试论碳酸盐岩上覆红土的形成模式及演化趋势

据长期对岩溶及红土化作用等的研究成果,本文全面系统地分析了碳酸盐岩上覆红土的形成及演化规律,提出了一个新的碳酸盐岩上覆红土的形成模式,进而深入阐明了碳酸盐岩上覆红土的演化规律及其在现代气候条件下的演化趋势等,在解决岩溶及红土学术界存在的碳酸盐岩上覆红土的形成、碳酸盐岩与上覆红土之间的相互关系及其发展演化规律等一系列重大疑难问题上向前迈进了一步,对相关学科的发展将产生积极的推动作用.     

GPS-measured land subsidence in Ojiya City, Niigata Prefecture, Japan

Land subsidence caused by compression of clay layers in Ojiya City, Japan was measured by global positioning system (GPS) between 1 April 1996 and 31 December 1998.

Three baselines were selected in and around the city, and height difference on a WGS-84 ellipsoid was measured by GPS on each baseline. The ground at the GPS station in the city subsides and rebounds 7 cm every winter and spring, respectively. Measurement accuracy was 9.5 mm standard deviation. Ground water level was observed at a well near the GPS station. Regression analysis between total strain, calculated as ratio of the height difference displacement to the total thickness of the clay layers, and the layers' effective stress change with ground water level change gave good correlation. The slope of regression line 7.0×10⁻¹¹ m²/N was obtained as an average apparent coefficient of volume compressibility of the layers.     

Architecture of coastal and alluvial deposits in an extensional basin: the Carboniferous Joggins Formation of eastern Canada

Abstract The Joggins Formation was deposited in the Cumberland Basin, which experienced rapid mid‐Carboniferous subsidence on bounding faults. A 600 m measured section of coastal and alluvial plain strata comprises cycles tens to hundreds of metres thick. The cycles commence with coal and fossiliferous limestone/siltstone intervals, interpreted as widespread flooding events. These intervals are overlain by coarsening‐upward successions capped by planar‐based sandstone mounds, up to 100 m in width that represent the progradation of small, river‐generated delta lobes into a standing body of open water developed during transgression. The overlying strata contain sand‐rich heterolithic packages, 1–8 m thick, that are associated with channel bodies 2–3 m thick and 10–50 m wide. Drifted plant debris, Calamites groves and erect lycopsid trees are preserved within these predominantly green‐grey heterolithic sediments, which were deposited on a coastal wetland or deltaic plain traversed by channel systems. The cycles conclude with red siltstones, containing calcareous nodules, that are interbedded with thin sandstones and associated with both single‐storey channel bodies (1–1·5 m thick and 2–3 m wide) and larger, multistorey channels (3–6 m thick) with incised margins. Numerous channel bodies at the same level suggest that multiple‐channel, anastomosed river systems were developed on a well‐drained floodplain. Many minor flooding surfaces divide the strata into parasequences with dominantly progradational and aggradational stacking patterns. Multistorey channel bodies are relatively thin, fine grained and modestly incised, and palaeosols are immature and cumulative. The abundance and prominence of flooding surfaces suggests that base‐level rise was enhanced, whereas the lack of evidence for abrupt basinward stepping of facies belts, coupled with the absence of strong fluvial incision and mature palaeosols, suggests that base‐level fall was suppressed. These architectural features are considered to reflect a tectonic architectural signature, in accordance with the high‐subsidence basinal setting. Evidence for restricted marine influence and variation in floral assemblages suggests modulation by eustatic and climatic effects, although their relative importance is uncertain.     

岩溶地区桩基的有限元分析

岩溶地区长桩存在着遇洞率的问题。为了研究岩溶地区桩的受力特点,采用有限元法模拟岩溶地区桩基的工作方式,分析了岩层厚度对桩的影响以及桩的受力状态,并研究了去桩的可能性。计算结果表明:岩层厚度对桩的影响较大,岩层的位置对桩的应力不产生影响,仅对桩的位移产生影响。     

岩溶发育区供水井施工工艺

分析了岩溶区供水井施工困难的原因，并从钻井、成井工艺方面就防治地面塌陷和克服井孔弯曲、坍塌、延长供水井寿命等问题进行了探讨。     

边坡及其它类工程地质问题研究

本文提出有关边坡工程地质研究方面的一些新概念，看法和问题，并概述了属地这一专题的边坡及其它各类工程地质问题的研究成果。     

Lithospheric Stretching,Subsidence and Thermal History Modeling: Application to Yinggehai,Qiongdongnan and Songliao Basins in East China

ＬｉｔｈｏｓｐｈｅｒｉｃＳｔｒｅｔｃｈｉｎｇ，ＳｕｂｓｉｄｅｎｃｅａｎｄＴｈｅｒｍａｌＨｉｓｔｏｒｙＭｏｄｅｌｉｎｇ：ＡｐｐｌｉｃａｔｉｏｎｔｏＹｉｎｇｇｅｈａｉ，ＱｉｏｎｇｄｏｎｇｎａｎａｎｄＳｏｎｇｌｉａｏＢａｓｉｎｓｉｎＥａｓｔＣｈｉｎａ＊Ｌｉ...     

ON BIO-EFFECTS ON KARST LANDSCAPE IN JIUZHAIGOU CONSERVATION, SICHUAN PROVINCE, CHINA—WITH SPECIAL REFERENCE TO A MICROMORPHOLOFICAL APPROACH

1.ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｓｅａｒｃｈｏｎｂｉｏｋａｒｓｔｓｔｒｅｔｃｈｆｒｏｍｎｉｎｅｔｅｅｎｔｈｃｅｎｔｕｒｙ,ｙｅｔｏｎｌｙｒｅｃｅｎｔｌｙ,ｍｏｒｅｅｆｆｉｃｉｅｎｔａｎｄｓｙｓｔｅｍａｔｉｃｒｅｓｅａｒｃｈｈａｓｂｅｅｎｐｕｔｆｏｒｗａｒｄｗｉｔｈｔｈｅａｐｐｅａｒａｎｃｅｏｆｒｅｌａｔｅｄｓｐｅｃｉａｌｔｅｒｍｉｎｏｌｏｇｙａｎｄｄｅｔａｉｌｅｄｒｅｖｉｅｗｓ[3,11,30,3638],ａｎｄｉｔｓｅｅｍｓｔｈａｔｔｈｅｒｅｉｓｓｔｉｌｌｌａｃｋｏｆｂｉｏｋａｒｓｔｉｎａｌｐｉｎｅｅｎｖｉｒｏ…     

APPROACH TO KARST SOLUTION PROCESS RESPONSES ON CLIMATE

ＩｎｔｒｏｄｕｃｔｉｏｎＳｏｌｕｔｉｏｎａｓａｋａｒｓｔｇｅｏｍｏｒｐｈｏｌｏｇｉｃａｌｐｒｏｃｅｓｓｉｎｌａｎｄｆｏｒｍｄｅｖｅｌｏｐｍｅｎｔｈａｓｌｏｎｇｂｅｅｎｒｅｃｏｇｎｉｚｅｄ.Ｓｉｎｃｅｔｈｅｋａｒｓｔｐｒｏｃｅｓｓｅｓａｒｅａｌｍｏｓｔｅｎｔｉｒｅｌｙｓｏｌｕｔｉｏｎ,ｔｈｏｕｇｈｋａｒｓｔｌａｎｄｆｏｒｍｓａｒｅｎｏｔｏｎｌｙｃａｕｓｅｄｂｙｓｏｌｕｔｉｏｎｂｕｔａｌｓｏｂｙｅｒｏｓｉｏｎ,ｔｈｅｃｉｒｃｕｌａｔｉｏｎａｎｄｃｈｅｍｉｃａｌｃｏｍｐｏｓｉｔｉｏｎｓｏｆｋａｒｓｔｕｎ…     

The effects of the spinel—garnet phase transition on the formation of rifted sedimentary basins

We have examined the effects of the spinel-garnet phase transition on subsidence of extensional sedimentary basins. For a constant positive Clapeyron slope ( dP/dT ), the phase boundary moves downwards in the syn-rift and upwards in the post-rift phase. For a non-linear Clapeyron curve ( dP/dT > 0 above 900°C and dP/dT < 0 below 900°C), theory predicts for the reaction of the spinel-garnet phase transition, the direction of phase boundary movement is dependent on the stretching factor, the position of the Clapeyron curve and the lithospheric thickness. A smaller syn-rift and larger post-rift subsidence are predicted for a deeper phase boundary and a thicker lithosphere. The model with a non-linear Clapeyron curve is applied to the subsidence histories of a young extensional basin (Gulf of Lion) and an old continental margin (eastern Canada). The observed syn-rift uplift and the larger post-rift subsidence can be reasonably explained by this model, where the optimum depth of the phase boundary for eastern Canada (˜90 km) is consistent with the estimate from seismic observations and is larger than that for the Gulf of Lion (˜ 50 km). The depth of the spinel-garnet phase boundary is sensitive to the composition of mantle rocks and increases with the extraction of basaltic components from the lithosphere, compatible with our result that the phase boundary is deeper for an older and thicker lithosphere. Thus the surface movement associated with the rifting for these areas may reflect the chemical evolution of the continental lithosphere.