Excursion to St. Leonards: Saturday,May 21st, 1921     

W.J. Lewis Abbott 《Proceedings of the Geologists' Association. Geologists' Association》1921,32(4):226-IN3

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Notes on some pleistocene sections in and near London     

W.J. Lewis Abbott 《Proceedings of the Geologists' Association. Geologists' Association》1890,11(8):473-480

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Implications of estimated and measured thermal conductivity for oceanic heat flow studies     

Carol A. Stein  Dallas H. Abbott 《Marine Geophysical Researches》1991,13(4):311-329

Heat flow data provide constraints on the thermal structure and evolution of the oceanic lithosphere. Because precise determination of the heat flux requires that both the thermal gradient and the thermal conductivity be well determined we have examined the thermal conductivities used in a new Pacific Basin heat flow data set. 43% of the 1600 heat flow determinations rely on values estimated by various methods, rather than directly measured. Although the measured and estimated conductivities have comparable means, the measured conductivities have a standard deviation 50% larger than the estimated, suggesting that the estimated values underestimate the actual variation. We investigate the limitations of using such estimates by examining factors controlling the variations of measured conductivity values. We find that the variation between the closest adjacent sites increases with increasing separation, such that sites within 200 km are on average noticeably closer in conductivity than sites further apart. Contributing to this effect may be the variation of conductivity with lithology (with mean conductivity highest for carbonate oozes, intermediate for deep-sea clays, and least for siliceous oozes) and a possible trend of decreasing conductivity with increasing seafloor depth. Tests with the measured data suggest that the best method for estimating conductivity is using the mean value measured within 200 km. The mean of a larger geographical region is a somewhat poorer predictor, and using the oceanwide mean and the value at the nearest site are poorer still. Approximately 29% of the estimated values were not based on measurements from a reference site. For most others, the reference site was the nearest measurement from the same cruise, typically a large distance away. For those sites where conductivity was not measured, 78% had measured conductivity within 200 km and were reestimated using the local mean, whereas the remaining 22% were reestimated using the regional mean. The resulting change in the estimated conductivity averaged 9% using the local mean and 6% using the regional mean. We suggest that such a procedure be used to improve the utility of the heat flow data set, as an alternative to discarding the large fraction of the available data that does not incorporate measured conductivities.  相似文献   

Crossing new frontiers: extending tephrochronology as a global geoscientific research tool     

Peter M. Abbott  Britta J. L. Jensen  David J. Lowe  Takehiko Suzuki  Daniel Veres 《第四纪科学杂志》2020,35(1-2):1-8

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Predicting financial barriers to formal healthcare utilisation among poor older people under the Livelihood Empowerment Against Poverty Programme in Ghana     

Oduro Appiah  Joseph  Agyemang-Duah  Williams  Fordjour  Audrey Amponsah  Adei  Dina 《GeoJournal》2022,87(1):333-347

GeoJournal - Poor older people surviving under the Livelihood Empowerment Against Poverty (LEAP) programme continue to experience financial difficulties to formal healthcare utilisation despite the...  相似文献   

Kinetics of the Reactions of IO with HO2 and O(3P)     

Carlos E. Canosa-mas  Mark L. Flugge  Dina Shah  Alison Vipond  Richard P. Wayne 《Journal of Atmospheric Chemistry》1999,34(1):153-162

A discharge-flow tube coupled with resonance fluorescence and chemiluminescence detection has been used to investigate the reactions IO + HO₂ products (1) and IO + O(³P) I + O₂(2), at T = 296 ± 1 K and P = 1.7 - 2 Torr. The rate constants k_-1 and k₂ have been found to be (7.1 ± 1.6) × 10^-11 cm³ molecule^-1 s^-1 and (1.35 ± 0.15) × 10^-10 cm³ molecule^-1 s^-1, respectively.  相似文献   

重庆南川地区龙潭组页岩气地质特征与甜点优选     

何贵松  何希鹏  高玉巧  陈程  王德喜  张培先  周頔娜 《地质学报》2022,96(6):2131-2142

海陆过渡相富有机质含气页岩是页岩气勘探的重要领域。利用地震、钻井、测井、分析测试等资料，选择重庆南川地区为研究对象，对我国南方四川盆地东南缘地区二叠统龙潭组页岩气勘探潜力系统评价。从沉积环境、岩性组合、有机地化、储层物性、含气性、矿物组成等页岩气成藏地质条件等方面入手，探讨了页岩气富集主控因素，优选了甜点区和甜点段。研究结果表明：① 南川地区龙潭组处于潟湖相，富有机质黑色泥页岩发育，累厚50~65 m，单层厚度26~32 m，埋深主体在1000~4000 m之间。② 地球化学指标适中，TOC含量2. 0%~3. 0%，Ro为2. 0%~2. 2%，有机质类型为Ⅲ~Ⅱ2型。③ 含气性较好，气测全烃一般3%~25. 5%，含气量1. 5~3. 5 m3/t。④ 硅质、碳酸盐矿物等脆性矿物含量较高，具有较大页岩气勘探潜力。⑤ 龙潭组页岩气富集高产具有相带控烃、保存控富、可压控产“三控”规律，即潟湖相影响泥页岩厚度及地化指标，控制页岩气富集烃源基础；保存条件影响地层压力和滞留气含量，控制页岩气富集的程度；可压裂性影响改造体积和缝网复杂程度，控制页岩气井产量。⑥ 初步建立了南川地区龙潭组页岩气甜点区目标评价方法和标准，优选出具有一定构造稳定区面积、页岩气成藏指标较好、埋深适中的阳春沟背斜、东胜背斜为Ⅰ类区。⑦ 建立了以TOC、孔隙度、含气量、脆性矿物含量四项主要参数为指标的储层综合评价指数（RCEI），优选出潭三段为页岩气勘探甜点段，潭三段上部为水平井最优穿层靶窗。  相似文献   

Petrology of the Nandewar Volcano,N.S.W., Australia     

M. J. Abbott 《Contributions to Mineralogy and Petrology》1969,20(2):115-134

The Nandewar Mountains, N.S.W., Australia, are the remains of a Miocene continental alkaline volcano whose products range from olivine basalts to comendites and alkali rhyolites. Intermediate hawaiites, mugearites and benmoreites predominate in the shield, in which olivine basalts are rare, and the trachytic rocks form many intrusions into the shield. The Nandewar alkaline series shows extreme fractionation of a relatively differentiated alkali olivine basalt magma, saturated with silica, to yield extremely oversaturated peralkaline comendites and peraluminous alkali rhyolites. The nature of the ferromagnesian phases forming was controlled by low oxygen fugacities. Throughout the series clinopyroxenes range from diopsidic augite, through sodic ferrohedenbergites to hedenbergite-acmite solid solutions. Riebeckite-arfvedsonite solid solutions appear in the trachytes and comendites, and aenigmatite appears in some of the peralkaline rocks. The feldspars in the series fractionate from calcic labradorite through potash oligoclase and calcic anothoclase towards the minimum melting alkali feldspar composition, Ab₆₅Or₃₅. The compositions of the alkali rhyolites approach the minimum in the system SiO₂-KAlSi₃O₈-NaAlSi₃O₈. All the mineralogical and chemical evidence points to the development of the Nandewar series by the processes of extreme crystallization differentiation of an alkali olivine basalt parent magma. No significant contamination occurred, xenoliths and xenocrysts are absent, and volatile transfer and metasomatism played a minor role.  相似文献   

Comparison of the Jurassic and Cretaceous sedimentary cycles of Somalia and Madagascar: implications for the Gondwana breakup     

Peter Luger  M. Gröschke  M. Bussmann  A. Dina  W. Mette  A. Uhmann  H. Kallenbach 《International Journal of Earth Sciences》1994,83(4):711-727

The Jurassic and Cretaceous sedimentary history of northern Somalia and the Morondava Basin of south-western Madagascar have been studied. Both regions display an independent facial development; however, a comparison of the sequential evolution of the Mesozoic sedimentary successions in these two presently widely separated areas reveals a surprisingly high level of similarity, which probably reflects major events during the disintegration of Eastern Gondwana during the Jurassic and Cretaceous. Although in Jurassic times the onset of transgressions and regressions in both areas compares well with eustatic development, major deviations in combination with the tectonic activities of different degrees are observed in the Early and Late Cretaceous synchronously in both regions. Transgressions are observed in Toarcian, Bajocian (not dated in northern Somalia), Callovian, Valanginian (Madagascar only), Aptian and Campanian times. Tectonism is noted before the Aptian and Campanian transgressions in northern Somalia and the Morondava Basin of south-western Madagascar.  相似文献   

The contested and negotiated dominance of Anglophone geography in Greece     

Dina Vaiou 《Geoforum》2004,35(5):529-531

In this comment, I discuss the dominance of Anglophone geographical literature in Greece, arguing that it is a recent and still contested phenomenon, to do with broader historical/political circumstances, as well as with the development of geographical studies at university level. In the context of the power-knowledge system, in which Anglophone debates, theory production and spaces of academic communication and exchange dominate, radical academics in Greece are caught in a complex web of contradictions, have to negotiate their/our paths across languages, plural voices, local and international communities.  相似文献