Date : 2024-11-01DOI: 10.1016/j.sedgeo.2024.106759
Lianchao Luo , Huaguo Wen , Enrico Capezzuoli , Sándor Kele , Orlando Vaselli , Zhipeng Lu , Yaxin Xu , Huixuan Huang , Lei Du , Andrea Brogi
Geochemical characterization is extensively employed in travertine research, yet few studies have explored the potential of travertine geochemistry for elucidating the subterranean details of spring systems. In this study, we systematically characterized the geochemical signatures (δ13C, δ18O, 87Sr/86Sr, REEs, Zr, Th, Sr, Mn) of travertine from six spring systems in Tengchong (SW China) and compared them with those of potential reservoir rocks, aiming to understand travertine origin and assess reservoir conditions. Our results revealed substantial variations in the δ13C and δ18O of travertine among the examined systems, but the water temperature and parent CO2 assessments suggest a hot spring thermogene origin of the travertine. The 87Sr/86Sr of the studied travertine also varies significantly among the systems and overlaps with that of potential reservoir rocks. However, only the springs systems with reservoir temperatures exceeding 150 °C are likely to have precipitated travertine with 87Sr/86Sr resembling the whole-rock 87Sr/86Sr of the reservoir rocks. REE contamination by exogenous detritus and FeMn (oxyhydr)oxides was noted, emphasizing the need for careful REE contamination evaluation in travertine research. The REE comparison reveals that the studied travertine does not fully replicate the REE signature of its potential reservoir rocks, but the REE pattern, (Eu/Eu*)SN, and (Ce/Ce*)SN characteristics of the travertine reveal informative reservoir conditions. In summary, this study shows that the geochemistry of the travertine offers valuable insights into its origin and reservoir conditions. These findings could assist in the geochemical interpretation of travertine and the exaction of hypogean reservoir conditions from travertine.
{"title":"Geochemical (δ13C, δ18O, 87Sr/86Sr, REEs) characterization of travertine in Tengchong, China: Insights into travertine origin and reservoir conditions","authors":"Lianchao Luo , Huaguo Wen , Enrico Capezzuoli , Sándor Kele , Orlando Vaselli , Zhipeng Lu , Yaxin Xu , Huixuan Huang , Lei Du , Andrea Brogi","doi":"10.1016/j.sedgeo.2024.106759","DOIUrl":"10.1016/j.sedgeo.2024.106759","url":null,"abstract":"<div><div>Geochemical characterization is extensively employed in travertine research, yet few studies have explored the potential of travertine geochemistry for elucidating the subterranean details of spring systems. In this study, we systematically characterized the geochemical signatures (δ<sup>13</sup>C, δ<sup>18</sup>O, <sup>87</sup>Sr/<sup>86</sup>Sr, REEs, Zr, Th, Sr, Mn) of travertine from six spring systems in Tengchong (SW China) and compared them with those of potential reservoir rocks, aiming to understand travertine origin and assess reservoir conditions. Our results revealed substantial variations in the δ<sup>13</sup>C and δ<sup>18</sup>O of travertine among the examined systems, but the water temperature and parent CO<sub>2</sub> assessments suggest a hot spring thermogene origin of the travertine. The <sup>87</sup>Sr/<sup>86</sup>Sr of the studied travertine also varies significantly among the systems and overlaps with that of potential reservoir rocks. However, only the springs systems with reservoir temperatures exceeding 150 °C are likely to have precipitated travertine with <sup>87</sup>Sr/<sup>86</sup>Sr resembling the whole-rock <sup>87</sup>Sr/<sup>86</sup>Sr of the reservoir rocks. REE contamination by exogenous detritus and Fe<img>Mn (oxyhydr)oxides was noted, emphasizing the need for careful REE contamination evaluation in travertine research. The REE comparison reveals that the studied travertine does not fully replicate the REE signature of its potential reservoir rocks, but the REE pattern, (Eu/Eu*)<sub>SN</sub>, and (Ce/Ce*)<sub>SN</sub> characteristics of the travertine reveal informative reservoir conditions. In summary, this study shows that the geochemistry of the travertine offers valuable insights into its origin and reservoir conditions. These findings could assist in the geochemical interpretation of travertine and the exaction of hypogean reservoir conditions from travertine.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"473 ","pages":"Article 106759"},"PeriodicalIF":2.7,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.sedgeo.2024.106757
Alexis Godet , Jacob Byerly , Matthew Bourdon , Marina Suarez
Climate and environmental instability during the early Aptian culminated with the unfolding of the Oceanic Anoxic Event (OAE) 1a, which resulted in the deposition of black shales in deep marine settings and a typical negative spike followed by a positive excursion in δ13C values. In Vercors (southern France) the Urgonian platform developed prior to and coeval to the OAE1a, but the impact of this paleoenvironmental crisis on the ecology of benthic ecosystems is yet to be quantified. We gathered field and petrographic data to identify sequence boundaries and maximum flooding surfaces that are biostratigraphically dated and correlated between four localities within the study area. A composite δ13C curve is built where the C3 to C7 isotope segments from the literature are identified, pinpointing the onset of the OAE1a above the last episode of deposition of Urgonian facies rich in rudist bivalves. Furthermore, thin section point counting data are used to quantify the proportion of allochems in samples and to trace changes in the ecology of ecosystems. The principal component analysis of point counting data helps define ecological tiers: a diversified, photozoan association with rudists, green algae, and benthic foraminifera dominated ecosystems before the OAE1a and up to the C7 segment, while a less diversified heterozoan association with bryozoans and crinoids developed after the OAE1a. To explore the triggers for this change, the principal component analysis of elemental geochemical data highlights an increased nutrient and detrital input as major triggering mechanisms for ecological adjustments and changes in the biodiversity of ecosystems. In particular after the OAE1a, an increase in detrital and nutrient input leads to the replacement of photozoan by heterozoan assemblages more adapted to these stressful conditions. This research directly links paleoenvironmental deterioration to paleoecological changes and quantifies the amount of adaptation of ecosystems.
{"title":"Quantifying paleoecological impact of the OAE1a on shallow marine ecosystems from southeastern France","authors":"Alexis Godet , Jacob Byerly , Matthew Bourdon , Marina Suarez","doi":"10.1016/j.sedgeo.2024.106757","DOIUrl":"10.1016/j.sedgeo.2024.106757","url":null,"abstract":"<div><div>Climate and environmental instability during the early Aptian culminated with the unfolding of the Oceanic Anoxic Event (OAE) 1a, which resulted in the deposition of black shales in deep marine settings and a typical negative spike followed by a positive excursion in δ<sup>13</sup>C values. In Vercors (southern France) the Urgonian platform developed prior to and coeval to the OAE1a, but the impact of this paleoenvironmental crisis on the ecology of benthic ecosystems is yet to be quantified. We gathered field and petrographic data to identify sequence boundaries and maximum flooding surfaces that are biostratigraphically dated and correlated between four localities within the study area. A composite δ<sup>13</sup>C curve is built where the C3 to C7 isotope segments from the literature are identified, pinpointing the onset of the OAE1a above the last episode of deposition of Urgonian facies rich in rudist bivalves. Furthermore, thin section point counting data are used to quantify the proportion of allochems in samples and to trace changes in the ecology of ecosystems. The principal component analysis of point counting data helps define ecological tiers: a diversified, photozoan association with rudists, green algae, and benthic foraminifera dominated ecosystems before the OAE1a and up to the C7 segment, while a less diversified heterozoan association with bryozoans and crinoids developed after the OAE1a. To explore the triggers for this change, the principal component analysis of elemental geochemical data highlights an increased nutrient and detrital input as major triggering mechanisms for ecological adjustments and changes in the biodiversity of ecosystems. In particular after the OAE1a, an increase in detrital and nutrient input leads to the replacement of photozoan by heterozoan assemblages more adapted to these stressful conditions. This research directly links paleoenvironmental deterioration to paleoecological changes and quantifies the amount of adaptation of ecosystems.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"473 ","pages":"Article 106757"},"PeriodicalIF":2.7,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.sedgeo.2024.106754
Karol Jewuła , Wiesław Trela , Artur Kędzior , Anna Fijałkowska-Mader , Natalia Wasielka
The Early Triassic period was characterised by significant climatic perturbations driven by generally high global temperatures. Several significant shifts in the stable carbon and oxygen isotopes were recognised in the marine settings in the Olenekian age deposits that were linked to short-lasting but relatively high-amplitude climatic events. The record of these events in the continental strata is far less understood due to the stratigraphic incompleteness of such deposits. However, in the Holy Cross Mountains (Poland), the Olenekian continental deposits are well preserved, and sedimentation was relatively continuous, making them an ideal candidate for studying the effects of climate changes and their preservation in continental settings. As such, sedimentological analysis of five wells and one outcrop (over 530 m logged in total), integrated with new and legacy palynological data, allowed the reconstruction and dating of major steps in the palaeoenvironmental evolution of the SE part of the Central European (Germanic Basin), and its comparison with the marine-based climatic models for the Early Triassic. The lower and middle Olenekian stage is represented by fine-grained deposits of dry floodplain interbedded with sandstones deposited within fluvial distributary channels and terminal splays. The palaeosols are mainly represented by aridisols (calcisols), indicating a relatively dry, though not extreme, climate as some water was necessary to support relict plant cover. Towards the mid-Spathian times, the climate became more humid - lacustrine deposits appeared, and palaeosols displayed features of an elevated water table (gleyed vertisols and inceptisols). Frequent storms and floods also affected the lacustrine sedimentation, reflecting volatile climatic conditions. In the late Spathian time, continental sedimentation continued, and the dominance of vertisols and more stacked fluvial channels in the sequence is linked with an increased seasonality, with more pronounced humid seasons. The continental setting lasted until the latest Spathian time, when a marine transgression occurred, marking a new phase in the basin development.
{"title":"Facies architecture, pedogenesis and palynology of the Olenekian dryland setting – A sedimentary record of Early Triassic climate oscillations in the SE Germanic Basin","authors":"Karol Jewuła , Wiesław Trela , Artur Kędzior , Anna Fijałkowska-Mader , Natalia Wasielka","doi":"10.1016/j.sedgeo.2024.106754","DOIUrl":"10.1016/j.sedgeo.2024.106754","url":null,"abstract":"<div><div>The Early Triassic period was characterised by significant climatic perturbations driven by generally high global temperatures. Several significant shifts in the stable carbon and oxygen isotopes were recognised in the marine settings in the Olenekian age deposits that were linked to short-lasting but relatively high-amplitude climatic events. The record of these events in the continental strata is far less understood due to the stratigraphic incompleteness of such deposits. However, in the Holy Cross Mountains (Poland), the Olenekian continental deposits are well preserved, and sedimentation was relatively continuous, making them an ideal candidate for studying the effects of climate changes and their preservation in continental settings. As such, sedimentological analysis of five wells and one outcrop (over 530 m logged in total), integrated with new and legacy palynological data, allowed the reconstruction and dating of major steps in the palaeoenvironmental evolution of the SE part of the Central European (Germanic Basin), and its comparison with the marine-based climatic models for the Early Triassic. The lower and middle Olenekian stage is represented by fine-grained deposits of dry floodplain interbedded with sandstones deposited within fluvial distributary channels and terminal splays. The palaeosols are mainly represented by aridisols (calcisols), indicating a relatively dry, though not extreme, climate as some water was necessary to support relict plant cover. Towards the mid-Spathian times, the climate became more humid - lacustrine deposits appeared, and palaeosols displayed features of an elevated water table (gleyed vertisols and inceptisols). Frequent storms and floods also affected the lacustrine sedimentation, reflecting volatile climatic conditions. In the late Spathian time, continental sedimentation continued, and the dominance of vertisols and more stacked fluvial channels in the sequence is linked with an increased seasonality, with more pronounced humid seasons. The continental setting lasted until the latest Spathian time, when a marine transgression occurred, marking a new phase in the basin development.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"472 ","pages":"Article 106754"},"PeriodicalIF":2.7,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.sedgeo.2024.106756
Lianji Liang , Zhihao Lu , Qitao Zhang , Hongshui Tian , Fuchu Dai , Hanchao Jiang , Ning Zhong
Soft sediment deformation structures (SSDSs) in lacustrine sediments could record paleoearthquakes in tectonically active areas. However, their interpretations of deformation and triggering mechanisms still exist disagreement due to the lack of understanding of natural formation processes of SSDSs. In this study, two large shaking table experiments of saturated lacustrine sedimentary sequences, including Model 1 (simple stratigraphic system of thick silty-clay and sand layer) and Model 2 (stratigraphic systems of thin silty-clay and sand alternating layers) were carried out at the different peak ground accelerations (PGA) in order to simulate the earthquake-triggered SSDSs on the basis of field investigation in Tashkorgan of western China. The results showed that there were no SSDSs formed at the PGA 0.125g, and the excess pore-water pressure ratio (γμ) measured in the sand layer was lower than 0.1; sand volcanos, pipes and sand veins were formed at the PGA 0.25g, and the γμ value of the sand layer reached about 0.2 with the maximum liquefied depths of nearly 30 cm, indicating that weak liquefaction occurred in the sand layer; sand volcanos, pipes, sand veins, diapirs, load and flame structures, ball-and-pillow structures, silty-clay deformation structures were formed at the PGA 0.5g and 0.8g, and the γμ value of sand layer reached about 0.91 and 0.94 with the maximum liquefied depths of nearly 60 cm and 100 cm, respectively. The γμ value of silty-clay layers measured in all the tests was lower than 0.1, indicating that little liquefaction but thixotropy happened in the silty-clay layers. The tests showed that liquefied SSDSs could form at the PGA 0.25g, while thixotropic and gravity-driven SSDSs could form until the PGA reached 0.5g. This study also provided insights for single or closely spaced shaking events being responsible of superposed deformed beds. The simulated SSDSs have striking resemblance to that of ones identified in the field, supporting the earthquake triggering of SSDSs in the Tashkorgan area.
{"title":"Shaking table simulation of soft sediment deformation structures in lacustrine sediments","authors":"Lianji Liang , Zhihao Lu , Qitao Zhang , Hongshui Tian , Fuchu Dai , Hanchao Jiang , Ning Zhong","doi":"10.1016/j.sedgeo.2024.106756","DOIUrl":"10.1016/j.sedgeo.2024.106756","url":null,"abstract":"<div><div>Soft sediment deformation structures (SSDSs) in lacustrine sediments could record paleoearthquakes in tectonically active areas. However, their interpretations of deformation and triggering mechanisms still exist disagreement due to the lack of understanding of natural formation processes of SSDSs. In this study, two large shaking table experiments of saturated lacustrine sedimentary sequences, including Model 1 (simple stratigraphic system of thick silty-clay and sand layer) and Model 2 (stratigraphic systems of thin silty-clay and sand alternating layers) were carried out at the different peak ground accelerations (PGA) in order to simulate the earthquake-triggered SSDSs on the basis of field investigation in Tashkorgan of western China. The results showed that there were no SSDSs formed at the PGA 0.125<em>g</em>, and the excess pore-water pressure ratio (γ<sub><em>μ</em></sub>) measured in the sand layer was lower than 0.1; sand volcanos, pipes and sand veins were formed at the PGA 0.25<em>g</em>, and the γ<sub><em>μ</em></sub> value of the sand layer reached about 0.2 with the maximum liquefied depths of nearly 30 cm, indicating that weak liquefaction occurred in the sand layer; sand volcanos, pipes, sand veins, diapirs, load and flame structures, ball-and-pillow structures, silty-clay deformation structures were formed at the PGA 0.5<em>g</em> and 0.8<em>g</em>, and the γ<sub><em>μ</em></sub> value of sand layer reached about 0.91 and 0.94 with the maximum liquefied depths of nearly 60 cm and 100 cm, respectively. The γ<sub><em>μ</em></sub> value of silty-clay layers measured in all the tests was lower than 0.1, indicating that little liquefaction but thixotropy happened in the silty-clay layers. The tests showed that liquefied SSDSs could form at the PGA 0.25<em>g</em>, while thixotropic and gravity-driven SSDSs could form until the PGA reached 0.5<em>g</em>. This study also provided insights for single or closely spaced shaking events being responsible of superposed deformed beds. The simulated SSDSs have striking resemblance to that of ones identified in the field, supporting the earthquake triggering of SSDSs in the Tashkorgan area.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"472 ","pages":"Article 106756"},"PeriodicalIF":2.7,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.sedgeo.2024.106755
Sergio A. Celis , Damián Moyano-Paz , Sebastián Richiano , José I. Cuitiño , Francisco J. Rodríguez-Tovar
<div><div>An integrated analysis of ichnological and sedimentological features in ancient successions provides a robust dataset of high-resolution interpretations of environmental parameters, encompassing both depositional and ecological aspects. By characterising discrete and recurring bioturbation patterns in the Puerto Madryn Formation (Late Miocene, Argentine Patagonia), we arrive at key knowledge about predominant environmental stresses within transgressive phase shallow marine and estuarine systems, shedding light on their palaeoenvironmental implications. Given the inherent complexities of coastal settings, including the challenges posed by omission/erosion surfaces, it becomes imperative to consider the intricate interplay of multiple depositional processes and environmental factors.</div><div>Through a detailed integration of sedimentological and ichnological approaches, we discern the establishment of a wave-dominated system overlain by a tide-dominated estuarine system.</div><div>The wave-dominated marine system involves tabular bodies extending laterally over tens of kilometres, with upward fining and coarsening successions from the mid- to lower-shoreface to offshore-shelf environments. The influence of waves and tides on these systems is discussed in the absence of physical sedimentary structures and the need to find elements that bring us closer to elucidating whether waves or tidal processes influence shoreface to offshore systems. The ichnological assemblages allow for the characterisation of <em>Cruziana</em> ichnofacies with proximal (<em>Taenidium</em> and <em>Thalassinoides</em>), archetypal (<em>Asterosoma</em>, <em>Chondrites</em>, <em>Cylindrichnus</em>, <em>Ophiomorpha</em>, ?<em>Rhizocorallium</em>, <em>Rosselia</em>, <em>Scolicia</em>, <em>Sinusichnus</em>, <em>Siphonichnus</em>, <em>Teichichnus</em>, and <em>Thalassinoides</em>), and distal expressions (<em>Chondrites</em>, <em>Helicodromites</em>, <em>Phycodes</em>, <em>Thalassinoides</em>, and ?<em>Zoophycos</em>) in the lower shoreface to lower offshore and transitional settings with the shelf. However, the transition from these deposits to <em>Chondrites</em>-dominated beds associated with lower offshore to shelf environments—determined by changes in oxygenation, nutrients, and energy conditions—impedes assignment of all the successions to a particular ichnofacies.</div><div>The tide-dominated estuarine system features wide, channel-shaped bodies filled with sandy to heterolithic facies, interpreted as intertidal and subtidal deposits. To differentiate between estuary mouths and other settings, the analysis involved characterisation of transgressive and regressive surfaces, ichnological assemblages, and facies distribution, determining net sediment movement—whether landwards or seawards—and its influence on system classification. The ichnological assemblages could be assigned to the <em>Skolithos</em> (<em>Arenicolites</em>, <em>Gyrolithes</em>, <em>Maiakarichnus</
{"title":"Ichnological indicators of physico-chemical stresses in wave- to tide-dominated Miocene shallow marine environments (Argentine Patagonia)","authors":"Sergio A. Celis , Damián Moyano-Paz , Sebastián Richiano , José I. Cuitiño , Francisco J. Rodríguez-Tovar","doi":"10.1016/j.sedgeo.2024.106755","DOIUrl":"10.1016/j.sedgeo.2024.106755","url":null,"abstract":"<div><div>An integrated analysis of ichnological and sedimentological features in ancient successions provides a robust dataset of high-resolution interpretations of environmental parameters, encompassing both depositional and ecological aspects. By characterising discrete and recurring bioturbation patterns in the Puerto Madryn Formation (Late Miocene, Argentine Patagonia), we arrive at key knowledge about predominant environmental stresses within transgressive phase shallow marine and estuarine systems, shedding light on their palaeoenvironmental implications. Given the inherent complexities of coastal settings, including the challenges posed by omission/erosion surfaces, it becomes imperative to consider the intricate interplay of multiple depositional processes and environmental factors.</div><div>Through a detailed integration of sedimentological and ichnological approaches, we discern the establishment of a wave-dominated system overlain by a tide-dominated estuarine system.</div><div>The wave-dominated marine system involves tabular bodies extending laterally over tens of kilometres, with upward fining and coarsening successions from the mid- to lower-shoreface to offshore-shelf environments. The influence of waves and tides on these systems is discussed in the absence of physical sedimentary structures and the need to find elements that bring us closer to elucidating whether waves or tidal processes influence shoreface to offshore systems. The ichnological assemblages allow for the characterisation of <em>Cruziana</em> ichnofacies with proximal (<em>Taenidium</em> and <em>Thalassinoides</em>), archetypal (<em>Asterosoma</em>, <em>Chondrites</em>, <em>Cylindrichnus</em>, <em>Ophiomorpha</em>, ?<em>Rhizocorallium</em>, <em>Rosselia</em>, <em>Scolicia</em>, <em>Sinusichnus</em>, <em>Siphonichnus</em>, <em>Teichichnus</em>, and <em>Thalassinoides</em>), and distal expressions (<em>Chondrites</em>, <em>Helicodromites</em>, <em>Phycodes</em>, <em>Thalassinoides</em>, and ?<em>Zoophycos</em>) in the lower shoreface to lower offshore and transitional settings with the shelf. However, the transition from these deposits to <em>Chondrites</em>-dominated beds associated with lower offshore to shelf environments—determined by changes in oxygenation, nutrients, and energy conditions—impedes assignment of all the successions to a particular ichnofacies.</div><div>The tide-dominated estuarine system features wide, channel-shaped bodies filled with sandy to heterolithic facies, interpreted as intertidal and subtidal deposits. To differentiate between estuary mouths and other settings, the analysis involved characterisation of transgressive and regressive surfaces, ichnological assemblages, and facies distribution, determining net sediment movement—whether landwards or seawards—and its influence on system classification. The ichnological assemblages could be assigned to the <em>Skolithos</em> (<em>Arenicolites</em>, <em>Gyrolithes</em>, <em>Maiakarichnus</","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"472 ","pages":"Article 106755"},"PeriodicalIF":2.7,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.sedgeo.2024.106753
Piotr Łapcik
Submarine sediment density flows play a pivotal role in transporting clastic material to the deep sea. The volume of sediment they transport, which bypasses a specific point or geographical location, shapes the stratigraphic record of the entire turbidite systems. Hence, recognition of bypass-dominated zones is crucial in facies prediction and understanding the architecture of turbidite systems. This understanding is linked to the economic aspects of exploring hydrocarbon deposits, the occurrence of geohazards that impact submarine infrastructure, the distribution of pollutants, and carbon sequestration.
In the western part of the Ropianka Fm (Skole Nappe, Polish Outer Carpathians), three bed types showing evidence of sediment bypass were identified in the channel-mouth setting of marl-dominated slope and base-of-slope successions. The varying proportions of these bed types in studied successions and relationship with adjacent facies associations led to the identification of two channel-mouth zones. This study provides insights into deposits with characteristics differing from the previously described channel-mouth setting, evidenced by a significantly lower sand-to-mud ratio and smaller scale of erosional and depositional structures. The reported channel-mouth zones are interpreted as the marginal parts of a channel mouth, formed by subcritical flows. This study broadens the understanding of the channel-mouth setting by introducing dynamic and mud-dominated zones that experience sediment bypass and weak erosion. The identified bed types and typical characteristics of Marginal channel-mouth zones 1 and 2 can serve as a reference for interpreting marginal areas of channel-mouth settings in mud-dominated successions with scattered thin-bedded and coarse-grained deposits in other deep-water basins.
{"title":"Sediment bypass in a marl-dominated margin of a turbidite system in a narrow basin setting","authors":"Piotr Łapcik","doi":"10.1016/j.sedgeo.2024.106753","DOIUrl":"10.1016/j.sedgeo.2024.106753","url":null,"abstract":"<div><div>Submarine sediment density flows play a pivotal role in transporting clastic material to the deep sea. The volume of sediment they transport, which bypasses a specific point or geographical location, shapes the stratigraphic record of the entire turbidite systems. Hence, recognition of bypass-dominated zones is crucial in facies prediction and understanding the architecture of turbidite systems. This understanding is linked to the economic aspects of exploring hydrocarbon deposits, the occurrence of geohazards that impact submarine infrastructure, the distribution of pollutants, and carbon sequestration.</div><div>In the western part of the Ropianka Fm (Skole Nappe, Polish Outer Carpathians), three bed types showing evidence of sediment bypass were identified in the channel-mouth setting of marl-dominated slope and base-of-slope successions. The varying proportions of these bed types in studied successions and relationship with adjacent facies associations led to the identification of two channel-mouth zones. This study provides insights into deposits with characteristics differing from the previously described channel-mouth setting, evidenced by a significantly lower sand-to-mud ratio and smaller scale of erosional and depositional structures. The reported channel-mouth zones are interpreted as the marginal parts of a channel mouth, formed by subcritical flows. This study broadens the understanding of the channel-mouth setting by introducing dynamic and mud-dominated zones that experience sediment bypass and weak erosion. The identified bed types and typical characteristics of Marginal channel-mouth zones 1 and 2 can serve as a reference for interpreting marginal areas of channel-mouth settings in mud-dominated successions with scattered thin-bedded and coarse-grained deposits in other deep-water basins.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"472 ","pages":"Article 106753"},"PeriodicalIF":2.7,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1016/j.sedgeo.2024.106745
Caineng Mu , Xiaobo Huang , Liya Da , Anqing Chen , James G. Ogg , Huan Lu , Yuzhu Ge , Jian Luo , Siyu Xiong , Haiyang Cao , Mingcai Hou
Micrite envelopes are common early diagenetic features in marine carbonate grains. Most case studies of micrite envelopes focus on those with calcium-carbonate compositions. This paper documents a new type of lacustrine dolomicrite envelopes, coating both terrigenous grains and bioclasts, which developed in the upper Shahejia Formation of early Oligocene age in the middle of the Bohai Bay Basin. These dolomicrite envelopes on grains in a lacustrine mixed sedimentary environment are puzzling for their formation and linkage with the porosity preservation of porosity among grains. We investigate the microstructure and formation mechanism of these dolomicrite envelopes that coat grains through the study of the mineralogy, petrology and porosity characteristics. These studies show that there are two occurrences of the dolomicrite envelopes, i.e., coating on detrital grains and coating on carbonate grains, with a multi-layer microstructure. A potential two stage model to interpret the formation of dolomicrite envelopes incorporates an initial illite coating followed by dolomite encrustation. The illite coating played an important role in the precipitation of the dolomite. Post-envelope diagenetic processes include sparry cementation and destructive dissolution. The quantitative content of dolomicrite envelopes positively correlates with the preserved porosity, which suggests that their formation contributed to resisting compaction and protecting porosity among grains. Indeed, the dolomicrite envelopes appear to have aided in maintaining a kind of extremely high-quality reservoir for hydrocarbon exploration within the Shahejia Formation of the Bohai Bay Basin. In addition, the coating film seems to be conducive to the exchange of anions, thereby resulting in the dissolution of interior feldspar-, bioclast- or ooid-grains. In summary the Shahejia Formation of the Bohai Bay Basin provides a new type of dolomicrite envelope on grains in a lacustrine setting.
{"title":"A new type of dolomicrite envelope formed in Oligocene lacustrine sediments and its significance for preserving porosity, Bohai Bay Basin, North China","authors":"Caineng Mu , Xiaobo Huang , Liya Da , Anqing Chen , James G. Ogg , Huan Lu , Yuzhu Ge , Jian Luo , Siyu Xiong , Haiyang Cao , Mingcai Hou","doi":"10.1016/j.sedgeo.2024.106745","DOIUrl":"10.1016/j.sedgeo.2024.106745","url":null,"abstract":"<div><p>Micrite envelopes are common early diagenetic features in marine carbonate grains. Most case studies of micrite envelopes focus on those with calcium-carbonate compositions. This paper documents a new type of lacustrine dolomicrite envelopes, coating both terrigenous grains and bioclasts, which developed in the upper Shahejia Formation of early Oligocene age in the middle of the Bohai Bay Basin. These dolomicrite envelopes on grains in a lacustrine mixed sedimentary environment are puzzling for their formation and linkage with the porosity preservation of porosity among grains. We investigate the microstructure and formation mechanism of these dolomicrite envelopes that coat grains through the study of the mineralogy, petrology and porosity characteristics. These studies show that there are two occurrences of the dolomicrite envelopes, i.e., coating on detrital grains and coating on carbonate grains, with a multi-layer microstructure. A potential two stage model to interpret the formation of dolomicrite envelopes incorporates an initial illite coating followed by dolomite encrustation. The illite coating played an important role in the precipitation of the dolomite. Post-envelope diagenetic processes include sparry cementation and destructive dissolution. The quantitative content of dolomicrite envelopes positively correlates with the preserved porosity, which suggests that their formation contributed to resisting compaction and protecting porosity among grains. Indeed, the dolomicrite envelopes appear to have aided in maintaining a kind of extremely high-quality reservoir for hydrocarbon exploration within the Shahejia Formation of the Bohai Bay Basin. In addition, the coating film seems to be conducive to the exchange of anions, thereby resulting in the dissolution of interior feldspar-, bioclast- or ooid-grains. In summary the Shahejia Formation of the Bohai Bay Basin provides a new type of dolomicrite envelope on grains in a lacustrine setting.</p></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"472 ","pages":"Article 106745"},"PeriodicalIF":2.7,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142239517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-10DOI: 10.1016/j.sedgeo.2024.106746
Xiqiang Zhou , Xiyuan Chen , Tongxuan Du , Jian Sun , Dongjie Tang , Run Li , Kang-Jun Huang , Yi Ding , Daizhao Chen
Marine calcium cycling is closely linked with carbon cycling in the ocean, in which authigenic carbonates precipitated in sediments play a non-negligible role. However, calcium cycling during authigenic carbonate precipitation in organic-rich, shaly sediments in geological history remains underexplored. This study focuses on carbonate concretions (aggregates of authigenic carbonates) in the lower Cambrian Niutitang Formation, South China, to provide insights into calcium cycling during their growth. Sedimentological and mineralogical observations suggest that these concretions were formed through concentric growth by authigenic calcite and pyrite precipitation during the early diagenetic stage. Geochemical analyses reveal internal variations in “M-shaped” δ13Ccarb trends (from −11.9 ‰ to −4.4 ‰) and diverse δ34Spyr trends (from 4.7 ‰ to 14.0 ‰) along core-to-rim transects. These findings suggest formation through microbial sulfate reduction by organic matter in a shallow depth beneath the sediment–water interface. In contrast to the dynamic δ13Ccarb and δ34Spyr variations and multi-stage concentric growth, these carbonate concretions display nearly uniform δ44/40Cacarb values (from 0.80 ‰ to 1.03 ‰, average 0.96 ± 0.06 ‰, 1SD) and consistent internal trends, which are further attributed to strongly seawater-buffered porewater calcium geochemistry and small calcium isotope fractionation due to calcite precipitation at slow rates. This study confirms that early diagenetic carbonate concretions in the lower Cambrian Niutitang Formation are characterized by much heavier δ44/40Ca values compared to coeval shallow platform carbonates. In light of abundant authigenic carbonates observed in the lower Cambrian successions, their roles in calcium isotope mass balance in the early Cambrian ocean warrant further investigation in the future. Therefore, early diagenetic carbonate concretions in black shales could provide valuable insights into porewater and seawater calcium isotope signals, as well as early diagenetic and marine calcium cycling in geological history.
{"title":"Carbon–sulfur–calcium isotopic variability of lower Cambrian shale-hosted carbonate concretions: Insights into growth mechanisms and calcium cycling","authors":"Xiqiang Zhou , Xiyuan Chen , Tongxuan Du , Jian Sun , Dongjie Tang , Run Li , Kang-Jun Huang , Yi Ding , Daizhao Chen","doi":"10.1016/j.sedgeo.2024.106746","DOIUrl":"10.1016/j.sedgeo.2024.106746","url":null,"abstract":"<div><div>Marine calcium cycling is closely linked with carbon cycling in the ocean, in which authigenic carbonates precipitated in sediments play a non-negligible role. However, calcium cycling during authigenic carbonate precipitation in organic-rich, shaly sediments in geological history remains underexplored. This study focuses on carbonate concretions (aggregates of authigenic carbonates) in the lower Cambrian Niutitang Formation, South China, to provide insights into calcium cycling during their growth. Sedimentological and mineralogical observations suggest that these concretions were formed through concentric growth by authigenic calcite and pyrite precipitation during the early diagenetic stage. Geochemical analyses reveal internal variations in “M-shaped” δ<sup>13</sup>C<sub>carb</sub> trends (from −11.9 ‰ to −4.4 ‰) and diverse δ<sup>34</sup>S<sub>pyr</sub> trends (from 4.7 ‰ to 14.0 ‰) along core-to-rim transects. These findings suggest formation through microbial sulfate reduction by organic matter in a shallow depth beneath the sediment–water interface. In contrast to the dynamic δ<sup>13</sup>C<sub>carb</sub> and δ<sup>34</sup>S<sub>pyr</sub> variations and multi-stage concentric growth, these carbonate concretions display nearly uniform δ<sup>44/40</sup>Ca<sub>carb</sub> values (from 0.80 ‰ to 1.03 ‰, average 0.96 ± 0.06 ‰, 1SD) and consistent internal trends, which are further attributed to strongly seawater-buffered porewater calcium geochemistry and small calcium isotope fractionation due to calcite precipitation at slow rates. This study confirms that early diagenetic carbonate concretions in the lower Cambrian Niutitang Formation are characterized by much heavier δ<sup>44/40</sup>Ca values compared to coeval shallow platform carbonates. In light of abundant authigenic carbonates observed in the lower Cambrian successions, their roles in calcium isotope mass balance in the early Cambrian ocean warrant further investigation in the future. Therefore, early diagenetic carbonate concretions in black shales could provide valuable insights into porewater and seawater calcium isotope signals, as well as early diagenetic and marine calcium cycling in geological history.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"472 ","pages":"Article 106746"},"PeriodicalIF":2.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142324110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-06DOI: 10.1016/j.sedgeo.2024.106740
Yazhou Hu , Timothy P. Topper , Junming Zhou , Zhao Wang , Bing Pan , Yue Liang , Fan Liu , Zhifei Zhang
Siliciclastic grains, characterized by concentrated Al, Si, K and other elements, are typical components of ooids, but their distribution and contribution to ooid formation are uncertain. Coatings have played a significant role in small shelly fossil preservation in early Cambrian phosphate or phosphatic carbonates. However, the relationship between ooid construction and the preservation of small shelly fossils has not been fully elucidated. Herein, we report well-developed flaggy ooids containing siliciclastic grains from a middle Cambrian carbonate–siliciclastic depositional system in North China. We observe that ooids consist of multiple layers of dark and light laminae. The dark laminae with a high organic content and flexible appearance are interpreted as biofilms. The distribution of detrital grains is closely coupled with these dark laminae and the filamentous structures around fossil shells, which indicates that the detrital particles are bound by the biofilms or filamentous structures. The high occurrence and compacted nature of siliciclastic particles observed in these ooids reveal that detrital grains could be the main contributing factor in ooid formation in the middle Cambrian Longwanggou section. Those flaggy ooids composed of clay-size detrital grains finely mimic the shell morphology and microstructure, providing another important window for the preservation of small shelly fossils in the Cambrian.
{"title":"Organic matter binding detrital grains contributing to ooid formation and small shelly fossil preservation, a case from the middle Cambrian, southern North China","authors":"Yazhou Hu , Timothy P. Topper , Junming Zhou , Zhao Wang , Bing Pan , Yue Liang , Fan Liu , Zhifei Zhang","doi":"10.1016/j.sedgeo.2024.106740","DOIUrl":"10.1016/j.sedgeo.2024.106740","url":null,"abstract":"<div><p>Siliciclastic grains, characterized by concentrated Al, Si, K and other elements, are typical components of ooids, but their distribution and contribution to ooid formation are uncertain. Coatings have played a significant role in small shelly fossil preservation in early Cambrian phosphate or phosphatic carbonates. However, the relationship between ooid construction and the preservation of small shelly fossils has not been fully elucidated. Herein, we report well-developed flaggy ooids containing siliciclastic grains from a middle Cambrian carbonate–siliciclastic depositional system in North China. We observe that ooids consist of multiple layers of dark and light laminae. The dark laminae with a high organic content and flexible appearance are interpreted as biofilms. The distribution of detrital grains is closely coupled with these dark laminae and the filamentous structures around fossil shells, which indicates that the detrital particles are bound by the biofilms or filamentous structures. The high occurrence and compacted nature of siliciclastic particles observed in these ooids reveal that detrital grains could be the main contributing factor in ooid formation in the middle Cambrian Longwanggou section. Those flaggy ooids composed of clay-size detrital grains finely mimic the shell morphology and microstructure, providing another important window for the preservation of small shelly fossils in the Cambrian.</p></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"472 ","pages":"Article 106740"},"PeriodicalIF":2.7,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0037073824001635/pdfft?md5=ede7a9af10abe03ac7629e4fe103a519&pid=1-s2.0-S0037073824001635-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.sedgeo.2024.106731
Xiaotian Shen , Xing Jian , Wei Zhang , Ping Guan
Detrital single-mineral geochemistry and geochronology are strong tools in provenance studies and indicate great potentials in addressing issues in earth sciences. Various biases (both natural and artificial) exist objectively and may mislead provenance interpretations. Both the sedimentary sorting process and hand-picking in-laboratory processing may lead to analyzed grain textural (e.g., size and shape) variability and thus may introduce biases in single-mineral provenance analysis. Here, we take the Mesozoic–Cenozoic Qaidam basin, northeastern Tibet, as an example to investigate the relationship between single-mineral grain texture and detrital zircon geochronological and detrital tourmaline, rutile and garnet geochemical data and to explain how grain texture affects detrital single-mineral provenance interpretations. Results indicate that Precambrian zircons take less proportions in coarse (>125 μm), subrounded and high aspect ratio (>2) fractions than Phanerozoic zircons. Parent rock lithology discrimination results of detrital tourmaline and garnet in different grain size fractions show significant differences. Zr-temperature values of detrital rutile have an increasing trend with increasing grain size. The geochemistry of detrital tourmaline, rutile and garnet shows no dependence with grain aspect ratio and roundness. We suggest that inheritance of grain texture features from parent rocks is the major reason. Detrital zircons from recycled (meta)sedimentary rocks tend to be smaller and more rounded than those from igneous rocks. Detrital tourmaline, rutile and garnet grains from different parent rock types vary in size. Grain textural bias may cause the underestimated contributions of the Qilian Shan to the Cenozoic Qaidam basin if small detrital zircons were not involved in the analysis. Quantitative description of the source-to-sink system of the Cenozoic Qaidam is also influenced by grain textural bias. This study highlights the underestimated grain textural bias in single-mineral provenance studies. We suggest that a comprehensive understanding of potential sedimentary sources, depositional processes, sample petrographic features and laboratory analysis procedures is important to reliable provenance interpretations and to related implications in earth sciences.
{"title":"Grain textural bias in detrital single-mineral provenance studies","authors":"Xiaotian Shen , Xing Jian , Wei Zhang , Ping Guan","doi":"10.1016/j.sedgeo.2024.106731","DOIUrl":"10.1016/j.sedgeo.2024.106731","url":null,"abstract":"<div><p>Detrital single-mineral geochemistry and geochronology are strong tools in provenance studies and indicate great potentials in addressing issues in earth sciences. Various biases (both natural and artificial) exist objectively and may mislead provenance interpretations. Both the sedimentary sorting process and hand-picking in-laboratory processing may lead to analyzed grain textural (e.g., size and shape) variability and thus may introduce biases in single-mineral provenance analysis. Here, we take the Mesozoic–Cenozoic Qaidam basin, northeastern Tibet, as an example to investigate the relationship between single-mineral grain texture and detrital zircon geochronological and detrital tourmaline, rutile and garnet geochemical data and to explain how grain texture affects detrital single-mineral provenance interpretations. Results indicate that Precambrian zircons take less proportions in coarse (>125 μm), subrounded and high aspect ratio (>2) fractions than Phanerozoic zircons. Parent rock lithology discrimination results of detrital tourmaline and garnet in different grain size fractions show significant differences. Zr-temperature values of detrital rutile have an increasing trend with increasing grain size. The geochemistry of detrital tourmaline, rutile and garnet shows no dependence with grain aspect ratio and roundness. We suggest that inheritance of grain texture features from parent rocks is the major reason. Detrital zircons from recycled (meta)sedimentary rocks tend to be smaller and more rounded than those from igneous rocks. Detrital tourmaline, rutile and garnet grains from different parent rock types vary in size. Grain textural bias may cause the underestimated contributions of the Qilian Shan to the Cenozoic Qaidam basin if small detrital zircons were not involved in the analysis. Quantitative description of the source-to-sink system of the Cenozoic Qaidam is also influenced by grain textural bias. This study highlights the underestimated grain textural bias in single-mineral provenance studies. We suggest that a comprehensive understanding of potential sedimentary sources, depositional processes, sample petrographic features and laboratory analysis procedures is important to reliable provenance interpretations and to related implications in earth sciences.</p></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"471 ","pages":"Article 106731"},"PeriodicalIF":2.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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