四川江油渔洞子飞仙关组巨鲕灰岩的成因解释——在微观及超微世界里认识华南早三叠世巨鲕灰岩的成因

作为错时相沉积之一的巨鲕灰岩在我国华南早三叠世地层中广泛出现,在寒武纪之后本已消失的这种沉积类型为什么会在早三叠世又重新出现?在四川江油渔洞子下三叠统飞仙关组鲕粒灰岩的底部,产有一套巨鲕灰岩,通过高倍显微镜及扫描电镜的深入研究,首次发现在巨鲕灰岩的鲕粒和围岩中充满丰富的疑似底栖蓝细菌、疑似颗粒状浮游蓝细菌及其他超微化石。根据这些疑似底栖蓝细菌的结构和构造特点,可以划分出下列几种类型:疑似蛛网状蓝细菌,疑似微球状蓝细菌,疑似网格状蓝细菌,疑似蠕虫状蓝细菌,疑似直管状蓝细菌,疑似链状蓝细菌,疑似花瓣状蓝细菌和Renalsis,疑似颗粒状浮游蓝细菌(主要有两种类型:简单的椭球粒和螺旋状球粒)。超微化石包括钙球和铃铛形超微化石。疑似底栖和浮游蓝细菌及其他超微生物的大量繁盛,是二叠纪-三叠纪之交海洋生态环境恶化、海洋底栖动物大灭绝所产生的后果。这一发现不仅使我们在微观世界和超微世界里重新认识巨鲕灰岩的成因,它是生物和沉积两种主要因素共同作用的结果,从而对巨鲕灰岩的时代分布做出了很好的解释;同时,也可以帮助我们重塑当时该地区的海洋古生态系统。     

塔里木盆地哈得逊油田断裂特征与油气运移

通过断裂分析及构造演化,并结合油气地化指标,综合研究认为,哈得逊油气的总体运移特征为“多期充注,晚期成藏”,即有垂向又有横向。海西末期-喜山期主干断层继承性活动,形成断穿石炭系底部的复活断层及伴生断层,沟通寒武系、奥陶系油源。晚加里东期、晚海西期来自寒武-奥陶系的油气沿羊屋2 井区深大断裂纵向运移,哈得逊石炭系整体南倾,未发育有效圈闭,两期油气均未有效成藏。晚喜山期受南北向造山运动影响,石炭系地层发生翘倾作用,形成有效圈闭。同时,古生界的深大油源断裂复活,聚集在奥陶系古油藏中的油气沿断裂垂向调整至石炭系东河砂岩,并在北倾斜坡的背景下,油气自北向南短距离侧向运移,聚集于哈得逊石炭系圈闭中,形成现今哈得逊油藏。     

西藏双湖地区南措铜金矿区花岗闪长岩锆石U-Pb年代学、岩石地球化学及成因

对南措铜金矿区与成矿相关的黑云母花岗闪长岩体进行了岩相学、锆石U-Pb年代学、岩石地球化学等方面的研究。结果表明:该岩体年龄为153.40±0.67 Ma,属晚侏罗世。岩石为准铝质-过铝质岩石,属钙碱性系列。LaN/YbN=9.31~12.65,轻重稀土元素分馏明显,δEu=1.21~1.66,Eu表现为正异常;样品微量元素表现为相对富集大离子亲石元素(LILE)K、与高场强元素(HFSE)Sr、Zr,而亏损高场强元素(HFSE)U、Nb、Ce、Nd、P的特征。岩体具有I型花岗岩特征。样品Zr/Hf值为42.23~45.82,平均值为44.2;Rb/Sr比值为0.07~0.19,平均值为0.13;Nd/Th值为1.65~2.18,平均为1.99,具壳源岩浆的特征,并有地幔物质混入。样品的Mg#值为49.80~57.22,Sr值为443.3~874.9,Yb值为0.80~1.39,Y值为8.96~16.60,Na2O/K2O2(2.18~2.97),为洋壳型埃达克岩,并在上升过程中可能有少量地幔楔物质混入。结合前人研究成果认为,该花岗闪长岩形成于晚侏罗世班公湖—怒江洋盆向北俯冲的火山弧环境。     

广西田林县徕周金矿床地质特征

徕周金矿床位于右江盆地,矿体主要赋存于下三叠统罗楼组泥质砂岩、砂质泥岩中断裂破碎带(F3、F4、F6)中;矿区内普遍发育硅化、黄铁矿化和方解石化。研究认为徕周金矿是以沉积岩为容矿岩石受构造严格控制的中低温热液矿床;矿区内下三叠统罗楼组地层中主断裂与次级断裂交汇处是下一步找矿的重点。     

Satellite estimates and subpixel variability of rainfall in a semi-arid grassland

卫星估雨精度的不确定性受到当地降雨类型和像元内降雨非均匀性影响,而结合这两个关键因素开展半干旱草原卫星估雨的研究有限.2009年夏,我们在中国锡林郭勒半干旱草原用多部微雨雷达和雨量计构建了9 km卫星像元降雨观测网,观测了像元内降雨非均匀性(空间变异系数CV),并评估了卫星估雨精度.结果表明:(1)CV值受像元内平均降雨量,降雨类型,降雨云面积及移向等影响,如高Cv值的降雨过程大多为平均降雨量小,对流性降雨过程,降雨云边缘像元CV值较高;(2)TRMM 3B42V7卫星估雨产品适用性较好,CMORPH和PERSIANN次之,但TRMM 3B42V7易在半干旱草原湖泊处高估降雨.     

南部非洲花岗岩型与伟晶岩型钽矿床地质特征

钽作为一种重要的稀有金属矿产,广泛应用于各种工业领域。世界上的钽矿床成因主要为内生成矿,尤以花岗岩型和伟晶型最为重要,碰撞造山过程导致的多期次岩浆活动是有利的钽矿成矿环境。南部非洲钽矿资源丰富且品位高,主要为花岗岩型和伟晶岩型钽矿床,空间上主要分布在卡普瓦尔克拉通、刚果克拉通、津巴布韦克拉通以及基巴拉、泛非、达马拉等碰撞环境下形成的同造山—后造山构造带内,时间上主要集中在太古宙(2.85~2.58 Ga)、古元古代(2.48~2.0 Ga)、晚中元古代—早新元古代(1026~880 Ma)以及泛非活动期(500~440 Ma),且不同钽矿带内含钽矿物稀有及稀土元素分布特征差异较大。南部非洲发育大量与钽矿形成密切相关的花岗岩及伟晶岩岩体,资源潜力巨大,未来有望成为世界上主要的钽资源接续基地。     

Structural Setting and Kinematic Analysis of the Halaban Region,Eastern Arabian Shield,Saudi Arabia

The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret the relationship between the different lithologies and the tectonic setting,in order to elucidate the nature of kinematic analysis in the Halaban region.The kinematic analyses were applied to feldspar porphyroclasts,quartz and hornblende for twentysix samples.The kinematic vorticity number (W_m) for deformed rocks in the study area ranged from～0.6 to 0.9.The direction of the long axes for finite strain data (X axes) revealed a WNW trend with shallow dipping.The direction of the short axes for finite strain data (Z axes) were represented by vertical with associated horizontal foliation.The results of the kinematic vorticity and strain analyses are characterized by simple shear with different degrees of deformation in the Halaban region.Furthermore,our finite strain data shows no significant volume change during deformation.The subhorizontal foliation was synchronized with thrusting and deformation.Furthermore,throughout the overlying nappes,the same attitudes of tectonic contacts are observable,the nappes in the orogens being formed from simple shear deformation.     

《古地理学报》2022年审稿专家

2020年共有17位来自全国各高等院校、科研院所和生产单位的专家学者参与了《古地理学报》来稿的评审工作。特在此列出(按音序排列,排名不分先后),谨向你们致以衷心的感谢!并祝愿你们在新的一年里身体健康,万事如意!     

Spatial landslide susceptibility assessment using machine learning techniques assisted by additional data created with generative adversarial networks

In recent years,landslide susceptibility mapping has substantially improved with advances in machine learning.However,there are still challenges remain in landslide mapping due to the availability of limited inventory data.In this paper,a novel method that improves the performance of machine learning techniques is presented.The proposed method creates synthetic inventory data using Generative Adversarial Networks(GANs)for improving the prediction of landslides.In this research,landslide inventory data of 156 landslide locations were identified in Cameron Highlands,Malaysia,taken from previous projects the authors worked on.Elevation,slope,aspect,plan curvature,profile curvature,total curvature,lithology,land use and land cover(LULC),distance to the road,distance to the river,stream power index(SPI),sediment transport index(STI),terrain roughness index(TRI),topographic wetness index(TWI)and vegetation density are geo-environmental factors considered in this study based on suggestions from previous works on Cameron Highlands.To show the capability of GANs in improving landslide prediction models,this study tests the proposed GAN model with benchmark models namely Artificial Neural Network(ANN),Support Vector Machine(SVM),Decision Trees(DT),Random Forest(RF)and Bagging ensemble models with ANN and SVM models.These models were validated using the area under the receiver operating characteristic curve(AUROC).The DT,RF,SVM,ANN and Bagging ensemble could achieve the AUROC values of(0.90,0.94,0.86,0.69 and 0.82)for the training;and the AUROC of(0.76,0.81,0.85,0.72 and 0.75)for the test,subsequently.When using additional samples,the same models achieved the AUROC values of(0.92,0.94,0.88,0.75 and 0.84)for the training and(0.78,0.82,0.82,0.78 and 0.80)for the test,respectively.Using the additional samples improved the test accuracy of all the models except SVM.As a result,in data-scarce environments,this research showed that utilizing GANs to generate supplementary samples is promising because it can improve the predictive capability of common landslide prediction models.