نتایج جستجو برای: geochemical ratios

تعداد نتایج: 134511  

2015
Mace G. Barron Jill Awkerman Sandy Raimondo

Barrier islands of Northwest Florida were heavily oiled during the Deepwater Horizon spill, but less is known about the impacts to the shorelines of the associated estuaries. Shoreline sediment oiling was investigated at 18 sites within the Pensacola Bay, Florida system prior to impact, during peak oiling, and post-wellhead capping. Only two locations closest to the Gulf of Mexico had elevated ...

2014
Brandon Lee Drake Wirt H. Wills Marian I. Hamilton Wetherbee Dorshow

Strontium isotope sourcing has become a common and useful method for assigning sources to archaeological artifacts.In Chaco Canyon, an Ancestral Pueblo regional center in New Mexico, previous studiesusing these methods have suggested that significant portion of maize and wood originate in the Chuska Mountains region, 75 km to the West [corrected]. In the present manuscript, these results were t...

Journal: :Lithos 2023

Widespread orogenesis associated with supercontinent assembly generates extensive collisional mountain chains high elevations that are crucial for modulating the interaction between atmosphere and lithosphere. However, not all supercontinents formed over Earth's history shared same topography. This study investigates temporal variation last 1.5 Ga in La/Zr ratio of continental-arc mafic volcani...

2010
N. J Pearson

Introduction High precision in situ analysis of trace-element compositions and isotope ratios has revolutionised geochronology and geochemistry over the past decade. Most of the advances are due to the proliferation of laser-ablation microprobe inductively coupled plasma mass spectrometry (ICP-MS) and the rapid development of the multi-collector (MC-) ICP-MS. One of the main benefits of in situ...

2004
Fenglin Niu Alan Levander Catherine M. Cooper Cin-Ty Aeolus Lee Adrian Lenardic David E. James

S–P travel-time residuals and receiver-function images are used to infer the Vp/Vs (compressional to shear wave velocity) ratio of the lithospheric mantle beneath southern African and the topography of the underlying 410-km discontinuity. Low Vp/Vs ratios provide evidence independent of geochemical observations for a highly depleted root (Mg#f92–94) beneath the Kaapvaal craton. The receiver-fun...

2015
Lei Dou Tingting Li L. Dou T. T. Li

Soil heavy metal pollution is one of the main environmental problems in Pearl River Delta Economic Zone of China. Based on multi-purpose regional geochemical survey, regional eco-geochemical assessment, local eco-geochemical assessment and comprehensive appraisal, the eco-geochemical survey and assessment in Pearl River Delta Economic Zone of 41,698 km2 were completed. Samples from soils were c...

2004
Alireza Panahi Qiuming Cheng Graeme F. Bonham-Carter

Combined geostatistical and multifractal power-spectrum modelling of geochemical distributions can provide suitable indicators of metal dispersion, and is capable of analysing complex problems for targeting potential areas for mineral exploration. A case study analysing lake sediment geochemical data for the Gowganda area is presented and development of the methodology for spatial analysis of t...

Journal: :Geobiology 2013
J Huang X Chu T W Lyons N J Planavsky H Wen

Acanthomorphic acritarch fossils, including some interpreted to be the fossils of the earliest animal embryos, first appear in the lower Doushantuo Formation of the Yangtze Gorges area (YGA). Further, the complete paleontological and geochemical record for the YGA has played a central role in defining the global biological and geochemical backdrop that presaged and witnessed the dawn of diverse...

Journal: :زمین شناسی اقتصادی 0
مریم عبدی محمد حسن کریم پور

the kuh shah prospecting area is located in tertiary volcano-plutonic belt of the lut block. more than seventeen subvolcanic intermediate to acidic intrusive rocks, diorite to syenite in composition, were identified in the study area. the intrusions are related to hydrothermal alteration zones and contain argillic, propylitic, advanced argillic, silicified, quartz-sericite-pyrite, gossan and hy...

2016
Robert E. Danczak Steven B. Yabusaki Kenneth H. Williams Yilin Fang Chad Hobson Michael J. Wilkins

Citation: Danczak RE, Yabusaki SB, Williams KH, Fang Y, Hobson C and Wilkins MJ (2016) Snowmelt Induced Hydrologic Perturbations Drive Dynamic Microbiological and Geochemical Behaviors across a Shallow Riparian Aquifer. Front. Earth Sci. 4:57. doi: 10.3389/feart.2016.00057 Snowmelt Induced Hydrologic Perturbations Drive Dynamic Microbiological and Geochemical Behaviors across a Shallow Riparian...

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