scholarly journals Upper Cretaceous volcanoclastic deposits from the Haţeg basin, south Carpathians (Romania): K-Ar ages and intrabasinal correlation

2011 ◽  
Vol 38 (2) ◽  
pp. 182-188 ◽  
Author(s):  
Ana-Voica Bojar ◽  
Stanislaw Halas ◽  
Hans-Peter Bojar ◽  
Dan Grigorescu ◽  
Stefan Vasile
Keyword(s):  
Volcanic Activity ◽  
Upper Cretaceous ◽  
The Other ◽  
Volcanic Centre ◽  
Marine Deposits ◽  
Mineral Phases ◽  
Palaeomagnetic Data ◽  
Haţeg Basin ◽  
Volcanic Bomb

AbstractIn order to constrain the age of the Upper Cretaceous continental Densuş-Ciula Formation from the Haţeg basin, South Carpathians, and correlate it with the other continental unit that occurs in the region, the Sânpetru Formation, we separated and dated by the K-Ar method biotites and amphiboles from volcanoclastic deposits. The mineral phases analysed are from two tuff layers and volcanic bombs cropping out near Rachitova village. Two tuff layers from the Densuş-Ciula Formation give early Maastrichtian ages of 69.8±1.3 and 71.3±1.6 Ma, respectively. The ages determined for the tuff layers constrain the age of deposition for the Densuş-Ciula Formation and enable further correlations with the available palaeomagnetic data from the deposits occurring along the Sibişel Valley that belong to the Sânpetru Formation. The volcanic bombs collected near to Răchitova village are andesites and dacites. The age determined by K-Ar method on hornblende separated from a volcanic bomb is 82.7±1.5 Ma, which is older than the underlying Campanian marine deposits in turbidite facies. This suggests that the volcanic bombs were re-deposited during the early Maastrichtian. Thus, the volcanics found at Răchitova have at least two origins: one type is related to an explosive synsedimentary volcanic activity, and the other type is represented by older andesitic/dacitic bombs, which most probably originate from a volcanic centre situated in the Haţeg region.

Diversity, morphology, and phylogeny of coleoid cephalopods from the Upper Cretaceous Plattenkalks of Lebanon-Part I: Prototeuthidina

2011 ◽  
Vol 85 (2) ◽  
pp. 234-249 ◽  
Author(s):  
Dirk Fuchs ◽  
Neal Larson
Keyword(s):  
Digestive Tract ◽  
Upper Cretaceous ◽  
Soft Part ◽  
Phylogenetic Analyses ◽  
Early Jurassic ◽  
The Other ◽  
Large Collection ◽  
Shaped Body ◽  
Cretaceous Deposits

Morphologic analyses of a large collection of coleoid cephalopods from the Lebanese Upper Cretaceous yielded a much higher diversity than previously assumed and revealed numerous extraordinarily well-preserved, soft-part characters. An analysis of the Prototeuthidina, a gladius-bearing group with a slender torpedo-shaped body, revealed two species:Dorateuthis syriacaandBoreopeltis smithin. sp. Previously unknown soft-part characters, such as the digestive tract, the gills, and the cephalic cartilage considerably improved our knowledge ofD. syriaca.Since none of the investigated specimens show more than eight arms, similarities with modern squids are regarded as superficial.Boreopeltis smithin. sp. is erected on the basis of its comparatively wideParaplesioteuthis-like gladius. The latter species represents the first unambiguous record of this genus in Upper Cretaceous deposits. Phylogenetic analyses indicate that the prototeuthidid clade consists of two lineages. The plesioteuthidid lineage originates from early JurassicParaplesioteuthisand leads toPlesioteuthisandDorateuthis.The other lineage is morphologically more conservative and leads toBoreopeltis.

Multi-Aged Small Pterosaur Track Assemblage from the Upper Cretaceous of Korea

2021 ◽  
Author(s):  
Jongyun Jung ◽  
Min Huh ◽  
Koo-Geun Hwang ◽  
Hyun-Joo Kim ◽  
Byung-Do Choi ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Korean Peninsula ◽  
Upper Cretaceous ◽  
Global Distribution ◽  
The Other

Abstract The pterosaur is the earliest and largest powered flying vertebrate, even earlier and larger than the other extant archosaurian group, birds. However, evidence for this flying reptile, including the diversity of the small-sized pterosaur after the mid-Cretaceous, and their ecology, has remained elusive. Here we present numerous and dense pterosaur track assemblages from the Hwasun Seoyuri tracksite in the Upper Cretaceous Jangdong Formation of the Neungju Basin in Korea. The pterosaur track assemblage, assigned to Pteraichnus isp., consists of various sized, randomly oriented manus-dominated tracks with several pes claw marks. These features commonly indicate the semi-aquatic behavior and multi-age gregariousness of pterosaurs. The supposed trackmaker of pterosaur tracks would be the small-sized pterodactyloid that inhibited the Late Cretaceous Korean Peninsula, but that has not previously been reported. This ichnological evidence for the global distribution of small-sized pterosaurs could be interpreted to mean that the pterosaur fauna in the Late Cretaceous was more distributed and diverse than was previously known.

Submarine volcanic activity and giant amygdale formation along the Panama island arc as a precursor to 6000-year-old agate exploitation on Pedro González Island

2021 ◽  
pp. 1-16
Author(s):  
Stewart D Redwood ◽  
David M Buchs ◽  
David Edward Cavell
Keyword(s):  
Volcanic Activity ◽  
Bimodal Distribution ◽  
Island Arc ◽  
Early Miocene ◽  
Tool Manufacture ◽  
Marine Deposits ◽  
Large Size ◽  
Hydrothermal Processes ◽  
Field Evidence ◽  
Geochemical Study

Abstract An extensive deposit of agate occurs in Pedro González Island in the Gulf of Panama. Previous archaeological research showed that the agate was exploited between 6200 and 5600 cal BP to make stone tools found at the oldest known Preceramic human settlement in the Pearl Island archipelago. We constrain here the origin and geological context of the agate through a geological and geochemical study of the island. We show that it includes primary volcanic breccias, lavas, and tuffaceous marine deposits with sedimentary conglomerates and debris flow deposits, which we define as the Pedro González Formation. This formation records submarine to subaerial volcanic activity along an island arc during the Oligo-Miocene, confirming previous regional models that favour progressive emergence of the isthmus in the early Miocene. The igneous rocks have an extreme tholeiitic character that is interpreted to reflect magmatic cessation in eastern Panama during the early Miocene. The agate is hosted in andesitic lavas in unusually large amygdales up to 20–40 cm in diameter, as well as small amygdales (0.1–1.0 cm) in a bimodal distribution, and in veins. The large size of the agates made them suitable for tool manufacture. Field evidence suggests that the formation of large amygdales resulted from subaqueous lava–sediment interaction, in which water released from unconsolidated tuffaceous deposits at the base of lava flows rose through the lavas, coalesced, and accumulated below the chilled lava top, with subsequent hydrothermal mineralization. These amygdales could therefore be regarded as an unusual result of combined peperitic and hydrothermal processes.

scholarly journals V.—Note on an Undescribed Area of Lower Greensand or Vectian in Dorset

1891 ◽  
Vol 8 (10) ◽  
pp. 456-458 ◽  
Author(s):  
A. J. Jukes-Browne
Keyword(s):  
Lower Cretaceous ◽  
Small Area ◽  
Upper Cretaceous ◽  
The Other ◽  
Present Communication ◽  
The Subject ◽  
Geological Magazine

Until recently no outcrop of the Vectian or Lower Greensand was known to occur between Lulworth on the coast of Dorset and the neighbourhood of Devizes in Wiltshire. It was supposed that, with the exception of a small area of Wealden in the Vale of Wardour, the whole of the Lower Cretaceous Series in Dorset and South Wilts was concealed and buried beneath the overlapping Upper Cretaceous strata. A recent examination of this district however has revealed two areas where the Vectian sands emerge from beneath the Gault. One of these has already been indicated in the pages of the Geological Magazine; the other is the subject of the present communication.

Etude anatomique et paleogeographique de deux tiges de palmiers fossiles (Palmoxylon ligerinum Crie) recoltes aux environs de Savigne-sur-Lathan (Indre-et-Loire)

1949 ◽  
Vol S5-XIX (7-9) ◽  
pp. 601-609 ◽  
Author(s):  
Edouard Boureau
Keyword(s):  
Upper Cretaceous ◽  
The Other

Abstract Describes two specimens of mineralized plant stems collected in the vicinity of Savigne-sur-Lathan, Indre-et-Loire, France, which could definitely be assigned to Palmoxylon ligerinum. One was found in a loose block on the surface of beds attributed to the Bartonian (Eocene); the other is a reworked fragment found in Vindobonian (Miocene) deposits. Discussion of the affinities and stratigraphic distribution (upper Cretaceous?-Tertiary) of P. ligerinum is included.

scholarly journals Sueria laxinervis, a new fossil species of Cycadales from the Upper Cretaceous Quiriquina Formation in Cocholgüe, Bíobío Region, Chile

Phytotaxa ◽  
2019 ◽  
Vol 402 (2) ◽  
pp. 126
Author(s):  
TOSHIHIRO YAMADA ◽  
TAKAE F. YAMADA ◽  
KAZUO TERADA ◽  
TAKESHI A. OHSAWA ◽  
ATSUSHI YABE ◽  
...  
Keyword(s):  
Upper Cretaceous ◽  
Epidermal Cells ◽  
The Other ◽  
Vascular Bundles ◽  
Fossil Species

A new fossil cycad species, Sueria laxinervis, is described from the Upper Cretaceous (Maastrichtian) Quiriquina Formation in Cocholgüe, Bíobío Region, Chile. The generic assignment is supported by the taeniopterid-type leaf with haplocheilic stomata and sinuate anticlinal walls of leaf epidermal cells, while S. laxinervis clearly differs from the other two described Sueria species in its sparse veins and large epidermal cells. The vascular bundles of the midrib are arranged in an inverted-omega shape, supporting the placement of Sueria in Cycadales.

The ichnogenus Tubotomaculum: an enigmatic pellet-filled structure from Upper Cretaceous to Miocene deep-marine deposits of southern Spain

2014 ◽  
Vol 88 (6) ◽  
pp. 1189-1198 ◽  
Author(s):  
Jose Carlos García-Ramos ◽  
María Gabriela Mángano ◽  
Laura Piñuela ◽  
Luis A. Buatois ◽  
Francisco J. Rodríguez-Tovar
Keyword(s):  
Upper Cretaceous ◽  
Western Mediterranean ◽  
Bottom Current ◽  
Nodule Formation ◽  
Organic Detritus ◽  
Marine Deposits ◽  
Hydrocarbon Seeps ◽  
Reducing Conditions ◽  
Mud Volcanism ◽  
Fluid Venting

The trace-fossil name Tubotomaculum has been extensively used to refer to spindle-shaped pellet-filled tubes present in Upper Cretaceous to Miocene deep-marine deposits of the western Mediterranean region. However, it has never been formally diagnosed, and accordingly it was regarded as a nomen nudum. In this paper, we formally introduce the ichnogenus Tubotomaculum, including the new ichnospecies Tubotomaculum mediterranensis. Bioglyphs, represented by scratch traces that may be present on the basal and lateral surfaces of the structure, suggesting production by crustaceans. The functional meaning of these structures challenges the simple model of a mining strategy. Instead, the storing of pellets to use them as a bacteria-enriched resource during times when organic detritus was scarce is suggested. The association with chemoautothrophic bacteria in modern analogs of Tubotomaculum provides a crucial piece of evidence to support the cache model. Integration of information from modern environments and the fossil record points to a connection between Tubotomaculum, mud volcanism, fluid venting, and hydrocarbon seeps. The presence of bioglyphs suggests firmgrounds that may have resulted from bottom current scouring of the sea sediment, leading to erosional exhumation of previously buried compacted sediment, which was therefore available for colonization by the infauna. However, an alternative scenario involves enriched fluids related to mud-volcanism resulting in reducing conditions that favored carbonate precipitation and nodule formation just a few centimeters below the sediment-water interface.

Origins and assessment of snowball Earth hypotheses

2007 ◽  
Vol 144 (4) ◽  
pp. 633-642 ◽  
Author(s):  
W. BRIAN HARLAND
Keyword(s):  
Nineteenth Century ◽  
The Other ◽  
The Arctic ◽  
Snowball Earth ◽  
Late Nineteenth Century ◽  
Personal View ◽  
Tropical Environments ◽  
Palaeomagnetic Data ◽  
Marine Facies ◽  
Late Nineteenth

Brian Harland was for many years an editor of this journal. He was also a seminal figure in the origins of the current ‘snowball Earth’ debate, having recognized in 1964 the significance of coupling emerging palaeomagnetic data on palaeolatitude with his interpretations of diamictites. Harland worked extensively in the Arctic and knew well many of the workers involved in the arguments surrounding the origin of diamictites. He thus had a unique perspective on the evidence and the disputes surrounding it. This was his last paper but he was not able to complete it before he died. However, with the help of Professor Ian Fairchild to whom we are indebted, the editors have lightly revised this work which is presented as the personal view of one of the key figures with a very broad stratigraphic appreciation of the problems of ‘snowball Earth’.Records of Precambrian glaciation onwards from the late nineteenth century led to the concept of one or more major ice ages. This concept was becoming well advanced by the mid 1930s, particularly through the compilation of Kulling in 1934. Even so tillite stratigraphy shows that glaciation was exceptional rather than typical of Earth history. Some Proterozoic tillites, sandwiched between warm marine facies, indicate low, even equatorial palaeolatitudes as determined magnetically, and more recently led to ideas of a snow- and ice-covered ‘snowball Earth’. However, interbedded non-glacial facies as well as thick tillite successions requiring abundant snowfall both militate against the hypothesis of extreme prolonged freezing temperatures referred to here as an ‘iceball Earth’ in which all oceans and seas were sealed in continuous ice cover. On the other hand tropical environments were interrupted by glaciation several times in the Proterozoic, something that did not recur in the Phanerozoic. The term ‘snowball Earth’ is consistent with the established view of extremely widespread Proterozoic glaciation, but the ‘iceball Earth’ version of this is not compatible with the geological record.

Sign in / Sign up

Export Citation Format

Share Document