scholarly journals Substrate type and palaeodepth do not affect the Middle Jurassic taxonomic diversity of crinoids

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12017
Author(s):  
Mariusz A. Salamon ◽  
Anna Feldman-Olszewska ◽  
Sreepat Jain ◽  
Bruno B.M. Ferré ◽  
Karolina Paszcza ◽  
...  

Crinoids are largely considered as good indicators for determining environmental conditions. They are robust proxies for inferring changes in salinity and sedimentation rate and for inferring substrate type. Some crinoid groups (e.g., certain comatulids, cyrtocrinids, millericrinids) have a depth preference, thus, making them useful for palaeodepth estimation. The hypotheses that crinoid distribution is substrate-dependent (rock type) or palaeodepth-dependent is tested here based on (a) archival Bathonian-Callovian (Middle Jurassic) crinoid occurrences from Poland and (b) newer finds from five boreholes from eastern Poland. Qualitative data suggests that isocrinids and cyclocrinids occur in both carbonate and siliciclastic rocks. The cyrtocrinids and roveacrinids occur within carbonate rocks, whereas the comatulids are exclusive to siliciclastics. In terms of palaeodepth, most crinoid groups dominate in shallow environments with the sole exception of cyrtocrinids, that are ubiquitous and occur in both shallow (near shore and shallow marine) and slightly deeper (deeper sublittoral to open shelf) settings. The occurrences of the cosmopolitan taxa, Chariocrinus andreae and Balanocrinus subteres (isocrinids), is independent of both substrate type and palaeodepth. Quantitative analyses (Analysis Of Variance; ANOVA) based on substrate type, i.e., substrate-dependency (claystones, sandstones and limestones), and palaeodepth i.e., palaeodepth-dependency (near shore, shallow-marine, mid-ramp and offshore), corroborate qualitative results. Statistical analysis suggest that the distribution of crinoids shows a strong substrate-dependency but not for palaeodepth, although very weak significance (low p value) is noted for near shore and shallow marine settings and crinoid distribution.

Author(s):  
Lars Stemmerik ◽  
Gregers Dam ◽  
Nanna Noe-Nygaard ◽  
Stefan Piasecki ◽  
Finn Surlyk

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stemmerik, L., Dam, G., Noe-Nygaard, N., Piasecki, S., & Surlyk, F. (1998). Sequence stratigraphy of source and reservoir rocks in the Upper Permian and Jurassic of Jameson Land, East Greenland. Geology of Greenland Survey Bulletin, 180, 43-54. https://doi.org/10.34194/ggub.v180.5085 _______________ Approximately half of the hydrocarbons discovered in the North Atlantic petroleum provinces are found in sandstones of latest Triassic – Jurassic age with the Middle Jurassic Brent Group, and its correlatives, being the economically most important reservoir unit accounting for approximately 25% of the reserves. Hydrocarbons in these reservoirs are generated mainly from the Upper Jurassic Kimmeridge Clay and its correlatives with additional contributions from Middle Jurassic coal, Lower Jurassic marine shales and Devonian lacustrine shales. Equivalents to these deeply buried rocks crop out in the well-exposed sedimentary basins of East Greenland where more detailed studies are possible and these basins are frequently used for analogue studies (Fig. 1). Investigations in East Greenland have documented four major organic-rich shale units which are potential source rocks for hydrocarbons. They include marine shales of the Upper Permian Ravnefjeld Formation (Fig. 2), the Middle Jurassic Sortehat Formation and the Upper Jurassic Hareelv Formation (Fig. 4) and lacustrine shales of the uppermost Triassic – lowermost Jurassic Kap Stewart Group (Fig. 3; Surlyk et al. 1986b; Dam & Christiansen 1990; Christiansen et al. 1992, 1993; Dam et al. 1995; Krabbe 1996). Potential reservoir units include Upper Permian shallow marine platform and build-up carbonates of the Wegener Halvø Formation, lacustrine sandstones of the Rhaetian–Sinemurian Kap Stewart Group and marine sandstones of the Pliensbachian–Aalenian Neill Klinter Group, the Upper Bajocian – Callovian Pelion Formation and Upper Oxfordian – Kimmeridgian Hareelv Formation (Figs 2–4; Christiansen et al. 1992). The Jurassic sandstones of Jameson Land are well known as excellent analogues for hydrocarbon reservoirs in the northern North Sea and offshore mid-Norway. The best documented examples are the turbidite sands of the Hareelv Formation as an analogue for the Magnus oil field and the many Paleogene oil and gas fields, the shallow marine Pelion Formation as an analogue for the Brent Group in the Viking Graben and correlative Garn Group of the Norwegian Shelf, the Neill Klinter Group as an analogue for the Tilje, Ror, Ile and Not Formations and the Kap Stewart Group for the Åre Formation (Surlyk 1987, 1991; Dam & Surlyk 1995; Dam et al. 1995; Surlyk & Noe-Nygaard 1995; Engkilde & Surlyk in press). The presence of pre-Late Jurassic source rocks in Jameson Land suggests the presence of correlative source rocks offshore mid-Norway where the Upper Jurassic source rocks are not sufficiently deeply buried to generate hydrocarbons. The Upper Permian Ravnefjeld Formation in particular provides a useful source rock analogue both there and in more distant areas such as the Barents Sea. The present paper is a summary of a research project supported by the Danish Ministry of Environment and Energy (Piasecki et al. 1994). The aim of the project is to improve our understanding of the distribution of source and reservoir rocks by the application of sequence stratigraphy to the basin analysis. We have focused on the Upper Permian and uppermost Triassic– Jurassic successions where the presence of source and reservoir rocks are well documented from previous studies. Field work during the summer of 1993 included biostratigraphic, sedimentological and sequence stratigraphic studies of selected time slices and was supplemented by drilling of 11 shallow cores (Piasecki et al. 1994). The results so far arising from this work are collected in Piasecki et al. (1997), and the present summary highlights the petroleum-related implications.


2014 ◽  
Vol 57 ◽  
pp. 631-651 ◽  
Author(s):  
Benjamin Brigaud ◽  
Benoît Vincent ◽  
Christophe Durlet ◽  
Jean-François Deconinck ◽  
Emmanuel Jobard ◽  
...  

2011 ◽  
Vol 85 (6) ◽  
pp. 1199-1215 ◽  
Author(s):  
Richard L. Squires

The neogastropod genusPyropsisConrad, 1860 (family Pyropsidae Stephenson, 1941) is recognized for the first time from Upper Cretaceous shallow-marine siliciclastic rocks in the region extending from Vancouver Island, British Columbia southward to southern California. Four new species were detected:Pyropsis aldersoni(earliest Coniacian, southern California),Pyropsis californica(early Coniacian, northern California),Pyropsis louellae(late Coniacian or early Santonian, northern California), andPyropsis grahami(late early Campanian, Vancouver Island).A critical review of the global reports ofPyropsis, a genus that has been commonly confused with other genera (especiallyTudiclaRöding, 1798), establishes thatPyropsishad an amphitropical distribution and lived in warm-temperate waters adjacent to a broad tropical realm. It is rare to uncommon wherever found, and its geologic range is middle Cenomanian to an age near the Cretaceous/Paleogene boundary (probably earliest Paleocene). It was moderately widespread before the Maastrichtian but was predominantly restricted to the New World during the Maastrichtian.


2012 ◽  
Vol 62 (3) ◽  
pp. 403-419 ◽  
Author(s):  
Jolanta Smoleń

ABSTRACT Smoleń, J. 2012. Faunal dynamics of foraminiferal assemblages in the Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn, Kraków-Silesia Homocline, Poland. Acta Geologica Polonica, 62(3), 403-419. Warszawa. The faunal dynamics of benthic foraminifera in the Middle Jurassic ore-bearing clays of Gnaszyn (Kraków- Częstochowa Upland, south-central Poland) are used to reconstruct sedimentary environments. Two types of foraminiferal assemblages, distinct in their quantitative and qualitative composition, were distinguished; type I assemblages, characterizing intervals between horizons with sideritic concretions; and type II assemblages, characterising horizons with sideritic concretions. Benthic foraminifers were further subdivided into eight ecological morphogroups, based on their morphological features and micro-habitats. Type I assemblages consist mostly of plano/concavo-convex, small-sized epifaunal morphotypes, with a restricted occurrence of shallow infaunal forms and a scarcity of deep infaunal taxa, which suggests low-oxygen conditions in both sediment and bottom waters, and a high sedimentation rate in an outer shelf environment. Type II assemblages are characterized by high taxonomic diversity, high specimen abundance and variability of epifaunal and infaunal morphotypes representing a mixed group of specialized feeding strategies. This suggests optimum living conditions controlled by a lower sedimentation rate, relatively well-oxygenated bottom waters and sufficient or high food supply.


2019 ◽  
Vol 5 (1) ◽  
pp. 8-18
Author(s):  
Valentino Hary ◽  
Bahtiar Firdiansyah

The aim of this research is to produce a training model for attacking football and also to refute its effectiveness for children aged 16 years. As for the steps in developing the research, the Borg and Gall steps involved 15 subjects for the small test and 60 for the large test. Qualitative data were obtained from observations, documentation and interviews; meanwhile, for the quantitative data using the effectiveness test. The trial of this study used pre and post tests with 10 opposing criteria. In mathematical calculations the significance of the difference t-count = -28.971, db = 43 and p-value = 0.00 <0.05, which means it contains significance before and after giving treatment. It can be concluded that the model is applied effectively to improve the ability for attacking amongst school students aged 16 years. Thus, representing the differences in motor skills highlights the principle of specificity for attacking training at the age of 16 must be considered that the load of portions in the exercise program can be maximized.  


2020 ◽  
Author(s):  
Abel Yalew ◽  
Wondwosen T/Silasie ◽  
Anchamo Anato ◽  
Anteneh Fikrie

Abstract Background: Despite high prevalence, food aversions are closely linked to the dietary intake of pregnant women. Thus, understanding this behavior is important in addressing the issue of maternal nutrition. Therefore, the aim of this study is to provide information on the prevalence and associated factors of food aversion and its relationship with the nutritional status of pregnant women in Boricha Woreda, Sidama Zone, Southern Ethiopia, 2019.Methods: A community based mixed cross sectional study was conducted among 505 randomly selected pregnant mothers at Boricha Woreda, Southern Ethiopia from June 1-20, 2019. Pre-tested and structured face-to-face interview questionnaire and focus group discussion guide were used to collect quantitative and qualitative data respectively. The quantitative data were cleaned, coded and entered into Epi Info version 7.1.4.0 and then exported to SPSS IBM version 20 for further analysis. The qualitative data were analyzed manually using a content analysis.The bi-variable and multivariable logistic regression was used to identify the possible factors of food aversion. Pearson’s Chi-square test was used to assess the relationship between food aversion and nutritional status of pregnant women. AOR with the respective 95% CIs was used to declare statistical significance.Results: Nearly, seven-in-ten (69.2%) of the pregnant women were averted of at least one food. Cereal (45.9%) and enset (44.2%) were averted by majority of the participants. The mean (±SD) MUAC measurement was 22.7 (±2.4) cm. For age group 19 – 23 [AOR= 2.36, 95%CI (1.32 – 4.21)] and 24 – 28 of years [AOR= 2.84, 95% CI (1.61 – 5.01)], nausea [AOR= 1.70, 95%CI (1.10 – 2.65)] and having additional meal [AOR= 1.70, 95% CI (1.06 – 2.73)] were significantly associated with food aversion. Maternal nutritional status and food aversion was statistically significant (p-value=0.008).Conclusion: High prevalence of food aversions (69.2%) and under nutrition (34.6%) among pregnant women is found. Therefore, the Woreda Health Office needs to intensify the integration of maternal nutrition into ANC services and training of health providers as well as critical appraisal of health extension workers should also be considered.


2003 ◽  
Vol 1 ◽  
pp. 813-863 ◽  
Author(s):  
Michael Engkilde ◽  
Finn Surlyk

The Middle Jurassic Pelion Formation – Fossilbjerget Formation couplet of Jameson Land, East Greenland, is a well-exposed example of the Middle Jurassic inshore–offshore successions characteristic of the rifted seaways in the Northwest European – North Atlantic region. Early Jurassic deposition took place under relatively quiet tectonic conditions following Late Permian – earliest Triassic and Early Triassic rift phases and the Lower Jurassic stratal package shows an overall layer-cake geometry. A long-term extensional phase was initiated in Middle Jurassic (Late Bajocian) time, culminated in the Late Jurassic (Kimmeridgian–Volgian), and petered out in the earliest Cretaceous (Valanginian). The Upper Bajocian – Middle Callovian early-rift succession comprises shallow marine sandstones of the Pelion Formation and correlative offshore siltstones of the Fossilbjerget Formation. Deposition was initiated by southwards progradation of shallow marine sands of the Pelion Formation in the Late Bajocian followed by major backstepping in Bathonian–Callovian times and drowning of the sandy depositional system in the Middle–Late Callovian. Six facies associations are recognised in the Pelion–Fossilbjerget couplet, representing estuarine, shoreface, offshore transition zone and offshore environments. The north–southtrending axis of the Jameson Land Basin had a low inclination, and deposition was sensitive to even small changes in relative sea level which caused the shorelines to advance or retreat over tens to several hundreds of kilometres. Eight composite sequences, termed P1–P8, are recognised and are subdivided into a total of 28 depositional sequences. The duration of the two orders of sequences was about 1–2 Ma and 360,000 years, respectively. The Upper Bajocian P1–2 sequences include the most basinally positioned shallow marine sandstones, deposited during major sealevel lowstands. The lowstands were terminated by significant marine flooding events, during which sandstone deposition was restricted to northern, more proximal parts of the basin. The Upper Bajocian – Middle Bathonian P3–4 sequences show an overall progradational stacking pattern. The sequence boundary at the top of P4 marks a significant shift in stacking pattern, and the Upper Bathonian – Middle Callovian P5–8 sequences show large-scale backstepping, terminating in a widespread condensed succession at the distal, southern end of the basin. The largescale backstepping was governed by combined tectonically-induced subsidence, reflecting increased rates of extension, and eustatic sea-level rise. The depositional trends of the Pelion Formation – Fossilbjerget Formation couplet provide a well-exposed analogue to contemporaneous subsurface deposits which form major hydrocarbon reservoirs on the west Norway shelf, and in the Northern North Sea.


2020 ◽  
Vol 8 (3) ◽  
pp. 497
Author(s):  
Marisa Yoestara ◽  
Zaiyana Putri

This study aimed at reporting differences in terms of the university students’ TOEFL self-efficacy in the test skill and the English skills tested in TOEFL namely listening, structure, and reading. In conducting the study, the explanatory sequential mixed method was used as the study design, where the quantitative data from the survey was conducted first followed by the follow-up interview as the qualitative data. To collect the data in this study, a specifically designed self-efficacy questionnaire of TOEFL was distributed to the total sample of 200 university students across different disciplines from Syiah Kuala University and the University of Serambi Mekkah. The interview was then conducted with 3 selected students to have a deeper understanding of the study result. In terms of the data analysis, one-way ANOVA and t-test were used to describe the quantitative data, while the qualitative data was described and elaborated in words with detailed explanations. The result showed that there was a significant difference among the test skill and the English skills in TOEFL, where F= 13.61 (3, 796), p<0.05. The result also revealed that within the gender, only reading skill had a significant difference, where t198= -2.003, p <. 005, and within the language course participation, all the test skills and TOEFL skills were significantly different as the p-value of each skill was smaller than .005 (p< .005).


Sign in / Sign up

Export Citation Format

Share Document