珠江口盆地番禺低隆起东部珠江组沉积环境的恢复

对珠江口盆地番禺低隆起东部L16井中新统珠江组的岩心观察分析,岩性包括碎屑岩、碳酸盐岩以及碎屑-碳酸盐的混积岩。珠江组可划分为11种沉积微相类型;建立了三角洲—滨岸—碎屑与碳酸盐混积滨岸—碳酸盐台地—浅海陆棚(23.8 Ma~18.5 Ma)沉积演化序列。地震地质解释证实了珠江组早期东沙三角洲的存在;古珠江三角洲与东沙三角洲构成了研究区珠江组下段的沉积主体。恢复了研究区珠江组沉积相及其演化,重点刻画了SQ2—TST时期由陆到海的变迁,而海平面变化是这一变迁的主要控制因素。     

基于GP RMax的隧道衬砌检测数值模拟及应用

利用基于时间域有限差分法( FDTD)的GPRMax,针对常用的400、900、1500 MHz三种不同中心频率的天线,数值模拟了隧道衬砌不同钢筋网密度、不同钢筋直径及其下方的钢拱架、空气界面等目标体的探地雷达反射及干扰信号图像特征;在混凝土试件上开展实验研究,并运用克希霍夫积分偏移处理了数值模拟和实验数据,压制了钢筋的绕射波和多次波,提高了钢筋网下方弱反射信号的成像效果;通过对比分析数值模拟、实验测量和工程实测结果,为探地雷达在隧道衬砌检测中取得更好的探测效果提供了借鉴。     

西藏北冈底斯扎独顶A型花岗岩锆石U-Pb年代学、地球化学及其地质意义

西藏北冈底斯早白垩世花岗岩分布广泛;扎独顶岩体作为其中的一个典型代表,其分布广泛,呈岩基型式产出,在岩性上属二长花岗岩。在岩石化学上扎独顶岩体具有富Si O2(70.05%~74.97%)和K2O(4.09%~5.35%),贫Ca O(0.93%~2.19%)、Ti O2(0.22%~0.52%)和Al2O3(12.81%~14.24%)的特征;属于准铝质-弱过铝质(A/CNK=0.99~1.0)高钾钙碱性系列。岩体稀土元素总量偏高(∑REE=199.36×10-6~247.91×10-6),相对富集轻稀土元素(LREE/HREE=5.82~6.88),Eu负异常明显(δEu=0.30~0.45),球粒陨石标准化分布模式呈向右缓倾的V型。微量元素显示其富集Rb、Th、K、Zr和Hf,亏损Nb、Ta、Sr、Ba、P和Ti,(Zr+Nb+Ce+Y)平均值为427.63。全岩锆石饱和温度(828~838°C)表明岩浆形成温度高。上述岩石地球化学特征表明扎独顶岩体为A型花岗岩。扎独顶岩体LA-ICP-MS锆石U-Pb年龄为(103.8±1.0)Ma,表明其形成于早白垩世晚期;在构造判别图解上位于碰撞后的A2型花岗岩区,是在碰撞后岩石圈伸展背景下,由于软流圈物质上涌导致岩石圈地幔与壳源熔体部分熔融并经历过一定程度的混合作用而形成的。     

Re–Os and U–Pb Geochronology of Porphyry and Skarn Types Copper Deposits in Jilin Province,NE China

Jilin Province in NE China lies on the eastern edge of the Xing–Meng Orogenic Belt. Mineral exploration in this area has resulted in the discovery of numerous large, medium, and small sized Cu, Mo, Au, and Co deposits. To better understand the formation and distribution of both the porphyry and skarn types Cu deposits of the region, we examined the geological characteristics of the deposits and applied zircon U–Pb and molybdenite Re–Os isotope dating to constrain the age of the mineralization. The Binghugou Cu deposit yields a zircon U–Pb age for quartz diorite of 128.1 ± 1.6 Ma; the Chang'anpu Cu deposit yields a zircon U–Pb age for granite porphyry of 117.0 ± 1.4 Ma; the Ermi Cu deposit yields a zircon U–Pb age for granite porphyry of 96.8 ± 1.1 Ma; the Tongshan Cu deposit yields molybdenite Re–Os model ages of 128.7 to 130.2 Ma, an isochron age of 129.0 ± 1.6 Ma, and a weighted mean model age of 129.2 ± 0.7 Ma; and the Tianhexing Cu deposit yields molybdenite Re–Os model ages of 113.9 to 115.2 Ma, an isochron age of 114.7 ± 1.2 Ma, and a weighted mean model age of 114.7 ± 0.7 Ma. The new ages, combined with existing geochronology data, show that intense porphyry and skarn types Cu mineralization was coeval with Cretaceous magmatism. The geotectonic processes responsible for the genesis of the Cu mineralization were probably related to lithospheric thinning. By analyzing the accumulated molybdenite Re–Os, zircon U–Pb, and Ar–Ar ages for NE China, it is concluded that the Cu deposits formed during multiple events coinciding with periods of magmatic activity. We have identified five phases of mineralization: early Paleozoic (~476 Ma), late Paleozoic (286.5–273.6 Ma), early Mesozoic (~228.7 Ma), Jurassic (194.8–137.1 Ma), and Cretaceous (131.2–96.8 Ma). Although Cu deposits formed during each phase, most of the Cu mineralization occurred during the Cretaceous.     

鲁北新生代隐伏火山岩及其石油地质意义

鲁北新生代隐伏火山岩可划分为3个喷发期6个亚期,9种火山岩岩石类型和同期侵入的辉绿岩。它们形成在近大陆边缘的板内裂谷型盆地,对于富有机质生油岩的沉积、各种储集体的形成、多种含油圈闭类型的形成以及有机质成熟向烃类转化都是非常有利的。作为储集岩主要有玄武安山岩、辉绿岩和湖底玄武质凝灰岩。储油空间主要为次生孔隙和裂缝。火山岩及其有关岩石在本区不仅形成了特殊的油气藏,而且还可作为盖层、封堵层、披复构造的基岩,因此对石油地质勘探有重要意义。     

Club convergence and spatial distribution dynamics of carbon intensity in China’s construction industry

Climate change caused by carbon emissions continuously threatens sustainable development. Due to China’s immense territory, there are remarkable regional differences in carbon emissions. The construction industry, which has strong internal industrial differences, further leads to carbon emission disparity in China. Policymakers should consider spatial effects and attempt to eliminate carbon emission inequality to promote the sustainable development of the construction industry and realize emission reduction targets. Based on the classic Markov chain and spatial Markov chain, this paper investigates the club convergence and spatial distribution dynamics of China’s carbon intensity in the construction industry from 2005 to 2014. The results show that the provincial carbon intensity in the construction industry is characterized by “convergence clubs” during the research period, and very low-level and very high-level convergence clubs have strong stability. Moreover, the carbon intensity class transitions of provinces tend to be consistent with that of their neighbors. Furthermore, the transition of carbon intensity types is highly influenced by their regional backgrounds. The provinces with high carbon emissions have a negative influence on their neighbors, whereas the provinces with low carbon emissions have a positive influence. These analyses provide a spatial interpretation to the “club convergence” of carbon intensity.     

Cyclic degradation and non-coaxiality of soft clay subjected to pure rotation of principal stress directions

Foundation soils are often under non-proportional cyclic loadings. The deformation behaviour and the mechanism of non-coaxiality under continuous pure principal stress rotation for clays are not clearly investigated up to now. In order to study the effect of pure principal stress rotation, a series of cyclic undrained tests on Shanghai soft clay subjected to cyclic rotation of principal stress directions keeping the deviatoric stress constant under the pure rotation condition were conducted using hollow cylinder apparatus. Based on this, the evolutions of excess pore pressure and strains during cyclic loading were investigated, together with the effects of the intermediate principal stress parameter and the deviatoric stress level on stress–strain stiffness and non-coaxiality. The result can provide an experimental basis for constitutive modelling of clays describing the behaviour under non-proportional loadings.     

Analysis of urbanisation-induced land subsidence in Shanghai

Since 1980, land subsidence has accelerated and groundwater levels have decreased in the centre of Shanghai, although the net withdrawn volume of groundwater has not increased. Theoretical analysis of the monitored data shows that the decrease in the groundwater level is the primary reason for the observed land subsidence. Meanwhile, the net withdrawn volume of groundwater in the urban centre of Shanghai has not increased during this period. Many underground structures have been constructed in the multi-aquifer-aquitard system of Shanghai since 1980. This paper discusses the factors related to the development of land subsidence during the process of urbanisation in Shanghai during the past 30?years. These factors include additional load during and after structure construction, the cut-off and/or partial cut-off effect of underground structures in aquifers, the decrease in the groundwater level due to leakage of underground structures and the reduction in recharge of groundwater from the surroundings.     

Fluorine in tourmalines

The determination of the fluorine content of courmalines yielded 0.28% as an average value for schorlites and dravites and 0.97% for elbaites. The plot of the fluorine contents against the lithium contents shows that the distribution of projection points for pink or green elbaites differs from that for lithian indigolites. Tourmalines are poorer in fluorine than lightcoloured micas at the same stage of pegmatite evolution. Individual regions with pegmatite occurrences can be characterized as rich or poor in fluorine according to the fluorine contents in the tourmalines and micas contained in the pegmatites.