东汤峪地质构造特征及其对温泉的控制

在东汤峪地区已有地质工作的基础上,进一步研究了区内地质构造特征,着重分析了山前断裂的构造特征及演化史,认为山前断裂经历了挤压和拉张交替作用的多期(次)活动过程;并探讨了该区温泉的构造控制因素,认为东汤峪温泉主要由区内山前断裂所控制。     

A microfaunal and sedimentary record of environmental change within the late Holocene sediments of Boca do Rio (Algarve,Portugal)

The foraminifera and ostracods observed in a late Holocene sedimentary sequence within a fluvial valley at Boca do Rio in the coastal zone of the western Algarve, Portugal, reveal a general, though not smooth transition from marine to fluvial conditions. The relative influence of these two environments appears to depend on the degree of permeability of the barrier system at the coast. Optically stimulated luminescence dates and palaeoecological information obtained from the sequence suggest that barrier formation may be related to changes in climate and/or patterns of ocean current circulation. An unusual deposit rich in sand and gravel found within the otherwise mud-dominated sequence has been dated at AD 1801 ± 76 years. This deposit contains foraminifera and ostracods which indicate marine conditions, and which contrast markedly with the brackish-water, estuarine assemblages found in the mud deposits. The rapid transition in the foraminifera and ostracod assemblages indicates a short-lived coastal flooding, which may represent the tsunami associated with the Lisbon earthquake of AD 1755. The variations in the foraminifera and ostracod assemblages also suggest subsidence during the earthquake, with uplift having occurred in the period since then.     

Geochemical features of aquatic environment in crater and barrier lakes in northeast of China

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Causes and Predictability of the 2021 Spring Southwestern China Severe Drought

In the spring of 2021, southwestern China (SWC) experienced extreme drought, accompanied by the highest seasonal-mean temperature record since 1961. This drought event occurred in the decaying phase of a La Ni?a event with negative geopotential height anomalies over the Philippine Sea, which is distinct from the historical perspective. Historically, spring drought over SWC is often linked to El Ni?o and strong western North Pacific subtropical high. Here, we show that the extreme drought in the spring of 2021 may be mainly driven by the atmospheric internal variability and amplified by the warming trend. Specifically, the evaporation increase due to the high temperature accounts for about 30% of drought severity, with the contributions of its linear trend portion being nearly 20% and the interannual variability portion being about 10%. Since the sea surface temperature forcing from the tropical central and eastern Pacific played a minor role in the occurrence of drought, it is a challenge for a climate model to capture the 2021 SWC drought beyond one-month lead times.     

Investigation of discharge and groundwater contamination characteristics around the Karasu Spring, Muş Area, Turkey

The study area is 35 km east of the city center of Mu, Turkey. The rock units in the area include Paleozoic Bitlis Metamorphites, Cenozoic flysch and Solhan Volcanities and Pliocene formations. A long-term discharge change was monitored in the Karasu spring. The amount of water discharged by the spring during June 3 and October 11, 2002 was 7.18×10⁶ m³ while its storage capacity during May 26 and November 11, 2002 was 4.42×10⁶ m³.NH₄ – N, NO₂ – N, NO₃ – N, total PO₄ – P, SO₄ and total organic carbon (TOC) contamination were determined in the recharge area of the spring and other well and spring waters in the vicinity. NH₄ – N, NO₂ – N, NO₃ – N, total PO₄ – P, SO₄ and total organic carbon contamination around the Budak, ivbai, Gölbai, Sazlikbai and Altinova villages are well above the drinking water standards of the Turkish Standard Institute (TSE) and World Health Organization (WHO) (1984). Similarly, water samples of K₄, K₅ and K₆ branches of the Karasu spring and S₁, S₂, S₃ and S₄ points in the swamp area yielded concentrations much more than limit values.     

Characterization of Earthquake Dynamics in Northeastern India Regions: A Modern Nonlinear Forecasting Approach

— The Northeastern India (NEI) region, is seismotectonically one of the most active regions of the world. Earlier studies of NEI earthquake data have provided contrasting evidence for the presence of randomness and low-dimensional strange attractor. Here, in the present study, we assess the dimensionality of an earthquake-generating mechanism by nonlinear predictability analyses on phase portrait constructed by monthly frequency earthquake time series which was obtained from the NOAA catalogue. The result of nonlinear forecasting analyses suggests that the earthquake processes in the NEI region evolve on a non-random high-dimensional chaotic system. Such a complex high-dimensional earthquake behavior is indicative of heterogeneous geological structures in which weak fault zones and/or individual fault interactions might have strength fluctuations due to pore pressure variation. Further, K₂ entropy analysis was performed to isolate the non-random component from the data. The analysis reveals a quasi-coherent time structure, (K₂ 0.08/month) which corresponds to a seasonal time scale of about 12 months. We argue that stochastic resonance created by seasonality bias may have combined with noise to affect the pore pressure variation leading to subsequent earthquake triggering. It is interesting to note that most earthquakes and swarm activities occurred during or after the monsoon season. Geological and geophysical evidence also reconciles with the above view. Evidence for high-dimensional chaos associated with seasonal bias in the NEI region may provide useful constraints for testing models and criteria to assess earthquake hazards on a more rigorous and quantitative basis.Received: 1 September 2001     

0205号威马逊台风路径对上海地区风暴增水的影响分析

对0205号威马逊台风路径成因进行了分析，并对此台风路径对上海地区风暴增水的影响进行了初步分析。     

近44年来滦河口障壁岛演变过程及其影响因素研究——以唐山市龙岛为例

为掌握滦河口障壁岛的演变特征、为海岛保护与适度利用提供数据支撑，以唐山市龙岛为例，基于RS及GIS技术，分析了近44年来障壁岛的演变特征，并探讨了影响海岛演变的主要因素。分析显示，近44年来海岛面积和长度分别呈减少和增加的趋势，海岛质心位置向西南偏西方向迁移，海岛外海一侧岸线不断后退，平均后退速率达7.37 m/a，其中1978—1984年、1996—2003年、2008—2013年及2018—2019年海岛侵蚀后退明显。研究认为，由于滦河口的自然迁移，河流输沙减少，受沿岸输沙特征影响，海岛主体部分侵蚀而两端沙嘴处堆积，海岛自然状态下已出现5~6 m/a的侵蚀。航道整治挖岛及景区建设挖岛导致近年来海岸典型断面平均后退速率达到研究期内最大值14.27 m/a，海岛长度也出现明显减少，是影响海岛演变的首要因素。滦河流域大型水库的修建使滦河输沙急剧减少，海岛岸线侵蚀加剧、海岛面积明显减少，是研究时段内影响海岛演变的次要原因。风暴潮是影响海岛演变的主要的突发性因素，尤其是2018年内短期内密集过境的台风，造成海岛岸线典型断面平均后退达10.25 m。当前，海岛的保护与适度利用要遵循海岛演变特征，严格禁止不必要的挖岛采砂，并采取海滩修复、构筑透水潜堤等工程措施对重点功能区海岸线加以防护。     

春末黄东海域溶解氧垂直结构及氧最大值初步分析

根据1987年5～6月中日合作对黄东海域进行综合调查的溶解氧资料,讨论了该海区溶解氧垂直结构及氧最大值分布。指出在南黄海北部、中部及东海北部和中部的中层存在明显的溶解氧垂直分布最大值,它总是和冷水同存。并对氧最大值及垂直结构同温跃层及冷暖水之间关系进行了初步分析。     

海南岛小海沙坝-泻湖-潮汐通道体系自动调整及恶化

本文运用历史地图对比方法，结合现场考察及水文泥沙测量资料，分析海南岛小海口门近40a来的变化过程，找出小海口门在人为作用下的演变规律．结果表明，小海沙坝—泻湖—潮汐通道体系曾是一个稳定的系统，它通过口门断面、地形调整以适应在人类活动作用下口门动力的变化并保持相对平衡．三大人为活动的综合影响，尤其是盐墩三岛的围垦及冈箱养殖，破坏了口门维持的最后动力(潮汐动力)，使小海沙坝—泻湖—潮汐通道体系失去了调整作用，直接导致了口门的迅速缩小．因此小海综合治理的首要任务是小海口门的治理。