Noble gas abundance patterns in deep-sea basalts — Primordial gases from the mantle     

Jack Dymond  Lewis Hogan 《Earth and Planetary Science Letters》1973,20(1):131-139

Rapidly cooled portions of eleven samples of mid-ocean ridge tholeiitic basalt pillows have noble gas abundance patterns which resemble the solar rare gas pattern rather than the noble gas pattern of the terrestrial atmosphere. We conclude that these samples contain primordial noble gases. In contrast, holocrystalline samples and a sample from the interior of a basalt pillow have noble gas abundance patterns which resemble the sea water pattern. Whereas the quenched glossy margins of basalt pillows record a non-atmospheric gas reservoir, these slowly cooled samples apparently have undergone exchange of their noble gases with those dissolved in sea water.  相似文献   

Composition,physical properties and origin of sodic anorthites from the ejected plutonic blocks of the Soufrière Volcano,St. Vincent,West Indies     

Dr. John F. Lewis 《Contributions to Mineralogy and Petrology》1969,21(3):272-294

Three complete analyses and one partial analysis are recorded of unzoned sodic anorthites having compositions An_94,9, An_94,0, An_92,7 and An₉₂ (mol per cent). Although crystallising at a high temperature the K and Sr contents are low. X-ray parameters show the material to be in a relatively high structural state comparable with material from Japanese volcanics. Available data indicate small but real differences in optical parameters between sodic anorthites of volcanic and plutonic origin but this needs further clarification. Refractive indices and specific gravities of the analysed samples are also recorded. Anorthite (An₉₀-An₁₀₀) occurs widely as phenocrysts in basic lavas and as crystal ejecta in the calc-alkaline rock suites of the circumoceanic islands. Anorthite can be precipitated from sub-alkaline magmas under certain conditions and does not require the postulation of special magmas or of contamination. It is apparent that factors other than the normative feldspar composition of the magma determine the composition of the plagioclase precipitated. Evidence from experimental work on synthetic systems indicates that an increase in both hydrostatic pressure and water vapour pressure will influence the plagioclase composition but it is not possible to evaluate these effects fully at the present time. The occurrence of anorthite is interpreted as evidence of extensive crystal accumulation at depth from fractionating basic magmas in circumoceanic calc-alkaline suites.  相似文献   

Circular meander pools     

John J. Alford  Robert H. Baumann  Anthony J. Lewis 《地球表面变化过程与地形》1982,7(2):183-188

Aerial photographs led to the detection of a previously undescribed type of river meander. These features are characterized by nearly circular pools located at the apex of the bend and are widely distributed on small to medium sized coastal plain streams in the southeastern United States. Bathymetric evidence shows that the structure of meanders containing circular pools is distinctive. Field and laboratory evidence suggests that these features are formed by a short-lived countercurrent that develops during the flood cycle.  相似文献   

Comment on “rejection of palaeomagnetic observations” by P.L. McFadden     

Nicholas I. Fisher  Toby Lewis  Mary E. Willcox 《Earth and Planetary Science Letters》1983,64(2):316-317

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Forest carbon storage and tree carbon pool dynamics under natural forest protection program in northeastern China   总被引：1，自引：1，他引：0  

Yawei Wei  Dapao Yu  Bernard Joseph Lewis  Li Zhou  Wangming Zhou  Xiangmin Fang  Wei Zhao  Shengnan Wu  Limin Dai 《中国地理科学(英文版)》2014,24(4):397-405

The Natural Forest Protection(NFP) program is one of the Six Key Forestry Projects which were adopted by the Chinese Government since the 1980s to address important natural issues in China. It advanced to protecting and restoring the structures and functions of the natural forests through sustainable forest management. However, the role of forest carbon storage and tree carbon pool dynamics since the adoption of the NFP remains unknown. To address this knowledge gap, this study calculated forest carbon storage(tree, understory, forest floor and soil) in the forest region of northeastern(NE) China based on National Forest Inventory databases and field investigated databases. For tree biomass, this study utilized an improved method for biomass estimation that converts timber volume to total forest biomass; while for understory, forest floor and soil carbon storage, this study utilized forest type-specific mean carbon densities multiplied by their areas in the region. Results showed that the tree carbon pool under the NFP in NE China functioned as a carbon sink from 1998 to 2008, with an increase of 6.3 Tg C/yr, which was mainly sequestrated by natural forests(5.1 Tg C/yr). At the same time, plantations also acted as a carbon sink, reflecting an increase of 1.2 Tg C/yr. In 2008, total carbon storage in forests covered by the NFP in NE China was 4603.8 Tg C, of which 4393.3 Tg C was stored in natural forests and 210.5 Tg C in planted forests. Soil was the largest carbon storage component, contributing 69.5%–77.8% of total carbon storage; followed by tree and forest floor, accounting for 16.3%–23.0% and 5.0%–6.5% of total carbon storage, respectively. Understory carbon pool ranged from 1.9 to 42.7 Tg C, accounting for only 0.9% of total carbon storage.  相似文献   

A comprehensive look at technology transfer     

Joanna I. Lewis 《Climate Policy》2015,15(1):177-179

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Bay of Bengal cyclone extreme water level estimate uncertainty   总被引：4，自引：3，他引：1  

Matt Lewis  Kevin Horsburgh  Paul Bates 《Natural Hazards》2014,72(2):983-996

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As the world warmed: Human adaptations across the Pleistocene–Holocene boundary     

Lewis R. Binford 《Geoarchaeology》1999,14(4):369-371

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