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Upper Cretaceous (Maastrichtian) charophyte gyrogonites from the Lameta Formation of Jabalpur, Central India: palaeobiogeographic and palaeoecological implications

Khosla A.

Acta Geologica Polonica

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2014

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Vol. 64, no. 3

311--323

EN

A charophyte gyrogonite assemblage consisting of Platychara cf. sahnii, Nemegtichara grambastii and Microchara sp. is reported herein from two localities (Bara Simla Hill and Chui Hill sections) of the Lameta Formation at Jabalpur. The Lameta Formation locally underlying the Deccan traps has been shown to be pedogenically modified alluvial plain deposits containing one of the most extensive dinosaur nesting sites in the world. They are associated with dinosaur bones and freshwater ostracod assemblages that suggest a Late Cretaceous (Maastrichtian) age. This is the first detailed systematic account of charophyte gyrogonites from the Lameta Formation. This charophyte assemblage is compatible with the biostratigraphic attribution provided by the ostracods. From a biogeographic viewpoint, it exhibits considerable similarity to other infratrappean assemblages of the Nand, Dongargaon, and Dhamni-Pavna sections (Maharashtra), and some intertrappean assemblages of Kora in Gujarat, Rangapur in Andhra Pradesh and Gurmatkal in South India. Globally, the genus Microchara is well distributed throughout Eurasia, whereas the genus Platychara occurs richly in the Upper Cretaceous deposits of Europe, Asia, America and Africa. However, at the specific level, Platychara cf. sahnii shows close affinities with charophytes from the Maastrichtian of Iran whilst Nemegtichara grambastii shows distinct affinities with two species of Early Palaeogene deposits of China and Mongolia. The presence of charophyte gyrogonites in the Lameta sediments is attributed to local lacustrine and palustrine conditions within a flood plain environment.

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The disappearance of stonewort populations in lobelia lakes of the Kashubian Lakeland (NW Poland)

Bociąg K., Rekowska E., Banaś K.

Oceanological and Hydrobiological Studies

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2011

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Vol. 40, No.2

30-36

EN

The subject of this work is a comparative analysis of stonewort populations in 5 lobelia lakes of the Kashubian Lakeland based on literature data from the mid-1970s and the authors' own studies from 2006. In the 1970s 15 sites of 7 stonewort species: Chara delicatula, C. fragilis, C. tomentosa, C. rudis, Nitella flexilis, N. opaca and N. mucronata were recorded in the lakes under study. The populations of C. delicatula and N. flexilis occupied the area from 0.3 to 6 m deep and were characterized by 20% cover on average. Thirty years later, in 2006, the presence of only 6 out of 15 stands was confirmed: 3 of C. delicatula and 3 of N. flexilis. Thus, a total of 9 stands (60%) and 5 species (71%) had disappeared completely. The majority of the preserved populations survived in a vestigial form. Population areas of C. delicatula reached a depth of 2 m and their cover did not exceed 5%. Populations of N. flexilis occupied the littoral up to a depth of 7 m and had 10% cover. The disappearance of stoneworts was probably caused by both anthropogenic factors and natural processes.

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Manganese accumulation by two species of Chara

Urbaniak J.

Oceanological and Hydrobiological Studies

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2010

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Vol. 39, No.4

145-154

EN

This paper reports the results of Mn accumulation in two species of green algae: Chara globularis and Chara hispida. The results of laboratory and field experiments show a rapid accumulation of Mn by charophytes and demonstrate that deposit formation on the plant surface in the so-called adsorption phase occurs in Mn accumulation. Both species can be an important factor in Mn circulation in lakes.

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Late Triassic charophytes around the bone-bearing bed at Krasiejów (SW Poland) : palaeoecological and environmental remarks

Zatoń M., Piechota A., Sienkiewicz E.

Acta Geologica Polonica

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2005

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Vol. 55, no. 3

283-293

EN

Thousands of Late Carnian (Late Triassic) charophyte gyrogonites belonging to four species [Stellatochara germanica KOZUR & REINHARDT, Stomochara starozhilovae (KISIELEVSKY), Stenochara kisielevskyi BILAN and Porochara triassica (SAIDAKOVSKY)] occur in the beds around the vertebrate-bearing level at Krasiejów, SW Poland. The abundant and wellpreserved gyrogonites generally attest to fossilization in situ. Information about the habitat of recent charophytes is useful for reconstruction of their past environments. The factors limiting the habitat of modern charophytes suggests that these algae, and other micro- and macrofauna sedimented within the bone-bearing bed, lived in a shallow, freshwater environment (probably lacustrine). Above the bone bed, there is a rapid drop in gyrogonite abundance. This could have been caused by changes in environmental conditions: increase in salinity, or increase in water energy.The preliminary mineralogical data suggest arid to semi-arid climate.