Topic
Frostwork
About: Frostwork is a research topic. Over the lifetime, 5 publications have been published within this topic receiving 33 citations.
Papers
TL;DR: A drapery speleothem (DRA-1) from Castanar Cave in Spain was subjected to a detailed petrographical study in order to identify its primary and diagenetic features as mentioned in this paper.
Abstract: A drapery speleothem (DRA-1) from Castanar Cave in Spain was subjected to a detailed petrographical study in order to identify its primary and diagenetic features. The drapery’s present day characteristics are the result of the combined effects of the primary and diagenetic processes that DRA-1 underwent. Its primary minerals are calcite, aragonite and huntite. Calcite is the main constituent of the speleothem, whereas aragonite forms as frostwork over the calcite. Huntite is the main mineral of moonmilk which covers the tips of aragonite. These primary minerals have undergone a set of diagenetic processes, which include: 1) partial dissolution or corrosion that produces the formation of powdery matt-white coatings on the surface of the speleothem. These are seen under the microscope as dark and highly porous microcrystalline aggregates; 2) total dissolution produces pores of few cm2 in size; 3) calcitization and dolomitization of aragonite result in the thickening and lost of shine of the aragonite fibres. Microscopically, calcitization is seen as rhombohedral crystals which cover and replace aragonite forming mosaics that preserve relics of aragonite precursor. Dolomitization results in the formation of microcrystalline rounded aggregates over aragonite fibres. These aggregates are formed by dolomite crystals of around 1 μm size. The sequence of diagenetic processes follows two main pathways. Pathway 1 is driven by the increase of saturation degree and Mg/Ca ratio of the karstic waters and is visible in the NW side of the drapery. This sequence of processes includes: 1) aragonite and huntite primary precipitation and 2) dolomitization. Pathway 2 is driven by a decrease in the degree of saturation of calcite and aragonite and Mg/Ca ratio of the cave waters, and it is observed in the SE side of the drapery. The diagenetic processes of the second pathway include: 1) calcitization of aragonite; 2) incomplete dissolution (micritization) of both aragonite and calcite; 3) total dissolution. This study highlights the importance of diagenetic processes on speleothems and their complexity. The correct interpretation of these processes is crucial for the understanding of possible changes in the chemistry of waters, temperature, or pCO2 and so is critical to the correct interpretation of the paleoenvironmental significance of speleothems.
27 citations
1 Jan 2006
TL;DR: Ochtina Aragonite Cave as discussed by the authors is a 300 m long cryptokarstic cavity with simple linear sections linked to a geometrically irregular spongework labyrinth.
Abstract: Ochtina Aragonite Cave is a 300 m long cryptokarstic cavity with simple linear sections linked to a geometrically irregular spongework labyrinth. The limestones, partly metasomatically altered to ankerite and siderite, occur as lenses in insoluble rocks. Oxygen-enriched meteoric water seeping along the faults caused siderite/ankerite weathering and transformation to ochres that were later removed by mechanical erosion. Corrosion was enhanced by sulphide weathering of gangue minerals and by carbon dioxide released from decomposition of siderite/ankerite. The initial phreatic speleogens, older than 780 ka, were created by dissolution in density-derived convectional cellular circulation conditions of very slow flow. Thermohaline convection cells operating in the flooded cave might also have influenced its morphology. Later vadose corrosional events have altered the original form to a large extent. Water levels have fluctuated many times during its history as the cave filled during wet periods and then slowly drained. Mn-rich loams with Ni-bearing asbolane and birnessite were formed by microbial precipitation in the ponds remaining after the floods. Allophane was produced in the acidic environment of sulphide weathering. La-Nd-phosphate and REE enriched Mn-oxide precipitated on geochemical barriers in the asbolane layers. Ochres containing about 50 wt.% of water influence the cave microclimate and the precipitation of secondary aragonite. An oldest aragonite generation is preserved as corroded relics in ceiling niches truncated by corrosional bevels. TIMS and alpha counting U series dating has yielded ages of about 500-450 and 138-121 ka, indicating that there have been several episodes of deposition, occurring during Quaternary warm periods (Elsterian 1/2, Eemian). Spiral and acicular forms representing a second generation began to be deposited in Late Glacial (14 ka – Allerod) times. The youngest aragonite, frostwork, continues to be deposited today. Both of the younger generations have similar isotopic compositions, indicating that they originated in conditions very similar, or identical, to those found at present in the cave.
6 citations
1 Jan 2003
TL;DR: Arab et al. as discussed by the authors presented a map of the As Sulb karst region, the area with the highest known concentration of limestone and lava caves in Saudi Arabia.
Abstract: 1 ARABIC ABSTRACT 2 INTRODUCTION 3 GENERAL CHARACTERISTICS OF CAVES IN SAUDI ARABIA 3 THE CAVES OF THE AS SULB PLATEAU 4 FRIENDLY CAVE 6 SURPRISE CAVE 8 KAHF AL RUTUWBAH/GECKO CAVE 13 THE NATURAL COOLER OF MURUBBEH CAVE 15 CAVES OF THE FAR NORTH 23 LAVA-TUBE CAVES 23 PROBLEMS OF DEPLETION AND SAFEGUARD OF DESERT CAVES 24 SAUDI SOCIETY AND SPELEOLOGICAL TOURISM 26 THE DEVELOPMENT OF A SHOW CAVE IN A DESERT 26 PROCEDURES REQUIRED FOR TOURIST CAVE DEVELOPMENT 28 TIME TABLE FOR TOURIST CAVE DEVELOPMENT IN THE KINGDOM 28 CALCULATING COSTS 29 POTENTIAL TRAFFIC AND INCOME FROM TOURIST CAVES IN THE KINGDOM .....30 RELATION OF TOURIST CAVE DEVELOPMENT TO AQUIFER PROTECTION 30 RELATION OF TOURIST CAVE DEVELOPMENT TO CAVE AND KARST PROTECTION 31 FINAL REMARKS 31 ACKNOWLEDGMENTS 31 REFERENCES 31 APPENDICES ILLUSTRATIONS FIGURES Figure 1. Geological map of Saudi Arabia showing the As Sulb karst region, the area with the highest known concentration of limestone and lava caves. 4 Figure 2. A tray speleothem found in Surprise Cave, featuring clusters of popcorn on grape coralloids and frostwork resting on a flat, horizontal tray-like surface 5 Figure 3. Map of Friendly Cave. 6 Figure 4. The entrance to Friendly Cave is large enough for the insertion of a circular staircase...6 Figure 5. The strategic use of lamps in this picture demonstrates how proper lighting can make Friendly Cave very attractive for tourism. 7
2 citations
1 Jan 2012
TL;DR: Helictites are tubular speleothems that are found growing from cave walls and floors with no particular orientation with respect to gravity, usually composed of the mineral calcite as mentioned in this paper.
Abstract: Helictites are tubular speleothems that are found growing from cave walls and floors with no particular orientation with respect to gravity. They are generally curved, contain a central canal, and are usually composed of the mineral calcite. A subaqueous variety of helictite has been found in Lechuguilla Cave, growing downward in pools. Frostwork (or anthodites) are sprays of crystals, usually aragonite, that do not contain central canals. Shields are flat disc-shaped speleothems attached to cave walls at one edge. They grow around the perimeter of the disc by water fed through a medial crack. Helictite bushes are a rare, branching speleothem, fractions of a meter in height, presently of unknown genesis.
1 citations
TL;DR: In this article, a V-shaped shallow chamber measuring 110 × 40 m was discovered serendipitously when an adit was driven into the hill in connection with iron ore mining.
Abstract: An unusual cave is located in the hills southeast of the town of Thabazimbi in the Limpopo Province. This cave, a V-shaped shallow chamber measuring 110 × 40 m, was discovered serendipitously when an adit was driven into the hill in connection with iron ore mining. It has no natural entry point and no externally derived sediment is found in it. It is situated within the upper part of the Malmani Subgroup and although it was formed as a solution cavity, requiring a phreatic environment, dripwater flow must subsequently have been low: no large speleothems (stalactites, stalagmites or flowstones) were ever formed in the cave. Instead, evaporation produced crystallictitic frostwork bushes consisting of aragonite (metastably grown due to enhanced Mg-content) which were in part redissolved followed by the secondary formation of calcite corals and encrustations. This sequence of events can be understood in the context of an enclosed cave where the CO2 content of the air is high.
U/Th disequilibrium dating of two aragonite frostwork samples from the cave yielded two very different ages (155.1 ± 7.4 and 67.2 ± 3.4 ka), thus showing that the formation of this type of frostwork occurred (probably episodically) over a long period of time. The two dates broadly coincide with the waning stages of periods of low total inorganic carbon (TIC) as well as high clastic input in the Tshwaing crater sediment record, both indicating enhanced rainfall at that locality. The younger age coincides with a brief negative excursion in chlorine content and a positive potassium anomaly at Tshwaing, both also indicating high rainfall. However, both ages are also coeval with glacial maxima, thus underlining earlier observations from the Tshwaing record that in southern Africa, wet periods are not necessarily coeval with northern hemisphere interglacials.
1 citations
Performance Metrics
| Year | Papers |
|---|---|
| 2018 | 1 |
| 2012 | 2 |
| 2006 | 1 |
| 2003 | 1 |