scholarly journals SOME SPECIFIC FEATURES OF THE LATE ORDOVICIAN EVOLUTION IN THE BALTIC BASIN

1989 ◽  
Vol 38 (2) ◽  
pp. 83
Author(s):  
L Hints ◽  
T Meidla ◽  
J Nõlvak ◽  
L Sarv
Facies ◽  
2019 ◽  
Vol 66 (1) ◽  
Author(s):  
Björn Kröger ◽  
Amelia Penny ◽  
Yuefeng Shen ◽  
Axel Munnecke

Abstract The Late Ordovician succession of the Baltic Basin contains a characteristic fine-grained limestone, which is rich in calcareous green algae. This limestone occurs in surface outcrops and drill-cores in an extensive belt reaching from Sweden across the Baltic Sea to the Baltic countries. This limestone, which is known in the literature under several different lithological names, is described and interpreted, and the term “Baltic limestone facies” is suggested. The microfacies, from selected outcrops from the Åland Islands, Finland and Estonia, consists of calcareous green algae as the main skeletal component in a bioclastic mudstone-packstone lithology with a pure micritic matrix. Three types of calcitarch, which range in diameter from c. 100–180 μm, are common. Basinward, the youngest sections of the facies belt contain coral-stromatoporoid patch reefs and Palaeoporella-algal mounds. The Baltic limestone facies can be interpreted as representing the shallow part of an open-marine low-latitude carbonate platform.


2016 ◽  
Vol 154 (4) ◽  
pp. 683-706 ◽  
Author(s):  
BJÖRN KRÖGER ◽  
LINDA HINTS ◽  
OLIVER LEHNERT

AbstractThe widespread growth of reefs formed by a framework of biogenic constructors and frame-lacking carbonate mounds began on Baltica during Ordovician time. Previously, Ordovician reef and mound development on Baltica was considered to be sporadic and local. A review of all known bioherm localities across the Baltic Basin reveals a more consistent pattern. Ordovician bioherms grew in a wide E–W-aligned belt across the Baltic Basin and occur in several places in Norway. Substantial reef development began simultaneously across the region during the late Sandbian – early Katian interval and climaxed during the late Katian Pirgu age. The current spatiotemporal distribution of bioherms is a result of interdependent factors that involve original drivers of reef development such as relative sea level, climate during the time of deposition and effects of post-depositional erosion. Oceanographic conditions were likely more favourable during times of cooler global climates, low sea level and glacial episodes. At the same time, the likelihood that bioherms are preserved from long-term erosion is higher when deposited during low sea level in deeper parts of the basin. A main factor controlling the timing of the reef and mound evolution was Baltica's shift toward palaeotropical latitudes during Late Ordovician time. The time equivalence between initial reef growth and the Guttenberg isotope carbon excursion (GICE) suggests that global climatic conditions were important.


Author(s):  
S. A. Lebedev ◽  
Yu. I. Troitskaya ◽  
G. V. Rybushkina ◽  
M. N. Dobrovolsky

2007 ◽  
Vol 57 (3-4) ◽  
pp. 355-370 ◽  
Author(s):  
Martin Jakobsson ◽  
Svante Björck ◽  
Göran Alm ◽  
Thomas Andrén ◽  
Greger Lindeberg ◽  
...  

1971 ◽  
Vol 24 (4) ◽  
pp. 553-556
Author(s):  
D. J. Lindsay

By the North European Trade Axis is meant the trade route from Ushant and Land's End, up the English Channel, through the Dover Strait fanning out to serve eastern England, the north coast of continental Europe and leading to the Baltic Basin. Recent events in this area have left a feeling that some form of tightening of control is not only desirable, but is rapidly becoming imperative. There is a basic conflict between the two forms of shipping using the area: the local users who use the area more or less constantly, and the long-distance traders, usually much larger, which arrive in the area for a brief stay after a prolonged period at sea, which has usually been in good weather conditions. Frequently these latter ships have a very poor notion of the hornet's nest into which they are steaming when they arrive. The net result is all too often the same: the local users, with familiarity breeding contempt, wander about as they see fit, with scant regard for routing or the regulations; all too often the big ships arrive from sea with navigating staffs who are too confused, sometimes too ignorant—and sometimes too terrified—to do much more than blunder forward in a straight line hoping for the best. Quite obviously this is not a total picture, and there are large numbers of ships which navigate perfectly competently, but the minority of those which do not seem to be rising rapidly, and show every sign of continuing to increase.


2021 ◽  
pp. 105328
Author(s):  
P. Słomski ◽  
J. Szczepański ◽  
T. Topór ◽  
M. Mastalerz ◽  
A. Pluymakers ◽  
...  

Author(s):  
Linda Hints ◽  
David A. T. Harper

ABSTRACTTwo Ordovician plectambonitoid genera, Alwynella and Grorudia, occur in drill core sections of Latvia in the East Baltic, and in exposures and loose blocks on the Swedish Island of Öland in the Baltic Sea. The new material confirms differences between the two taxa that are assigned herein to separate families, Alwynellidae fam. nov. and Grorudiidae Cocks & Rong, 1989. In particular, the undercut cardinalia separates Alwynella from Grorudia and indicates its proximity to the sowerbyellids. The genus Grorudia, which is externally similar to Alwynella, is more closely related to the palaeostrophomenines. A new species Grorudia morrisoni sp. nov. is established in the East Baltic. The specimens from Öland are included tentatively within the genus Grorudia due to lack of interiors. Both Alwynella and Grorudia were confined to deeper-water facies in the Baltic palaeobasin, within successions ranging in age from latest Mid (late Llanvirn) to earliest Late Ordovician (mid Caradoc).


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