The ichnological importance and interest of the Geological Museum of Lisbon collections: Cladichnus lusitanicum in continental facies from the Lower Cretaceous of the Lusitanian Basin (Portugal)

The revision of the classic collections of trace fossils housed in the Geological Museum of the former Geological Survey of Portugal is bringing new information to well established ichnogenera. Through the revision of the type material of Taenidium lusitanicum Heer, 1881 and other specimens housed in the Geological Museum of Lisbon and the National Museum of Natural History and Science we reinstate the ichnospecies Cladichnus lusitanicum (Heer). This is the only ichnospecies of Cladichnus occurring in environment typical from the Scoyenia ichnofacies in otherwise typical turbidite forms

Understanding along-strike variability in controlling mechanisms of paleoenvironmental conditions and stratigraphic architecture. Ordovician successions in the Alborz Mountains of Iran at the northern Gondwana margin

Changes in stacking patterns of facies, stratal architecture and shoreline trajectory along depositional strike are mainly dependent on along-strike differences in factors such as physical processes (rivers, waves, tides), tectonics, eustatic changes, sediment supply, and local physiography. The lower-upper Ordovician successions (Lashkerak Formation) deposited in a Peri-Gondwana shallow continental shelf have been interpreted using the sequence stratigraphic concepts. This approach allowed to highlight main differences along-strike in the co-existing depositional systems (coastal plains, estuaries, deltas, and shoreline to shelf systems) in the Alborz basin along the northern edge of Gondwana. On the basis of sedimentary and ichnological characteristics, the siliciclastic successions are divided into four facies associations: (i) Wave-dominated estuarine, (ii) Wave-dominated shoreface-offshore complex, (iii) Mixed fluvial (F)- and wave (W)-influenced delta (Fw and Wf), and (iv) Tide-dominated, fluvial-influenced delta (Tf). Six third-order depositional sequences (DS1-DS6) were recognized, each of them are bounded by unconformities and pronounced shifts in the facies. Along depositional strike (NE/SW- a distance of c. 150 km), significant intrabasinal changes in sediment supply produced evident lateral changes in the shoreline trajectory and stratal architecture, of the DS1-DS3 (Tremadocian-Floian), may be attributed to differences in physical processes (rivers, waves, tides activity) and topographic irregularities derive probably by different rates of subsidence in the basin. During the deposition of the DS1-DS3, a significant along-strike differences in the composition of ichnological suites and the lifestyle of benthonic organisms, dependent on the relative supremacy of wave, storm, river, and tidal processes. Sedimentary supply and processes are the main controlling factors for the stratigraphic architecture rather than the tectonic activity between Tremadocian and Floian. While during the Darriwilian-Katian interval (DS4-DS6), the tectonic activity predominates with the beginning of extensional phases related to the rifting in the Alborz basin causing the activation of syn-depositional normal faults and the development of block-faulted craton-ward margin. Typically, differential subsidence due to extensional tectonic activity causes the uplift of tectonic blocks west of the Alborz Basin into the emerging areas, on one hand, and simultaneous deepening-upward stacking patterns (i.e., increased subsidence rates) in the hanging-wall depocenters of east of the Alborz Basin, on the other hand. This outcrop-based study suggests that the identification of genetically related depositional units in a larger paleogeographic context is fundamental for understanding along-strike variability in controlling mechanisms of the spatial distribution and stratigraphic architecture of coexisting and linked depositional systems

The Penha Garcia Ichnological Park at Naturtejo UNESCO Global Geopark (Portugal): a Geotourism Destination in the Footprint of the Great Ordovician Biodiversification Event

Penha Garcia Ichnological Park is the most important fossil site and one of the most significant geosites of international relevance, in the territory of Naturtejo UNESCO Global Geopark. This municipal protected area is a key site for the study of trace fossil diversity at high paleolatitudes in the early stages of the Great Ordovician Biodiversification Event. Most famous among 21 ichnotaxa is Cruziana, interpreted as foraging burrows of trilobites, present in high abundance and excellent preservation. They are among the largest fossils found anywhere in the Lower Paleozoic, not uncommonly several meters long and over 20 cm wide, covering large bedding planes almost completely. The birthplace of Naturtejo Geopark is now a nature school, one of the most visited outdoor sites by schools in Portugal. It also became a reference for geotourism in this country because of the Fossil Trail that allows visitors to access a natural fossil art gallery in the Variscan-folded cliffs of the Ponsul Gorge. The Fossil Home provides the interpretation of the local geoheritage, and additional attractions are the Templar castle and church viewpoints, the climbing school, the secular watermills, the views over the lake in the heart of the syncline, and the Pego river pool. This is a major geotourism destination in the center of Portugal. The in situ conservation of fossils in this ‘outside museum’ is a challenging subject, which is being monitored using 3D high-resolution modeling of the whole gorge and the main fossil sites there to an mm-scale precision

Rusophycus do Ordovícico Médio de Barrancos-Oliva de la Frontera (Portugal-Espanha) e do leste das Montanhas de Alborz (Irão)

Resumo alargadoSUMÁRIO: Rusophycus leifeirikssoni é descrito nas formações Lashkerak, Irão (parte inferior da Unidade 2) e Colorada, na Zona de Ossa-Morena, atribuídas ao Ordovícico Médio e correspondendo a ambientes deposicionais similares. Na Formação Colorada descreve-se ainda uma nova icnoespécie de Rusophycus, interpretada como comportamento de busca de alimento e abundante na famosa Pedreira do Mestre André.info:eu-repo/semantics/publishedVersio