Geology最新文献

{"title":"Magma-carbonate interactions drive CO2 production and metal enrichment in shallow dikes and sills at volcanic arcs","authors":"R.A. Morris, D. Canil, J. Spence","doi":"10.1130/g51439.1","DOIUrl":"https://doi.org/10.1130/g51439.1","url":null,"abstract":"The contribution of CO2 from crustal carbonates into arc magmas is debated, as is its role in the long-term C cycle. To better understand the contributions and mechanisms that drive CO2 production in arc magmas, we examined in detail basaltic dike and sill contacts with carbonate in the Jurassic Bonanza arc on Vancouver Island, Canada. We discovered discrete boundary melts that formed along dike and sill margins in contact with limestone, which display unique Ca, U, and Sr enrichments, Si depletion, and 87Sr/86Sr that approaches host limestone values (∼0.708). Binary mixing modeling indicates ∼20%−25% limestone assimilation into basalt formed the boundary melts. Contrasting viscosities between boundary and interior melts hinder mixing and chemical homogenization but appear to promote uphill diffusion and metal enrichment within systems that cool in minutes to days. While shallow dikes and sills may be volumetrically minor in an arc magma system, the open flow of magma and large surface area in channels greatly enhances magma-carbonate interactions, and ultimately CO2 production, likely over that of more common and voluminous plutons.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"5 8","pages":""},"PeriodicalIF":5.8,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138591298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ERRATUM: Microbial sulfate reduction plays an important role at the initial stage of subseafloor sulfide mineralization","authors":"Tatsuo Nozaki, Toshiro Nagase, Takayuki Ushikubo, Kenji Shimizu, Jun-ichiro Ishibashi, the D/V Chikyu Expedition 909 Scientists","doi":"10.1130/g47943e.1","DOIUrl":"https://doi.org/10.1130/g47943e.1","url":null,"abstract":"ORIGINAL ARTICLE: 2021, v. 49, no. 6, p. 222–227, https://doi.org/10.1130/G47943.1. First published 7 October 2020.","PeriodicalId":12642,"journal":{"name":"Geology","volume":" 36","pages":""},"PeriodicalIF":5.8,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138481024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hearing Assessment After Total Annular Excision Tympanoplasty- Our Institutional Experience.","authors":"Devisha Agarwal, Manish Chandra","doi":"10.1007/s12070-023-04083-8","DOIUrl":"10.1007/s12070-023-04083-8","url":null,"abstract":"<p><strong>Objective: </strong>The objectives of this study were to record graft uptake, hearing status and any complication(s) after total annular excision (TAE) tympanoplasty and to compare them with previously operated underlay tympanoplasty patients.</p><p><strong>Design: </strong>Prospective study.</p><p><strong>Methods: </strong>Patients with chronic otitis media mucosal type aged between 15-45 years attending our outpatient department were assessed and eligible patients who gave consent for the study were included.</p><p><strong>Result: </strong>Patients of chronic otitis media mucosal type who underwent TAE tympanoplasty had 80% graft uptake. Post TAE tympanoplasty patients had good hearing assessed by tuning fork test and pure tone audiometry. Maximum improvement in hearing was seen at 500Hz frequency by pure tone audiometry in TAE tympanoplasty group. Histopathological examination of remnant tympanic membrane showed mucosalization.</p><p><strong>Conclusion: </strong>TAE tympanoplasty can effectively prevent development of granular myringitis.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1007/s12070-023-04083-8.</p>","PeriodicalId":12642,"journal":{"name":"Geology","volume":"24 1","pages":"3711-3717"},"PeriodicalIF":4.8,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10645727/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85839389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Delayed Onset of a Contralateral \"White-Eyed Shunt\" Posterior Draining Carotid-Cavernous Fistula Following Ipsilateral \"Red-Eyed Shunt\".","authors":"Molly P Aldred, Subahari Raviskanthan, Peter W Mortensen, Richard P Klucznik, Andrew G Lee","doi":"10.1097/WNO.0000000000001546","DOIUrl":"10.1097/WNO.0000000000001546","url":null,"abstract":"","PeriodicalId":12642,"journal":{"name":"Geology","volume":"44 1","pages":"e201-e203"},"PeriodicalIF":4.8,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85780585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The application of dual clumped isotope thermometer (Δ47 and Δ48) to the understanding of dolomite formation","authors":"Chaojin Lu, Peter K. Swart","doi":"10.1130/g51576.1","DOIUrl":"https://doi.org/10.1130/g51576.1","url":null,"abstract":"Although several studies have shown the possibility of kinetic isotopic effects during the precipitation of carbonates using the dual clumped isotope proxy (Δ47 and Δ48), this approach has not yet been applied to the study of dolomite. We present Δ47 and Δ48 values of two types of Cenozoic Bahamian dolomites formed by distinctly different mechanisms. One dolomite, present in a core drilled on the island of San Salvador, is believed to have formed from normal seawater in the open system, while the other, taken from the Clino core drilled on the margin of the Great Bahama Bank, was precipitated associated with microbial sulfate reduction in the closed system. The Δ48-derived temperatures of San Salvador dolomites are consistent with their Δ47-temperatures, which are in turn close to the expected value of normal seawater. In contrast, dolomites from Clino show slightly elevated Δ47-derived temperatures (∼15 °C higher than the expected) and significantly increased Δ48-temperatures (∼145 °C) that are positively correlated with the sulfur isotopes of carbonate associated sulfate, in excess of +30‰. Such an association suggests a non-equilibrium process driven by microbial sulfate reduction, which elevates the alkalinity and depresses the pH of dolomitizing fluids. Notably, the greater amplitude of disequilibrium in Δ48 relative to Δ47 values demonstrates the sensitivity of the Δ48 proxy to kinetic isotope effects in dolomite. Conclusively, this study shows the potential of the dual clumped isotope proxy to identify microbial-mediated dolomitization in modern and ancient records.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"63 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136283291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Warming, acidification, and calcification feedback during the first hyperthermal of the Cenozoic—The Latest Danian Event","authors":"Margareta Harbich, James S.K. Barnet, James W.B. Rae, Dick Kroon","doi":"10.1130/g51330.1","DOIUrl":"https://doi.org/10.1130/g51330.1","url":null,"abstract":"The Latest Danian Event (LDE; ca. 62.15 Ma) is a major double-spiked eccentricity-driven transient warming event and carbon cycle perturbation (hyperthermal) in the early Paleocene, which has received significantly less attention compared to the larger events of the late Paleocene−early Eocene. A better understanding of the nature of the LDE may broaden our understanding of hyperthermals more generally and improve our knowledge of Earth system responses to extreme climate states. We present planktic and benthic foraminiferal Mg/Ca and B/Ca records that shed new light on changes in South Atlantic temperature and carbonate chemistry during the LDE. Our planktic Mg/Ca record reveals a pulsed increase in sea-surface temperature of at least ∼1.5 °C during the older carbon isotope excursion, and ∼0.5 °C during the younger isotope excursion. We observe drops in planktic and benthic B/Ca, synchronous with pronounced negative excursions in benthic δ13C, which suggest a shift in the carbonate system toward more acidic, dissolved inorganic carbon−rich conditions, in both the surface and deep ocean. Conditions remained more acidic following the LDE, which we suggest may be linked to an enhanced ocean alkalinity sink due to changes in the makeup of planktic calcifiers, hinting at a novel feedback between calcifier ecology and ocean-atmosphere CO2.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"349 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135475548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Age variability and decadal time-averaging in oyster reef death assemblages","authors":"Stephen R. Durham, Gregory P. Dietl, Quan Hua, John C. Handley, Darrell Kaufman, Cheryl P. Clark","doi":"10.1130/g50778.1","DOIUrl":"https://doi.org/10.1130/g50778.1","url":null,"abstract":"Using paleoecological data to inform resource management decisions is challenging without an understanding of the ages and degrees of time-averaging in molluscan death assemblage (DA) samples. We illustrate this challenge by documenting the spatial and stratigraphic variability in age and time-averaging of oyster reef DAs. By radiocarbon dating a total of 630 oyster shells from samples at two burial depths on 31 oyster reefs around Florida, southeastern United States, we found that (1) spatial and stratigraphic variability in DA sample ages and time-averaging is of similar magnitude, and (2) the shallow oyster reef DAs are among the youngest and highest-resolution molluscan DAs documented to date, with most having decadal-scale time-averaging estimates, and sometimes less. This information increases the potential utility of the DAs for habitat management because DA data can be placed in a more specific temporal context relative to real-time monitoring data. More broadly, the results highlight the potential to obtain decadal-scale resolution from oyster bioherms in the fossil record.Decades of work on molluscan death assemblages (DAs) have successfully documented temporal changes in community composition or species attributes from direct assessments of the remains themselves (e.g., Kowalewski et al., 2000; Kidwell, 2007; Dietl and Durham, 2016; Albano et al., 2021) or from proxy information derived from them (e.g., Gillikin et al., 2019). Despite the promise of such geohistorical records for conservation paleobiology, examples of their use by resource managers are still uncommon (Groff et al., 2023). One reason is the difficulty of putting DA data in temporal context. Geochronological analyses (e.g., radiocarbon dating) are expensive and difficult to interpret, leading many conservation paleobiological studies to work around age-related uncertainties by citing general assumptions and/or studies from similar depositional settings (e.g., Dietl and Durham, 2016).However, assemblage- or specimen-level chronological control is often required to meaningfully compare DA data with the annual or subannual real-time monitoring data typically used for resource management. This was the case for the Historical Oyster Body Size (HOBS) project in Florida, southeastern United States—codeveloped by the Florida Department of Environmental Protection (FDEP) Office of Resilience and Coastal Protection (ORCP) and the Paleontological Research Institution (PRI; Dietl et al., 2023)—which aimed to use oyster reef DA samples to supplement real-time monitoring data on oyster body sizes for ORCP’s Statewide Ecosystem Assessment of Coastal and Aquatic Resources (SEACAR) project (www.floridadep.gov/SEACAR).The aquatic preserves managed by ORCP were established between 1966 and 2020 to be maintained “in an essentially natural or existing condition” (Florida Administrative Code R.18-20.001[2]; Florida Department of State, 1997). Thus, management of each preserve is often focused","PeriodicalId":12642,"journal":{"name":"Geology","volume":"57 46","pages":""},"PeriodicalIF":5.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71512732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-resolution chronostratigraphy of late Mesozoic sequences in northern North China: Implications for the linkages among intracontinental orogeny, volcanism, Jehol Biota, and Pacific plate subduction","authors":"Qiang Ma, Yuting Zhong, Qingzhu Yin, Magdalena H. Huyskens, Liang Ma, Xiaoping Xia, Qing-Ren Meng, Zhong-He Zhou, Yi-Gang Xu","doi":"10.1130/g51535.1","DOIUrl":"https://doi.org/10.1130/g51535.1","url":null,"abstract":"Subduction of the paleo-Pacific plate during the late Mesozoic is thought to have been responsible for the destruction of the North China craton, manifested by intense volcanism, lithospheric deformation, and dramatic changes in surface morphology and terrestrial ecosystems. However, the timing and correlations of these consequential events remain obscure. This issue was addressed here by carrying out a high-resolution geochronologic study on the Upper Jurassic−Lower Cretaceous sequences of the Luanping basin, northern Hebei Province, China. Secondary ion mass spectrometry (SIMS) and chemical abrasion−isotope dilution−isotope ratio mass spectrometry (CA-ID-IRMS) zircon U-Pb ages from samples near the boundaries of the stratigraphic units help to redefine the chronostratigraphic framework of this basin and more importantly reveal that the second phase of the Yanshanian orogeny, representing a tectonic transition from flat to steep subduction of the paleo-Pacific plate, occurred within 0.87 ± 0.10 m.y. between 134.162 ± 0.091 Ma and 133.295 ± 0.043 Ma. Crustal extension then followed and resulted in development of rift basins and vigorous volcanism. The Jehol Biota came into being in Lower Cretaceous successions formed after ca. 130 Ma. The late Mesozoic Luanping basin therefore records how the subduction of the paleo-Pacific plate drove intracontinental orogeny, volcanism, basin development, and ecosystem evolution.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"29 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135221878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A unique record of prokaryote cell pyritization","authors":"Nathan Barling, Farid Saleh, Xiaoya Ma","doi":"10.1130/g51352.1","DOIUrl":"https://doi.org/10.1130/g51352.1","url":null,"abstract":"Prokaryotes, including bacteria, are a major component of both modern and ancient ecosystems. Although fossilized prokaryotes are commonly discovered in sedimentary rocks, it is rare to find them preserved in situ alongside macrofossils, particularly as pyritized cells in sites of exceptional fossil preservation. We examined prokaryotes preserved in the Lower Cretaceous Crato Formation of Brazil and demonstrate the widespread presence of spherical microorganisms preserved on the surface of Crato invertebrate fossils. These microorganisms were pyritized, covering decaying carcasses, 1.14 ± 0.01 μm in size, hollow with smooth surfaces, and can be found as aggregates resembling modern prokaryotes, particularly, coccoid bacterial colonies. It is likely that the observed microorganisms covered the carcasses before permissive conditions were established for pyritization, which must have been so rapid as to inhibit the autolysis of their delicate membranes. This is a new record of prokaryote fossils preserved in pyrite in association with macrofossils, which highlights the unique diagenetic and paleoenvironmental conditions of the Crato Formation that facilitated this mode of fossilization.Prokaryotes, including bacteria, play a major role in ecosystems and provide some of the earliest evidence of life on Earth (e.g., Homann, 2019; Javaux 2019). Bacteria in the fossil record can be preserved in stromatolites, thrombolites, and simple microbial mats (e.g., Noffke et al., 2003; Peters et al., 2017; Gueriau et al., 2020). They can also be phosphatized (Cosmidis et al., 2013) in association with decaying macrofossils, replicating the anatomy of the degrading tissue (e.g., Wilby and Briggs, 1997). In some cases, bacteria can be preserved as carbonaceous material or in pyrite, but this type of preservation is biased toward cyanobacteria that have relatively resistant cell walls (Wilson and Taylor, 2017; Demoulin et al., 2019). Outside of these narrow windows of preservation (see also Toporski et al., 2002), bacterial occurrences in the fossil record become rarer and highly debated (e.g., Nims et al., 2021). Numerous spherical and elongated microstructures associated with macrofossils have been reported globally and were interpreted as the remains of microorganisms that contribute to the decomposition of organic material (e.g., Lindgren et al., 2015; Schweitzer et al., 2015). However, these microstructures were interpreted as melanosomes by other researchers (e.g., Vinther, 2015, 2016, and references therein). Interestingly, although pyritization is a main pathway for macrofossil preservation in the fossil record and is mediated by sulfate-reducing bacteria, there is little evidence of prokaryote pyritization alongside macrofossils. This is because preservation by pyrite in Lagerstätten is commonly believed to be too coarse to preserve minute organisms such as prokaryotes. Our study aims to investigate microorganism preservation in the Lower Cretaceous Crato F","PeriodicalId":12642,"journal":{"name":"Geology","volume":"40 48","pages":""},"PeriodicalIF":5.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71491854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linking source and sink: The timing of deposition of Paleogene syntectonic strata in Central Asia","authors":"Feng Cheng, Andrew V. Zuza, Marc Jolivet, Andreas Mulch, Niels Meijer, Zhaojie Guo","doi":"10.1130/g51382.1","DOIUrl":"https://doi.org/10.1130/g51382.1","url":null,"abstract":"Determining the age of siliciclastic continental sequences in the absence of comprehensive biostratigraphy or radiometric dating of geological markers (e.g., volcanic layers) is inherently challenging. This issue is well exemplified in the current debate on the age of Cenozoic terrestrial strata in Central Asia, where competing age models constrained by non-unique paleomagnetic correlations are interpreted to reflect the growth of the Tibetan Plateau and its impact on Central Asian climate change. Here we present a new approach to evaluate competing age models by comparing the onset of rapid basement exhumation constrained by low-temperature thermochronology in the sediment source region with the initiation of growth strata in the adjacent sedimentary sink. We first validate this method in regions with well-constrained age models and subsequently apply this approach to the Tarim and Qaidam Basins in the northern Tibetan Plateau. The results of this analysis show that syntectonic sedimentation had already initiated during the Paleocene–Eocene and was followed by intensified Oligocene–Miocene mountain building along the northern margin of the plateau. Based on this refined Paleogene tectonic history, we further arrive at a temporal correlation between Paleogene tectonism in Northern Tibet and the retreat of the Proto-Paratethys Sea, a major water body that extended across Eurasia and was closely associated with climatic and biodiversity changes. We thus highlight the previously underestimated role tectonics in Northern Tibet had in the evolution and demise of the Proto-Paratethys Sea during the Paleogene.Because correlation of paleomagnetic data from continental basins to the Geomagnetic Polarity Time Scale (Ogg, 2020) is commonly non-unique, magnetostratigraphy alone can lead to dramatically different age models for continental siliciclastic sequences in the absence of fossils or radiometrically datable volcanic ash layers (Lowe, 2011). This inevitably leads to contrasting models for the timing, rates, and duration of tectonic and paleoclimatic processes. This fundamental challenge is well exemplified in Cenozoic terrestrial strata in Central Asia (Figs. 1A–1E), where competing age models have strongly diverging implications for the growth of the Tibetan Plateau (Ji et al., 2017; Staisch et al., 2020; Wang et al., 2022) and its association with Asia paleo-environments including the retreat of the Proto-Paratethys Sea, a major water body that covered large surfaces of Eurasia during the Paleogene (Bosboom et al., 2017; Sun and Liu, 2006; Zheng et al., 2015).The two largest terrestrial basins in the Cenozoic Tibetan orogen are the Tarim and Qaidam Basins, which contain critical archives of mountain building and paleoclimate (Fig. 1B). The growth strata and thick-bedded conglomerates in the Lulehe Formation, the basal stratigraphic unit of Cenozoic strata in the Qaidam Basin (Fig. 1D), are interpreted as synorogenic sediments that record the initiati","PeriodicalId":12642,"journal":{"name":"Geology","volume":"40 51","pages":""},"PeriodicalIF":5.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71491852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}