Crystallization pathways, fabrics and the capture of climate proxies in speleothems: Examples from the tropics

Frisia, Silvia; Borsato, Andrea; Hartland, Adam; Faraji, Mohammadali; Demény, Attila; Drysdale, Russell N.; Marjo, Christopher E.

doi:10.1016/j.quascirev.2022.107833

Cited by 12 publications

(9 citation statements)

References 104 publications

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“…Dashed vertical lines for each record display event beginning and end according to individual study criteria, and bracket on event initiation (b-d) represent the average approximate error for the respective record. rates which create macro (intercrystalline) and micro-scale (intracrystalline) porosity within the columnar calcite fabric (Faraji et al, 2022;Frisia et al, 2022). The fluorescence as observed in thin section is usually stimulated by a high concentration in humic acids (Sliwinski & Stoll, 2021) and is indicative of high flushing of organic matter from the soil during high rainfall/infiltration events.…”

Section: Resultsmentioning

confidence: 99%

“…TM‐17 calcite fabric as observed in optical microscopy vary between compact columnar translucent calcite (Cc) and porous opaque calcite (Cp) layers (Frisia, 2015) (Figure 5b). Compact layers are usually indicative of constant and slow drip rates (dry periods), whereas porous fabrics are associated with higher and variable drip rates which create macro (intercrystalline) and micro‐scale (intracrystalline) porosity within the columnar calcite fabric (Faraji et al., 2022; Frisia et al., 2022). The fluorescence as observed in thin section is usually stimulated by a high concentration in humic acids (Sliwinski & Stoll, 2021) and is indicative of high flushing of organic matter from the soil during high rainfall/infiltration events.…”

Section: Discussionmentioning

confidence: 99%

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High‐Resolution, Multiproxy Speleothem Record of the 8.2 ka Event From Mainland Southeast Asia

Wood,

Johnson,

Lewis

et al. 2023

Paleoceanog and Paleoclimatol

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The 8.2 ka event is the most significant global climate anomaly of the Holocene epoch, but a lack of records from Mainland Southeast Asia (MSEA) currently limits our understanding of the spatial and temporal extent of the climate response. A newly developed speleothem record from Tham Doun Mai Cave, Northern Laos provides the first high‐resolution record of this event in MSEA. Our multiproxy record (δ18O, δ13C, Mg/Ca, Sr/Ca, and petrographic data), anchored in time by 9 U‐Th ages, reveals a significant reduction in local rainfall amount and weakening of the monsoon at the event onset at ∼8.29 ± 0.03 ka BP. This response lasts for a minimum of ∼170 years, similar to event length estimates from other speleothem δ18O monsoon records. Interestingly, however, our δ13C and Mg/Ca data, proxies for local hydrology, show that abrupt changes to local rainfall amounts began decades earlier (∼70 years) than registered in the δ18O. Moreover, the δ13C and Mg/Ca also show that reductions in rainfall continued for at least ∼200 years longer than the weakening of the monsoon inferred from the δ18O. Our interpretations suggest that drier conditions brought on by the 8.2 ka event in MSEA were felt beyond the temporal boundaries defined by δ18O‐inferred monsoon intensity, and an initial wet period (or precursor event) may have preceded the local drying. Most existing Asian Monsoon proxy records of the 8.2 ka event may lack the resolution and/or multiproxy information necessary to establish local and regional hydrological sensitivity to abrupt climate change.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

High‐Resolution, Multiproxy Speleothem Record of the 8.2 ka Event From Mainland Southeast Asia

Wood,

Johnson,

Lewis

et al. 2023

Paleoceanog and Paleoclimatol

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“…2 and 3), with the laminated specimens being characterised by complex fabric-type relationships. Consequently, in the descriptions provided in Table 2, fabrics have been grouped according to the most prominent type classified by Frisia (2015) and revised for the columnar types by Frisia et al (2022). The following groups have been defined: Fabric group 1—typical of LC1, PN5, PN6, CC4, FS04, FM13, and MO1—consists of predominant columnar compact, elongated columnar, and columnar open (FM13 and MO1; Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Speleothem fabrics were observed, when feasible, for 30-μm-thick thin sections, using a Zeiss Axioskop petrographic microscope at the Museo delle Scienze (MUSE, Italy), in both plane-polarized and cross-polarized light modes. Fabrics were classified according to conceptual criteria reported in Frisia (2015) and Frisia et al (2022). For samples for which not enough material was available to obtain thin sections, fabrics were determined from high-resolution scans of polished specimens (Table 2).…”

Section: Methodsmentioning

confidence: 99%

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The incorporation of chlorine and cosmogenic ³⁶Cl into speleothem carbonate

Johnston,

Frisia,

Borsato

et al. 2023

Quat. res.

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Cave carbonate mineral deposits (speleothems) contain trace elements that are intensively investigated for their significance as palaeoclimate and environmental proxies. However, chlorine, which is abundant in marine and meteoric waters, has been overlooked as a potential palaeo-proxy, while cosmogenic 36Cl could, in principle, provide a solar irradiance proxy. Here, total Cl concentrations analysed from various speleothems were low (3–14 mg/kg), with variations linked to crystal fabrics. High-resolution synchrotron radiation micro X-ray fluorescence (μ-XRF) trace element mapping showed Cl often associated with Na, Si, and Al. We propose that speleothems incorporate Cl in two fractions: (1) water soluble (e.g., fluid inclusions) and (2) water insoluble and strongly bound (e.g., associated with detrital particulates). However, disparities indicated that alternate unidentified mechanisms for Cl incorporation were present, raising important questions regarding incorporation of many trace elements into speleothems. Our first measurements of 36Cl/Cl ratios in speleothems required large samples due to low Cl concentrations, limiting the potential of 36Cl as a solar irradiance proxy. Critically, our findings highlight a knowledge gap into how Cl and other trace elements are incorporated into speleothems, how the incorporation mechanisms and final elemental concentrations are related to speleothem fabrics, and the significance this may have for how trace elements in speleothems are interpreted as palaeoclimate proxies.

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Phreatic overgrowths on speleothems (POS) from the Mallorca caves: Morphology, mineralogy, and crystal fabric classification

Entrena,

Auqué,

Gimeno

et al. 2024

Earth Surf Processes Landf

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Phreatic overgrowths on speleothems (POS) are unique precipitates that are found in a small number of coastal caves around the world, like those in the Mallorca Island. Their growth is directly related to the water level of the brackish lakes connected to the sea characteristic of these caves and, therefore, they can be very reliable indicators of past sea levels. The study presented here characterizes and classifies an important number of POS samples collected in the coastal caves of Mallorca. The characterization includes not only the observations made on 117 handheld samples and on 102 thin sections from POS, but also the study of their mineralogy and their location in the caves. This study has provided the basis for a systematization of all these characteristics, some of which are reported here for the first time in POS samples. The results indicate that (1) most of the POS precipitate on stalactites, (2) calcite POS show branched internal and external texture and their most common crystal fabric is mosaic calcite and (3) aragonite POS show globular external texture and fan‐shaped internal texture, and their principal crystal fabric is needle‐like. All the aragonitic samples have been found above or at the same heights as the current sea level, which indicates that they have probably formed during warmer climates. The calcite POS have been found at heights above and below the present sea level and are interpreted as to have formed during cold and rainy periods. The systematization proposed in this paper could be applied and checked in other POS worldwide. Additionally, the combination of these results with the information obtained from studies on the present precipitation of these phreatic speleothems in some Mallorca caves has provided an insight on their formation conditions which will enlarge the utility of these speleothems as palaeoenvironmental indicators.

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Crystallization pathways, fabrics and the capture of climate proxies in speleothems: Examples from the tropics

Cited by 12 publications

References 104 publications

High‐Resolution, Multiproxy Speleothem Record of the 8.2 ka Event From Mainland Southeast Asia

High‐Resolution, Multiproxy Speleothem Record of the 8.2 ka Event From Mainland Southeast Asia

The incorporation of chlorine and cosmogenic ³⁶Cl into speleothem carbonate

Phreatic overgrowths on speleothems (POS) from the Mallorca caves: Morphology, mineralogy, and crystal fabric classification

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Crystallization pathways, fabrics and the capture of climate proxies in speleothems: Examples from the tropics

Cited by 12 publications

References 104 publications

High‐Resolution, Multiproxy Speleothem Record of the 8.2 ka Event From Mainland Southeast Asia

High‐Resolution, Multiproxy Speleothem Record of the 8.2 ka Event From Mainland Southeast Asia

The incorporation of chlorine and cosmogenic 36Cl into speleothem carbonate

Phreatic overgrowths on speleothems (POS) from the Mallorca caves: Morphology, mineralogy, and crystal fabric classification

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The incorporation of chlorine and cosmogenic ³⁶Cl into speleothem carbonate