Formation and diagenesis of inorganic Ca?Mg carbonates in the lacustrine environment

Müller, German; Irion, Georg; Förstner, Ulrich

doi:10.1007/bf00637354

Cited by 402 publications

(190 citation statements)

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“…8). This indicates that the environmental conditions within the lake did not change significantly during Unit II and low Mg/Ca ratios (\2) are inferred for the lake water (Müller et al 1972). Both terrestrial and aquatic biomarker dD values show a trend towards enriched values during this time interval.…”

Section: Mineral Compositionmentioning

confidence: 78%

“…It is less soluble than carbonate minerals aragonite, calcite and high-Mg-calcite. Occurrence of this CaCO 3 form could imply an increased water supply, as melt water from surrounding glaciers, or as runoff from higher precipitation, leading to dilution of the other minerals (Müller et al 1972). Alternatively, as proposed by Bayon et al (2007), low-Mg calcite may be of biogenic origin, formed by infaunal organisms such as ostracodes, which are abundant during this interval.…”

Section: Mineral Compositionmentioning

confidence: 91%

“…In addition, precipitation of high-Mg calcite in the lower part of the core section implies elevated Mg/Ca ratios in the lake water (2-12) associated with higher salinities, indicating lake shrinkage (Fig. 8) (Müller et al 1972). Lower lake levels are also indicated by elevated Mn concentrations that point to oxidation of the hypolimnion and effective water column mixing (Yancheva et al 2007).…”

Section: Mineral Compositionmentioning

confidence: 99%

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A multi-proxy approach to reconstruct hydrological changes and Holocene climate development of Nam Co, Central Tibet

et al. 2009

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Holocene lake level fluctuations were reconstructed from a 2.7-m sediment core from Nam Co, Central Tibet, China dating to [7.2 cal ka BP. Results were compared to existing lake records from the Tibetan Plateau to infer variations in the strength of the Asian Monsoon. Geomorphological features in the Nam Co catchment, such as beach ridges and lake terraces, indicate high lake stands during the late Glacial. A major low stand is suggested for the Last Glacial Maximum (LGM). Sands and sandy silts at the base of the core are transgressive facies, with material transported by melt water and deposited under rising lake level conditions that followed the LGM low stand. Variations in grain size, major elements, biomarker stable isotopes and minerals in the core suggest a climate evolution reflected in at least five depositional units and subunits. Sediments in Unit I (*7.2 to *5.4 cal ka BP) were deposited at highest lake levels. Large amounts of allogenic minerals and allochthonous organic matter suggest high precipitation and melt water input, implying positive water balance. Increasing aquatic productivity points to favourable environmental conditions. Unit II (*5.4 to *4.0 cal ka BP) marks a transition between favourable, stable hydrological conditions and lake level decrease. Lower lake levels were a consequence of drier climate with less monsoonal precipitation, higher evaporation rates, and increased moisture recycling in the catchment. Unit III (*4.0 to *1.4 cal ka BP) reflects the driest periods recorded, at *3.7 cal ka BP and 1.6 cal ka BP. Lake shrinkage and salinization was interrupted as suggested by the deposition of Unit IV (*1.4 to *0.8 cal ka BP), when increased precipitation and runoff that might be related to the Medieval Warm Period, led to a stable, but still low lake level. Unit V (800 cal years BPpresent) is characterized by progressive lake shrinkage due to intense evaporation. Paleolimnol (2010) 43:625-648 DOI 10.1007 data indicate the lake level is rising. Comparison of the Nam Co record with other lake records from the Tibetan Plateau suggests general agreement with the broader picture of Holocene environmental evolution. The timing of dry and wet climate conditions at lake sites across Tibet indicates a gradually decreasing influence of the southern monsoon during the Holocene, from NW to SE. Nevertheless, further research is needed to improve our understanding of Holocene spatio-temporal hydrological variations across the Asian continent.

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Section: Mineral Compositionmentioning

confidence: 78%

Section: Mineral Compositionmentioning

confidence: 91%

Section: Mineral Compositionmentioning

confidence: 99%

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A multi-proxy approach to reconstruct hydrological changes and Holocene climate development of Nam Co, Central Tibet

et al. 2009

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“…[9] In lake environments, carbonate phases are controlled by salinities and Mg/Ca ratios of lake water [Müller et al, 1972]. As salinity increases, low-Mg calcite precipitates first, followed by high-Mg calcite, aragonite, and finally dolomite.…”

Section: Mid-holocene Drying Inferred From Dolomite Precipitation Andmentioning

confidence: 99%

Timing and spatial distribution of mid‐Holocene drying over northern China: Response to a southeastward retreat of the East Asian Monsoon

Jiang

Liu

2007

J. Geophys. Res.

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[1] To determine the timing and spatial distribution of mid-Holocene drying over northern China, the mineralogical and oxygen isotopic composition of authigenic carbonate from a closed lake at Bayanchagan, southern Inner Mongolia, were measured. Further analysis and synthesis of the spatial geological data were performed. Results from Lake Bayanchagan show a significant drying at 6000 calendar years (cal years) B.P., indicated by dolomite precipitation and a striking rise in d 18 O values. The synthesis of spatial data reveals a zonal distribution for timing of drying over northern China in the mid-Holocene, which began at 9000-7000 cal years B.P. in deserts of north-central China. At 7000-5500 cal years B.P., drying extended into the desert-steppe transitional zone and at $4500 cal years B.P. into northeastern and south-central China. This pattern indicates that the east Asian summer monsoon has significantly retreated southeastward since the mid-Holocene, which may be related to orbitally induced Northern Hemisphere insolation changes. A retreat of $400-550 km is inferred for the front of the summer monsoon from 6500 to 4500 cal years B.P.

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“…Likewise, the occurrence of other Mg-bearing carbonates (magnesite and protodolomite) support this mid to late Holocene enrichment in magnesium. Based mainly on observational evidence provided by Müller et al (1972), Eugster and Kelts (1983), and others, it is generally held that (1) Mg-calcite forms in saturated solutions having Mg/Ca ratios of about 1-5, (2) aragonite in solutions with ratios of 5-50, (3) dolomite (protodolomite) in 50-100, and (4) magnesite in solutions with ratios >100. In addition to elevated Mg/Ca ratios, protodolomite also indicates that carbonate alkalinity levels were, at least periodically, very high in the lake (Fig.…”

Section: +mentioning

confidence: 99%

Paleolimnology of Lake Manitoba: the Lithostratigraphic Evidence

Teller

2004

gpq

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Lake Manitoba, the largest lake in the prairie region of North America, is one of the most intensively studied lacustrine basins in western Canada. New AMS 14C dating, together with mineralogical, geochemical, and lithostratigraphic analyses of the 14-m-thick, offshore sediment sequence, document a complex Holocene history in which water levels and limnological conditions were controlled by the interplay of changing climate, variable river and groundwater inflow, and differential isostatic rebound. Varves, ice-rafted debris, and clast-rich laminated sediment record deposition in the lake when the basin was part of proglacial Lake Agassiz. As Agassiz retreated northward, Lake Manitoba became isolated by about 8500 14C yrs BP, and for the next 800 years was characterized by mainly shallow water to dry conditions. Deeper and more stable water conditions returned to the Lake Manitoba basin by 7700 14C yrs BP probably due to the damming effect of differential isostatic rebound and decreasing aridity. For the next 3000 years, relatively stable lake levels and water compositions were maintained, reflecting a delicate balance between differential isostatic rebound, climate, inflow of the Assiniboine River, and groundwater contribution. At ~4500 14C yrs BP the Assiniboine River was rerouted to its present easterly path, by-passing Lake Manitoba, and resulting in loss of a significant component of the lake’s hydrologic budget. Water levels dropped and the offshore sediments were once again subaerially exposed. By 3700 14C yrs BP, a cooler and wetter climate, together with continued southward transgression of water, compensated for the loss of fluvial input, resulting in reflooding of the basin. By about 2000 years ago the lake had evolved from a shallow, saline, and alkaline pool to its present depth and extent.Le lac Manitoba, le plus grand lac des Grandes Plaines de l’Amérique du Nord, est l’un des bassins lacustres le plus intensément étudiés de l’Ouest du Canada. De nouvelles dates 14C SMA, ainsi que des analyses minéralogiques, géochimiques et lithostratigraphiques de la séquence sédimentaire de 24 m d’épaisseur au large du rivage témoignent d’une évolution complexe du lac, à l’Holocène. Au cours de cette période, les niveaux lacustres et les conditions limnologiques ont été influencés par les effets combinés des changements climatiques, de la variation des apports d’eaux lacustre et souterraine et d’un relèvement isostatique différentiel. Les varves, les débris glaciels et les sédiments en lamines riches en éléments détritiques ont constitué l’apport sédimentaire au lac lorsque le bassin faisait partie du Lac glaciaire Agassiz. Après la vidange du lac glaciaire vers le nord, le lac Manitoba a été isolé vers 8500 BP ; pendant les 800 années suivantes, le lac était caractérisé par des eaux peu profondes et un climat sec. Des eaux plus profondes et plus stables ont caractérisé le lac vers 7700 BP, probablement en raison de l’endiguement qu’a entraîné le relèvement isostatique différentiel et une moins grande aridité. Pe...

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Formation and diagenesis of inorganic Ca?Mg carbonates in the lacustrine environment

Cited by 402 publications

References 8 publications

A multi-proxy approach to reconstruct hydrological changes and Holocene climate development of Nam Co, Central Tibet

A multi-proxy approach to reconstruct hydrological changes and Holocene climate development of Nam Co, Central Tibet

Timing and spatial distribution of mid‐Holocene drying over northern China: Response to a southeastward retreat of the East Asian Monsoon

Paleolimnology of Lake Manitoba: the Lithostratigraphic Evidence

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