Showing papers on "Varve published in 1980"
TL;DR: In this article, the authors show that Lacustrine Middle Devonian (Old Red Sandstone) sediments show climatically controlled cycles resulting from the longterm rise and fall of lake levels in an enclosed basin.
Abstract: Synopsis Lacustrine Middle Devonian (Old Red Sandstone) sediments show climatically-controlled cycles resulting from the long-term rise and fall of lake levels in an enclosed basin. Lithologies present were deposited in deep (stratified), shallow and impermanent lakes. Varves, the common recurrence of specific lithologies and the cyclic growth of cosmoid fish scales suggest a marked seasonal climate. Fish faunas were subject both to minor seasonal controls and more profound long-term effects. When lake level was low the faunas may have died out. When the lake overflowed, population replenishment and/or exchange with neighbouring basins was possible. Consequently fish faunas show erratic distributions (involving sudden influxes and extinctions) and no undoubted phylogenetic lineages. Discrete faunal assemblages form internally correlatable “stratigraphic zones”.
73 citations
TL;DR: In this paper, a 95 cm-long box core raised from the Gulf of California was used to establish a sediment accumulation rate of 0.19 cm/yr in a 95-cm-long core, indicating a constant rate of sediment accumulation.
42 citations
TL;DR: In this article, the authors obtained 3.5 kHz reflection profiles along more than 3500 km of shiptrack in Lake Superior within the last 2 yr. The acoustic character of profiles is categorized as: (I) a single, strong reflector at the lake floor, (II) a thick, acoustically transparent layer overlying a strong reflectors, and (III) relatively thick sediment with internal acoustic reflectors.
35 citations
Journal Article•
TL;DR: In this article, nine morphotypes are recognized among biogenic traces recorded in the varved deposits at Plecewice (Mazovia Lowland, Central Poland) and their formation is attributed to life activities of mollusks (pelecypods and gastropods) and arthropods.
Abstract: Nine morphotypes are recognized among biogenic traces recorded in the varved deposits at Plecewice (Mazovia Lowland, Central Poland). Their formation is attributed to life activities of mollusks (pelecypods and gastropods) and arthropods. A comparison of the trace-bearing deposits from Plecewice to those Mazovian varved deposits devoid of biogenic, traces is sugestive of more favorable conditions for both organic life and trace preservation having been in distal and perhaps the external part of intermediate zone than in proximal zone of varve sedimentation.
11 citations
4 citations