ABSTRACT
Carbonate geothermometry is a fundamental tool for quantitative assessment of the geothermal and geochemical evolution of diagenetic and hydrothermal systems, but it remains difficult to obtain accurate and precise formation temperatures of low-temperature calcite samples (below ~ 40 to 60 °C). Here, we apply three geothermometry methods (∆47-thermometry, nucleation-assisted fluid inclusion microthermometry-hereafter NA-FIM-and oxygen isotope thermometry) to slow-growing subaqueous calcite spar samples to cross-validate these methods down to 10 °C. Temperatures derived by NA-FIM and Δ47-thermometry agree within the 95% confidence interval, except for one sample. Regression analyses suggest that the real uncertainty of ∆47-thermometry exceeds the 1 SE analytical uncertainty and is around ± 6.6 °C for calcite spar that formed at 10-50 °C. The application of δ18O thermometry was limited to a few samples that contained sufficient primary fluid inclusions. It yielded broadly consistent results for two samples with two other geothermometers, and showed higher temperature for the third spar. We also found that calcite with steep rhombohedral morphologies is characteristic of low temperatures (11-13 °C), whereas blunt rhombohedra prevail in the 10-29 °C domain, and the scalenohedral habit dominates > 30 °C. This suggests that the calcite crystal morphology can be used to qualitatively distinguish between low- and higher-temperature calcite.
ABSTRACT
Alteration of conventional carbonate stable isotopes (δ18O, δ13C) in cave walls has been shown to be a useful tool to identify cave formation driven by deep-seated processes, i.e., hypogene karstification. If combined with a prior information on the paleowater stable isotope composition, further insights can be obtained on the temperature and the source of the paleowater. Clumped isotope composition (Δ47) of carbonates is an independent measurement of temperature, and if combined with the conventional stable isotopes, can provide information on the paleowater stable isotope composition. On the example of Provalata Cave (N. Macedonia), we apply for the first time, both conventional and clumped stable isotope analysis, and identify two different isotope alteration trends, reflecting two distinct hydrothermal events: an older, hotter one, where isotope alteration was likely related to isotope diffusion, lowering the δ18O values of the carbonate; and a younger one, related to the cave formation by low-temperature CO2-rich thermal waters, with dissolution-reprecipitation as the alteration mechanism, causing decrease in δ18O values, and unexpected increase in δ13C values. The findings are further corroborated by additional insight from optical petrography and cathodoluminescence microscopy, as well as fluid inclusion analysis of secondary calcite crystals related to the cave forming phase.
ABSTRACT
OBJECTIVE: To describe the first case of IVF pregnancy in a pancreas-kidney recipient. DESIGN: Case report. SETTING: Reproductive Medicine Department, Hôpital Edouard Herriot, Lyon, France. INTERVENTION(S): In vitro fertilization in a pancreas-kidney recipient. PATIENT(S): A 39 year-old nulliparous woman, with primary infertility and a history of pancreas-kidney transplant at 29 years of age. MAIN OUTCOME MEASURE(S): Multidisciplinary agreement for the couple to be managed by IVF. Follow-up of pregnancy and delivery. RESULT(S): Singleton IVF pregnancy in a pancreas-kidney recipient, maintained up to 34 weeks. Cesarian delivery ahead of labor. No severe maternal or fetal complications. Live birth. Normal postpartum renal function and glycemia. CONCLUSION(S): An IVF pregnancy is feasible in a pancreas-kidney recipient. Such treatment should follow agreement by all the medical teams following the patient. Pregnancy in a pancreas-kidney recipient is at-risk, requiring close monitoring.
