The Cretaceous Period

2020 ◽  
pp. 1023-1086
Author(s):  
A.S. Gale ◽  
J. Mutterlose ◽  
S. Batenburg ◽  
F.M. Gradstein ◽  
F.P. Agterberg ◽  
...  
Keyword(s):  
Cretaceous Period

scholarly journals REE and Sr–Nd Isotope Characteristics of Cambrian–Ordovician Carbonate in Taebaek and Jeongseon Area, Korea

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 326
Author(s):  
Tae-Hyeon Kim ◽  
Seung-Gu Lee ◽  
Jae-Young Yu
Keyword(s):  
Depositional Environment ◽  
Sea Water ◽  
Geological Time ◽  
Nd Isotope ◽  
Diagenetic Processes ◽  
Platform Margin ◽  
Carbonate Formations ◽  
Diagenetic History ◽  
Cretaceous Period ◽  
Ree Patterns

Carbonate formations of the Cambro-Ordovician Period occur in the Taebaek and Jeongseon areas, located in the central–eastern part of the Korean Peninsula. This study analyzed the rare earth element (REE) contents and Sr–Nd isotope ratios in these carbonates to elucidate their depositional environment and diagenetic history. The CI chondrite-normalized REE patterns of the carbonates showed negative Eu anomalies (EuN/(SmN × GdN)1/2 = 0.50 to 0.81), but no Ce anomaly (Ce/Ce* = CeN/(LaN2 × NdN)1/3 = 1.01 ± 0.06). The plot of log (Ce/Ce*) against sea water depth indicates that the carbonates were deposited in a shallow-marine environment such as a platform margin. The 87Sr/86Sr ratios in both Taebaek and Jeongseon carbonates were higher than those in the seawater at the corresponding geological time. The 87Sr/86Sr ratios and the values of (La/Yb)N and (La/Sm)N suggest that the carbonates in the areas experienced diagenetic processes several times. Their 143Nd/144Nd ratios varied from 0.511841 to 0.511980. The low εNd values and high 87Sr/86Sr ratios in the carbonates may have resulted from the interaction with the hydrothermal fluid derived from the intrusive granite during the Cretaceous Period.

scholarly journals Two new long-rostrum cranefly species from the Cretaceous Iberian amber (Diptera, Limoniidae, Helius)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Iwona Kania-Kłosok ◽  
Wiesław Krzemiński ◽  
Antonio Arillo
Keyword(s):  
Environmental Conditions ◽  
Lower Cretaceous ◽  
Fossil Record ◽  
First Record ◽  
Northern Spain ◽  
Fossil Species ◽  
Body Morphology ◽  
Cretaceous Period ◽  
Basque Cantabrian Basin

AbstractFirst record of the genus Helius—long-rostrum cranefly from Maestrazgo Basin (eastern Spain, Iberian Penisula) is documented. Two new fossil species of the genus Helius are described from Cretaceous Spanish amber and compared with other species of the genus known from fossil record with particular references to these known from Cretaceous period. Helius turolensis sp. nov. is described from San Just amber (Lower Cretaceous, upper Albian) Maestrazgo Basin, eastern Spain, and Helius hispanicus sp. nov. is described from Álava amber (Lower Cretaceous, upper Albian), Basque-Cantabrian Basin, northern Spain. The specific body morphology of representatives of the genus Helius preserved in Spanish amber was discussed in relation to the environmental conditions of the Maestrazgo Basin and Basque-Cantabrian Basin in Cretaceous.

First freshwater gastropod preserved in amber suggests long-distance dispersal during the Cretaceous Period

2021 ◽  
pp. 1-8
Author(s):  
Tingting Yu ◽  
Thomas A. Neubauer ◽  
Adrienne Jochum
Keyword(s):  
New Species ◽  
Freshwater Snail ◽  
Aquatic Biota ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Burmese Amber ◽  
Freshwater Gastropod ◽  
The Family ◽  
Cretaceous Period ◽  
Globally Distributed

Abstract Burmese amber continues to provide unique insights into the terrestrial biota inhabiting tropical equatorial forests during mid-Cretaceous time. In contrast to the large amount and great diversity of terrestrial species retrieved so far, aquatic biota constitute rare inclusions. Here we describe the first freshwater snail ever preserved in amber. The new species Galba prima sp. nov. belongs in the family Lymnaeidae, today a diverse and near globally distributed family. Its inclusion in terrestrial amber is probably a result of the amphibious lifestyle typical of modern representatives of the genus. The finding of a freshwater snail on the Burma Terrane, back then an island situated at some 1500 km from mainland Asia, has implications for the dispersal mechanisms of Mesozoic lymnaeids. The Cenomanian species precedes the evolution of waterfowl, which are today considered a main vector for long-distance dispersal. In their absence, we discuss several hypotheses to explain the disjunct occurrence of the new species.

Subsidence and sea-level rise in the Thames Estuary

1972 ◽  
Vol 272 (1221) ◽  
pp. 121-130 ◽  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Average Rate ◽  
Thames Estuary ◽  
The North ◽  
Storm Waves ◽  
Late Cretaceous Period ◽  
The North Sea ◽  
Sea Area ◽  
Cretaceous Period

The development of the area, of the Thames Estuary is briefly traced since the late Cretaceous period, with its present outline being due to a combination of factors. The overall subsidence of the North Sea area, the ‘Alpine5 fold movements, and the transgression of the sea since the retreat of the Weichselian icesheets have all contributed. The positions of the shore-line during the critical phase, 9600 b.p. to 8000 b.p., of this last transgression of the sea are shown. Subsequent to this main transgressive phase, erosion of the shoreline has been rapid due to storm-waves and tidal current action. An estimation of the average rate of subsidence and/or sea-level rise is given based on the concept of sedimentary equilibrium in which a figure of 12.7 cm (5 in) per century is arrived at.

The Cretaceous Period

2005 ◽  
pp. 344-383 ◽  
Author(s):  
J. G. Ogg ◽  
F. P. Agterberg ◽  
F. M. Gradstein
Keyword(s):  
Cretaceous Period

scholarly journals Paleontology of the Bears Ears National Monument: history of exploration and designation of the monument

2018 ◽  
Author(s):  
Jessica Uglesich ◽  
Robert J Gay ◽  
M. Allison Stegner ◽  
Adam K Huttenlocker ◽  
Randall B Irmis
Keyword(s):  
Fossil Record ◽  
Landscape Scale ◽  
Ice Age ◽  
Bureau Of Land Management ◽  
National Monument ◽  
Resource Protection ◽  
History Of ◽  
Last Ice Age ◽  
Dry Climates ◽  
Cretaceous Period

Bears Ears National Monument (BENM) is a new, landscape-scale national monument jointly administered by the Bureau of Land Management and the Forest Service in southeastern Utah as part of the National Conservation Lands system. As initially designated, BENM encompasses 1.3 million acres of land with exceptionally fossiliferous rock units. These units comprise a semi-continuous depositional record from the Pennsylvanian Period through the middle of the Cretaceous Period. Additional Quaternary and Holocene deposits are known from unconsolidated river gravels and cave deposits. The fossil record from BENM provides unique insights into several important paleontological periods of time, including the Pennsylvanian-Permian transition from fully aquatic to more fully terrestrial tetrapods; the rise of the dinosaurs following the Triassic-Jurassic extinction; and the response of ecosystems in dry climates to sudden temperature increases at the end of the last ice age and across the Holocene. While the paleontological resources of BENM are extensive, they have historically been under-studied. Here we summarize prior paleontological work in BENM and review the data used to support paleontological resource protection in the 2016 BENM proclamation.

Rare earth element characteristics and K–Ar ages of the Band Ziarat ophiolite complex, southeastern Iran

1996 ◽  
Vol 33 (11) ◽  
pp. 1534-1542 ◽  
Author(s):  
A. A. Hassanipak ◽  
A. Mohamad Ghazi ◽  
J. M. Wampler
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Western Boundary ◽  
Crustal Rocks ◽  
Fault Systems ◽  
Major Fault ◽  
High Level ◽  
Ocean Ridge ◽  
Cretaceous Period

The Band Ziarat complex of southeastern Iran is located on the western boundary of the Jaz Murian depression and is bounded by two major fault systems. The principal rock units of this complex are a gabbro sequence that includes low-and high-level cumulate gabbros, a late intrusive sequence that consists of diorite and plagiogranite, and a volcanic sequence that includes diabase dikes and a lesser amount of basaltic lava. Mantle rocks are virtually absent because of the presence of the two bounding fault systems, but we consider the complex to be an ophiolite in nature. Rare earth element (REE) whole-rock data clearly differentiate the classic ophiolitic lithologies for the crustal rocks in this complex. Based on the REE data, there are two distinct types of basalt present at Band Ziarat: (i) those that formed from an initial basaltic melt with a light rare earth element (LREE) enriched signature (similar to intraplate basalts), and (ii) those that have LREE-depleted patterns (similar to normal mid-ocean-ridge basalts). The data also suggest (i) that the gabbros are accumulates and were derived from a source slightly enriched in LREE, with fractionation controlled by removal of clinopyroxene or hornblende and plagioclase, and (ii) that the late intrusive rocks as well as a majority of the diabase dikes are cogenetic and were derived from the same LREE-enriched source. K–Ar ages ranging from 134 ± 4 to 146 ± 5 Ma for low-level gabbros and from 121 ± 4 to 130 ± 4 Ma for high-level gabbros were measured on five hornblende and two whole-rock samples, which suggests that these rocks may have formed early in the Cretaceous period.

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