The wide, trans-oceanic geographical distribution of myodocope ostracods during the Silurian (especially during the Ludlow and Pridoli epochs), and their widespread preservation in rocks of that age, permits the establishment of a transcontinental biostratigraphy of comparable resolution to coeval graptolite/chitinozoan/conodont biozones. Seven myodocope biozones, extending from the Homerian Stage, upper Wenlock Series Cyrtograptus lundgreni graptolite biozone to the middle part of the Ludfordian Stage of the Ludlow Series, enable a time-resolution for each biozone of circa 1 million years. These biozones can provide high-resolution correlation across Europe into Arctic Russia and Central Asia. There is also the potential for a myodocope biostratigraphy applicable from the uppermost Silurian (Pridoli) to the Carboniferous.
Micro-CT scanning reveals unprecedented three-dimensional soft anatomy of the early Cambrian (Epoch 2, Age 3) euarthropod Chuandianella ovata.We interpret the presence of an elongate, antenniform first appendage, and a short uniramous second appendage, followed by 10 homonomous biramous appendages comprising a short paddle-shaped exopod and a unique feather-like limb-branch with at least 27 podomeres each of which bears a long blade-like endite with a short terminal seta: we interpret this as the endopod.Alternative interpretations, that these limbs might represent an epipod+basipod or epipod+exopod arrangement, are unlikely, in that they would require either the complete reduction of the exopod or the endopod.We also find no evidence for head appendage morphologies that would support a more crownward position, for example among pancrustaceans, that has previously been suggested for C. ovata.
Event stratigraphy is used to help characterise the Anthropocene as a chronostratigraphic concept, based on analogous deep-time events, for which we provide a novel categorization. Events in stratigraphy are distinct from extensive, time-transgressive 'episodes' – such as the global, highly diachronous record of anthropogenic change, termed here an Anthropogenic Modification Episode (AME). Nested within the AME are many geologically correlatable events, the most notable being those of the Great Acceleration Event Array (GAEA). This isochronous array of anthropogenic signals represents brief, unique events evident in geological deposits, e.g.: onset of the radionuclide 'bomb-spike'; appearance of novel organic chemicals and fuel ash particles; marked changes in patterns of sedimentary deposition, heavy metal contents and carbon/nitrogen isotopic ratios; and ecosystem changes leaving a global fossil record; all around the mid-20th century. The GAEA reflects a fundamental transition of the Earth System to a new state in which many parameters now lie beyond the range of Holocene variability. Globally near-instantaneous events can provide robust primary guides for chronostratigraphic boundaries. Given the intensity, magnitude, planetary significance and global isochroneity of the GAEA, it provides a suitable level for recognition of the base of the Anthropocene as a series/epoch.
Abstract We consider the Anthropocene as a physical, chronostratigraphic unit across terrestrial and marine sedimentary facies, from both a present and a far future perspective, provisionally using an approximately 1950 CE base that approximates with the ‘Great Acceleration’, worldwide sedimentary incorporation of A-bomb-derived radionuclides and light nitrogen isotopes linked to the growth in fertilizer use, and other markers. More or less effective recognition of such a unit today (with annual/decadal resolution) is facies-dependent and variably compromised by the disturbance of stratigraphic superposition that commonly occurs at geologically brief temporal scales, and that particularly affects soils, deep marine deposits and the pre-1950 parts of current urban areas. The Anthropocene, thus, more than any other geological time unit, is locally affected by such blurring of its chronostratigraphic boundary with Holocene strata. Nevertheless, clearly separable representatives of an Anthropocene Series may be found in lakes, land ice, certain river/delta systems, in the widespread dredged parts of shallow-marine systems on continental shelves and slopes, and in those parts of deep-water systems where human-rafted debris is common. From a far future perspective, the boundary is likely to appear geologically instantaneous and stratigraphically significant.
Abstract. Some 40 bradoriid and phosphatocopid (Arthropoda) species are known from the Cambrian of the former Soviet Union. The faunas occur chiefly in Asia (mostly Siberia and Kazakhstan; also Kirghizia); west of the Urals bradoriid and phosphatocopid faunas are sparse, occurring in the Leningrad region, Belarus and Estonia. Most specimens are recovered as crack-out material from clastic and impure carbonate rocks; acid resistant valves from limestones are a minor component of the known faunas.Early Cambrian (Atdabanian-Botomian) faunas are widespread; middle and late Cambrian faunas are scarcer and are known largely from Siberia and Kazakhstan. Though many species are seemingly short-ranging, currently most have only local biostratigraphic significance, with only a few having practical international correlative value.Palaeogeographically, faunas west of the Urals show affinites with those of the Early Palaeozoic Baltica and Avalonia palaeocontinents (Olenellid trilobite realm). Siberian and central Asian (Kazakhstan, Kirghizia, Gorny–Altay–Mongolian belt) faunas show clear affinities with those of palaeocontinental South China and eastern Gondwana (Redlichiid trilobite realm).
Ctenophores have a descriptive array of common names including comb jellies, sea combs, sea walnuts, or sea gooseberries. The discovery of sclerotized and lightly armored ctenophores from the Chengjiang Lagerstätte reveals that more robust forms occurred in the past, perhaps reflecting intensified ecological interactions in the early Cambrian ecosystem. All extant ctenophores are carnivores, mostly using long tentacles to ensnare prey. However, Chengjiang ctenophores seemingly lack tentacles and may have engulfed prey in a similar manner to that suggested for Burgess Shale ctenophores that also lack tentacles. The Chengjiang biota includes Stromatoveris psygmoglena Shu et al., a frond-like fossil with supposed ctenophore affinities. Similar to extant ctenophores, M. octonarius was probably pelagic and achieved locomotion by action of the multitude of tiny cilia on each comb row. A ctenophore affinity is based on features such as the oral-aboral axis, aboral organ, possession of eight softtissue flaps, and a close resemblance to other Chengjiang ctenophore taxa.
Tasmania is an Australian island state with incredible geodiversity, second only to Scotland. State
geoheritage conservation frameworks recognise over 1100 geosites of from sub-regional through to
international significance. Tasmania is famous for hosting the world‘s largest exposure of dolerite, providing
substantial evidence of continental drift and plate tectonics through its occurrence in the former Gondwanan
supercontinent. Mount Wellington and the encompassing Wellington Park (250 km2) is a well expressed and
accessible representation of a significant doleritic landscape typical of the Tasmanian landscape, and lies on
the edge of Tasmania‘s largest city, Hobart. It provides the most extensive and well developed high altitude
periglacial terrain in Tasmania unaffected by glaciation. The landscape evolution of the park has resulted in
numerous dolerite boulder fields, talus slopes and rock columns including the well-illustrated columnar-jointed Organ Pipes sill immediately below the summit of Mount Wellington. Additionally, the Wellington
Park features string bogs, extensive Jurassic sandstone cliffs and outcrops, Permian mudstones with
extensive fossil deposition, all within relatively accessible locations relative to the Mount Wellington summit
drive. Additionally, the geodiversity of the Wellington Park supports the most biologically diverse area in
Tasmania due to marked variation in climate and soils. Despite the educational deficit of Tasmania‘s 500,000
citizens relative to the rest of Australia, Tasmanians have a strong sense of place and very good awareness
and understanding of the value of the landscape, and particularly strong environmental intelligence. For
instance, Tasmanians in general are aware of the broad geology of the Wellington Park as a ‗Dolerite
landform‘ and can identify significant features with ease. Tasmanians have a strong connection to the
outdoors, and spend substantially more time in natural and remote places than other Australians. Thus - the
notion of a Geopark in Tasmania is one that is expected to be embraced by the public at large, and can be
used to provide meaningful context to the surrounding landscape. A successful UNESCO Geopark
designation would provide significant social and economic benefits for Tasmanians through educational and
tourism opportunities. Notably, a Tasmanian Geopark would be the only Geopark in Australia. Currently,
over 300,000 people visit the Wellington Park each year and this is managed by a state management body of
rangers and scientists. Local indigenous people are actively involved in the management of the park to
ensure that culturally significant sites are interpeted and appreciated. The annexation of a Geopark would
involve a network of trails, both new and existing, to access a number of geosites that provide educational
and recreational experiences for a wide range of people while conserving the landscape for future
generations. This would have flow on effects to local communities surrounding the park, presenting
additional opportunities for 'natural tourism‘ which currently attracts 2 million tourists per year. Here we
outline a suitability analysis for the Wellington Park using geoheritage, geospatial and vulnerability
assessment as well as stakeholder analyses so as to present a case for admission to the Asia Pacific Geoparks
Network and as a UNESCO Global Geopark.
The establishment of chronostratigraphic units such as geological Systems and Series depends upon an ability to equate succession in rock strata with the passage of time, and upon a pervasive Law of Superposition. These assumptions hold true at a gross scale. But, at fine scales of stratigraphic resolution, they commonly break down. Thus, bioturbation in Phanerozoic marine deposits typically homogenizes sedimentary packages spanning millennia, affecting biostratigraphic, isotopic and paleomagnetic signals, and post-burial mass transport phenomena such as large-scale sedimentary slumps and intra-stratal diapirs locally disrupt superpositional relationships on a larger scale. Furthermore: the multi-stage transport of microfossils prior to final burial complicates the relationship between depositional and biostratigraphic ages; paleomagnetic signals, imposed at shallow burial depths, may be distinct from depositional ages; and high precision zircon U-Pb dates from tuff layers determine time of crystallization in the magma, rather than depositional age. In such circumstances, depositional units cannot be unambiguously equated with time units: because they include multiple temporal components, they cannot be subdivided precisely into time-rock units. By contrast, the different phenomena which have contributed to constructing sedimentary deposits, pre-, syn- and post-depositional, may be effectively accommodated within a unitary geological time framework.
Taphonomy, the study of the physical, biological, and chemical processes that occur from the death of an organism through to discovery of a fossil, involves consideration of transport, decomposition, burial, and diagenesis. A comprehensive investigation of the sedimentological and quantitative taphonomic analyses of both background and event beds in the Chengjiang biota reveals that in general lateral transport seems to have been limited, and that fossil communities therefore likely reflect accurately in vivo communities. Nearly all examples of published Chengjiang fossils are from the surface or subsurface, from sedimentary layers that have been subjected to extensive weathering. Nerve tissues are extremely labile and their preservation attests to the ability of the Chengjiang environment to capture precise details of animal anatomy. The extensive weathering of the deposit is the likely cause, especially because where iron sulfide is oxidized to form iron oxides sulfuric acid is produced and this may have contributed to the dissolution of biominerals.
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