Hexactinellid sponge assemblages across the Campanian– Maastrichtian boundary in the Middle Vistula River section, central Poland

2012 ◽  
Vol 62 (4) ◽  
pp. 561-580 ◽  
Author(s):  
Ewa Świerczewska-Gładysz

ABSTRACTŚwierczewska-Gładysz, E. 2012. Hexactinellid sponge assemblages across the Campanian-Maastrichtian boundary in the Middle Vistula River section, central Poland. Acta Geologica Polonica, 62 (4), 561-580. Warszawa.The sponge fauna from the Upper Campanian-lowermost Maastrichtian succession of the Middle Vistula River valley (central Poland) is represented mainly by dictyid hexactinellid sponges (Hexactinosida and Lychniscosida). Their greatest abundance and taxonomic variability is noted in the “Inoceramus” inkermanensis Zone (Upper Campanian), and they are less diverse in the overlying (Upper Campanian) Trochoceramus costaecus Zone and lower “Inoceramus” redbirdensis Zone. In the upper “Inoceramus” redbirdensis Zone (basal Maastrichtian in the sense of the Tercis rather than the Boreal definition) they are extremely rare. With the beginning of the Maastrichtian the number of dictyid sponges gradually increases.The observed changes in the abundance and taxonomic variability of the dictyid sponges indicate environmental changes in the latest Campanian-earliest Maastrichtian sea in the area. It seems that changes in basin bathymetry, confined to eustatic sea-level changes in the latest Campanian and early Maastrichtian, were the most important factor. Progressive shallowing of the basin in the latest Campanian drastically restricted the development of dictyids. In the peak regression, the sea level could have fallen to only several tens of metres. The gradual recovery of the sponge assemblages correlates with subsequent deepening of the basin with the start of the Maastrichtian

2012 ◽  
Vol 62 (4) ◽  
pp. 535-559 ◽  
Author(s):  
Norbert Keutgen ◽  
Zbigniew Remin ◽  
Ireneusz Walaszczyk

ABSTRACT Keutgen, N., Remin, Z. and Walaszczyk, I. 2012. Early representatives of the belemnite genus Belemnella (Cephalopoda) from the uppermost Campanian-Lower Maastrichtian of the Middle Vistula River section, central Poland. Acta Geologica Polonica, 62 (4), 535-559. Warszawa. Representatives of the belemnite genus Belemnella from the uppermost Campanian and lowermost Maastrichtian of the Middle Vistula River Valley section (central Poland) have been studied, using the species concept proposed by Schulz in 1979. Results have been compared to a recently proposed new interpretation of the genus Belemnella based on artificial neural networks, as put forward by Remin in 2007 and 2012. In the interval studied, four taxa have been recognised: Bln. longissima, Bln. inflata, Bln. obtusa and Bln. vistulensis, the last-named being a senior synonym of Bln. pseudobtusa. Three additional forms have been left in open nomenclature: Bln. cf. lanceolata , Bln. ex gr. lanceolata/inflata and Belemnella sp. Based on their documented vertical ranges, three Belemnella standard zones, as originally distinguished in the Kronsmoor section by Schulz (1979), northern Germany, have been defined, in ascending order: the Bln. lanceolata, Bln. vistulensis and Bln. obtusa zones. The bases of the lanceolata and obtusa zones in the Middle Vistula River Valley section can be directly correlated with the same zones at Kronsmoor, and appear to be isochronous within limits of stratigraphic resolution. The base of the vistulensis Zone (Bln. vistulensis according to the species concept of Schulz in 1979), however, is probably diachronous, being older in the Middle Vistula section. Although Schulz’s and Remin’s species concepts differ quite considerably, they do result in similar stratigraphic subdivisions of the Kronsmoor and Middle Vistula River sections.


2012 ◽  
Vol 62 (1) ◽  
pp. 91-116 ◽  
Author(s):  
Marcin Machalski

ABSTRACT Machalski, M. 2012. Stratigraphically important ammonites from the Campanian-Maastrichtian boundary interval of the Middle Vistula River section, central Poland. Acta Geologica Polonica, 62 (1), 91-116. Warszawa. The formal definition of the Global Stratotype Section and Point (GSSP) for the base of the Maastrichtian Stage at Tercis, southwest France, is based on the first or last occurrences of twelve taxa, including three species of ammonites, Pachydiscus (Pachydiscus) neubergicus, Diplomoceras cylindraceum, and Nostoceras (Nostoceras ) hyatti. The taxonomy and stratigraphical distribution of these, and allied forms, are studied, on the basis of material from the opoka succession across the upper Campanian-lowermost Maastrichtian boundary in the Middle Vistula River section, central Poland. In view of the imprecise location of two ammonite GSSP markers in that section, a direct ammonite-based correlation with the GSSP at Tercis is impossible. However, data available indicate that in the Middle Vistula River section the first occurrence of Pachydiscus (P.) neubergicus and the last occurrence of Nostoceras (N.) hyatti are situated significantly higher than the first occurrence of Belemnellalanceolata, the traditional belemnite marker for the base of the Maastrichtian Stage in the Boreal Realm, and that Diplomoceras cylindraceum appears significantly below this level. There are no unequivocal records of Pachydiscus (P.) neubergicus from the Belemnella lanceolata Zone s.l. in the Middle Vistula River section.


2020 ◽  
Author(s):  
P.C. Pretorius ◽  
T.B. Hoareau

AbstractMolecular clock calibration is central in population genetics as it provides an accurate inference of demographic history, whereby helping with the identification of driving factors of population changes in an ecosystem. This is particularly important for coral reef species that are seriously threatened globally and in need of conservation. Biogeographic events and fossils are the main source of calibration, but these are known to overestimate timing and parameters at population level, which leads to a disconnection between environmental changes and inferred reconstructions. Here, we propose the Last Glacial Maximum (LGM) calibration that is based on the assumptions that reef species went through a bottleneck during the LGM, which was followed by an early yet marginal increase in population size. We validated the LGM calibration using simulations and genetic inferences based on Extended Bayesian Skyline Plots. Applying it to mitochondrial sequence data of crown-of-thorns starfish Acanthaster spp., we obtained mutation rates that were higher than phylogenetically based calibrations and varied among populations. The timing of the greatest increase in population size differed slightly among populations, but all started between 10 and 20 kya. Using a curve-fitting method, we showed that Acanthaster populations were more influenced by sea-level changes in the Indian Ocean and by reef development in the Pacific Ocean. Our results illustrate that the LGM calibration is robust and can probably provide accurate demographic inferences in many reef species. Application of this calibration has the potential to help identify population drivers that are central for the conservation and management of these threatened ecosystems.


2014 ◽  
Vol 41 (4) ◽  
pp. 361-368 ◽  
Author(s):  
Danuta Dzieduszyńska ◽  
Joanna Petera-Zganiacz ◽  
Juliusz Twardy ◽  
Piotr Kittel ◽  
Piotr Moska ◽  
...  

AbstractResults of OSL dating and sedimentary studies from the profile of the low alluvial terrace of the middle Warta River are presented. The samples were dated using the single-aliquot regenera-tive method. Dating was used to establish a timing of the Weichselian Late Glacial events in the river valley environment. Stable conditions on the floodplain are expressed by the deposition of organic-rich series radiocarbon dated at 12 900-12 600 cal BP and 11 600-10 770 cal BP. Samples for OSL dating were collected from the mineral material deposited during the intensification of flood events during the Weichselian decline. The results obtained for the alluvia range from 12.78 ± 0.62 ka b2k to 14.33 ± 0.74 ka b2k. Sedimentological criteria allowed to distinguish between particular flood events. Overestimation of OSL ages is probably a result of rapidity of environmental changes in that time.


2000 ◽  
Vol 54 (3) ◽  
pp. 384-393 ◽  
Author(s):  
Brian L. Sherrod ◽  
Robert C. Bucknam ◽  
Estella B. Leopold

At a marsh on the hanging wall of the Seattle fault, fossil brackish water diatom and plant seed assemblages show that the marsh lay near sea level between ∼7500 and 1000 cal yr B.P. This marsh is uniquely situated for recording environmental changes associated with past earthquakes on the Seattle fault. Since 7500 cal yr B.P., changes in fossil diatoms and seeds record several rapid environmental changes. In the earliest of these, brackish conditions changed to freshwater ∼6900 cal yr B.P., possibly because of coseismic uplift or beach berm accretion. If coseismic uplift produced the freshening ∼6900 cal yr B.P., that uplift probably did not exceed 2 m. During another event about 1700 cal yr B.P., brackish plant and diatom assemblages changed rapidly to a tidal flat assemblage because of either tectonic subsidence or berm erosion. The site then remained a tideflat until the most recent event, when an abrupt shift from tideflat diatoms to freshwater taxa resulted from ∼7 m of uplift during an earthquake on the Seattle fault ∼1000 cal yr B.P. Regardless of the earlier events, no Seattle fault earthquake similar to the one ∼1000 cal yr B.P. occurred at any other time in the past 7500 years.


2021 ◽  
Author(s):  
Anna Karkani ◽  
Giannis Saitis ◽  
Konstantinos Tsanakas ◽  
Niki Evelpidou ◽  
Efthimios Karymbalis ◽  
...  

<p>The study of environmental changes in coastal areas provide useful information for past conditions and constitute a powerful tool for accurate palaeogeographic reconstructions. Several coastal landforms are present on the coastal zone, with different response to environmental change. Coastal wetlands and lagoons are particularly sensitive to local paleoenvironmental changes and provide an excellent opportunity to reconstruct the evolution of the coastal zone evolution and the sea level changes. In this context, the aim of this work is to elucidate the coastal evolution of Psatha bay, Alkyonides Gulf, Greece, through coastal drillings and geomorphological sea level markers.</p><p>The study area is located at the eastern end of Corinth Gulf, in the Gulf of Alkyonides. Psatha is bounded by active neotectonic structures, which have been a determining factor in its development. In this work we adopt a multiproxy approach through the study of coastal drillings and beachrocks, and micro-topography constructed after photogrammetric processing of very high resolution and accuracy images acquired by several Unmanned Aerial System flights. We coupled detailed beachrock mapping, microstratigraphic analysis and luminescence dating to study beachrock outcrops found up to 1 m above the present sea-level. For the palaeoenvironmental reconstruction, multiproxy analyses were undertaken, which included sedimentological analysis of the core, paleontological analysis of macrofauna and microfauna and radiocarbon dating. The results of this work will contribute to the better understanding of a coastal site in a tectonically active area and the relative sea level changes.</p>


2019 ◽  
Vol 94 ◽  
pp. 61-79
Author(s):  
Takashi Chiba ◽  
Shigeo Sugihara ◽  
Yoshiaki Matsushima ◽  
Yusuke Arai ◽  
Kunihiko Endo

ABSTRACTTo help characterise the palaeogeographic and lacustrine environmental changes that resulted from the Holocene transgression and residual subsidence in the eastern Kanto Plain of central Japan, we analysed four drill cores and reviewed other core data from the southern part of the Lake Inba area. Fossil diatom assemblages yielded evidence of centennial-scale palaeogeographic and salinity responses to sea-level changes since the late Pleistocene. We determined that the seawater incursion into the Lake Inba area during the Holocene transgression occurred at approximately 9000 yr. We also recognised a late Holocene regression event corresponding to the Yayoi regression, considered to have occurred from ca. 3000 to ca. 2000 yr, and a subsequent transgression. Our data clarify some of the palaeogeographic changes that occurred in the Lake Inba area and document an overall trend toward lower salinity in the lake during the regression. In particular, the environment in Lake Inba changed from brackish to freshwater no later than 1000 yr. From the detailed palaeogeographic and palaeo-sea-level reconstruction, we recognised that residual subsidence occurred during the Holocene in this area. Thus, comparison of sea-level reconstructions based on modelling and fossil diatom assemblages is effective in interpreting Holocene long-term subsidence.


2007 ◽  
Vol 50 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Eduard G. Reinhardt ◽  
Norman A. Easton ◽  
R. Timothy Patterson

ABSTRACT Foraminiferal and sedimentological analysis of an underwater stratigraphie section from an Amerindian habitation site at Montague Harbour, British Columbia has further documented late Holocene sea level changes. It appears that part of the documented transgression was caused by tectonic subsidence of the area (Event 1 at approx. 3500 calendar years BP and Event 2 sometime before 1100 calendar years BP) and was recognized in the stratigraphie record by rapid environmental changes. The environmental changes caused by rapid shifts in water depth were recognized through sedimentological and foraminiferal evidence. The tectonic subsidence events, coupled with gentle late Holocene transgression, caused the breaching of Montague Harbour's northwestern channel. The breaching of the channel improved water circulation and increased salinity within the harbour. The salinity changes are reflected in the shift from a low salinity Cribroelphidium excavatum (Terquem, 1876) phenotype "clavata" dominated biofacies (1) at the base of the section to a higher salinity Buccella tenerrima (Bandy, 1950) and Elphidiella hannai (Cushman and Grant, 1927) dominated biofacies (2) at the top. These sea-level changes would have eventually forced local Amerindian settlements inland. The 14C dating of wood and shell, indicates that the recovery of archaeological remains of the Charles culture (ca.6500-3200 years BP) requires investigation in deeper waters.


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