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104 ADVANCES IN PALAEOICHTHYOLOGY enabled us to come to the conclusion that two oryctocoenoses most probably originated from the same palaeobiocoenosis, differing mainly in the character of transportation and burial conditions (Lukševičs 1992). No spores or conodonts have been found in the Ketleri Formation, therefore the age of the formation (corresponding to the expansa conodont zone; Esin et al. 2000) could be judged only from its position above the Žagare Formation. Dolomite of the Žagare Formation yeilds conodonts providing the possibility to correlate it with the interval from marginifera to postera Zones (Esin et al. 2000). The underlying Švete Formation (in Lithuania; corresponds to the Sniķere and Tērvete formations in Latvia) contains conodonts of the postera Zone (Middle – Lower styriacus Zone of the previous conodont zonation; Žeiba and Valiukevičius 1972). Results Sedimentology. The detailed studies of the outcrop of the Ketleri Formation on the left bank of Ciecere River, opposite the former Pavāri hamlet, show a sandstone body with a total thickness of more than 3 m, most of which is only visible after major excavation and cleaning of the wall-shaped outcrop. The lithology of the section is shown in Figure 2. Very fine-grained to fine-grained white or light yellow almost unconsolidated quartzose sandstone dominates the sequence. An erosional surface, interpreted here as a relatively shallow (about 0,5 m deep) and at least 8 m wide erosional channel, is traced in the lower part of the section (Fig. 3). Measurements of dip suggest that a stream flowing from NNE to SSW formed this erosional channel. The same direction is characteristic for the whole cross-stratified deposits of the Ketleri Formation (Savvaitova 1974). In accordance with the results from a grain-size analysis (Fig. 4), the erosional channel was filled by a well-sorted fine-grained sand in the lower part (Fig. 3, layer 6, sample 6A) and more silty moderately sorted material in the upper part (sample 6), showing fining upward sequence which contains numerous vertebrate remains in the bottom part of infilling, but no admixture of dispersed clay particles. Vertebrate remains are unevenly spread in the rocks, mainly forming accumulations in the bottom part of the sandstone infilling of the erosional channel. Accumulations were found also below a thin clay layer (number 5 in Fig. 3) underlying the erosional surface. Large-scale cross-bedding is characteristic for the lower and middle part of the channel infilling. Small-scale current(?) ripples are also noticed above the cross-stratified sandstone. Cross-stratified beds are rather thick in the lower part and very thin in the middle part, usually bearing layers of mica on their surfaces. Measurements of crossstratified beds show their bipolar orientation (Fig. 5), and their dip azimuth is almost perpendicular to the axis of the erosional channel. Such orientation is usually explained by the influence of inter-tidal streams (Reineck and Singh 1980). Laminae of the crossbedded layers show variable angle of dip, in some places the high angle reaches 37 o . Deformations of sandstone bedding and intrabasinal conglomerate consisting of clay pebbles noticed mainly in the left side of the outcrop (along the right edge of the erosional channel) indicate the role of slump processes in the filling of sides of the channel. Another erosional surface (below the layer 7, Fig. 3) lies above the filling of the erosional channel, trapping animal remains. The azimuth and dip angle of the upper channel are
E. Lukševičs, I. Zupiņš. Sedimentology, fauna, and taphonomy of Pav āri 105 Fig. 2. Geologic section of the Pavari outcrop and a stratigraphic sequence of selected Devonian and Carboniferous lithostratigraphic units in Kurzeme. 1, ripple marks; 2, clay pebbles; 3, fish remains. in general the same as parameters of the lower one. Higher up there is a bed of greenish clayey silt and very fine-grained sandstone of changeable thickness, which is overlaid by sandy-clayey silt (layer 8). This is a rather thick unit of changeable colour, greenish in the lower and uppermost part, and dark red in the middle part. It is obvious that the middle portion of the layer shows the primary red colour while it is secondarily changed along the underlying and overlaying sandstone. No clear structure is observed within the layer, apart from thin lenses of more sandy material and some lenses of more clayey
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LATVIJAS UNIVERSITĀTES RAKSTI 679.
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LATVIJAS UNIVERSITĀTES RAKSTI 679.
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Contents Ervīns Lukševičs and Ģ
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ACTA UNIVERSITATIS LATVIENSIS, 2004
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Ervīns Lukševičs, Ģirts Stinkul
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Olga Afanassieva. Microrelief on th
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D.K. Elliott, E. Mark-Kurik, E.B. D
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C.G.Miller, T. Marss, H. Blom. New
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Page 59 and 60: H.-P. Schultze, T. Marss. Revisitin
Page 81 and 82: O.A. Lebedev. A new tetrapod from R
Page 101 and 102: E. Lukševičs, I. Zupiņš. Sedime
Page 103: E. Lukševičs, I. Zupiņš. Sedime
Page 121 and 122: J. Valiukevičius. Silurian acantho
Page 149 and 150: V. Pernegre, V. Dupret. Biostratigr
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V. Pernegre, V. Dupret. Biostratigr
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V. Pernegre, V. Dupret. Biostratigr
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Ž. Žigaite. New telodont from Tuv
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