Palaeogene lacustrine record in Mallorca (NW Mediterranean, Spain): depositional, palaeogeographic and palaeoclimatic implications for the ancient southeastern Iberian margin
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Paleogene
Tufa
Tethys Ocean
Calcareous deposits known as tufa or travertine contain biogenic carbon and are a potential source of geochronologic information. Many dated samples from Karstic regions in Yugoslavia proved that 14 C analyses of tufa can provide reliable data reflecting climatic conditions in the past. Systematic dating of tufa samples revealed two distinct groups of deposits: recent tufa deposits, with a sharp age limit of ∼6000 ± 500 years BP, and old tufa deposits with 14 C age ranges from 25,000 ± 2300 years BP to the lowest limit of our 14 C dating system (∼37,000 years). A histogram based on the initial activity A O = 0.85 shows the age distribution of randomly sampled tufas vs sample frequency. A time gap between ∼6000 BP and ∼23,000 BP is evident, reflecting cooler climatic conditions. The start of peat deposition is coincident with that of tufa growth in the Holocene. Paleoclimatic implications of tufa growth periods obtained by 14 C dating are as follows: climatic conditions that favor tufa formation at least in karstic regions, are very stringent. Therefore, climatic conditions, such as mean annual temperature and humidity, as well as hydrologic and vegetational conditions, must have been very similar in periods of tufa growth. While recent tufa deposits are coincident with the warm Holocene period, old tufa can be associated with warm interstadials in the Würm.
Tufa
Absolute dating
Stadial
Geochronology
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At the Miette Hot Springs site, relict tufa stretches for nearly 500 m along the west side of Sulphur Creek valley and rises up to 30 m above the valley floor. The tufa, composed of low-Mg calcite, precipitated from waters discharged from a line of perched springs. 14 C dating of bone material embedded in the tufa indicates that tufa precipitation took place between ~4500 and 2500 years BP under cool and moist climatic conditions. The spring biota was dominated by filamentous microbes (mainly Phormidium and Oscillatoria), with fewer diatoms (including Cymbella), testate protozoans (including Quadrulella), ostracodes (including Darwinula, Heterocypris, Cadonia, and Cyclocypris), and various bryophytes. The ecological preferences of these microbes indicate that the spring water had near-neutral pH, was Ca, HCO 3 , and H 2 SSO 4 rich, and emerged at 5065 °C. Landslides disrupted the west wall of Sulphur Creek valley during and after tufa growth. The relict tufa is divided into six morphotypes that reflect variations in water flow down the steep and rugged flow path. Domal tufa is located around the spring vents, roll-over tufa developed where water flowed over sharp lips or structural barricades, vertical tufa formed where calcite was precipitate from water flowing down steep to vertical inclines, flat-banded tufa reflects precipitation on a gentle slope, and wedge-shaped tufa formed where more rapid downslope calcite precipitation caused a progressive decrease in slope. The tufa contains stromatolitic facies (including streamer, porous laminar, dense laminar) and nonstromatolitic facies (bedded, crenulated) that reflect variations in the biology, water temperature, and style of flow of different parts of the spring flow path.
Tufa
Algal mat
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Tufa accumulations from the Gostilje River Basin and the Sopotnica River Basin in SW Serbia are represented by both active and fossil tufa precipitates. The aim of this study is to distinguish and describe different tufa facies and to determine the environmental conditions, based on stable isotope data. We also compare our analysis with other tufa deposits in Europe. Four facies are distinguished: moss tufa, algal tufa, stromatolitic laminated tufa, and phytoclastic tufa. The dominant constituent of all tufa samples is low Mg-calcite, whereas the presence of sylvite is noted in two samples from the Gostilje River Basin. The δ18O values range from −9.07‰ to −10.79‰ (mean value: −9.81‰), while the δ13C values range from −6.50‰ to −10.34‰ (mean values −9.01‰). The stable isotope values (δ13C and δ18O) indicate that these tufa deposits were precipitated from cold, ambient water supported by CO2 of an atmospheric origin. We emphasize that this is the first data about stable isotope analyses of tufa deposits from Serbia.
Tufa
δ18O
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Tufa
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Data from cores,well logs,paleontology and seismic survey have been comprehensively studied in this paper to reveal the evolutionary history of the Oujiang Sag in the Paleogene.Sedimentary facies,such as deltaic,fan deltaic,lacustrine,coastal and shallow marine facies were recognized.The tectonic evolution and filling history of this region in the Paleogene can be divided into three stages.In the early Paleocene,the prototype of the sag was formed by faulting and filled with deltaic-lacustrine-fan deltaic depositional systems.During the stage from the middle to late Paleocene,with the gradually weakening of the faulting activity,deltaic-coastal-shallow marine-fan deltaic depositional systems were developed.By the end of the late Paleocene,deltaic deposition prevailed due to the expansion of the Fujian uplift.In the Eocene,deltaic-coastal-shallow marine depositional systems were well developed owing to the depression of the sag.
Paleogene
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Tufa
Stromatolite
δ18O
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The Late Cretaceous to early Paleogene shallow marine carbonates in the Tethys Himalaya in southern Tibet are important historical witnesses of the evolution of the northern Indian continental margin, the closure of the Neo-Tethys Ocean and the initial India-Asia continental collision. The polarizing microscope was used to collect polarizing microphotographs of carbonate or mixed carbonate-siliciclastic rocks from late Cretaceous Bolinxiala Formation, Jiubao Formation, Zhepure Shanpo Formation and early Paleogene Zongpu Formation in the Tethys Himalaya of southern Tibet. The photomicrograph dataset includes 445 carbonate or mixed carbonate-siliciclastic samples from 5 stratigraphic sections. The location, stratigraphic age, petrographic characteristics of these samples are described in detail. It is expected to provide basic geological information for the reconstruction of sedimentary environment before and after the initial Indi-Asia continental collision and the timing of initial India-Asia continental collision.
Paleogene
Siliciclastic
Tethys Ocean
Carbonate platform
Continental Margin
continental collision
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Tufa
Trace element
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