Pub Date : 2024-07-01DOI: 10.5038/1827-806x.53.2.2507
L. Hose, V. Polyak, Harvey DuChene, J. D. Powell, L. Melim, Gretchen M. Baker, Donald Davis, Y. Asmerom
Twenty-five caves displaying evidence of hypogene speleogenesis in White Pine County, Nevada, were studied between May 2022 and October 2023. Results demonstrate that the central Basin and Range Province is a major hypogenic cave region with speleogenesis dating back to the Middle Miocene. The U-Pb radiometric dates of cave mammillaries obtained so far cover a wide span of time, ranging between 14 Ma to 2 Ma. Tectonic shearing along the Snake Range Décollement up to about 22 Ma probably brackets the maximum age of speleogenesis. Thus, speleogenesis began between 22-14 Ma, which predates most of the Basin and Range extensional tectonism of the Late Miocene. Robust dates for the common mammillaries in the region have been hard to obtain mostly due to Pb contamination. There are elevated levels of Pb throughout the area, likely due to mineralized fluids associated with the décollement. While 11 mammillary samples (from 10 caves) have been assessed for U-Pb dating viability, five contained too much Pb for analysis. Hypogenic features in these caves include mammillaries, tilted folia, bubble trails, cupolas, ceiling vents/tubes, floor vents, acid lake basins, pseudoscallops (cusps), and boneyard (megacusps). A common and newly identified feature of these caves is extensive secondary deposits of a complex mixture with silt-sized calcite and quartz grains. Some quartz grains have calcite overgrowths, suggesting authigenic growth. We named these lithified, and very porous, deposits “calc-siltite”. Sulfuric acid speleogenesis (SAS) has been clearly demonstrated in only one cave, Lehman Caves, but is strongly suspected in at least four other study sites (Old Mans, Cathedral, #041709-NS-012, and #LC01 caves). However, the great antiquity of these hypogenic caves means that they have probably experienced climatic and surface geomorphologic changes resulting in extensive alterations by epigenic groundwater. The evidence specific to demonstrating SAS processes may have been removed or covered by later epigenic activities.
2022 年 5 月至 2023 年 10 月期间,研究人员对内华达州白松县 25 个显示下新世成岩证据的洞穴进行了研究。研究结果表明,盆地和山脉省中部是一个主要的低成洞穴区,其岩浆生成可追溯到中新世。迄今为止获得的洞穴乳状岩U-Pb放射性测定年代涵盖的时间跨度很大,从14Ma到2Ma不等。蛇岭地层在大约 22 Ma 之前的构造剪切可能括进了岩浆形成的最大年龄。因此,岩浆形成开始于 22-14 Ma 之间,早于晚中新世的大部分盆地和山脉伸展构造运动。主要由于铅污染,很难获得该地区常见猛犸象的可靠年代。整个地区的铅含量都很高,这很可能是由于与地壳有关的矿化流体造成的。虽然对 11 个哺乳动物样本(来自 10 个洞穴)进行了铀-铅测年可行性评估,但其中 5 个样本的铅含量过高,无法进行分析。这些洞穴的下生特征包括乳状液、倾斜叶片、气泡轨迹、冲天炉、天花板通风口/管、地板通风口、酸性湖盆、假扇贝(尖顶)和骨架(巨型尖顶)。在这些洞穴中,一个新发现的共同特征是广泛的二次沉积物,这些沉积物是淤泥大小的方解石和石英颗粒的复杂混合物。一些石英颗粒有方解石过度生长,表明是自生的。我们将这些岩石化且多孔的沉积物命名为 "方解石-粉砂岩"。硫酸成岩(SAS)只在雷曼洞穴这一个洞穴中得到了明确的证实,但至少在其他四个研究地点(老曼斯洞穴、大教堂洞穴、#041709-NS-012 和 #LC01 洞穴)都有强烈的怀疑。然而,这些低成因洞穴年代久远,很可能经历了气候和地表地貌的变化,导致表生地下水的广泛改变。证明 SAS 过程的具体证据可能已被后来的表生活动清除或覆盖。
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Pub Date : 2024-07-01DOI: 10.5038/1827-806x.53.2.2509
M. Temovski, Zsófia Ruszkiczay-Rüdiger, K. Molnár, László Rinyu, Alexander Wieser, Oscar Marchhart, László Palcsu
A combination of morphological observations, geochemical data from calcite minerals and geochronology by burial age dating and U-series is used to constrain the geological and geomorphological setting and the evolutionary stages of a hypogene karst system. This methodological suit is applied to Melnička Peštera, a horizontal cave developed in carbonate breccia overlying dolomite marble in Melnica locality (N. Macedonia), where hydrothermal karst development occurred in both dolomite and calcite marble. The passage morphology of the cave, having a reverse triangle, Laughöhle cross-sections, suggests development near the water table by slowly moving waters. Calcite crusts are found throughout the cave, and based on their relationship to passage morphology, appear to pre-date main horizontal passage formation. Their carbonate stable and clumped isotope and fluid inclusion noble gas compositions indicate cooling of the hydrothermal system with an increased contribution of shallower groundwater. U-series data suggests Early Pleistocene deposition of the calcite crusts. Water table notches and convectional features carved into breccia bedrock and calcite crusts point to subsequent development at and above the water table by condensation corrosion. The solutional aggressiveness near the water table was likely related to CO2, that previously degassed from the deeper parts of the system where calcite was depositing, and redissolved in the cooler, shallower waters. Due to poor connection with the surface, the cave air above the water table likely had high pCO2, that further helped to maintain aggressiveness of the groundwater at the water-air contact, and boosted condensation corrosion above it, preventing deposition of related secondary calcite minerals. The cave-hosting carbonate breccia deposited as an alluvial fan filling up a paleovalley cut into Upper Miocene sediments. Cosmogenic nuclide burial age dating of quartz fragments confirms Early Pliocene age for the breccia, and constrains the paleovalley incision to Late Miocene, likely related to base level lowering caused by the Messinian Salinity Crisis.
通过形态观察、方解石矿物的地球化学数据以及埋藏年代测定法和 U 系列的地质年代测定法,对下伏岩溶系统的地质和地貌环境以及演化阶段进行了综合分析。Melnička Peštera 是一个水平洞穴,位于马其顿北部 Melnica 地区白云石大理岩上覆盖的碳酸盐角砾岩中,热液岩溶在白云石和方解石大理岩中均有发育。该洞穴的通道形态呈反三角状,横截面为劳厄勒(Laughöhle),表明是由缓慢流动的水流在地下水位附近形成的。方解石结壳遍布整个洞穴,根据其与通道形态的关系,似乎早于主要水平通道的形成。它们的碳酸盐稳定同位素和团块同位素以及流体包裹体惰性气体成分表明,热液系统冷却后,浅层地下水的贡献增加。U 系列数据表明方解石结壳沉积于早更新世。在角砾岩基岩和方解石结壳上刻画的地下水位缺口和对流特征表明,在地下水位及以上,方解石结壳随后通过冷凝腐蚀而形成。地下水位附近溶液的侵蚀性很可能与二氧化碳有关,二氧化碳之前从沉积方解石的水系深部脱气,在较浅的冷水中重新溶解。由于与地表连接不畅,地下水位以上的洞穴空气可能具有较高的 pCO2,这进一步帮助维持了水气接触处地下水的侵蚀性,并增强了其上方的冷凝腐蚀,阻止了相关次生方解石矿物的沉积。洞穴所在的碳酸盐角砾岩沉积为冲积扇,填满了切入上中新世沉积物的古山谷。石英碎片的宇宙成因核素埋藏年龄测定证实了角砾岩的上新世早期年龄,并将古山谷切口推定为中新世晚期,这可能与墨西拿盐度危机造成的基底降低有关。
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Pub Date : 2024-07-01DOI: 10.5038/1827-806x.53.2.2510
A. Erőss, Katalin Hegedűs-Csondo, Petra Kovács-Bodor, D. Szieberth, Ákos Horváth, G. Czuppon, Andrea Mindszenty, S. Leél-Őssy, J. Mádl-Szőnyi
The underwater Molnár János Cave in the hypogene Buda Thermal Karst system (Budapest, Hungary) provides a unique site to study the effects of flowing groundwater and the interplay of fluids of different origin. The aim of the present study is to characterize the groundwater in different parts of the cave with temporal resolution, hence describe the recent speleogenetic processes within the cave. This study uses natural radioisotopes (uranium, radium, and radon) besides stable isotope ratios of oxygen and hydrogen to identify the different fluid components. The results show that the majority of the cave is situated in the flow path of the intermediate flow system, discharging in the Boltív Spring. Thus, the dominant recent speleogenetic processes are connected to this lukewarm groundwater. In contrast to previous views, typical hypogene processes, such as mixing corrosion involving thermal waters, are restricted to a narrower area in the cave, to the contact zone of lukewarm waters and the warmer upper water layer around the largest partially air-filled chamber (Kessler Hall). The warmer water layer is the result of free convection. In the air-filled chambers condensation-corrosion might be active. However, its effect is limited to the largest room (Kessler Hall), as it is open to surface conditions. More active mixing corrosion probably occurs deeper, in the area of the Northeastern Margin Fault, which is indicated by the radon content in the Boltív Spring. Regarding the temporal processes, the main driving force can be linked to the water level fluctuations of the Danube, which regulates the discharge of the regional flow-related thermal water upwelling, thus affecting the mixing ratio of the lukewarm waters transported by the intermediate flow systems and the thermal waters, representing the regional flow path, including basinal components.
{"title":"Revealing the ongoing speleogenetic processes in an underwater cave through the application of natural radionuclides and stable isotopes: case study from the hypogene Buda Thermal Karst","authors":"A. Erőss, Katalin Hegedűs-Csondo, Petra Kovács-Bodor, D. Szieberth, Ákos Horváth, G. Czuppon, Andrea Mindszenty, S. Leél-Őssy, J. Mádl-Szőnyi","doi":"10.5038/1827-806x.53.2.2510","DOIUrl":"https://doi.org/10.5038/1827-806x.53.2.2510","url":null,"abstract":"The underwater Molnár János Cave in the hypogene Buda Thermal Karst system (Budapest, Hungary) provides a unique site to study the effects of flowing groundwater and the interplay of fluids of different origin. The aim of the present study is to characterize the groundwater in different parts of the cave with temporal resolution, hence describe the recent speleogenetic processes within the cave. This study uses natural radioisotopes (uranium, radium, and radon) besides stable isotope ratios of oxygen and hydrogen to identify the different fluid components. The results show that the majority of the cave is situated in the flow path of the intermediate flow system, discharging in the Boltív Spring. Thus, the dominant recent speleogenetic processes are connected to this lukewarm groundwater. In contrast to previous views, typical hypogene processes, such as mixing corrosion involving thermal waters, are restricted to a narrower area in the cave, to the contact zone of lukewarm waters and the warmer upper water layer around the largest partially air-filled chamber (Kessler Hall). The warmer water layer is the result of free convection. In the air-filled chambers condensation-corrosion might be active. However, its effect is limited to the largest room (Kessler Hall), as it is open to surface conditions. More active mixing corrosion probably occurs deeper, in the area of the Northeastern Margin Fault, which is indicated by the radon content in the Boltív Spring. Regarding the temporal processes, the main driving force can be linked to the water level fluctuations of the Danube, which regulates the discharge of the regional flow-related thermal water upwelling, thus affecting the mixing ratio of the lukewarm waters transported by the intermediate flow systems and the thermal waters, representing the regional flow path, including basinal components.","PeriodicalId":508425,"journal":{"name":"International Journal of Speleology","volume":"25 S2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141848641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.5038/1827-806x.53.2.2502
V. Polyak, Jeffrey Forbes, Michael N. Spilde, Paula Provencio, John Cochran, Y. Asmerom
The Mesa del Oro travertine, deposited by upwelling CO2-rich spring waters, is a large and thick mantle of calcite overlying soft Triassic Chinle Formation mudstones in western central New Mexico, USA. The travertine contains a system of small caves known as the Pronoun Cave Complex. Whut Cave is the largest known cave in the complex. While the travertine hydrologic system is no longer active, there is ample evidence that Whut Cave was formed by hypogene speleogenesis. The Whut Cave entrance is a small roughly circular shaft that descends ~four meters and intersects a linear fissure-controlled passage. Mn-oxide was once mined below the entrance, leaving a five-meter-deep pit that represents the path of upwelling waters that were likely charged with CO2 and supersaturated with CaCO3 once reaching the surface. The roomiest part of the cave is immediately adjacent to the entrance, defining where most of the upwelling of groundwater and gases took place. Gypsum and other sulfates were only noted microscopically. A sample of travertine at the surface near the entrance yielded a uranium-series age beyond the limit of the method and a δ234U age of 735 ± 109 ka BP (before present). A piece of breccia vein in the mine dump associated with the Mn-oxide ore, and a rill of a drape-like crust on the cave wall, both interpreted to be products of hypogene speleogenesis and representing the oldest speleogenetic material, yielded δ234U ages of 848 ± 110 and 723 ± 109 ka BP. Altogether, materials interpreted to be speleogenetic yielded ages of ~900 – 300 ka BP. Although the cave is dry and hydrologically inactive today, cave development by CO2 hypogene speleogenesis was coeval with endogenic travertine deposition and nearby volcanism. Our interpretation suggests that all these events are linked.
Mesa del Oro石灰华由富含二氧化碳的泉水上涌沉积而成,是覆盖在美国新墨西哥州中西部松软的三叠纪钦勒地层泥岩上的一大块厚厚的方解石地幔。石灰华中包含一个小型洞穴系统,被称为 "Pronoun 洞穴群"。Whut 洞穴是已知洞穴群中最大的洞穴。虽然石灰华水文系统已不再活跃,但有充分证据表明,Whut 洞穴是由下伏岩浆形成的。胡特岩洞的入口是一个大致呈圆形的小竖井,向下约四米,与一个线性裂缝控制通道相交。入口下方曾经开采过氧化锰,留下了一个五米深的坑洞,它代表了上涌水流的路径,这些上涌水流到达地表后很可能充满了二氧化碳,并含有过饱和的 CaCO3。洞穴最宽敞的部分紧挨着入口,这也是地下水和气体上涌的主要位置。只在显微镜下发现了石膏和其他硫酸盐。入口附近地表的一个洞石样本得出的铀系列年龄超出了该方法的极限,δ234U 年龄为 735 ± 109 ka BP(距今)。与氧化锰矿石有关的矿堆中的一块角砾岩脉和洞壁上的一条悬垂状地壳,都被解释为下成岩成岩的产物,代表了最古老的成岩物质,其δ234U 年龄分别为 848 ± 110 和 723 ± 109 ka BP。总之,被解释为成岩物质的年龄在公元前约 900 - 300 ka 之间。虽然该洞穴如今已经干涸,水文不活跃,但二氧化碳下成岩成洞与内生石灰华沉积和附近的火山活动同时发生。我们的解释表明,所有这些事件都是相互关联的。
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Pub Date : 2024-02-01DOI: 10.5038/1827-806x.53.1.2494
D. McFarlane, Joyce Lundberg
Cave guano deposits are increasingly being recognized as valuable repositories of paleo-climatic and paleo-environmental information. However, that value is constrained by rates of guano decomposition, and these rates have not been previously well-studied. Here we show that field and laboratory studies of deep insectivorous bat guano sequences in the caves of Borneo demonstrate the extreme dependence of decomposition rate on guano water content. Under tropical conditions, moist guanos exhibit decomposition coefficients (k) values of ~ 0.01, implying the loss of most of the organic content on decadal timescales. Under similar temperatures but drier conditions, k values drop to ~3 x 10-6, permitting significant organic (chitin) content to persist for tens of thousands of years. One of the implications of these findings for paleo-environmental records older than the limit of carbon dating is that a value for k can be calculated based on a single carbon date, which then allows an estimate of likely age at base of deposit.
人们越来越认识到,洞穴鸟粪沉积物是古气候和古环境信息的宝贵宝库。然而,这一价值受到鸟粪分解率的制约,而这些分解率以前还没有得到很好的研究。在这里,我们通过对婆罗洲洞穴中深层食虫蝙蝠鸟粪序列的实地和实验室研究,证明了鸟粪分解率与鸟粪含水量的极端依赖性。在热带条件下,潮湿鸟粪的分解系数(k)值约为 0.01,这意味着在十年的时间尺度内大部分有机成分都会流失。在温度相似但较为干燥的条件下,k 值会下降到约 3 x 10-6,从而使大量有机物(甲壳素)得以持续数万年。这些发现对于比碳年代测定极限更早的古环境记录的影响之一是,可以根据单个碳年代计算出 k 值,从而估算出沉积物底部的可能年龄。
{"title":"Rates of diagenesis of tropical insectivorous bat guano accumulations: implications for potential paleoenvironmental reconstruction","authors":"D. McFarlane, Joyce Lundberg","doi":"10.5038/1827-806x.53.1.2494","DOIUrl":"https://doi.org/10.5038/1827-806x.53.1.2494","url":null,"abstract":"Cave guano deposits are increasingly being recognized as valuable repositories of paleo-climatic and paleo-environmental information. However, that value is constrained by rates of guano decomposition, and these rates have not been previously well-studied. Here we show that field and laboratory studies of deep insectivorous bat guano sequences in the caves of Borneo demonstrate the extreme dependence of decomposition rate on guano water content. Under tropical conditions, moist guanos exhibit decomposition coefficients (k) values of ~ 0.01, implying the loss of most of the organic content on decadal timescales. Under similar temperatures but drier conditions, k values drop to ~3 x 10-6, permitting significant organic (chitin) content to persist for tens of thousands of years. One of the implications of these findings for paleo-environmental records older than the limit of carbon dating is that a value for k can be calculated based on a single carbon date, which then allows an estimate of likely age at base of deposit.","PeriodicalId":508425,"journal":{"name":"International Journal of Speleology","volume":"27 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140464935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-01DOI: 10.5038/1827-806x.53.1.2480
A. Demény, Ágnes Berentés, László Rinyu, I. Kovács, G. Surányi, Magdolna Virág
Clumped isotope measurements of carbonates and stable isotope analyses of water trapped in fluid inclusions are both promising techniques to determine carbonate formation temperatures. Cave-hosted carbonate deposits (speleothems) are excellent targets for such studies, but kinetic fractionations and diagenetic influences frequently deteriorate the temperature data obtained from these methods. However, subaqueous carbonate deposits may provide reliable data, as kinetic fractionations are less significant in underwater environments. In this study, subaqueous speleothems, whose formation temperatures were directly measured in the water, were investigated. Additionally, temperatures calculated from the oxygen isotope fractionations between calcite and fluid inclusion-hosted water were compared with clumped isotope temperatures obtained for subaqueous carbonate formations in cave-hosted lakes. The clumped isotope temperatures fit the measured and calculated fluid inclusion temperatures within the analytical precisions. Carbonate deposits formed at elevated temperatures (~50°C or above) may undergo post-formational calcite-water oxygen isotope exchange, altering the composition of the inclusion-hosted water. In contrast, subaqueous speleothems formed at about 20-25°C appear to preserve the primary isotopic compositions. Our study shows that subaqueous carbonate speleothems are useful targets for clumped isotope and inclusion water analyses, making them valuable paleotemperature archives.
{"title":"Subaqueous carbonate speleothems as paleotemperature archives – clumped isotope thermometry and stable isotope compositions of inclusion-hosted water","authors":"A. Demény, Ágnes Berentés, László Rinyu, I. Kovács, G. Surányi, Magdolna Virág","doi":"10.5038/1827-806x.53.1.2480","DOIUrl":"https://doi.org/10.5038/1827-806x.53.1.2480","url":null,"abstract":"Clumped isotope measurements of carbonates and stable isotope analyses of water trapped in fluid inclusions are both promising techniques to determine carbonate formation temperatures. Cave-hosted carbonate deposits (speleothems) are excellent targets for such studies, but kinetic fractionations and diagenetic influences frequently deteriorate the temperature data obtained from these methods. However, subaqueous carbonate deposits may provide reliable data, as kinetic fractionations are less significant in underwater environments. In this study, subaqueous speleothems, whose formation temperatures were directly measured in the water, were investigated. Additionally, temperatures calculated from the oxygen isotope fractionations between calcite and fluid inclusion-hosted water were compared with clumped isotope temperatures obtained for subaqueous carbonate formations in cave-hosted lakes. The clumped isotope temperatures fit the measured and calculated fluid inclusion temperatures within the analytical precisions. Carbonate deposits formed at elevated temperatures (~50°C or above) may undergo post-formational calcite-water oxygen isotope exchange, altering the composition of the inclusion-hosted water. In contrast, subaqueous speleothems formed at about 20-25°C appear to preserve the primary isotopic compositions. Our study shows that subaqueous carbonate speleothems are useful targets for clumped isotope and inclusion water analyses, making them valuable paleotemperature archives.","PeriodicalId":508425,"journal":{"name":"International Journal of Speleology","volume":"46 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140465765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}