Invasion of a karst aquifer by hydrothermal fluids: evidence from stable isotopic compositions of cave mineralization

Mineral deposits in the Cupp‐Coutunn/Promeszutochnaya cave system (Turkmenia, central Asia) record a phase of hydrothermal activity within a pre‐existing karstic groundwater conduit system. Hydrothermal fluids entered the caves through fault zones and deposited sulphate, sulphide and carbonate minerals under phreatic conditions. Locally, intense alteration of limestone wall rocks also occurred at this stage. Elsewhere in the region, similar faults contain economic quantities of galena and elemental sulphur mineralization. Comparisons between the Pb and S isotope compositions of minerals found in cave and ore deposits confirm the link between economic mineralization and hydrothermal activity at Cupp‐Coutunn. The predominance of sulphate mineralization in Cupp‐Coutunn implies that the fluids were more oxidized in the higher permeability zone associated with the karst aquifer. A slight increase in the δ³⁴S of sulphate minerals and a corresponding δ³⁴S decrease in sulphides suggest that partial isotopic equilibration occurred during oxidation. Carbonate minerals indicate that the hydrothermal fluid was enriched in ¹⁸O (δ¹⁸O_SMOW ～ + 10‰) relative to meteoric groundwater and seawater. Estimated values for δ¹³C_DIC (δ¹³C_PDB ～ ? 13‰) are consistent with compositions expected for dissolved inorganic carbon (DIC) derived from the products of thermal decomposition of organic matter and dissolution of marine carbonate. Values derived for δ¹³C_DIC and δ¹⁸O_water indicate that the hydrothermal fluid was of basinal brine origin, generated by extensive water–rock interaction. Following the hydrothermal phase, speleothemic minerals were precipitated under vadose conditions. Speleothemic sulphates show a bimodal sulphur isotope distribution. One group has compositions similar to the hydrothermal sulphates, whilst the second group is characterized by higher δ³⁴S values. This latter group may either record the effects of microbial sulphate reduction, or reflect the introduction of sulphate‐rich groundwater generated by the dissolution of overlying evaporites. Oxygen isotope compositions show that calcite speleothems were precipitated from nonthermal groundwater of meteoric origin. Carbonate speleothems are relatively enriched in ¹³C compared to most cave deposits, but can be explained by normal speleothem‐forming processes under thin, arid‐zone soils dominated by C4 vegetation. However, the presence of sulphate speleothems, with isotopic compositions indicative of the oxidation of hydrothermal sulphide, implies that CO₂ derived by reaction of limestone with sulphuric acid (‘condensation corrosion’) contributed to the formation of ¹³C‐enriched speleothem deposits.     

Red calcite: an indicator of paleo‐karst systems associated with bauxitic unconformities

A unique red calcite generation, which fills fractures/cavities, is hosted by Mesozoic carbonates in the Transdanubian Range, Hungary. Solid inclusions are located along growth zones of calcite. Hematite, the most abundant solid inclusion, gives the red colour of it. Outcrop‐scale geometry, mineralogical features and detrital mineral assemblage (hematite, gibbsite, goethite, kaolinite, smectite, illite, Cr‐spinel, monazite, xenotime, zircon, apatite and Ti‐oxide) of calcite precipitates suggest strong correlation between the calcite and nearby karst bauxite deposits. Fluid inclusion petrography and microthermometry (T < 50°C; salinity from 0 to 0.17 NaCl eq. w%) of primary fluid inclusions, and the stable isotope trend of the calcite, following the meteoric water line, clearly indicate vadose and phreatic meteoric origin in a near‐surface karst system. The late Cretaceous to mid‐Eocene unconformity‐related cavity‐filling deposits occur close to the surface; indicating that the most recent Quaternary exhumation re‐exposed those surfaces that existed at the time of calcite mineralization. Thus, red calcite precipitates are interpreted as being speleothems, vestiges of the subterranean part of the pre‐Middle Eocene karst. The infiltrated, fine bauxite particles enclosed by the calcite are the witnesses of the once areally extensive pre‐Middle Eocene bauxitic blanket that became partially eroded by the time of the deposition of the cover beds. Red calcite when found in core samples may provide good evidence on bauxite formation associated with the overlying unconformity, even if it was later removed by erosion. Therefore, presence or absence of red calcite may be used as distinguishing criteria between karst episodes with or without bauxite formation.     

Late Pleistocene Crocuta crocuta spelaea (Goldfuss, 1823) clans as prezewalski horse hunters and woolly rhinoceros scavengers at the open air commuting den and contemporary Neanderthal camp site Westeregeln (central Germany)

Late Pleistocene Ice Age Crocuta crocuta spelaea ( Goldfuss, 1823) hyenas from the open-air gypsum karst site Westeregeln (Saxony-Anhalt, central Germany) is dated into the early to middle Late Pleistocene. Hyena clans apparently used the karst for food storage and as “commuting den”, where typical high amounts (15% of the NISP) of hyena remains appear, also faecal pellets in concentrations for den marking purposes. Additionally small carnivores Meles, Vulpes and Mustela appear to have used some cavities as dens. Several hundreds of lowland “mammoth steppe fauna” bones (NISP = 572) must have been accumulated primarily by hyenas, and not by Neanderthals at the contemporary hyena/human camp site. Abundant caballoid horse remains of “E. germanicus Nehring, (1884)” are revised by the holotype and original material to the small E. c. przewalskii horse. Woolly rhinoceros Coelodonta antiquitatis remains are also abundant, and were left in several cases with typical hyena scavenging damages. Rangifer tarandus (11%) is mainly represented by numerous fragments of shed female antlers that were apparently gathered by humans, and antler bases from male animals that were collected and chewed in few cases (only large male antlers) by hyenas. The large quantities of small reindeer antlers must have been the result of collection by humans; their stratigraphic context is unclear but such large quantities most probably resulted from schamanic activities. The hyena site overlaps with a Middle Palaeolithic Neanderthal camp, as well as possibly with a later human Magdalénian site.     

Exploring the vertical: science and sociality in the field among cavers in Venezuela

Recent scholarship on vertical geographies has lead to a critical reexamination of the relationship between space and power. In this paper, I develop a vertical geographies approach in an unexplored context and with a less tested method: that of cave explorers and scientists in the field in Venezuela, from an ethnographic perspective. Ethnographic analysis of exploration in practice, viewed in relation to a multi-dimensional environment and the social dynamics, bodies, and technologies involved in traversing it, illustrates the ways vertical geographies are constructed and experienced. For the Venezuelan Speleological Society, a group dedicated to cave exploration and science since 1967, examining these geographies highlights culturally specific ways the tension between sports and science in speleology play out and how new members are socialized in the field. Specifically, attention to verticality highlights the role that age, masculinist heroics, and other embodied dimensions play in the construction of speleological geographies. More broadly, an ethnographic focus on exploration, with humans probing the earth's sinuous contours, guards against thinking of verticality abstractly—doing so risks simplifying and even misrepresenting multi-dimensional and processual engagements among humans, their technologies, and the environment.     

History of Deforestation and Reforestation in the Dinaric Karst

The term karst derives from the Kras plateau, which is in the northwestern part of the area now known as the Dinaric Karst. The landscape consists mostly of Mesozoic carbonate rocks and stretches along the Adriatic Sea coast for a distance of 600 km. Although the region lies parallel to the sea, the Mediterranean temperature influence is limited to a narrow coastal belt, except for the amount of precipitation, which can reach 5000 mm yr^?1. Forests belonging to the Mediterranean and Euro‐Siberian – North American region, covered the primary Dinaric Karst. Human deforestation of the Karst began during the Neolithic period, 6500–6000 BC. Throughout history there have been two main reasons for deforestation; economic (the requirements of new land, pastures, timber use and trade), and social (local increases in population, mass migration, wars, raids). Mankind's perception of forest protection and preservation can be traced through documents going back to the 12th century. Reforestation is mentioned in some of them, but successful reforestation did not begin until the 1850s. Nowadays dense natural forests, extensive forest plantations, dry karst shrublands and also completely barren karst areas can all be found on the Dinaric Karst.     

Evaluating Ethnopedological Knowledge Systems for Classifying Soil Quality. A Case Study in Bo Hamlet with Muong People of Northern Vietnam

Ethnopedological knowledge is incorporated in a case study for sustainable land management of mountain karst areas in Vietnam. The research is based on a multidisciplinary approach, including participation of local inhabitants for identifying and classifying local indicators of soil quality, next to scientifically sound approaches to soil quality assessment based on analytical soil data and a statistical treatment of the results. The case study focuses on Bo hamlet, located in the Ngo Luong commune of the Tan Lac district, Hoa Binh province. The participatory approach reveals that local people of the Muong ethnic group distinguish seven land use types and six soil types. They also identified nine local indicators of soil quality: presence of earthworms; crop productivity; topsoil colour; presence of a humus layer; soil surface compaction; erosion; slope gradient; surface water, and soil moisture status. Based on this indigenous knowledge, 19 soil samples from nine soil profiles in Bo hamlet were analysed for fertility indicators. Laboratory results confirmed the validity of indigenous knowledge for identifying and classifying local indicators of soil fertility, compared to scientific standards of soil quality.     

喀斯特山区城市地域结构问题及其优化对策——以贵阳市为例

贵州喀斯特发育典型,碳酸盐岩出露面积占全省土地总面积的73%,全省主要城市都坐落在喀斯特地区,城市地域结构问题突出,并业已成为城市可持续发展的障碍。本文以贵阳市为例,在阐述贵阳城市地域结构现状问题的基础上,剖析了贵阳城市地域结构问题产生的原因,并据此提出了贵阳城市地域结构优化的对策措施。     

可溶性岩石旅游资源的类型及开发利用

碳酸盐岩及钙质砂岩、砂砾岩、黄土(胶结不紧固的粉砂岩)等,在适宜的自然地理环境和特定的区域地质构造条件下,不同程度的遭受水溶液(地下水及地表水)化学的溶蚀作用和物理的机械破坏,均可以形成不同类型并具有一定观尝价值的旅游资源。对可溶性岩石旅游资源开发利用的评价,不但要考虑是否达到旅游资源的标准和规模,还必须注重能否体现原始的自然风貌、协调的环境以及良好的效果等因素。     

Geomorphic perspectives on the sterkfontein australopithecine breccias

Breccias in the upper Sterkfontein cave system levels have yielded artifact assemblages as well as Homo and Australopithecus africanus remains. As mapped by the author, this sytem can be subdivided into a northern sector, comprising small, bedding-controlled passageways, and a southern one with large galleries controlled by subvertical fracture zones and partly filled with two generations of external, detrital sediment. A four-stage model describes the development of these deposits. The implications of this study include: (1) The caves formed in one rather than two phases, as a result of structural rather than watertable controls. (2) The lowest strata of both depositional generations, 50–60 m below the hillcrest are probably the oldest. T. C. Partridge's Sterkfontein Formation only includes approximately the upper half of the stratigraphic column recognized here. Deposits underlying those he described are also fossiliferous and probably substantially older than the 2·8+ million year age attributed to the lower units of the Sterkfontein Formation. (3) The Sterkfontein Formation, as defined by Partridge, is a composite stratotype, comprising one surface exposure and another underground, at mid to upper levels in the system. Their stratigraphic relationships are obscure and since the lower boundary of the Formation also is in doubt, erection of a formal stratotype is premature. Deep-lying breccias may ultimately warrant another component, extending the Sterkfontein Formation to the lowest known levels of the cave system.     

The archaeology of World War II karst defences in the Pacific

During World War II, the Japanese military, using either their own or civilian labour, excavated tunnels into the limestone of many Pacific islands and modified natural caves for use as command posts, hospitals, combat positions, storage, and shelter. Civilians also used caves to shelter themselves during the war. This article introduces the archaeology of WWII caves and tunnels referred to collectively as ‘karst defences.’ While karst defences exist across the Pacific, little is known about these sites both historically and archaeologically. Based on a study in Saipan, Commonwealth of the Northern Mariana Islands, and analysis of karst defence construction and function, this article demonstrates that karst defence use extends beyond what has been described in historical accounts. The authors find that the sites in Saipan were used by three different groups of people and identifies distinct Japanese military and civilian sites and evidence of post-war use by the United States.