نتایج جستجو برای: sedimentary phosphate

تعداد نتایج: 115052  

2016
Dan Matsumoto Yuki Sawai Masaki Yamada Yuichi Namegaya Tetsuya Shinozaki Daisuke Takeda Shigehiro Fujino Koichiro Tanigawa Atsunori Nakamura Jessica E. Pilarczyk

Erosional and sedimentary features associated with flooding have been documented in both modern and past cases. However, only a few studies have demonstrated the relationship between these features and the corresponding hydraulic conditions that produced them, making it difficult to evaluate the magnitude of paleo-flooding. This study describes the characteristics associated with inundation dep...

1998
ALAN GALLEY MARK HANNINGTON IAN JONASSON

Volcanogenic massive sulphide (VMS) deposits are also known as volcanic-associated, volcanic-hosted, and volcano-sedimentary-hosted massive sulphide deposits. They typically occur as lenses of polymetallic massive sulphide that form at or near the seafloor in submarine volcanic environments. They form from metal-enriched fluids associated with seafloor hydrothermal convection. Their immediate h...

Journal: :Global and planetary change 1990
J C Walker

Climate is an important environmental parameter of the early Earth, likely to have affected the origin and evolution of life, the composition and mineralogy of sedimentary rocks, and stable isotope ratios in sedimentary minerals. There is little observational evidence constraining Precambrian climates. Most of our knowledge is at present theoretical. Factors that must have affected the clima...

2015
Kirsten Zaczek Valentin R. Troll Mario Cachao Jorge Ferreira Frances M. Deegan Juan Carlos Carracedo Vicente Soler Fiona C. Meade Steffi Burchardt

The origin and life cycle of ocean islands have been debated since the early days of Geology. In the case of the Canary archipelago, its proximity to the Atlas orogen led to initial fracture-controlled models for island genesis, while later workers cited a Miocene-Quaternary east-west age-progression to support an underlying mantle-plume. The recent discovery of submarine Cretaceous volcanic ro...

2016
I. Campaña A. Pérez-González A. Benito-Calvo J. Rosell R. Blasco J. M. Bermúdez de Castro E. Carbonell J. L. Arsuaga

Gran Dolina is a cavity infilled by at least 25 m of Pleistocene sediments. This sequence contains the TD6 stratigraphic unit, whose records include around 170 hominin bones that have allowed the definition of a new species, Homo antecessor. This fossil accumulation was studied as a single assemblage and interpreted as a succession of several human home bases. We propose a complete stratigraphi...

Ali Rostamnejad Diba Ghonchepour Mostafa Moradi Dashtpagerdi Payman Rezaee

The coastal region of Chabahar Gulf with 1113.7km2 area has been located in the southeast of Iran. In this research, satellite images of ETM+ (2004) were used in order to zoning of sedimentary environments in this Gulf. Methodology of this research was baesd on synthesis of supervised and unsupervised classifications in GIS and ENVI softwares. Based on studies and calculat...

2015
Jacek Bełdowski Michał Miotk Janusz Pempkowiak

Methylmercury (MeHg) is the most bioavailable and toxic mercury species in the marine environment. MeHg concentration levels, methylation rates leading to MeHg formation, and methylation index (MI) are all used to assess the compliance of mercury to be methylated in the marine sedimentary environment. This paper reports on the works conducted on the MI upgrade. This paper proposes a new formula...

Journal: :University of Pennsylvania Law Review 1998

Journal: :Environmental monitoring and assessment 2012
B Nagender Nath N H Khadge Sapana Nabar Chandralata Raghukumar B S Ingole A B Valsangkar Rahul Sharma K Srinivas

An area of 0.6 km(2) in the manganese nodule field of the Central Indian Basin was physically disturbed and sediments discharged in the near bottom waters to simulate seabed mining and study its impact on benthic ecosystem. An estimated 2 to 3 tonnes of sedimentary organic carbon (C(org)) was resuspended into the water column during a 9-day experiment. The majority of the sediment cores from wi...

2015
Guy B. M S. Ono J. Gutzmer Y. Lin

23 24 Large rounded pyrite grains (>1 mm), commonly referred to as ‘buckshot’ pyrites, are a characteristic feature of 25 the auriferous conglomerates (reefs) in the Witwatersrand and Ventersdorp supergroups. Detailed petrographic 26 analyses of the reefs indicated that the vast majority of the buckshot pyrites are of reworked sedimentary origin, 27 i.e., that the pyrite originally formed in th...

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