贵州省册亨县百地金矿地质特征及找矿前景   总被引：3，自引：2，他引：1  

朱光荣  毛应江  季国松 《贵州地质》2008,25(3)

将册亨县百地金矿矿区划分为3个矿段,并简要描述各矿段(体)地质特征及取得的勘查进展情况。初步预测各矿体找矿前景及资源潜力。  相似文献   

贵州晴隆大厂晚二叠世初期河流相沉积特征——兼论与上下地层接触关系     

李明道 《贵州地质》2008,25(3)

晚二叠世初期,在晴隆大厂一带,以"大厂层"为基底的山间盆地中,形成了一条自北东流向南西的规模较大的曲流河。该河流微相发育,其沉积物包括河道砾岩、边滩砂屑岩和洪泛平原泥质岩等。这套沉积地层上与上二叠统峨眉山玄武岩下与"大厂层"或局部与中二叠统茅口组接触。此乃峨眉地幔隆起边缘的沉积效应。  相似文献   

How tides and river flows determine estuarine bathymetries     

D. Prandle 《Progress in Oceanography》2004,61(1):1-26

For strongly tidal, funnel-shaped estuaries, we examine how tides and river flows determine size and shape. We also consider how long it takes for bathymetric adjustment, both to determine whether present-day bathymetry reflects prevailing forcing and how rapidly changes might occur under future forcing scenarios.Starting with the assumption of a 'synchronous' estuary (i.e., where the sea surface slope resulting from the axial gradient in phase of tidal elevation significantly exceeds the gradient in tidal amplitude ), an expression is derived for the slope of the sea bed. Thence, by integration we derive expressions for the axial depth profile and estuarine length, L, as a function of and D, the prescribed depth at the mouth. Calculated values of L are broadly consistent with observations. The synchronous estuary approach enables a number of dynamical parameters to be directly calculated and conveniently illustrated as functions of and D, namely: current amplitude Û, ratio of friction to inertia terms, estuarine length, stratification, saline intrusion length, flushing time, mean suspended sediment concentration and sediment in-fill times.Four separate derivations for the length of saline intrusion, L_I, all indicate a dependency on (U_o is the residual river flow velocity and f is the bed friction coefficient). Likely bathymetries for `mixed' estuaries can be delineated by mapping, against and D, the conditions L<sub>I</sub>/L<1,E<sub>X</sub>/L<1 (E<sub>X</sub> is the tidal excursion) alongside the Simpson-Hunter criteria D/U<sup>3</sup><50 m<sup>−2</sup> s<sup>3</sup>. This zone encompasses 24 out of 25 `randomly' selected UK estuaries.However, the length of saline intrusion in a funnel-shaped estuary is also sensitive to axial location. Observations suggest that this location corresponds to a minimum in landward intrusion of salt. By combining the derived expressions for L and L_I with this latter criterion, an expression is derived relating D_i, the depth at the centre of the intrusion, to the corresponding value of U_o. This expression indicates U_o is always close to 1 cm s⁻¹, as commonly observed. Converting from U_o to river flow, Q, provides a morphological expression linking estuarine depth to Q (with a small dependence on side slope gradients).These dynamical solutions are coupled with further generalised theory related to depth and time-mean, suspended sediment concentrations (as functions of and D). Then, by assuming the transport of fine marine sediments approximates that of a dissolved tracer, the rate of estuarine supply can be determined by combining these derived mean concentrations with estimates of flushing time, F_T, based on L_I. By further assuming that all such sediments are deposited, minimum times for these deposition rates to in-fill estuaries are determined. These times range from a decade for the shortest, shallowest estuaries to upwards of millennia in longer, deeper estuaries with smaller tidal ranges.  相似文献   

河口环流和盐水入侵Ⅱ--径流量和海平面上升的影响   总被引：1，自引：0，他引：1  

胡松  朱建荣  傅得健  吴辉 《中国海洋大学学报(自然科学版)》2003,33(3):337-342

本文利用本序列上篇论文建立的理想河口数值模式,研究径流量和海平面上升对河口环流和盐水入侵的影响.在径流量增大的情况下,口门内表层向海的流速增大,底层向陆的密度流减弱,滞流点下移.口门外侧向口门的密度流增大,上升流趋于增强.口门内盐水入侵减弱,口外盐度减小、冲淡水扩展范围增大.在口门上游北岸底层盐度下降明显,口门处南岸表层盐度下降明显.径流量变化对盐水入侵影响十分巨大.在海平面上升的情况下,拦门沙区域向陆的密度流增强,滞流点上移,表层向海的流动增大.口门内盐水入侵增强,口外盐度增大,冲淡水扩展范围减小.海平面上升对盐水入侵影响十分明显,北岸底层盐度增大尤为特出.  相似文献   

Possible Density Change of the Origin of North Pacific Intermediate Water Due to Double Diffusion in the Mixed Water Region     

Ryuichiro?InoueEmail author  Jiro?Yoshida 《Journal of Oceanography》2005,61(5):871-883

In this study we test Talley's hypothesis that Oyashio winter mixed-layer water (26.5–26.6σ _θ) increases its density to produce the North Pacific Intermediate Water (NPIW) salinity minimum (26.7– 26.8σ_θ) in the Mixed Water Region, assuming a combination of cabbeling and double diffusion. The possible density change of Oyashio winter mixed-layer water is discussed using an instantaneous ratio of the change of temperature and salinity along any particular intrusion (R _l ). We estimate the range of R _l ^DD required to convert Oyashio winter mixed-layer water to the NPIW salinity minimum due to double diffusion, and then assume double-diffusive intrusions as this conversion mechanism. A double-diffusive intrusion model is used to estimate R _l ^DD in a situation where salt fingering dominates vertical mixing, as well as to determine whether Oyashio winter mixed-layer water can become the NPIW salinity minimum. Possible density changes are estimated from the model R _l ^DD by assuming the amount of density change due to cabbeling. From these results, we conclude that Oyashio winter mixed-layer water contributes to a freshening of the lighter layer of the NPIW salinity minimum (around 26.70σ_θ) in the MWR.  相似文献   

沿海城市海水入侵问题研究   总被引：5，自引：0，他引：5  

丁玲  李碧英  张树深 《海洋技术学报》2003,22(2):79-83

近年来，沿海城市的海水入侵问题逐渐成为人们关心的焦点之一。文章通过资料搜集与整理，对沿海城市的海水入侵状况作了全面描述与分析。系统地总结了海水入侵的若干特点及海水入侵的成因分析与规律，较为详细的分析了海水入侵的基本事实、基本矛盾和各发展阶段的发展原因，在此基础上总结了海水入侵的基本理论。为进一步的研究打下良好的基础。  相似文献   

南海东部海域柱样沉积物浊流沉积探讨     

章伟艳  张富元  张霄宇 《热带海洋学报》2003,22(3):36-43

利用1998年南海东部陆坡69号柱样、深海盆149号柱样、南部岛礁323号柱样沉积物的粒度、化学、古生物、矿物等鉴定分析测试资料,分析了南海东部海域发生浊流沉积的地质背景、产生浊流沉积的条件和诱发因素,进而发现南海东部浊流沉积发育,在南北陆坡及中部深海盆地均有浊流沉积层。从其出现层位看,为氧同位素2—4期,即晚更新世中晚期。从浊流沉积出现层数分析,具有自北向南浊流发生频次减弱的趋势。从浊流沉积物成分看,南海东部浊流沉积物具有多样性,北部陆坡以陆源为主,中部深海盆以陆源及火山源为主,南部岛礁以生物源为主。  相似文献   

Detailed measurements during a transient front in a small subtropical estuary     

Mark Trevethan  Hubert Chanson   《Estuarine, Coastal and Shelf Science》2007,73(3-4):735-742

High-resolution measurements of velocity and physio-chemistry were conducted before, during and after the passage of a transient front in a small subtropical system about 2.1 km upstream of the river mouth. Detailed acoustic Doppler velocimetry measurements, conducted continuously at 25 Hz, showed the existence of transverse turbulent shear between 300 s prior to the front passage and 1300 s after. This was associated with an increased level of suspended sediment concentration fluctuations, some transverse shear next to the bed and some surface temperature anomaly.  相似文献   

水成沉积与风成沉积及古土壤的磁组构特征   总被引：14，自引：2，他引：14  

张家强  李从先  丛友滋 《海洋地质与第四纪地质》1999,19(2):85-94

晚第四纪水成沉积、风成沉积、古土壤等的磁组构研究表明,不同成因的沉积物具有明显不同的磁组构特征。一般地,水成沉积的体积磁化率Ｋ受物源和水动力因素控制,Ｐ和Ｆ均＞１．０２,ｑ＜０．５;风成沉积的Ｋ受物源控制,内陆黄土的Ｋ明显高于沿海黄土及海岸风沙Ｋ,Ｐ和Ｆ均＜１．０２,ｑ的平均值＞０．５５;古土壤的Ｋ受母质沉积类型和成土环境的氧化还原条件控制,内陆古土壤的Ｋ偏高,沿海古土壤的Ｋ偏低,内陆古土壤的Ｋ远高于沿海古土壤的Ｋ,Ｐ和Ｆ均＜１．０２,ｑ的平均值在０．５左右。运用典型沉积的磁组构特征对比分析未知沉积物,可以得到未知沉积物的物源、沉积过程和环境信息。  相似文献   

利用卫星遥感资料对南海北部陆架海洋表层温度锋的分析   总被引：4，自引：0，他引：4  

王磊  王丽娅  魏皓 《中国海洋大学学报(自然科学版)》2004,34(3):351-357

利用7年(1993～1999)月平均的SST卫星遥感资料，分析了南海北部陆架区域海洋表层温度锋在一年中的逐月变化特征，表明南海北部陆架海洋表层温度锋存在明显的季节内变化。结合风场的卫星遥感资料，分析了东北季风对南海北部陆架温度锋的影响，表明东北季风风速的增加有利于温度锋强度的增强。通过对黑潮南海流套入侵较强的1999年2月与流套入侵较弱的1998年2月的SST卫星遥感资料的对比分析，考察了黑潮南海流套的入侵对南海北部陆架温度锋的影响，结果表明黑潮流套的较强入侵能够增加陆架温度锋的强度，对温度锋的走向也会产生一定的影响。  相似文献