东南沿海地震带（含台湾海峡地区）地震活动期的讨论

东南沿海地震带（含台湾海峡地区）地震活动存在一个３４０年左右的主要分期，目前处在１４００年以来的第二活动期。本文充分注意到７０余年的次级分期影响，分析表明，第二活动期可以简单划分为平静和释放两个阶段，释放阶段存在两个应变释放高潮时段自１９８６年进行第二高潮时段，１９９４年９月台湾海峡７．３级地震其主要标志之一，预计这一高潮时段将持续至２０４０年左右，其间可能会有效次Ｍ≥６级地震发生，并且不能排除继     

Helium in Phlegraean Fields soil gases: July 20th–26th — September 19th–25th, 1983

Two helium surveys were carried out at Phlegraean Fields in July and September 1983 aiming at locating loci of discontinuities (fractures) in the area on the basis of variations in helium concentrations following the bradyseismic crisis then in progress.     

Geology and geochemistry of Jurassic pelagic sediments, Scisti silicei Formation, southern Apennines, Italy

A better understanding of genesis and palaeoenvironmental setting of the Scisti silicei Formation (Lagonegro units, southern Italy) was achieved by means of geochemical analysis integrated with new stratigraphic information. Data show that major and trace element geochemistry of ancient clay-rich beds and banded cherts add new insights into the Mesozoic evolution of the Lagonegro basin. Sedimentary contributions to Jurassic shales sampled during this study were mainly derived from two major sources: (i) a dominant terrigenous fine-grained component, having affinity with average upper continental crust that had not undergone intense weathering and (ii) biogenic siliceous material. The latter component occurs in clay-rich layers from the “basal member” of the Scisti silicei Formation.

Composition varies up section and accounts for changes in the detrital supply due to bathymetric oscillations. The compositional variations from the basal to the overlying member are consistent with a distal source passing in time to a more “proximal” source, as indicated by sharp changes in the concentrations of detrital elements (Ti, Zr and Nb). It is likely that increased detrital input occurred through turbidity current deposition. Finally, the chemical features of the clay-rich layers from the upper cherty portion of the studied succession imply a progressive deepening of the basin.

The lack of any mafic and hydrothermal contributions in the Jurassic shales as well as the continental nature of detrital input suggests that the Lagonegro basin was located between two carbonate platforms, in accordance with the classical restoration of the African–Apulian palaeomargin. Thus, the basin acted as a preferential sink connected to the African cratonic areas through a southern entry point.     

Cenozoic Volcanism in South China Sea and Its Vicinity and South China Sea Spreading

The rock series, rock types and Sr-Nd isotopic dating of the Cenozoic volcanic rocks in the South China Sea are similar to those in its vicinity. On the basis of the spreading age of the South China Sea, the Cenozoic volcanic rocks are divided into three stages: the pre-spreading stage, the spreading stage and the post-spreading stage. The deep process characteristics of the asthenosphere and lithosphere may be inferred from the study on primary basaltic magma. The top layers of the asthenosphere both in the spreading stage and in the pre-spreading stage are closer to the earth surface than that in the post-spreading stage. From the pre-spreading stage to the spreading stage, the top layer of the asthenosphere decreased in depth, while the amount of interstitial partial melts increased. The evolution of the primary basaltic magma shows a progressive evolution sequence of the rifting volcanism and a faster lithospheric spreading velocity. From the spreading stage to the post-spreading stage, the top layer of the asthenosphere gradually increased in depth, but the amount of interstitial partial melts decreased. The evolution of primary basaltic magma shows a retrogressive evolution sequence of the rifting volcanism and a gradual decrease in the lithospheric spreading velocity. The depth recognized by the study on the Cenozoic volcanism demonstrates the deep environment for the formation and evolution of the South China Sea.     

Timing of magma extraction during the Campanian Ignimbrite eruption (Campi Flegrei Caldera)

A core drilled within the northern part of the city of Napoli has offered the unique opportunity to observe in one single sequence the superposition of the four pyroclastic flow units emplaced during the Campanian Ignimbrite (CI) eruption. Such a stratigraphic succession has never been encountered before in natural or in man made exposures. Therefore the CI sequence was reconstructed only on the basis of stratigraphic correlations and compositional data (in literature). The occurrence of four superposed CI flows, together with all the data available (in literature) allowed us to better constrain the chemical stratigraphy of the deposit and the compositional structure of the CI magma chamber. The CI magma chamber includes two cogenetic magma layers, separated by a compositional gap. The upper magma layer was contaminated by interaction with radiogenic fluids. The two magma layers were extruded either individually or simultaneously during the course of the eruption. In the latter case they produced a hybrid magma. But no evidence of input of new geochemically and isotopically distinct magma batches just prior or during the eruption has been found. Comparison with the exposed CI deposits has permitted reconstruction of variable eruption phases and related magma withdrawal and caldera collapse episodes. The eruption was likely to have began with phreatomagmatic explosions followed by the formation of a sustained plinian eruption column fed by the simultaneous extraction from both magma layers. Towards the end of this phase the upward migration of the fragmentation surface and the decrease in magma eruption rate and/or activation of fractures formed an unstable pulsating column that was fed only by the most-evolved magma layer. This plinian phase was followed by the collapse of the eruption column and the beginning of caldera formation. At this stage expanded pyroclastic flows fed by the upper magma layer in the chamber generated. During the following major caldera collapse episode, the maximum mass discharge rate was reached and both magma layers were tapped, generating expanded pyroclastic flows. Towards the end of the eruption, only the deeper and less differentiated magma layer was tapped producing more concentrated pyroclastic flows that traveled short distances.     

基于Kevin-Ian 3D模型的紧致时空数据模型

利用时间标识的方式来建立时空数据模型，无论是全局标识，还是各种程度的局部标识，都存在着许多问题；把时间当做独特的要素对待，不能较好地实现时空一体化。在研究Kevin-Ian 3D模型的基础上，提出了把时间和空间同等对待的紧致时空数据模型。该模型通过对时空中的点、线、面、体的描述，可以较好地解决时空数据库的数据冗余、时间拓扑等问题，同时具有较强的描述实体变化的能力。     

体应变数字记录特征与中强震关系初探

通过对溧阳地震台体应变资料的分析研究 ,发现南黄海中强震和台湾大震前后 ,溧阳台体应变观测到一些前兆异常反映 ,异常幅度达 1 4 4× 10 - 7;并且找出了南黄海地震以及台湾大震前溧阳台体应变观测的异常特征。     

The land use and land cover change database and its relative studies in China

In the mid-1990s, we established the national operative dynamic information serving systems on natural resources and environment. During building the land-use/land-cover change (LUCC) database for the mid-1990s, 520 scenes of remotely sensed images of Landsat Thematic Mapper (TM) were interpreted into land-use/land-cover categories at scale of 1:100,000 under overall digital software environment after being geo-referenced and ortho-rectified. The vector map of land-use/land-cover in China at the scale of 1:100,000 was recently converted into a 1-km raster database that captures all of the high-resolution land-use information by calculating area percentage for each kind of land use category within every cell. Being designed as an operative dynamic information serving system, monitoring the change in land-use/land-cover at national level was executed. We have completed the updating of LUCC database by comparing the TM data in the mid-1990s with new data sources received during 1999-2000 and 1989-1990. The LUCC database has supported greatly the national LUCC research program in China and some relative studies are incompletely reviewed in this paper.     

黄土丘陵沟壑区乡村社区恢复力时空演变及影响因素研究——以陕西省米脂县高渠乡为例

乡村人口与土地利用方式变革压力下,构建恢复力已成为保障区域社会—生态系统可持续发展的有效举措。以陕西省米脂县高渠乡为研究区,从社会、经济、制度、生态4个维度,运用熵权TOPSIS法对黄土丘陵沟壑区20个乡村的社区恢复力进行测度,探讨了2015—2019年社区恢复力的时空演变;利用障碍度模型分析了社区恢复力关键影响因子作用机制,并通过比较当前关键影响因子所处维度,将社区划分为不同类型,实现社区的分类治理。结果表明：①（① “四会”指村民议事会、红白理事会、道德评议会、禁毒禁赌会。） 研究期间社区恢复力由0.171提升到0.318,其中经济恢复力上升较为明显,制度、生态恢复力呈小幅提高,而社会恢复力则表现为下降;社区恢复力空间分异更加显著,呈现为“中部高、边缘低”的分布格局。② 研究期末社区恢复力关键影响因素中,经济维度有养殖业发展水平、种植业发展水平、农业产业化带动农户数、农民人均收入;制度维度为基层领导平均受教育年限、公平性管制、村民参与决策机会;社会维度为乡村公共空间比例、流动人口比例;生态维度为“三田”面积占比。③ 通过当前社区恢复力关键影响因子各维度障碍度大小排序,依次识别经济、制度、社会、生态恢复力低值区,最终将高渠乡20个乡村社区划分为3类,结合不同类型乡村社区的特点提出相应对策建议,以期为精准化、差异化管理提供决策参考。     

拉萨地块南缘晚白垩世角闪辉长岩、花岗斑岩副矿物微量元素特征对成岩成矿的指示

拉萨地块南缘记录了新特提斯洋俯冲到印度-欧亚大陆碰撞及碰撞后的岩浆作用,其中晚白垩世的岩浆作用对研究印度-欧亚大陆碰撞前成岩成矿作用具有重要的意义。本文以拉萨地块南缘100Ma的角闪辉长岩和68Ma花岗斑岩的锆石、磷灰石、榍石为研究对象,利用背散射、阴极发光(CL)、电子探针(EPMA)和LA-ICP-MS原位微区分析等方法,查明锆石、磷灰石、榍石的主、微量元素特征,进一步反演岩石源区性质、结晶历史及结晶条件,并对岩体含矿性进行评价,有助于探讨冈底斯成矿带晚白垩世岩浆成因机制和成矿潜力。研究结果表明,角闪辉长岩锆石初始饱和温度为598～626℃,锆石Ti结晶温度为645～758℃,磷灰石饱和温度为690～819℃,榍石Zr温度为602～778℃;磷灰石具有中等-弱的负铕异常(δEu=0. 67)、富集LREE,早期高温阶段锆石的结晶主要受到磷灰石结晶影响,随着温度降低,受到少量榍石结晶的影响;角闪辉长岩中的锆石在低的Hf、温度较高时却具有较高的Th、U含量显示岩浆源区受到更多俯冲板片出溶流体的影响,磷灰石具有较高的(La/Sm)N值以及Sr含量低于主岩,显示岩浆源区均一、熔体富Cl特征。花岗斑岩的锆石初始饱和温度为704～736℃,锆石Ti温度为630～799℃,磷灰石饱和温度为846～891℃,结合锆石的Ce/Sm、Yb/Gd以及磷灰石较大的负铕异常(δEu=0. 29),显示花岗斑岩中的锆石从高温到低温阶段都受到磷灰石和榍石的共同结晶影响,磷灰石的结晶受到斜长石影响;花岗斑岩中大部分锆石Ti结晶温度高于其初始饱和温度,磷灰石Sr-Ap/Sr-WR为0. 78～1. 45,具有较高的F/Cl(32. 87～67. 60)、低的(La/Sm)N,指示花岗斑岩岩浆源区不均一,受到多期岩浆熔体的脉冲式灌入并加入了更多镁铁质的岩浆熔体,其熔体具有低的Cl。此外,花岗斑岩锆石具有较高的Ce~(4+)/Ce~(3+)、磷灰石具有较高的SO_3、熔体中更富S,指示花岗斑岩具有高的氧逸度和成矿潜力。本文研究结果表明结合锆石、磷灰石和榍石微量元素特征可有效指示岩浆岩的源区组成、结晶历史、结晶条件以及成矿潜力,为岩石学的研究提供了一个新的思路。