Paleoecology of sublittoral Miocene echinoids from Sardinia: A case study for substrate controls of faunal distributions

2019 ◽  
Vol 93 (04) ◽  
pp. 764-784 ◽  
Author(s):  
Andrea Mancosu ◽  
James H. Nebelsick
Keyword(s):  
Middle Miocene ◽  
Energy Conditions ◽  
Storm Events ◽  
Soft Bottom ◽  
Faunal Composition ◽  
Low Diversity ◽  
Storm Wave ◽  
Sedimentary Succession ◽  
Hard Substrata

AbstractA rich echinoid fauna within the middle Miocene carbonate sedimentary succession cropping out along the coast between Santa Caterina di Pittinuri and S'Archittu (central-western Sardinia) allows the comparison of faunal gradients and preservation potentials from both hard and soft substrata. Three echinoid assemblages are recognized. Faunal composition, as well as taphonomic and sedimentological features and functional morphological interpretation of the echinoid test indicate an outer sublittoral setting. Assemblage 1 represents a highly structured environment within the photic zone, with mobile substrata occupied by infaunal irregular echinoids, mainly spatangoids, and localized hard substrata, provided by rhodolith beds, with epibenthic regular echinoids represented by the co-occurrence of the diadematidDiademaGray, 1825 and the toxopneustidsTripneustesL. Agassiz, 1841 andSchizechinusPomel, 1869. Assemblage 2 shows a higher diversity of irregular echinoids, dominated by the clypeasteroidsEchinocyamusvan Phelsum, 1774 andClypeasterLamarck, 1801 and different spatangoids, with the minute trigonocidaridGenocidarisA. Agassiz, 1869 among regular echinoids. This assemblage points to a soft-bottom environment with moderate water-energy conditions, periodically affected by storms. A low-diversity echinoid fauna in Assemblage 3, dominated by the spatangoidsBrissopsisL. Agassiz, 1840 andOvaGray, 1825, documents a deeper, soft-bottom environment, possibly below storm-wave base. These results indicate that the diversity of echinoid faunas originating in sublittoral environments is related to: (1) the presence of both soft and hard substrata, (2) differential preservation potentials of the various echinoid taxa, (3) intense bioturbation, and (4) sediment deposition by sporadic storm events.

Lithostratigraphy of the Kweekvlei Formation (Witteberg Group), Cape Supergroup

2017 ◽  
Vol 120 (3) ◽  
pp. 421-432 ◽  
Author(s):  
C. Browning ◽  
M. Reid
Keyword(s):  
South Africa ◽  
Transition Zone ◽  
Distal Part ◽  
Vascular Plant ◽  
Trace Fossil ◽  
Plant Debris ◽  
Lower Carboniferous ◽  
Fossil Assemblage ◽  
Low Diversity ◽  
Storm Wave

AbstractThe Lower Carboniferous, probably Tournaisian, Kweekvlei Formation is part of the Witteberg Group (Cape Supergroup) of South Africa. Together with the overlying Floriskraal Formation, it forms an upward-coarsening succession within the Lake Mentz Subgroup. Sedimentary features of the Kweekvlei Formation suggest deposition in a storm-wave dominated marine setting, within the storm-influenced, distal part of an offshore transition zone environment. This predominantly argillaceous formation preserves a low diversity trace fossil assemblage. Reworked vascular plant debris (including the problematic genus Praeramunculus sp.) and a shark spine have been reported for the Kweekvlei Formation. There are no known stratigraphic equivalents in South Africa.

scholarly journals Impact Assessment Analysis of Sea Level Rise in Denmark: A Case Study of Falster Island, Guldborgsund

2021 ◽  
Vol 13 (13) ◽  
pp. 7503
Author(s):  
Alexander Boest-Petersen ◽  
Piotr Michalak ◽  
Jamal Jokar Arsanjani
Keyword(s):  
Climate Change ◽  
Impact Assessment ◽  
Sea Level Rise ◽  
Sea Level ◽  
Alternative Methods ◽  
Projection Data ◽  
Storm Events ◽  
Cascading Effects ◽  
Local Levels

Anthropogenically-induced climate change is expected to be the contributing cause of sea level rise and severe storm events in the immediate future. While Danish authorities have downscaled the future oscillation of sea level rise across Danish coast lines in order to empower the coastal municipalities, there is a need to project the local cascading effects on different sectors. Using geospatial analysis and climate change projection data, we developed a proposed workflow to analyze the impacts of sea level rise in the coastal municipalities of Guldborgsund, located in Southeastern Denmark as a case study. With current estimates of sea level rise and storm surge events, the island of Falster can expect to have up to 19% of its landmass inundated, with approximately 39% of the population experiencing sea level rise directly. Developing an analytical workflow can allow stakeholders to understand the extent of expected sea level rise and consider alternative methods of prevention at the national and local levels. The proposed approach along with the choice of data and open source tools can empower other communities at risk of sea level rise to plan their adaptation.

scholarly journals Depositional Architecture and Facies of a Complete Reef Complex Succession: A Case Study of the Permian Jiantianba Reefs, Western Hubei, South China

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 533
Author(s):  
Beichen Chen ◽  
Xinong Xie ◽  
Ihsan Al-Aasm ◽  
Wu Feng ◽  
Mo Zhou
Keyword(s):  
Upper Permian ◽  
Field Observations ◽  
Comprehensive Description ◽  
Reef Facies ◽  
Reef Complex ◽  
Sedimentary Succession ◽  
Western Hubei ◽  
Depositional Architecture ◽  
Marginal Reef

The Upper Permian Changhsingian Jiantissanba reef complex is a well-known platform marginal reef, located in the western Hubei Province, China. Based on field observations and lithological analysis of the entire exposed reef complex, 12 reef facies have been distinguished according to their sedimentary components and growth fabrics. Each of the lithofacies is associated with a specific marine environment. Vertically traceable stratal patterns reveal 4 types of the lithologic associations of the Jiantianba reef: (1) heterozoan reef core association: developed in the deep marginal platform with muddy composition; (2) photozoan reef core association developed within the photic zone; (3) tide-controlled reef crest association with tidal-dominated characteristic of lithofacies in the shallow water; and (4) reef-bank association dominated by bioclastic components. The entire reef complex shows a complete reef succession revealing a function of the wave-resistant and morphological units. This study displays a complete sedimentary succession of Jiantianba reef, which provides a more accurate and comprehensive description of the reef lithofacies and a better understanding of the structure and composition of organic reefs.

scholarly journals A perspective on crassulacean acid metabolism photosynthesis evolution of orchids on different continents: Dendrobium as a case study

2019 ◽  
Vol 70 (22) ◽  
pp. 6611-6619
Author(s):  
Ming-He Li ◽  
Ding-Kun Liu ◽  
Guo-Qiang Zhang ◽  
Hua Deng ◽  
Xiong-De Tu ◽  
...  
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Middle Miocene ◽  
Acid Metabolism ◽  
Flowering Plants ◽  
Asian Clade ◽  
Wide Range ◽  
Cam Species ◽  
Climatic Cooling ◽  
Cam Photosynthesis

Abstract Members of the Orchidaceae, one of the largest families of flowering plants, evolved the crassulacean acid metabolism (CAM) photosynthesis strategy. It is thought that CAM triggers adaptive radiation into new niche spaces, yet very little is known about its origin and diversification on different continents. Here, we assess the prevalence of CAM in Dendrobium, which is one of the largest genera of flowering plants and found in a wide range of environments, from the high altitudes of the Himalayas to relatively arid habitats in Australia. Based on phylogenetic time trees, we estimated that CAM, as determined by δ 13C values less negative than –20.0‰, evolved independently at least eight times in Dendrobium. The oldest lineage appeared in the Asian clade during the middle Miocene, indicating the origin of CAM was associated with a pronounced climatic cooling that followed a period of aridity. Divergence of the four CAM lineages in the Asian clade appeared to be earlier than divergence of those in the Australasian clade. However, CAM species in the Asian clade are much less diverse (25.6%) than those in the Australasian clade (57.9%). These findings shed new light on CAM evolutionary history and the aridity levels of the paleoclimate on different continents.

Diversity of Edwardsiidae sea anemones (Cnidaria: Anthozoa: Actiniaria) from Brazil, with the description of a new genus and species

2019 ◽  
Vol 99 (5) ◽  
pp. 1087-1098 ◽  
Author(s):  
Rafael Antônio Brandão ◽  
Luciana Câmara Gusmão ◽  
Paula Braga Gomes
Keyword(s):  
New Genus ◽  
South Atlantic ◽  
Valid Species ◽  
Nematostella Vectensis ◽  
Soft Bottom ◽  
Sea Anemones ◽  
New Genus And Species ◽  
Western Atlantic ◽  
Low Diversity ◽  
The 1960S

AbstractEdwardsiidae is one of the most speciose families within order Actiniaria with ~75 valid species of burrowing sea anemones. Five edwardsiids have been recorded in South Atlantic waters with only two species known for Brazil:Nematostella vectensisandEdwardsia migottoi. Such low diversity is probably the result of a historical small number of specialists in the region combined with difficulties in collecting and identifying these small burrowing animals. Although edwardsiids have been reported from Brazil since at least the 1960s, these reports did not include proper descriptions or specific identification, making comparison to other valid species impossible. Here we describe a new genus,Isoscolanthusgen. nov., and two new species:Isoscolanthus iemanjaesp. nov.,Isoscolanthus janainaesp. nov. and we also describeScolanthus crypticussp. nov., the first species of the genus for Brazil.Isoscolanthusgen. nov. is easily distinguished from other edwardsiid genera by a combination of external (i.e. presence of periderm and nemathybomes in proximal end and 12 tentacles), microanatomical (i.e. four microcnemes) and cnidom features (i.e. pterotrichs in nemathybomes). In addition to the description of the new genus and species, we expand the range distribution ofNematostella vectensisandEdwardsia migottoiin the South-western Atlantic. The number of edwardsiids known from Brazil is raised from two to five species, substantially increasing the diversity of soft-bottom sea anemones for South Atlantic waters.

scholarly journals An alternative way to identify local geomagnetically quiet days: a case study using wavelet analysis

2016 ◽  
Vol 34 (4) ◽  
pp. 451-462 ◽  
Author(s):  
Virginia Klausner ◽  
Andrés Reinaldo Rodriguez Papa ◽  
Cláudia Maria Nicole Cândido ◽  
Margarete Oliveira Domingues ◽  
Odim Mendes
Keyword(s):  
Wavelet Analysis ◽  
Geomagnetic Activity ◽  
Solar Minimum ◽  
High Speed ◽  
Wavelet Coefficient ◽  
Magnetic Activity ◽  
New Method ◽  
Storm Events ◽  
High Speed Stream

Abstract. This paper proposes a new method to evaluate geomagnetic activity based on wavelet analysis during the solar minimum activity (2007). In order to accomplish this task, a newly developed algorithm called effectiveness wavelet coefficient (EWC) was applied. Furthermore, a comparison between the 5 geomagnetically quiet days determined by the Kp-based method and by wavelet-based method was performed. This paper provides a new insight since the geomagnetic activity indexes are mostly designed to quantify the extent of disturbance rather than the quietness. The results suggest that the EWC can be used as an alternative tool to accurately detect quiet days, and consequently, it can also be used as an alternative to determine the Sq baseline to the current Kp-based 5 quietest days method. Another important aspect of this paper is that most of the quietest local wavelet candidate days occurred in an interval 2 days prior to the high-speed-stream-driven storm events. In other words, the EWC algorithm may potentially be used to detect the quietest magnetic activity that tends to occur just before the arrival of high-speed-stream-driven storms.

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