Lacustrine deposits

Kn T-L, Lno S, Lowenstein TM, Li J (1998) U-series chronology of lacustrine deposits in Death Valley, California. QuatRes 50 261-275... 

Other potential monitors of historical trace elements are core samples of ice, peat, and lacustrine deposits. Each individual stratus reflects the environment in which it formed. Analyses of these core samples could reconstruct the past local and regional environmental history. 

Because of their specificity for particular bacterial groups and environmental conditions, they make excellent biomarkers. Another steroidal biomarker is gammacerane (Figure 22.19b), which has six six-membered carbon rings. It is used as an indicator of water-column stratification in marine and lacustrine deposits. 

The ensuing suite of minerals that theoretically precipitate are, however, different for these two scenarios. For example, drying by evaporation leads to precipitation of predominantly halite (NaCl), while freezing leads to predominantly hydrohalite (NaCl-2H20) (Fig. 5.14a-b). If states of mineral hydration are preserved in ocean or lacustrine deposits on Mars, then these records could provide valuable clues to the environmental history of Mars during the drying process. 

In the south of Moldova, the Karangatian epoch corresponds [8] to the lagoonal sediments of the second terrace of the Prut and Danube rivers they contain one or two layers with shells of Caspian didacnas separated by a layer of lacustrine deposits. 

The river mouth area is characterized by accumulative land forms flooded with river water and sometimes with water of the receiving basin, low-lying lands composed of interpenetrating layers of fluvial, marine, and lacustrine deposits. 

Valero-Garces B. L., Grosjean M., Kelts K., Schreier H., and Messerli B. (1999) Holocene lacustrine deposition in the Atacama Altiplano facies models, climate and tectonic forcing. Palaeogeogr. Palaeoclimatol. Palaeoecol. 151, 101-125. 

Pimentel, N.L.V. (2002) Pedogenic and early diagenetic processes in Palaeogene alluvial fan and lacustrine deposits from the Sado Basin (south Portugal). Sedimentary Geology 148, 123-138. 

Lacustrine deposits (a) perennial saline lake, (b) salt crust or saline pan, (c) saline mudflat, (d) dry mudflat and (e) shoreline commonly arranged in sequence outwards from the centre of a lake basin (Figure 10.3B and Figure 10.4). 

A) Horizontal beds forming a transition from floodplain deposits to a palustro-lacustrine environment and lacustrine limestones. (B) Lacustrine deposits with stromatolitic bioherms (C) Palustrine limestone with abundant root traces. (D) Lacustrine bottom-set sediments enriched in organic matter and showing thin turbiditic layers. (E) Palustrine limestone with a well developed palaeosol at the top. (F) Various types of crushed shell fragments in a lacustrine mud. (G) Lacustrine bioclastic and oolitic sand deposited near a shore. 

Bitumens, were separated by chromatography, urea clathration and 5A molecular sieve occlusion before and after analyses of many of the aliphatic sub-fractions by GC and gas chromatography-mass spectrometry (GC-MS). Experimental details are noted in a previous publication (16) in which the distribution of cyclic alkanes in two lacustrine deposits of Devonian (N.E. Scotland) and Permian (Autun, France) age, (the D and C series samples) were discussed, Chromatographic separation into aliphatic, aromatic and polar compounds of the bitumens extracted from the shales gave the results shown in Table VI. Carbon Preference Indices and pristane/phytane ratios were measured in this work space limitations precluded... 

Coarse-grained proximal deposits predominate in the Furado and Japoata-Penedo areas (Fig. 2), whereas fine-grained sandstones and mudstones predominate in the Caioba area. This distribution pattern represents a portion of the original deposi-tional association which was preserved within the late-developed rift basin. The connotation of proximal , middle and distal as used in this paper thus applies to the relative location within the central part of the fluvial system. The contemporaneous, most proximal alluvial fan and most distal lacustrine deposits are not preserved within the present basin configuration. 

Palaeosols were developed in the floodplain (interval 4) (Fig. 15) and marginal lacustrine deposits (intervals 1 and 5) (Figs 3 and 5). However, only a few palaeosol horizons have survived erosion. Intra-clastic palaeosol fragments are common in the... 

Coleman Raiswell, 1981), or they are intimately associated with the organic-rich shales of floodplain fine elastics and lacustrine deposits. The low 6 C values (-3.5 to -2.0%o pdb) of these cements suggest input of organically derived CO2. This excess carbon dioxide possibly mobilized the detrital carbonates or bioclasts in the shales or in the sandstones, resulting in locally pervasive calcite cementation. 

Fig. 13. Structure of the bottom of Long Island Sound revealed by acoustic reflection profiles made with 7-kHz acoustic pulses. (Upper echo is produced by a 2(X)-kHz echo sounder.) (a) Section of end moraine capped by boulders and almost buried by marine mud. (b) Thick deposit of marine mud in central Long Island Sound on top of outwash sand with reflector above thought to be surface of lacustrine deposits, (c) Sand-to-mud transition zone in central Long Island Sound. In all records each division on the vertical scale is 600 mm.

Erionite was considered an extremely rare mineral prior to the work of Deffeyes (22, 23) and Regnier (97), who showed it to be a common authigenic zeolite in the altered silicic tuffs of lacustrine deposits in north-central Nevada. Since then, erionite has been recognized in silicic bedded tuffs from many western states (Table II, Figure 3). Erionite, like chabazite, has not been reported from sedimentary rocks older than Eocene. Most occurrences of erionite are in upper Cenozoic lacustrine deposits. Extensive and relatively pure beds of erionite occur in southeastern Oregon, southeastern California, and north-central Nevada. 

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