Mineralogical characteristics and geological significance of Albian (Early Cretaceous) glauconite in Zanda, southwestern Tibet, China

Clay Minerals ◽  
2012 ◽  
Vol 47 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Xiang Li ◽  
Yuanfeng Cai ◽  
Xiumian Hu ◽  
Zhicheng Huang ◽  
Jiangang Wang
Keyword(s):  
Early Cretaceous ◽  
Depositional Environments ◽  
Indian Plate ◽  
Sea Levels ◽  
X Ray ◽  
Northern Margin ◽  
Mineralogical Characteristics ◽  
Antarctic Continent ◽  
Rising Sea Levels ◽  
Highly Evolved

AbstractEarly Cretaceous glauconite from the Xiala section, southwestern Tibet, China, was investigated by petrographic microscopy and scanning electron microscopy (SEM), X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, and electron probe microanalysis (EPMA). The investigations revealed that the glauconite in both sandstones and limestone is highly evolved. The glauconite in sandstone is autochthonous, but in limestone it may be derived from the underlying glauconitic sandstone. Based on analyses of the depositional environments and comparisons of glauconite-bearing strata in Zanda with sequences in adjacent areas, we conclude that the glauconitization at Zanda was probably associated with rising sea levels during the Late Albian, which represent the final separation of the Indian continent from the Australian-Antarctic continent. After the separation of the Indian continent from the Australian-Antarctic continent, cooling of the Indian continent resulted in subsidence and northward subduction of the Indian plate. A gradually rising sea level in Zanda, located along the northern margin of the Indian continent, was the cause of the low sedimentation rate. Continued transgression resulted in the occurrence of the highly evolved glauconite in this area.

Expanse of greater india in the cretaceous

2021 ◽  
Author(s):  
Jun Meng ◽  
Stuart Gilder ◽  
Yalin Li ◽  
Chengshan Wang
Keyword(s):  
Early Cretaceous ◽  
Plate Boundary ◽  
Vertical Axis ◽  
Indian Plate ◽  
Paleomagnetic Data ◽  
Fundamental Parameter ◽  
The Tibetan Plateau ◽  
Northern Margin ◽  
Indian Lithosphere ◽  
Tethyan Himalaya

<p>Knowing the original size of Greater India is a fundamental parameter to quantify the amount of continental lithosphere that was subducted to help form the Tibetan Plateau and to constrain the tectonic evolution of the India-Asia collision. Here, we report Early Cretaceous paleomagnetic data from the central and eastern Tethyan Himalaya that yield paleolatitudes consistent with previous Early Cretaceous paleogeographic reconstructions. These data suggest Greater India extended at least 2,675 ± 720 and 1,950 ± 970 km farther north from the present northern margin of India at 83.6°E and 92.4°E, respectively. The paleomagnetic data from Upper Cretaceous rocks of the western Tethyan Himalaya that are consistent with a model that Greater India extended ~2700 km farther north from its present northern margin at the longitude of 79.6°E before collision with Asia. Our result further suggests that the Indian plate, together with Greater India, acted as a single entity since at least the Early Cretaceous. An area of lithosphere ≥4.7 × 10<sup>6</sup> km<sup>2</sup> was consumed through subduction, thereby placing a strict limit on the minimum amount of Indian lithosphere consumed since the breakup of Gondwanaland. The pre-collision geometry of Greater India’s leading margin helped shape the India-Asia plate boundary. The proposed configuration produced right lateral shear east of the indenter, thereby accounting for the clockwise vertical axis block rotations observed there.</p>

Sideritic ironstones as indicators of depositional environments in the Weald Basin (Early Cretaceous) SE England

2017 ◽  
Vol 156 (3) ◽  
pp. 533-546 ◽  
Author(s):  
OLADAPO AKINLOTAN
Keyword(s):  
Trace Element ◽  
Elemental Composition ◽  
Early Cretaceous ◽  
Lower Cretaceous ◽  
Sedimentary Basins ◽  
Depositional Environments ◽  
X Ray ◽  
Depositional Settings ◽  
Clay Formation ◽  
Host Rocks

AbstractThe Lower Cretaceous Wealden sideritic ironstones have a wide occurrence and great potential to aid the reconstruction of the depositional environments of the Weald Basin in SE England. However, mineralogical and geochemical datasets on the ironstones are scarce in the literature. Geochemical and mineralogical data on the sideritic ironstones are presented from the Wadhurst Clay Formation within the Weald Basin. The mineralogy of the ironstones was examined using a PANalytical X'Pert Pro X-ray diffractometer and PANalytical's HighScore Plus software. Elemental composition of the ironstones was measured using a PANalytical MiniPal2 ED-XRF (benchtop X-ray spectrometer). The examination of the mineralogy of the Wealden ironstones confirms the presence of early diagenetic siderites. The trace-element assemblage shows that the sideritic ironstones are chemically pure pointing to a freshwater origin. The sideritic ironstones reveal anoxic conditions and palaeo-salinity in the basin. More generally, it is suggested that the composition of the host rocks has significant controls on the composition of sideritic ironstones in sedimentary basins. This work reinforces the importance of the composition of sideritic ironstones as useful non-traditional data for understanding the depositional settings of sedimentary basins, especially when traditional datasets are not readily available or insufficient.

An Imperial Disaster

2018 ◽  
Author(s):  
Benjamin Kingsbury
Keyword(s):  
Natural Disasters ◽  
Bay Of Bengal ◽  
Full Moon ◽  
Economic Power ◽  
Sea Levels ◽  
Natural Event ◽  
Cholera Epidemic ◽  
British Rule ◽  
Great Rivers ◽  
Rising Sea Levels

The storm came on the night of 31 October. It was a full moon, and the tides were at their peak; the great rivers of eastern Bengal were flowing high and fast to the sea. In the early hours the inhabitants of the coast and islands were overtaken by an immense wave from the Bay of Bengal — a wall of water that reached a height of 40 feet in some places. The wave swept away everything in its path, drowning around 215,000 people. At least another 100,000 died in the cholera epidemic and famine that followed. It was the worst calamity of its kind in recorded history. Such events are often described as "natural disasters." This book turns that interpretation on its head, showing that the cyclone of 1876 was not simply a "natural" event, but one shaped by all-too-human patterns of exploitation and inequality — by divisions within Bengali society, and the enormous disparities of political and economic power that characterized British rule on the subcontinent. With Bangladesh facing rising sea levels and stronger, more frequent storms, there is every reason now to revisit this terrible calamity.

scholarly journals Discovery of Lebambromyia in Myanmar Cretaceous Amber: Phylogenetic and Biogeographic Implications (Insecta, Diptera, Phoroidea)

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 354
Author(s):  
Davide Badano ◽  
Qingqing Zhang ◽  
Michela Fratini ◽  
Laura Maugeri ◽  
Inna Bukreeva ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Phase Contrast ◽  
First Record ◽  
Geographic Range ◽  
X Ray ◽  
Monophyletic Lineage ◽  
Cladistic Analyses

Lebambromyia sacculifera sp. nov. is described from Late Cretaceous amber from Myanmar, integrating traditional observation techniques and X-ray phase contrast microtomography. Lebambromyia sacculifera is the second species of Lebambromyia after L. acrai Grimaldi and Cumming, described from Lebanese amber (Early Cretaceous), and the first record of this taxon from Myanmar amber, considerably extending the temporal and geographic range of this genus. The new specimen bears a previously undetected set of phylogenetically relevant characters such as a postpedicel sacculus and a prominent clypeus, which are shared with Ironomyiidae and Eumuscomorpha. Our cladistic analyses confirmed that Lebambromyia represented a distinct monophyletic lineage related to Platypezidae and Ironomyiidae, though its affinities are strongly influenced by the interpretation and coding of the enigmatic set of features characterizing these fossil flies.

Potential impacts of global warming on water resources in southern California

2003 ◽  
Vol 47 (7-8) ◽  
pp. 165-168 ◽  
Author(s):  
M. Beuhler
Keyword(s):  
Global Warming ◽  
Surface Water ◽  
Water Resources ◽  
Southern California ◽  
Salt Water ◽  
Scenario Planning ◽  
Potential Range ◽  
Water Supplies ◽  
Sea Levels ◽  
Rising Sea Levels

Global warming will have a significant impact on water resources within the 20 to 30-year planning period of many water projects. Arid and semi-arid regions such as Southern California are especially vulnerable to anticipated negative impacts of global warming on water resources. Long-range water facility planning must consider global climate change in the recommended mix of new facilities needed to meet future water requirements. The generally accepted impacts of global warming include increased temperature, rising sea levels, more frequent and severe floods and droughts, and a shift from snowfall to rain. Precipitation changes are more difficult to predict. For Southern California, these impacts will be especially severe on surface water supplies. Additionally, rising sea levels will exacerbate salt-water intrusion into freshwater and impact the quality of surface water supplies. Integrated water resources planning is emerging as a tool to develop water supplies and demand management strategies that are less vulnerable to the impacts of global warming. These tools include water conservation, reclamation, conjunctive use of surface and groundwater and desalination of brackish water and possibly seawater. Additionally, planning for future water needs should include explicit consideration of the potential range of global warming impacts through techniques such as scenario planning.

scholarly journals Effects of climate change on spatiotemporal patterns of tropical cyclone tracks and their implications for coastal agriculture in Myanmar

2021 ◽  
Author(s):  
Akira Hirano
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Considerable Increase ◽  
Hot Spot ◽  
Coastal Region ◽  
Storm Surges ◽  
Coastal Areas ◽  
Spatiotemporal Patterns ◽  
Sea Levels ◽  
Rising Sea Levels

AbstractImportant aspects for understanding the effects of climate change on tropical cyclones (TCs) are the frequency of TCs and their tracking patterns. Coastal areas are increasingly threatened by rising sea levels and associated storm surges brought on by TCs. Rice production in Myanmar relies strongly on low-lying coastal areas. This study aims to provide insights into the effects of global warming on TCs and the implications for sustainable development in vulnerable coastal areas in Myanmar. Using TC records from the International Best Track Archive for Climate Stewardship dataset during the 30-year period from 1983 to 2012, a hot spot analysis based on Getis-Ord (Gi*) statistics was conducted to identify the spatiotemporal patterns of TC tracks along the coast of Myanmar. The results revealed notable changes in some areas along the central to southern coasts during the study period. These included a considerable increase in TC tracks (p value < 0.01) near the Ayeyarwady Delta coast, otherwise known as “the rice bowl” of the nation. This finding aligns with trends in published studies and reinforced the observed trends with spatial statistics. With the intensification of TCs due to global warming, such a significant increase in TC experiences near the major rice-producing coastal region raises concerns about future agricultural sustainability.

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