重庆市地学旅游资源研究

重庆市的地学旅游资源极其丰富，可划分为岩石圈旅游资源等4个大类、地质旅游资源等11个基本类型、地层旅游景观等18种景观和黔江县上白垩统正阳组剖面等107个景区(景点)。它们具有类型齐全、分布广泛、岩溶精品和森林独特的特点。从加强岩溶旅游资源调查等6个方面入手，就可提高对它们的开发利用程度.     

可解释性长短期记忆模型用于预测湖泊总磷浓度变化

对湖泊总磷的变化预测和来源识别对水资源调度和流域生态治理有着重要的意义,然而复杂的生化反应和水动力条件导致的非平稳性给湖泊总磷浓度的准确预测带来极大的困难。为克服这一挑战,本文引入了基于加权回归的季节趋势分解(seasonal and trend decomposition using Loess,STL)技术和夏普利加法(SHapley additive exPlanations,SHAP)结合长短期记忆网络(long short-term memory neural network,LSTM)和门控循环单元(gated recurrent unit,GRU)构建了一个可解释的预测框架,以增强对湖泊总磷浓度演变的预测并提高其可解释性。研究表明:(1)在骆马湖总磷浓度的预测中,该框架拥有较好的预报精度(R²=0.878),优于LSTM和卷积长短期记忆模型(convolutional neural networks and long short term memory network,CNN-LSTM)。当预测时间步长增加到8 h时,该框架有效提高了总磷浓度的预测精度,平均相对误差和均方根误差分别降低了47.1%和33.3%。从预测趋势来看,骆马湖在汛期的总磷平均浓度为0.158 mg/L,相较于非汛期的平均浓度,增加了202.1%。(2)运河来水是骆马湖总磷浓度最重要的影响因素,贡献权重为60.0%,并且不同断面(三湾、三场)的污染源受水动力、气象等因素的影响存在显著的时空差异。本文凸显了神经网络模型在预警水体污染方面的可实施性,并且为提高传统神经网络的学习能力和可解释性的开发与验证提供了重要方向。     

Past,present and future climatic forcing due to greenhouse gases

An advanced one-dimensional radiative-convective model (RCM) is used to estimate the past, present and fu-ture climatic forcings induced by greenhouse gases of anthropogenic origin, such as CO2, CH4, N2O and CFCs, in this paper. The results show that the decadal climatic forcing for the last decade is one-order bigger than that prior to the year 1900, and in the case of no control on the emission of the greenhouse gases the climatic forcing for the year 2100 will be almost 4 times as much as now.     

Primary dolostone related to the Cretaceous lacustrine hydrothermal sedimentation in Qingxi sag, Jiuquan Basin on the northern Tibetan Plateau

Based on comprehensive studies in petrography, petrofabric analysis and geochemistry, this paper describes a unique and rare laminated micritic ferruginous primary dolostone crystallized and precipitated from the alkaline hot brine under the conditions of the Mesozoic faulted lake basin. The main rock-forming mineral of this dolostone is ferruginous dolomite with a micritic structure. This dolomite mostly exhibits laminae of 0.1–1 mm thick and is often discovered with other minerals, such as albite, analcite, barite and dickite, which have at least two types of interbedded laminae. Petrogeochemistry reveals that this dolostone contains a large number of typomorphic elements of hydrothermal sedimentation, including Sb, Ba, Sr, Mn, and V. In addition, the LREE is in relatively high concentrations and possesses the typical REE distribution pattern with negative Eu anomaly. Oxygen isotope values (δ¹⁸O_PDB) range from 5.89‰ to 14.15‰ with an average of 9.69‰. The ratio of ⁸⁷Sr/⁸⁶Sr is between 0.711648 and 0.719546, with an average of 0.714718. These data indicate that the depositional environment is a stable, blocked, anoxic low-lying hot brine pool in the bottom of deep lake controlled by basement faults. The hydrothermal fluid is the alkaline hot brine formed by the combination of the infiltration lake water and mantle-derived magmatic water, consisting of many ions, including Ca²⁺, Mg²⁺ and Fe²⁺. Under the driving flow power of magmatic heat, gravity and compaction, the hydrothermal fluid overcame the overburden pressure and hydrostatic pressure of the lake water body, and boiled to explosion, and then the explosion shattered the original laminated micritic ferruginous primary dolostone near the vent and then formed a new type of dolostone called shattered “hydroexplosion breccias”. In the low-lying, unperturbed hot brine pool, far from the vent, the laminated micritic ferruginous primary dolostone was quickly crystallized and chemicals precipitated from the hydrotherm. This study of special rocks contributes to research into the causes of the formation of lacustrine carbonate rocks and dolostone. In particular, it provides new examples and research insights for future studies of the lacustrine dolomite from the similar Mesozoic and Cenozoic basins in China.     

星载激光光斑影像激光指向变化探测法

地面光斑足印的定位精度高度依赖于激光指向角的测量精度,星载激光光斑质心提取及其变化规律对激光指向角的分析具有重要的意义。本文基于ICESat/GLAS的激光剖面阵列（laser profile array,LPA）影像数据,首先利用灰度一阶矩阵法提取LPA的质心,精度优于0.3个像素,LPA相对定位精度优于0.11个像素。其次利用傅里叶变换和傅里叶级数拟合对LPA质心坐标的变化进行周期探测和建模分析,结果表明,激光光斑影像的质心坐标存在1.83×10^-4 Hz、3.36×10^-4 Hz、5.19×10^-4 Hz和6.71×10^-4 Hz 4个明显的周期变化,拟合结果的相关性R²达到了0.86,拟合精度可达0.4″,优于0.13个像素,得到了较好的结果。可为我国的高分七号和后续的卫星激光测高数据处理提供参考。     

Magma underplating and Hannuoba present crust-mantle transitional zone composition: Xenolith petrological and geochemical evidence

Studies on the deep-seated xenoliths from global volcanoes reveal that the present petrological crust-mantle boundary between the lower crust and the upper mantle actually is a transitional layer from mainly mafic granulites to ultramafic spinel lher-zolites[1,2], i.e. a transitional zone distinctive from the seismological Moho[3]. Oceanic lithosphere crust- mantle transitional zone can be established from the study on the exposed ophiolites. However, as for the continental lithosphere, since …     

长江口特大洪水浑浊带悬沙粒度分布特征

2020年长江流域发生了历史第二大洪水,大通站洪峰流量达到84 500 m3/s。本文基于2020年7月长江口特大洪水期间最大浑浊带多站位的水沙观测数据,重点分析了悬沙粒度组分的时空分布特征,并与常态水文条件下的粒度数据进行对比。结果表明：（1）最大浑浊带悬沙垂向平均中值粒径为10.4μm,变化范围为6～27μm,以黏性细颗粒泥沙为主;其中核心区南槽、北槽及北港的中值粒径分别为8.4μm、7.6μm和8.5μm,过渡区分别为7.2μm、16.4μm和14.5μm。（2）悬沙中值粒径垂向分布受不同组分影响,核心区底层中值粒径为8.8～9.6μm;底层黏土含量在28%～31%之间,粉砂含量在61%～64%之间,中值粒径主要受黏土及粉砂组分影响;过渡区北港和北槽垂向平均砂组分高达19%,南槽砂组分平均仅占5%,中值粒径主要受砂组分影响。（3）对比2013年洪季浑浊带数据,2020年粒径整体增大5.4μm,核心区黏土含量相较2013年减少12.7%,砂增加6.3%;过渡区北槽与北港平均粒径增大10μm。     

Monitoring Contact State of Laboratory Fault with Coda Transmission Waves

We monitored the amplitude changes of coda transmission waves around 500kHz across the frictional interface of a simulated 1.5-meter-long fault during normal stress holding test. We find that the amplitude of coda transmission waves increases with the logarithm of stationary contact time. Localized increase amounted to a level ranging from 4% to 16% along the fault is observed during the 1-hour experiment. We discuss that the frictional strength at mesoscopic scale, which is related to the amplitude of coda transmission waves, is responsible for the phenomenon. Combining the reported method with other complementary approaches will enhance the understanding of fault mechanism either at laboratory or on-site applications.     

玻璃包裹体裂变径迹在46O矿床中的应用

460矿床是火山岩型铀矿床。玻璃包裹体中裂变径迹研究表明:成矿岩体次流纹斑岩的原始铀含量为13.0ppm;裂变径迹测年龄法在强烈蚀变地区可以作为一种测年龄的有效辅助手段。