S. Schröder, J. P. Corella, X. M. Pellicer, P. Rook, A. Kara, X. Comas
Determination of the physical properties of subsurface geological bodies is essential for georesource management and geotechnical applications. In the absence of direct measurements, this usually passes via geophysical methods such as seismic and ground-penetrating radar. These require conversion to physical properties, and measurements at different scales to test for consistency. This approach is non-trivial in geobodies with heterogeneous patterns of properties. Tufa mounds—in-situ terrestrial carbonate buildups precipitating from geothermal waters—are characterised by high contrasts in facies and petrophysical properties from microscale to macroscale, and are therefore ideally suited to test the ability of non-invasive geophysical methods to estimate such contrasts, and to develop petrophysical models based on geophysical properties. Here, a laboratory-based study of a Pleistocene tufa mound in Spain is presented that combines (1) petrography, (2) digital 2D pore network analysis, (3) gas porosity and permeability measurements, (4) acoustic velocity measurements and (5) electromagnetic wave velocity and porosity determination from ground-penetrating radar, to develop empirical petrophysical models. These results show the consistency of petrophysical properties determined with different methods across various observational scales. Electromagnetically derived porosity positively correlates with gas porosity. Petrophysical properties depend on measurable rock fabric parameters and the degree of cementation, which provide predictive tools for subsurface geobodies. Strongly cemented peloidal-thrombolitic fabrics with intergranular and intercrystalline pores, and a dominance of small complex pores best transmit acoustic waves. Weak cementation and a significant fraction of large simple pores (framework, vegetation moulds) increase porosity and permeability of shrubby fabrics, while causing lower acoustic velocity. This study demonstrates that ground-penetrating radar models can be used in combination with direct measurements of physical subsurface properties to capture highly contrasting physical properties associated with different sedimentary facies that would not be achievable with other methods, thus improving the understanding of formational processes.
{"title":"Characterising the heterogeneous nature of tufa mounds by integrating petrographic, petrophysical, acoustic and electromagnetic measurements","authors":"S. Schröder, J. P. Corella, X. M. Pellicer, P. Rook, A. Kara, X. Comas","doi":"10.1002/dep2.259","DOIUrl":"10.1002/dep2.259","url":null,"abstract":"<p>Determination of the physical properties of subsurface geological bodies is essential for georesource management and geotechnical applications. In the absence of direct measurements, this usually passes via geophysical methods such as seismic and ground-penetrating radar. These require conversion to physical properties, and measurements at different scales to test for consistency. This approach is non-trivial in geobodies with heterogeneous patterns of properties. Tufa mounds—in-situ terrestrial carbonate buildups precipitating from geothermal waters—are characterised by high contrasts in facies and petrophysical properties from microscale to macroscale, and are therefore ideally suited to test the ability of non-invasive geophysical methods to estimate such contrasts, and to develop petrophysical models based on geophysical properties. Here, a laboratory-based study of a Pleistocene tufa mound in Spain is presented that combines (1) petrography, (2) digital 2D pore network analysis, (3) gas porosity and permeability measurements, (4) acoustic velocity measurements and (5) electromagnetic wave velocity and porosity determination from ground-penetrating radar, to develop empirical petrophysical models. These results show the consistency of petrophysical properties determined with different methods across various observational scales. Electromagnetically derived porosity positively correlates with gas porosity. Petrophysical properties depend on measurable rock fabric parameters and the degree of cementation, which provide predictive tools for subsurface geobodies. Strongly cemented peloidal-thrombolitic fabrics with intergranular and intercrystalline pores, and a dominance of small complex pores best transmit acoustic waves. Weak cementation and a significant fraction of large simple pores (framework, vegetation moulds) increase porosity and permeability of shrubby fabrics, while causing lower acoustic velocity. This study demonstrates that ground-penetrating radar models can be used in combination with direct measurements of physical subsurface properties to capture highly contrasting physical properties associated with different sedimentary facies that would not be achievable with other methods, thus improving the understanding of formational processes.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 1","pages":"70-90"},"PeriodicalIF":2.4,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.259","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139254383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Guo, L. A. M. Fitzgerald, J. M. Hewitt, O. Pampaloni, J. A. M. Green
Tides are a key driver of a range of Earth system processes, and we now have the capacity to simulate tidal dynamics on a range of temporal and spatial scales. Deep-time tidal model simulations have been used to provide insight into past ocean circulation patterns, evolution of life and the developments of the Earth-Moon system's orbital configuration. However, these tidal model simulations are relatively poorly constrained and validated because of a lack of readily available proxies. The feasibility of using two types of proxy is explored here; (1) sedimentary deposits which can directly estimate palaeotidal ranges, and (2) black shale, to constrain three palaeotidal model simulations for different time slices. Specifically, three palaeotidal range proxies were used for the early Devonian (400 Ma), three palaeotidal range proxies and five black shales for the lower Jurassic (185 Ma), and eight black shales for the early Cretaceous (95 Ma). Both tidal proxies confirm the tidal model results in most locations. The model results for 400 Ma and 185 Ma matched 2/3 of the palaeotidal range proxies for each of these periods. The locations of black shale were compared with tidal front locations predicted by the model outputs based on the Simpson–Hunter parameter and the model results from 95 to 185 Ma agree with the black shale proxies in 10/13 of the locations. In the cases where there is a disagreement, the model resolution is probably too low to fully resolve the details of the coastal topography, or—in one case—the palaeobathymetry is incorrect. Consequently, it is argued that it is worth expanding this type of work, and that such data can be used to validate both models and reconstructions.
潮汐是一系列地球系统过程的关键驱动力,我们现在有能力模拟各种时空尺度的潮汐动态。深时潮汐模型模拟已被用于洞察过去的海洋环流模式、生命进化和地月系统轨道配置的发展。然而,由于缺乏现成的代用指标,这些潮汐模型模拟的约束和验证相对较差。本文探讨了使用两种代用资料的可行性:(1)可直接估算古潮汐范围的沉积物;(2)黑页岩,以约束不同时间片的三种古潮汐模型模拟。具体来说,泥盆纪早期(400Ma)使用了三种古潮汐范围代用资料,侏罗纪晚期(185Ma)使用了三种古潮汐范围代用资料和五种黑色页岩,白垩纪早期(95Ma)使用了八种黑色页岩。两种潮汐代用资料在大多数地点都证实了潮汐模型的结果。400 Ma 和 185 Ma 的模型结果与这两个时期古潮汐范围代用资料的 2/3 相吻合。根据辛普森-亨特(Simpson-Hunter)参数,将黑页岩的位置与模型输出结果预测的潮汐前沿位置进行了比较,95-185 Ma 的模型结果与 10/13 个地点的黑页岩代用资料相吻合。在出现分歧的情况下,可能是模型的分辨率太低,无法完全解析沿岸地形的细节,或者是古测 量不正确。因此,有理由认为值得扩大这类工作的范围,这些数据可用来验证模式和重建。
{"title":"Testing geological proxies for deep-time tidal model simulations","authors":"B. Guo, L. A. M. Fitzgerald, J. M. Hewitt, O. Pampaloni, J. A. M. Green","doi":"10.1002/dep2.256","DOIUrl":"10.1002/dep2.256","url":null,"abstract":"<p>Tides are a key driver of a range of Earth system processes, and we now have the capacity to simulate tidal dynamics on a range of temporal and spatial scales. Deep-time tidal model simulations have been used to provide insight into past ocean circulation patterns, evolution of life and the developments of the Earth-Moon system's orbital configuration. However, these tidal model simulations are relatively poorly constrained and validated because of a lack of readily available proxies. The feasibility of using two types of proxy is explored here; (1) sedimentary deposits which can directly estimate palaeotidal ranges, and (2) black shale, to constrain three palaeotidal model simulations for different time slices. Specifically, three palaeotidal range proxies were used for the early Devonian (400 Ma), three palaeotidal range proxies and five black shales for the lower Jurassic (185 Ma), and eight black shales for the early Cretaceous (95 Ma). Both tidal proxies confirm the tidal model results in most locations. The model results for 400 Ma and 185 Ma matched 2/3 of the palaeotidal range proxies for each of these periods. The locations of black shale were compared with tidal front locations predicted by the model outputs based on the Simpson–Hunter parameter and the model results from 95 to 185 Ma agree with the black shale proxies in 10/13 of the locations. In the cases where there is a disagreement, the model resolution is probably too low to fully resolve the details of the coastal topography, or—in one case—the palaeobathymetry is incorrect. Consequently, it is argued that it is worth expanding this type of work, and that such data can be used to validate both models and reconstructions.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 5","pages":"515-526"},"PeriodicalIF":1.9,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.256","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135889007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Planar lamination is a ubiquitous component of modern and ancient fine-grained sediments deposited by subaqueous sediment gravity flows. These sediments commonly exhibit alternating sub-millimetre-thick, sharply bounded silt-rich and clay-rich layers that change little in thickness or sediment texture over lateral distances that range up to at least several tens of metres. Silt-rich layers are moderately to well-sorted and a few tens to hundreds of microns to a single silt-grain thick. In contrast, clay-rich layers are more poorly sorted, and a few tens to hundreds of microns thick. The thickness and regular alternation of these texturally differentiated interlayers, in addition to the absence of features suggesting transport bypass or deposition by migrating rugged bed forms, suggest alternating physical processes and related modes of deposition in the near-bed region immediately above the bed. Previous interpretations have focussed on clay flocculation, which is difficult to reconcile with the high fluid shear conditions in the near-bed region. Here it is suggested that in the millimetre to sub-millimetre-thick viscous sublayer at the base of a hydraulically smooth turbulent flow, a combination of high fluid shear and sediment concentration initially leads to shear thinning and enhanced mobility in the lower part of the flow, and for silt to continue settling to the bed forming a well-sorted silt lamina. As silt settles and clay-size sediment increases in concentration, hydrodynamic lubrication forces strengthen and reduce mobility of the near-bed part of the flow. This condition is then perturbed by a bedward-directed outer flow disturbance that dramatically increases frictional stresses and effective fluid viscosity and ultimately shear jamming that causes gelling and deposition of a poorly sorted clay-rich layer. This process is then repeated multiple times to build up a deposit composed of alternating silt-rich and clay-rich laminae overlain by structureless mud deposited directly from suspension.
{"title":"The origin of planar lamination in fine-grained sediment deposited by subaqueous sediment gravity flows","authors":"Omar N. Al-Mufti, R. William C. Arnott","doi":"10.1002/dep2.257","DOIUrl":"10.1002/dep2.257","url":null,"abstract":"<p>Planar lamination is a ubiquitous component of modern and ancient fine-grained sediments deposited by subaqueous sediment gravity flows. These sediments commonly exhibit alternating sub-millimetre-thick, sharply bounded silt-rich and clay-rich layers that change little in thickness or sediment texture over lateral distances that range up to at least several tens of metres. Silt-rich layers are moderately to well-sorted and a few tens to hundreds of microns to a single silt-grain thick. In contrast, clay-rich layers are more poorly sorted, and a few tens to hundreds of microns thick. The thickness and regular alternation of these texturally differentiated interlayers, in addition to the absence of features suggesting transport bypass or deposition by migrating rugged bed forms, suggest alternating physical processes and related modes of deposition in the near-bed region immediately above the bed. Previous interpretations have focussed on clay flocculation, which is difficult to reconcile with the high fluid shear conditions in the near-bed region. Here it is suggested that in the millimetre to sub-millimetre-thick viscous sublayer at the base of a hydraulically smooth turbulent flow, a combination of high fluid shear and sediment concentration initially leads to shear thinning and enhanced mobility in the lower part of the flow, and for silt to continue settling to the bed forming a well-sorted silt lamina. As silt settles and clay-size sediment increases in concentration, hydrodynamic lubrication forces strengthen and reduce mobility of the near-bed part of the flow. This condition is then perturbed by a bedward-directed outer flow disturbance that dramatically increases frictional stresses and effective fluid viscosity and ultimately shear jamming that causes gelling and deposition of a poorly sorted clay-rich layer. This process is then repeated multiple times to build up a deposit composed of alternating silt-rich and clay-rich laminae overlain by structureless mud deposited directly from suspension.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 5","pages":"496-514"},"PeriodicalIF":1.9,"publicationDate":"2023-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.257","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135758764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kamil Ahmed Qureshi, Muhammad Rizwan, Hammad Tariq Janjuhah, Ihtisham Islam, George Kontakiotis, Ahmer Bilal, Mohamad Arif
The Middle Triassic Tredian Formation is well exposed in the western region of the Salt Range. It is mostly composed of sandstone with minor alternations of shales and dolomite. This is the first integrated attempt using petrographical and geochemical features to reveal palaeoclimate during deposition of the Tredian Formation. This work sheds light on the petrographical and geochemical properties of the Tredian sandstone in order to date various layers and evaluate the palaeoclimate. The formation was sampled at two distinct stratigraphic layers for petrographic and geochemical analysis of major and trace elements. The sandstone of the Tredian Formation is sub-feldspathic to feldspathic arenite with sub-angular to rounded grains that are moderately to extensively sorted. The relative proportions of the quartz, feldspars and lithoclasts in the examined sandstone samples shows that the Tredian sediments originated from the interior of the craton during a transitional continental regime. Chemical index of alteration values of 59, chemical index of weathering values of 67, and plagioclase index of alteration values of 74.5 indicate a low to moderate degree of weathering in the Tredian sediment source region. Based on the silica content, SiO2/Al2O3 ratios (2.7–6.1; mean 4.1), and chemical maturity index, it is deduced that the Tredian Formation was deposited in chemically immature to sub-mature and dry to semi-arid conditions. Geochemical proxies indicate the acidic source of sediment and deposition on the passive margin of the Indian Plate. The trace element characteristics of the sediments, especially the Rb/Sr, Cu/Zn, Ni/Co, V/Cr and Sr/Ba ratios, indicate that the sediments originated from the first weathering cycle and support the notion that they were deposited in an oxidising continental environment. A semi-arid to arid palaeoclimate predominated through the Middle Triassic at the north-western passive continental margin of the Indian Plate in the south-eastern Neo-Tethys.
{"title":"An integrated petrographical and geochemical study of the Tredian Formation in the Salt and Trans-Indus Surghar ranges, North-West Pakistan: Implications for palaeoclimate","authors":"Kamil Ahmed Qureshi, Muhammad Rizwan, Hammad Tariq Janjuhah, Ihtisham Islam, George Kontakiotis, Ahmer Bilal, Mohamad Arif","doi":"10.1002/dep2.255","DOIUrl":"10.1002/dep2.255","url":null,"abstract":"<p>The Middle Triassic Tredian Formation is well exposed in the western region of the Salt Range. It is mostly composed of sandstone with minor alternations of shales and dolomite. This is the first integrated attempt using petrographical and geochemical features to reveal palaeoclimate during deposition of the Tredian Formation. This work sheds light on the petrographical and geochemical properties of the Tredian sandstone in order to date various layers and evaluate the palaeoclimate. The formation was sampled at two distinct stratigraphic layers for petrographic and geochemical analysis of major and trace elements. The sandstone of the Tredian Formation is sub-feldspathic to feldspathic arenite with sub-angular to rounded grains that are moderately to extensively sorted. The relative proportions of the quartz, feldspars and lithoclasts in the examined sandstone samples shows that the Tredian sediments originated from the interior of the craton during a transitional continental regime. Chemical index of alteration values of 59, chemical index of weathering values of 67, and plagioclase index of alteration values of 74.5 indicate a low to moderate degree of weathering in the Tredian sediment source region. Based on the silica content, SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratios (2.7–6.1; mean 4.1), and chemical maturity index, it is deduced that the Tredian Formation was deposited in chemically immature to sub-mature and dry to semi-arid conditions. Geochemical proxies indicate the acidic source of sediment and deposition on the passive margin of the Indian Plate. The trace element characteristics of the sediments, especially the Rb/Sr, Cu/Zn, Ni/Co, V/Cr and Sr/Ba ratios, indicate that the sediments originated from the first weathering cycle and support the notion that they were deposited in an oxidising continental environment. A semi-arid to arid palaeoclimate predominated through the Middle Triassic at the north-western passive continental margin of the Indian Plate in the south-eastern Neo-Tethys.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 1","pages":"33-50"},"PeriodicalIF":2.4,"publicationDate":"2023-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.255","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135758628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<p>The paper by Magalhães et al. (<span>2023</span>) concerns the Jurassic coastal outcrop between Consolação and São Bernardino beaches, in the western-central Lusitanian Basin (LB), Portugal (Figure 1). The authors used a sequence stratigraphic approach, defining multi-scale cycles and, based on nannofossils and dinoflagellate cysts (dinocysts) data, they re-assigned the section to the Middle Jurassic ‘Candeeiros Formation’; formerly the section had been established as part of the Upper Jurassic Alcobaça Formation (namely Fürsich et al., <span>2022</span>; Leinfelder, <span>1986</span>; Manuppella et al., <span>1999</span>; Schneider et al., <span>2009</span>; Werner, <span>1986</span>). Although the sedimentology and sequence analysis were detailed, we consider their assessment to be incorrect and oversimplified including, for example, the assigned age of the unit and the top of the section. Moreover, the new fossil data are too briefly discussed and based on limited data, and the local/regional geology is barely discussed.</p><p>The Alcobaça Formation, recently formalised by Fürsich et al. (<span>2022</span>), is an important unit of the Upper Jurassic of the LB (Figure 2). Fürsich et al. (<span>2022</span>) provided an extensive literature overview, in which the formation is thoroughly described, illustrated and correlated within the basin (including the Consolação section); they presented facies analysis, macropalaeontological and micropalaeontological taxonomic and palaeoecological data and palaeogeographical interpretations. However, this seminal work is not mentioned by Magalhães et al. (<span>2023</span>). The Alcobaça Formation is a mixed siliciclastic-carbonate succession; its age is constrained by macrofossil and microfossil data and strontium isotope values, and has been confidently considered to be mainly of Kimmeridgian age, although possible slight age extensions of its base and top have been discussed (Fürsich et al., <span>2022</span>; Kullberg & Rocha, <span>2014</span>; Leinfelder, <span>1986</span>; Manuppella et al., <span>1999</span>; Schneider et al., <span>2009</span>; Werner, <span>1986</span>).</p><p>If the part of the section described by Magalhães et al. (<span>2023</span>) were Middle Jurassic strata, then the local succession would be: the outcrops of Kimmeridgian Alcobaça Formation at the Consolação section, succeeded southwards by the Middle Jurassic (Bathonian/Callovian) ‘Candeeiros Formation’, in turn overlain by the much later Upper Jurassic Lourinhã Formation, the intervening units locally (and implausibly) not present. No considerations of plausible depositional geometries or regional correlations with nearby formations were made to support the drastic sequence changes implied.</p><p>At Cesareda zone, about 9 km eastwards, and at Baleal Peninsula, about 7 km north-westwards (Figure 1), Middle Jurassic carbonate outcrops occur, dated by ammonites from, respectively, Bajocian to Callovian and Bajocian/Bath
magalh<e:1>等人(2023)的论文涉及葡萄牙Lusitanian盆地(LB)中西部的consola<s:1> <s:1> o和s<e:1> o Bernardino海滩之间的侏罗纪海岸露头(图1)。作者使用层序地层学方法,定义了多尺度旋回,并根据纳米化石和鞭毛藻囊(dinocysts)数据,将该剖面重新划分为中侏罗世“Candeeiros组”;以前该剖面被确定为上侏罗统alcobaa组的一部分(即frsich et al., 2022;Leinfelder, 1986;Manuppella et al., 1999;Schneider et al., 2009;维尔纳,1986)。虽然沉积学和层序分析是详细的,但我们认为他们的评估是不正确的,过于简单,例如,包括单元和剖面顶部的指定年龄。此外,新的化石资料讨论过于简单,数据基础有限,对局部/区域地质的讨论很少。最近由f<s:1> rsich等人(2022)正式确定的alcobaa组是LB上侏罗统的一个重要单元(图2)。f<s:1> rsich等人(2022)提供了广泛的文献综述,其中对该地层进行了全面的描述,说明并在盆地(包括consolao剖面)内进行了对比;他们提出了相分析、宏观古生物学和微观古生物学分类和古生态资料以及古地理解释。然而,magalh<e:1>等人(2023)并没有提到这项开创性的工作。alcobaa组是一个混合的硅-塑料-碳酸盐序列;其年龄受到宏观化石和微化石数据以及锶同位素值的限制,尽管已经讨论了其底部和顶部可能存在轻微的年龄延长(f<s:1> rsich et al., 2022;Kullberg,罗查,2014;Leinfelder, 1986;Manuppella et al., 1999;Schneider et al., 2009;维尔纳,1986)。如果magalh<e:1>等人(2023)描述的部分剖面是中侏罗统地层,那么局部演替将是:中侏罗统(Bathonian/Callovian)“Candeeiros组”在consola<e:1> o剖面上的露头,向南由中侏罗统(Bathonian/Callovian)“Candeeiros组”接替,然后由晚得多的上侏罗统Lourinhã组覆盖,局部(令人难以置信的)不存在中间单元。没有考虑到合理的沉积几何或与附近地层的区域相关性来支持所隐含的剧烈序列变化。在向东约9公里的Cesareda带和向西北约7公里的Baleal半岛(图1),出现了中侏罗世碳酸盐岩露头,根据菊石的年代分别为bajoian - Callovian和bajoian /Bathonian (Azerêdo, 1988, 1993;gusamry et al., 1986;Ruget-Perrot, 1961)。顺便说一句,magalh<e:1>等人(2023)引用了Azerêdo(1988),但在参考文献中错误地将其指定为她1993年的论文;前一部作品是对巴勒剖面的原始研究。这些碳酸盐岩序列是在整个中侏罗统盛行的健康碳酸盐岩斜坡沉积体系框架内发育的(Azerêdo, 1988, 1993, 1998, 2007;Azerêdo et al., 2014,2020)。因此,只在那个小的局部区域同时出现一个硅-塑性体系是极不可能的。Magalhaes et al。(2023)地址(22页)的硅质碎屑的从上升Berlengas块向西流入到他们的研究区域,这将是由地形有界东高(底辟相关),因此输入不影响更遥远的碳酸盐沉积硅质碎屑的东部和北部(dos在塞拉Candeeiros-MCE一样,图1)。然而,中侏罗世部分在Baleal也是西部的建议“栅栏”,它只公开海洋碳酸盐岩。f<s:1> rsich等人(2022)提出了一个类似的模型,适用于consola<e:1> o亚盆地的alcobaa组(这些作者称之为alcobao亚盆地),但范围更广,涉及的是基默里吉纪时期LB历史和构造的一个较晚的不同阶段。magalh<e:1>等人(2023)援引了一个非常局部的解释,在中侏罗纪时期令人怀疑。我们没有讨论magalh<e:1>等人(2023)的层序地层学方法,也没有讨论旋回的定义标准,我们认为如果使用正确的时间框架,这可能对理解区域地层学做出积极的新贡献。然而,其层序J的上上限位于Lourinhã组之下,并不代表中、上侏罗统(Callovian/ oxford)不整合;而且,他们所研究的部分确定巴统/加罗纪时代的微古生物学证据并不可靠(下文将详细讨论)。此外,他们没有将他们的序列方案与LB中侏罗统区间的已发表旋回进行比较(Azerêdo et al., 2014, 2020)。magalh<e:1>等。 从客观上讲,认为所研究的<s:1> o Bernardino序列的顶部对应于中、上侏罗统不整合边界的直接说法是不正确的。这意味着magalh<e:1>等人(2023)用来约束研究层段的关键节点之一(与中/上侏罗统不整合相对应的顶部)是无效的。此外,中/上侏罗统盆地广泛的不整合(加里夫世晚期至牛津世早期)是LB的一个非常有约束和记录的事件(即Azerêdo et al., 2002;gusamry et al., 1986;Kullberg & Rocha, 2014;Leinfelder & Wilson, 1998;Ruget-Perrot, 1961)。它是在同一边界上存在于大西洋沿岸盆地上的主要不连续的区域表现(Norris & Hallam, 1995等),具有特定的沉积、构造、上升和气候过程的证据。在LB,它记录了明显的环境变化,覆盖着淡水和咸淡咸水潟湖到边缘海相cabaos组,该组分为海相Montejunto组(图2)。这些单元由不同的晚牛津/ kimimmeridian沉积接替,这些沉积与裂谷的开始和盆地的后续演化有关,即Abadia(南部),alcobaa和Lourinhã组(Kullberg & Rocha, 2014;Leinfelder & Wilson, 1998;Wilson et al., 1989;图2)晚侏罗世记录了向西和向南的硅屑进积的总体趋势,随着序列变得越来越具有大陆特征,如Lourinhã组具有局部侵蚀性(Leinfelder & Wilson, 1998;Manuppella et al., 1999;Mateus et al., 2017)。s<s:1> o Bernardino向Lourinhã组的过渡与盆地历史的更早阶段和中、上侏罗统不整合完全没有关系;并不是任何古地表都可以被认为与这种不整合相关。magalh<e:1>等人(2023)显然没有意识到区域地层学的相关方面。如果magalh<e:1>等人(2023)描述的部分剖面是中侏罗统地层,那么局部演替将是:
{"title":"Discussion on ‘Middle Jurassic multi-scale transgressive–regressive cycles: An example from the Lusitanian Basin’, by Magalhães et al., Depositional Record, 2023, 9(1), 174–202","authors":"Ana C. Azerêdo, Vânia F. Correia, Ángela Fraguas","doi":"10.1002/dep2.252","DOIUrl":"10.1002/dep2.252","url":null,"abstract":"<p>The paper by Magalhães et al. (<span>2023</span>) concerns the Jurassic coastal outcrop between Consolação and São Bernardino beaches, in the western-central Lusitanian Basin (LB), Portugal (Figure 1). The authors used a sequence stratigraphic approach, defining multi-scale cycles and, based on nannofossils and dinoflagellate cysts (dinocysts) data, they re-assigned the section to the Middle Jurassic ‘Candeeiros Formation’; formerly the section had been established as part of the Upper Jurassic Alcobaça Formation (namely Fürsich et al., <span>2022</span>; Leinfelder, <span>1986</span>; Manuppella et al., <span>1999</span>; Schneider et al., <span>2009</span>; Werner, <span>1986</span>). Although the sedimentology and sequence analysis were detailed, we consider their assessment to be incorrect and oversimplified including, for example, the assigned age of the unit and the top of the section. Moreover, the new fossil data are too briefly discussed and based on limited data, and the local/regional geology is barely discussed.</p><p>The Alcobaça Formation, recently formalised by Fürsich et al. (<span>2022</span>), is an important unit of the Upper Jurassic of the LB (Figure 2). Fürsich et al. (<span>2022</span>) provided an extensive literature overview, in which the formation is thoroughly described, illustrated and correlated within the basin (including the Consolação section); they presented facies analysis, macropalaeontological and micropalaeontological taxonomic and palaeoecological data and palaeogeographical interpretations. However, this seminal work is not mentioned by Magalhães et al. (<span>2023</span>). The Alcobaça Formation is a mixed siliciclastic-carbonate succession; its age is constrained by macrofossil and microfossil data and strontium isotope values, and has been confidently considered to be mainly of Kimmeridgian age, although possible slight age extensions of its base and top have been discussed (Fürsich et al., <span>2022</span>; Kullberg & Rocha, <span>2014</span>; Leinfelder, <span>1986</span>; Manuppella et al., <span>1999</span>; Schneider et al., <span>2009</span>; Werner, <span>1986</span>).</p><p>If the part of the section described by Magalhães et al. (<span>2023</span>) were Middle Jurassic strata, then the local succession would be: the outcrops of Kimmeridgian Alcobaça Formation at the Consolação section, succeeded southwards by the Middle Jurassic (Bathonian/Callovian) ‘Candeeiros Formation’, in turn overlain by the much later Upper Jurassic Lourinhã Formation, the intervening units locally (and implausibly) not present. No considerations of plausible depositional geometries or regional correlations with nearby formations were made to support the drastic sequence changes implied.</p><p>At Cesareda zone, about 9 km eastwards, and at Baleal Peninsula, about 7 km north-westwards (Figure 1), Middle Jurassic carbonate outcrops occur, dated by ammonites from, respectively, Bajocian to Callovian and Bajocian/Bath","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1153-1160"},"PeriodicalIF":2.4,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.252","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134947438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Schneider, F. T. Fürsich, W. Werner, C. S. Pierce
<p>In a recently published paper, Magalhães et al. (<span>2023</span>) re-studied the coastal section between the villages of Consolação and São Bernardino south of Peniche, central Portugal, and determined a novel Bathonian to early Callovian age for the exposed strata. They identified low-frequency to high-frequency transgressive–regressive sequences, and interpreted the depositional settings as offshore to shoreface for siliciclastic strata, with subordinate carbonate intervals associated with inner to outer ramp settings. Based on these new results, they assigned the studied strata to the Candeeiros Formation. We show that these conclusions are based on misinterpretation and the non-consideration of previously published contradictory data.</p><p>The Jurassic sedimentary succession of the Lusitanian Basin is unusually well-exposed along the Atlantic coast, and offers unique opportunities for study. The coastal section between the villages of Consolação and São Bernardino is a prime example, and has been studied repeatedly (Fürsich et al., <span>2022</span>; Mateus et al., <span>2017</span>; Taylor et al., <span>2014</span>; Werner, <span>1986</span>), but a modern sequence stratigraphic analysis of this succession has never been attempted. As such, the study of Magalhães et al. (<span>2023</span>) generally comes as a welcome addition. However, this study falls short in several aspects. Most significantly, its dissonance with previously published contradictory literature is not taken into account, and the interpretation of the data generated is selective and model-driven. We address these issues in the following sections, drawing on the literature, including a recently published study by the present authors (Fürsich et al., <span>2022</span>), accessible online approximately half a year before the submission of the manuscript of Magalhães et al. (<span>2023</span>), but not considered in their paper.</p><p>Magalhães et al. (<span>2023</span>) characterise the geodynamic evolution of the Lusitanian Basin in sufficient detail, and the literature cited in this section is relevant and up to date. However, despite the sequence stratigraphic focus of their study, the sedimentological evolution of the basin is barely addressed. In the context of a presumed Middle Jurassic age for the strata at Consolação, it would have been essential to focus on the Early to Middle Jurassic evolution of depositional environments in the Lusitanian Basin, but the lithostratigraphic scheme used is outdated, and numerous key studies are not cited. Magalhães et al. (<span>2023</span>) use the oversimplified scheme of largely concordant successive Coimbra, Brenha and Candeeiros formations, which was established by Shell Prospex Portuguesa in the 1970s, but never formally published (Witt, <span>1977</span>). This scheme has been superseded by much more detailed lithostratigraphy. In its revised, restricted sense, the Coimbra Formation of Moitinho de Almeida et al. (<span>19
这是对之前发表在《沉积记录》上的一篇文章的评论。
{"title":"Comment on: Magalhães et al., Middle Jurassic multi-scale transgressive–regressive cycles: An example from the Lusitanian Basin, The Depositional Record, 9, 174–202","authors":"S. Schneider, F. T. Fürsich, W. Werner, C. S. Pierce","doi":"10.1002/dep2.253","DOIUrl":"10.1002/dep2.253","url":null,"abstract":"<p>In a recently published paper, Magalhães et al. (<span>2023</span>) re-studied the coastal section between the villages of Consolação and São Bernardino south of Peniche, central Portugal, and determined a novel Bathonian to early Callovian age for the exposed strata. They identified low-frequency to high-frequency transgressive–regressive sequences, and interpreted the depositional settings as offshore to shoreface for siliciclastic strata, with subordinate carbonate intervals associated with inner to outer ramp settings. Based on these new results, they assigned the studied strata to the Candeeiros Formation. We show that these conclusions are based on misinterpretation and the non-consideration of previously published contradictory data.</p><p>The Jurassic sedimentary succession of the Lusitanian Basin is unusually well-exposed along the Atlantic coast, and offers unique opportunities for study. The coastal section between the villages of Consolação and São Bernardino is a prime example, and has been studied repeatedly (Fürsich et al., <span>2022</span>; Mateus et al., <span>2017</span>; Taylor et al., <span>2014</span>; Werner, <span>1986</span>), but a modern sequence stratigraphic analysis of this succession has never been attempted. As such, the study of Magalhães et al. (<span>2023</span>) generally comes as a welcome addition. However, this study falls short in several aspects. Most significantly, its dissonance with previously published contradictory literature is not taken into account, and the interpretation of the data generated is selective and model-driven. We address these issues in the following sections, drawing on the literature, including a recently published study by the present authors (Fürsich et al., <span>2022</span>), accessible online approximately half a year before the submission of the manuscript of Magalhães et al. (<span>2023</span>), but not considered in their paper.</p><p>Magalhães et al. (<span>2023</span>) characterise the geodynamic evolution of the Lusitanian Basin in sufficient detail, and the literature cited in this section is relevant and up to date. However, despite the sequence stratigraphic focus of their study, the sedimentological evolution of the basin is barely addressed. In the context of a presumed Middle Jurassic age for the strata at Consolação, it would have been essential to focus on the Early to Middle Jurassic evolution of depositional environments in the Lusitanian Basin, but the lithostratigraphic scheme used is outdated, and numerous key studies are not cited. Magalhães et al. (<span>2023</span>) use the oversimplified scheme of largely concordant successive Coimbra, Brenha and Candeeiros formations, which was established by Shell Prospex Portuguesa in the 1970s, but never formally published (Witt, <span>1977</span>). This scheme has been superseded by much more detailed lithostratigraphy. In its revised, restricted sense, the Coimbra Formation of Moitinho de Almeida et al. (<span>19","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1161-1166"},"PeriodicalIF":2.4,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.253","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134947439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Antonio J. C. Magalhães, Gerson J. S. Terra, Felipe Guadagnin, Daniel G. C. Fragoso, Mirian C. Menegazzo, Nuno L. A. Pimentel, Sissa Kumaira, Gerson Fauth, Alessandra Santos, David K. Watkins, Mauro D. R. Bruno, Daiane Ceolin, Simone Baecker-Fauth, Guilherme P. R. Gabaglia, Washington L. E. Teixeira, Francisco P. Lima-Filho
<p>We want to acknowledge the comments about our recently published paper. The exchange of ideas, data and interpretation improves our knowledge and is the right way to discuss science's advances.</p><p>This reply considers the points raised by Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>). In both manuscripts, these authors raised many issues about sedimentological and stratigraphic aspects that can be separated into two groups: (a) those related to the age of the studied succession; and (b) those assigning the studied succession to the Candeeiros Formation.</p><p>There is a long tradition of using macropalaeontology in the Lusitanian Basin, and many authors have used macrofossils as palaeoenvironmental indicators and to date sedimentary deposits. However, except for ammonoids, micropalaeontology data are much more accurate than those from corals or bivalves, for example. This is particularly important in the Consolação–São Bernardino succession because of the lack of micropalaeontological and biostratigraphical studies.</p><p>It is noteworthy that Magalhães et al. (<span>2023</span>) presented a hitherto unpublished micropalaeontological and biostratigraphical analysis of the Consolação–São Bernardino succession. The association of two fossil groups (calcareous nannofossil and dinoflagellates) support our biostratigraphic data, in which we performed taxonomic and biostratigraphic analyses with care and due importance. Hence, our analysis assures the age of the studied succession, which confirms the Bathonian<b>–</b>early Callovian age. Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>) questioned our age assignments, but failed to present their micropalaeontological and biostratigraphical analysis for the same Consolação–São Bernardino succession. Moreover, our findings were integrated with facies analysis, ichnofacies, petrography and macrofossil content to support the proposed age. Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>) have no doubts about the taxonomy presented, and their issues about our dating are based on reinterpretations of our data. They assumed that the literature had already defined the age of the studied succession, which we consider is beyond debate as a result of the new data. That paper acknowledged the previous studies in the Consolação-São Bernardino section. Still, the arguments by Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>) are not based on micropalaeontological data collected in the Consolação-São Bernadino section, but rather on correlations with supposed chronoequivalent units that do not consider our new age. Their comments failed to include irrefutable evidence of the Upper Jurassic age based on micropalaeontological data from the Consolação–São Bernardino succession to contrast with dates presented by Magalhães et al. (<span>2023</span>).</p><p>New data bring new interpretations. Even though all i
回复Azerêdo et al.(2023)和Schneider et al.(2023)的讨论和评论。
{"title":"Reply to the discussion and comments of Azerêdo et al. (2023) and Schneider et al. (2023) on the paper by Magalhães et al. ‘Middle Jurassic multi-scale transgressive–regressive cycles: An example from the Lusitanian Basin’, The Depositional Record, 9, 174–202","authors":"Antonio J. C. Magalhães, Gerson J. S. Terra, Felipe Guadagnin, Daniel G. C. Fragoso, Mirian C. Menegazzo, Nuno L. A. Pimentel, Sissa Kumaira, Gerson Fauth, Alessandra Santos, David K. Watkins, Mauro D. R. Bruno, Daiane Ceolin, Simone Baecker-Fauth, Guilherme P. R. Gabaglia, Washington L. E. Teixeira, Francisco P. Lima-Filho","doi":"10.1002/dep2.254","DOIUrl":"10.1002/dep2.254","url":null,"abstract":"<p>We want to acknowledge the comments about our recently published paper. The exchange of ideas, data and interpretation improves our knowledge and is the right way to discuss science's advances.</p><p>This reply considers the points raised by Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>). In both manuscripts, these authors raised many issues about sedimentological and stratigraphic aspects that can be separated into two groups: (a) those related to the age of the studied succession; and (b) those assigning the studied succession to the Candeeiros Formation.</p><p>There is a long tradition of using macropalaeontology in the Lusitanian Basin, and many authors have used macrofossils as palaeoenvironmental indicators and to date sedimentary deposits. However, except for ammonoids, micropalaeontology data are much more accurate than those from corals or bivalves, for example. This is particularly important in the Consolação–São Bernardino succession because of the lack of micropalaeontological and biostratigraphical studies.</p><p>It is noteworthy that Magalhães et al. (<span>2023</span>) presented a hitherto unpublished micropalaeontological and biostratigraphical analysis of the Consolação–São Bernardino succession. The association of two fossil groups (calcareous nannofossil and dinoflagellates) support our biostratigraphic data, in which we performed taxonomic and biostratigraphic analyses with care and due importance. Hence, our analysis assures the age of the studied succession, which confirms the Bathonian<b>–</b>early Callovian age. Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>) questioned our age assignments, but failed to present their micropalaeontological and biostratigraphical analysis for the same Consolação–São Bernardino succession. Moreover, our findings were integrated with facies analysis, ichnofacies, petrography and macrofossil content to support the proposed age. Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>) have no doubts about the taxonomy presented, and their issues about our dating are based on reinterpretations of our data. They assumed that the literature had already defined the age of the studied succession, which we consider is beyond debate as a result of the new data. That paper acknowledged the previous studies in the Consolação-São Bernardino section. Still, the arguments by Azerêdo et al. (<span>2023</span>) and Schneider et al. (<span>2023</span>) are not based on micropalaeontological data collected in the Consolação-São Bernadino section, but rather on correlations with supposed chronoequivalent units that do not consider our new age. Their comments failed to include irrefutable evidence of the Upper Jurassic age based on micropalaeontological data from the Consolação–São Bernardino succession to contrast with dates presented by Magalhães et al. (<span>2023</span>).</p><p>New data bring new interpretations. Even though all i","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1167-1173"},"PeriodicalIF":2.4,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.254","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135482482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mass extinction at the Cretaceous–Palaeogene boundary is widely attributed to sudden and severe climate changes forced by bolide impact and/or flood basalt volcanism. In terrestrial depositional settings, these changes may potentially be recorded by palaeosols. To test the ability of pedogenic features to record both long-term climate and shorter-term changes preceding and following the Cretaceous–Palaeogene extinction event, palaeosols in the Upper Cretaceous (Maastrichtian) Naashoibito Member of the Ojo Alamo Formation and the lower Palaeocene (Danian) Nacimiento Formation in the San Juan Basin of north-western New Mexico, USA, were examined, including data from previous studies. The fine-grained facies of the Naashoibito Member comprises grey to greenish-grey and red-banded mudstones displaying pedogenic features including colour mottling, root traces, cutans, ped fabrics, pedogenic slickensides and calcareous nodules. Aside from a high-chroma horizon at the formation base, palaeosols in the lower Nacimiento Formation are broadly similar to those observed in the Naashoibito Member. Lateral and vertical variability of the pedogenic features between correlated sections suggest that soil hydrology varied spatially and temporally from very saturated to seasonally well-drained, with temporal variations controlled by basin sedimentation rates. Abrupt and/or catastrophic climate events precisely at the Cretaceous–Palaeogene boundary are not recorded due to an unconformity at the top of the Naashoibito Member. However, the presence of kaolinite in the clay mineral assemblage of the Nacimiento Formation, particularly near the formation base, but not in the Naashoibito Member, indicates episodic warmth and short (104 years) intervals of more intense weathering conditions during the very early Danian as compared to the late Maastrichtian. Aside from short warm intervals, the overall palaeoclimate during deposition of both formations was warm and consistently subhumid to humid and seasonal, suggesting no substantial long-term (105–106) climate change took place across the Cretaceous–Palaeogene boundary in the San Juan Basin.
白垩纪-古近纪边界的大灭绝被广泛归因于由火流星撞击和/或洪水玄武岩火山作用造成的突然和严重的气候变化。在陆相沉积环境中,这些变化可能被古土壤记录下来。为了测试成土特征记录白垩纪-古近纪灭绝事件前后长期气候和短期气候变化的能力,研究人员对美国新墨西哥州西北部圣胡安盆地上白垩世(马斯垂克特)Naashoibito Ojo Alamo组成员和下古新世(达尼安)Nacimiento组的古土壤进行了研究,包括先前研究的数据。Naashoibito段细粒相由灰色至绿灰色和红带状泥岩组成,具有颜色斑驳、根迹、斑纹、带状组构、成土滑脱体和钙质结核等成土特征。除了地层底部的高色度层外,下Nacimiento组的古土壤与Naashoibito段的古土壤大致相似。相关剖面间成土特征的横向和纵向变异表明,土壤水文在空间和时间上从非常饱和到季节性良好排水,其时间变化受流域沉积速率控制。由于Naashoibito段顶部的不整合,没有精确记录白垩纪-古近纪边界的突变和/或灾难性气候事件。然而,在Nacimiento组的粘土矿物组合中,特别是在地层底部附近,而不是Naashoibito段,高岭石的存在表明,与马斯特里赫特晚期相比,大年纪早期的温暖和短暂(104年)间隔更强的风化条件。除了短暂的温暖间隔外,这两个地层沉积期间的整体古气候都是温暖的,并且一直是半湿润到湿润的,具有季节性,这表明圣胡安盆地在白垩纪-古近纪边界上没有发生实质性的长期(105 - 106)气候变化。
{"title":"Record of palaeoclimate across the Cretaceous–Palaeogene boundary from palaeosols in the west-central San Juan Basin, New Mexico, USA","authors":"Lawrence H. Tanner, Spencer G. Lucas","doi":"10.1002/dep2.251","DOIUrl":"10.1002/dep2.251","url":null,"abstract":"<p>The mass extinction at the Cretaceous–Palaeogene boundary is widely attributed to sudden and severe climate changes forced by bolide impact and/or flood basalt volcanism. In terrestrial depositional settings, these changes may potentially be recorded by palaeosols. To test the ability of pedogenic features to record both long-term climate and shorter-term changes preceding and following the Cretaceous–Palaeogene extinction event, palaeosols in the Upper Cretaceous (Maastrichtian) Naashoibito Member of the Ojo Alamo Formation and the lower Palaeocene (Danian) Nacimiento Formation in the San Juan Basin of north-western New Mexico, USA, were examined, including data from previous studies. The fine-grained facies of the Naashoibito Member comprises grey to greenish-grey and red-banded mudstones displaying pedogenic features including colour mottling, root traces, cutans, ped fabrics, pedogenic slickensides and calcareous nodules. Aside from a high-chroma horizon at the formation base, palaeosols in the lower Nacimiento Formation are broadly similar to those observed in the Naashoibito Member. Lateral and vertical variability of the pedogenic features between correlated sections suggest that soil hydrology varied spatially and temporally from very saturated to seasonally well-drained, with temporal variations controlled by basin sedimentation rates. Abrupt and/or catastrophic climate events precisely at the Cretaceous–Palaeogene boundary are not recorded due to an unconformity at the top of the Naashoibito Member. However, the presence of kaolinite in the clay mineral assemblage of the Nacimiento Formation, particularly near the formation base, but not in the Naashoibito Member, indicates episodic warmth and short (10<sup>4</sup> years) intervals of more intense weathering conditions during the very early Danian as compared to the late Maastrichtian. Aside from short warm intervals, the overall palaeoclimate during deposition of both formations was warm and consistently subhumid to humid and seasonal, suggesting no substantial long-term (10<sup>5</sup>–10<sup>6</sup>) climate change took place across the Cretaceous–Palaeogene boundary in the San Juan Basin.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1131-1152"},"PeriodicalIF":2.4,"publicationDate":"2023-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.251","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44824673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jon Hill, Graham Rush, Jeff Peakall, Michael Johnson, Luke Hodson, Natasha L. M. Barlow, Elisabeth T. Bowman, W. Roland Gehrels, David M. Hodgson, Georges Kesserwani
Tsunamis are a major hazard along many of the world's coastlines. To understand the impact of these events, a sufficiently long record of previous events is needed, which can be provided by their sedimentary deposits. A number of past events have left extensive sedimentary deposits that can be used to understand the hydrodynamics of the tsunami. The ca 8.15 ka Storegga submarine slide was a large, tsunamigenic mass movement off the coast of Norway. The resulting tsunami had estimated run-up heights of around 10 to 20 m on the Norwegian coast, over 30 m in Shetland and 3 to 6 m on the Scottish mainland coast. New cores were taken from the Ythan Valley in North-East Scotland, where Storegga tsunami deposits have previously been found. High-resolution sedimentary analyses of the cores, combined with statistical (changepoint) analysis, shows signatures of multiple waves. Moreover, detailed CT scans of the erosional basal surface reveal sole marks called skim marks. Taken in conjunction with the grain size and sedimentary fabric characteristics of the tsunami deposits, this indicates that the flow exhibited a high-concentration basal component, with an initial semi-cohesive phase and that deposition was dominantly capacity driven. A multiple wave hypothesis is tested by creating a high-resolution numerical model (metre-scale) of the wave inundation, coupled to a previously published regional model. The inundation model confirms that multiple waves passed over the site in agreement with the sedimentological analysis. The sensitivity of the model to the reconstructed palaeocoastal geomorphology is quantitatively explored. It is concluded that local palaeogeomorphological reconstruction is key to understanding the hydrodynamics of a tsunami wave group in relation to its sedimentary deposit. Combining sedimentological data with high-resolution inundation modelling is a powerful tool to help interpret the sedimentary record of tsunami events and hence to improve knowledge of their risks.
{"title":"Resolving tsunami wave dynamics: Integrating sedimentology and numerical modelling","authors":"Jon Hill, Graham Rush, Jeff Peakall, Michael Johnson, Luke Hodson, Natasha L. M. Barlow, Elisabeth T. Bowman, W. Roland Gehrels, David M. Hodgson, Georges Kesserwani","doi":"10.1002/dep2.247","DOIUrl":"10.1002/dep2.247","url":null,"abstract":"<p>Tsunamis are a major hazard along many of the world's coastlines. To understand the impact of these events, a sufficiently long record of previous events is needed, which can be provided by their sedimentary deposits. A number of past events have left extensive sedimentary deposits that can be used to understand the hydrodynamics of the tsunami. The <i>ca</i> 8.15 ka Storegga submarine slide was a large, tsunamigenic mass movement off the coast of Norway. The resulting tsunami had estimated run-up heights of around 10 to 20 m on the Norwegian coast, over 30 m in Shetland and 3 to 6 m on the Scottish mainland coast. New cores were taken from the Ythan Valley in North-East Scotland, where Storegga tsunami deposits have previously been found. High-resolution sedimentary analyses of the cores, combined with statistical (changepoint) analysis, shows signatures of multiple waves. Moreover, detailed CT scans of the erosional basal surface reveal sole marks called skim marks. Taken in conjunction with the grain size and sedimentary fabric characteristics of the tsunami deposits, this indicates that the flow exhibited a high-concentration basal component, with an initial semi-cohesive phase and that deposition was dominantly capacity driven. A multiple wave hypothesis is tested by creating a high-resolution numerical model (metre-scale) of the wave inundation, coupled to a previously published regional model. The inundation model confirms that multiple waves passed over the site in agreement with the sedimentological analysis. The sensitivity of the model to the reconstructed palaeocoastal geomorphology is quantitatively explored. It is concluded that local palaeogeomorphological reconstruction is key to understanding the hydrodynamics of a tsunami wave group in relation to its sedimentary deposit. Combining sedimentological data with high-resolution inundation modelling is a powerful tool to help interpret the sedimentary record of tsunami events and hence to improve knowledge of their risks.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"9 4","pages":"1046-1065"},"PeriodicalIF":2.4,"publicationDate":"2023-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.247","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44710204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There has been no consensus yet regarding the precise initial timing and duration of the late Mesozoic extensional tectonics in the South-eastern China Block. This work focusses on the growth strata of the Early Cretaceous red beds in the South-eastern China Block to determine the late Mesozoic tectonics and the precise timing of the initiation and duration of extensional tectonics in this area. Field observation of several terrigenous basins shows that the dip angles of the Cretaceous red beds have varied from moderate to gentle from basin edges to interiors (or centres). The visible and estimated thickness within a single bed increases slightly downwards from the upper to the lower part. These characteristics indicate that the sedimentary area of these beds has undergone an extensional process with expansion and deepening of the sedimentary basins. Rotation of the border surfaces (limbs) and downward warping of the hanging walls or retreat of the footwalls of listric normal faults causes three types of extensional growth (or syntectonic) strata in the deposits of different basins. Dating of the volcanic rocks related to the growth beds reveals that the sedimentary basins were enlarged and deepened when the Early Cretaceous strata were deposited in the South-eastern China Block from ca 140 to 137 Ma. Regionally, under the influence of Palaeo-Pacific plate rollback since ca 140 Ma, the South-eastern China Block stress field has led to lithospheric uplift and pull-apart structures near the surface, causing the half-graben basins to receive sedimentation. Although the extensional event was interrupted by a short compressional event during 120 to 105 Ma, with the oceanward retreat of the trench, the area of extension gradually enlarged and rejuvenated south-eastwards until the end of the Cretaceous. This Cretaceous extension event of the South-eastern China Block must belong to a worldwide geological event with global significance.
{"title":"Timing of the initiation and duration of the Cretaceous extensional regime in South-east China: Constraints from growth strata in terrigenous basins","authors":"Xinqi Yu, Jun Hu, Wei Li, Kun Liu, Ran Hao","doi":"10.1002/dep2.250","DOIUrl":"10.1002/dep2.250","url":null,"abstract":"<p>There has been no consensus yet regarding the precise initial timing and duration of the late Mesozoic extensional tectonics in the South-eastern China Block. This work focusses on the growth strata of the Early Cretaceous red beds in the South-eastern China Block to determine the late Mesozoic tectonics and the precise timing of the initiation and duration of extensional tectonics in this area. Field observation of several terrigenous basins shows that the dip angles of the Cretaceous red beds have varied from moderate to gentle from basin edges to interiors (or centres). The visible and estimated thickness within a single bed increases slightly downwards from the upper to the lower part. These characteristics indicate that the sedimentary area of these beds has undergone an extensional process with expansion and deepening of the sedimentary basins. Rotation of the border surfaces (limbs) and downward warping of the hanging walls or retreat of the footwalls of listric normal faults causes three types of extensional growth (or syntectonic) strata in the deposits of different basins. Dating of the volcanic rocks related to the growth beds reveals that the sedimentary basins were enlarged and deepened when the Early Cretaceous strata were deposited in the South-eastern China Block from <i>ca</i> 140 to 137 Ma. Regionally, under the influence of Palaeo-Pacific plate rollback since <i>ca</i> 140 Ma, the South-eastern China Block stress field has led to lithospheric uplift and pull-apart structures near the surface, causing the half-graben basins to receive sedimentation. Although the extensional event was interrupted by a short compressional event during 120 to 105 Ma, with the oceanward retreat of the trench, the area of extension gradually enlarged and rejuvenated south-eastwards until the end of the Cretaceous. This Cretaceous extension event of the South-eastern China Block must belong to a worldwide geological event with global significance.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 1","pages":"4-32"},"PeriodicalIF":2.4,"publicationDate":"2023-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.250","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49446829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}