High density neighborhoods: Who enjoys them?

To date, research into the subjective aspects of high density has focused mainly on the negative consequences of overcrowding. This study, in contrast, outlines some of the positive aspects of high density in neighborhoods, exploring the physical–spatial environment of two neighborhoods in the city of Haifa, Israel. It was found that while the relatively high residential density was similar in both neighborhoods (40 housing units per acre), this was more positively evaluated in one neighborhood as compared to the other. This can be attributed to some specific environmental and planning features. In particular, where physical planning enabled the potential advantages of high density to be realized, this was positively perceived and evaluated by local residents. Such advantages mainly comprised accessibility to a variety of services, more frequent public transportation, and access to open spaces within walking distance. Particularly advantageous were the increased opportunities for social gathering. At the same time, however, high density did not foster social relationships on the neighborhood level. The study further identified the gender and age groups that benefited most from the high density. Thus, women evaluated high density more positively than men. Young families with children and senior citizens (over 65) were also more likely to benefit, and to evaluate the high density environment more positively than other social groups.     

华北平原深层地下水14C年龄的TDIC校正与对比

用14C确定地下水年龄需要进行多种校正。在系统测定华北平原深层地下水14C含量的基础上,应用TDIC(Total Dissolved Inorganic Carbon,即总溶解无机碳)校正地下水14C年龄。将补给区地下水样的14C和TDIC含量作为初始14C活度和初始TDIC含量,对其他样品进行初始TDIC的14C活度校正,并用CAL-IB5.0分别计算了样品校正年龄(14C校)和TDIC校正后的校正年龄(14CTDIC校)。华北平原深层地下水14C校正年龄变化比例达-27.5%~44.4%,TDIC校正对14C年龄影响明显,地下水样品进行14C定年时需要先进行TDIC校正。根据华北平原地下水14C校正年龄和Cl-含量分布,华北平原深层地下水受到明显的海水入侵的影响,衡水—河间—任丘一线西侧地下水14C校正年龄代表了其真实年龄,而衡水—献县—天津一线东侧地下水14C校正年龄不能代表其真实年龄,只是海水和地下水混合后的表观年龄。     

徐淮地区冬小麦叶龄与有效积温的样条模式

分析冬小麦越冬前叶龄变化，温度有效性随播期，发育期变化及其对叶龄的影响。用样条回归方法，建立了叶龄与有效积温模式，并用该模式确定冬小麦适播期以及插补缺测的叶龄。     

Age and associated stress field of middle Miocene back-arc basalt magmatism in Northeast Japan

A large volume of middle Miocene basaltic rocks is widely distributed across the back-arc region of Northeast Japan, including around the Dewa Mountains. Petrological research has shown that basaltic rocks of the Aosawa Formation around the Dewa Mountains were generated as a result of the opening of the Sea of Japan. To determine the precise ages of the middle Miocene basaltic magmatism, we conducted U–Pb and fission-track (FT) dating of a rhyolite lava that constitutes the uppermost part of the Aosawa Formation. In addition, we estimated the paleostress field of the volcanism using data from a basaltic dike swarm in the same formation. The rhyolite lava yields a U–Pb age of 10.73 ±0.22 Ma (2σ) and a FT age of 10.6 ±1.6 Ma (2σ), and the paleostress analysis suggests a normal-faulting stress regime with a NW–SE-trending σ₃-axis, a relatively high stress ratio, and a relatively high magma pressure. Our results show that the late Aosawa magmatism occurred under NW–SE extensional stress and ended at ~ 11 Ma.     

黄河流域现代沉积物碎屑锆石U-Pb年龄物源探讨

在系统搜集与分析前人发表的现代黄河碎屑锆石U-Pb年龄及黄河流域内岩体锆石U-Pb年龄的基础上,对黄河上游到入海口6个站位及黄河支流2个站位现代沉积物样品碎屑锆石U-Pb年龄进行对比,结果发现200~350、350~500、700~1 000、1 000~1 800、1 800~2 000和2 000~2 600 Ma这6个年龄组是黄河流域沉积物U-Pb年龄的主要组成,其中又以200~350、350~500、1 800~2 000和2 000~2 600 Ma占主体,与黄河流域各可能物源区的U-Pb年龄对比,认为黄河上游物质主要来自松潘-甘孜造山带和很多近缘河水侵蚀的黄土,其可能源区包括华北板块、扬子板块、秦岭造山带、东昆仑造山带、柴达木板块北缘及祁连造山带,由于松潘-甘孜造山带和黄土高原黄土来源的复杂性其源区判别还需要借助其他指标加以确定,黄河中下游则有大量华北板块和大别-苏鲁造山带物质的加入。鉴于当前综合运用多种物源分析方法,对长江三角洲盆地若干钻孔地层研究取得的进展及黄河三角洲钻孔研究现状,提出对黄河三角洲钻孔沉积物开展精细物源示踪对黄河时空演化研究的重要性。     

甘肃北山西涧泉子富碱高钾花岗岩体的锆石LA-ICP-MS定年及其构造意义

位于甘肃北山南带的西涧泉子花岗岩体锆石的LA-ICP-MS年龄为266.1±2.2Ma、其Hf同位素的模式年龄为746～871Ma,εHf(t)=+1.3～+4.7,平均+2.7。西涧泉子花岗岩体以二长花岗岩为主,具有较高的SiO2含量(74.33%～76.67%)和Na2O+K2O含量(9.26%～9.57%),NK/A=0.9～1.08,富钾(Na2O/K2O1),属碱性系列;球粒陨石标准化分配模式图整体呈V字型,具相对平缓的富集轻稀土元素稀土配分模式,重稀土元素分馏不明显且相对亏损,Eu具有明显的负异常,δEu=0.10～0.16。在微量元素原始地幔标准化蛛网图上,亏损Nb、Ba、Sr、Ti,富集Rb、Th、K。结合区域地质背景,认为西涧泉子富碱高钾花岗岩体受音凹峡二叠纪裂谷带的影响强烈,为壳幔混合成因,是后碰撞环境裂谷作用阶段的产物,进而确定该地区在中二叠世进入裂谷作用阶段。     

碎屑锆石U-Pb年代学在地学应用中的现状

锆石U-Pb年代学作为地学研究中一种有效的定年方法,通过半个世纪的发展,已经形成了完善的理论体系和实验方法。随着其测试效率和精度不断提高,成本逐渐降低,其研究也朝更广的邻域延伸,近年来碎屑锆石U-Pb年代学在地学中得到了广泛的应用。本文重点介绍碎屑锆石U-Pb年代学在最大沉积年龄分析、物源分析、构造演化分析三方面的应用和扩展,以及碎屑锆石研究中需要注意的再循环锆石、锆石Pb丢失、锆石的滞后时间、锆石生产力差异以及分析结果存在误差导致的年龄偏差的问题。     

Cosmogenic nuclide burial age of the Sanying Formation and its implications

The Pliocene fluvial/lacustrine sediments of the Sanying Formation lie along the Red River fault and its northwest extension;their majority outcrops appear around Eryuan.The Sanying Formation is characterized by multiple intercalated coal layers and its unconformities contact with the underlying Triassic limestone and the overlying Quaternary coarse sediments.Cosmogenic nuclide burial dating confirms the Pliocene age of the Sanying Formation.The burial ages of the overlying Quaternary sediments provide the lower age limit of the Sanying Formation:2 Ma.Detrital zircon U-Pb age distribution suggests provenance of the Sanying Formation traced to the Songpan-Ganzi flysch belt.From the spatial distribution as well as sedimentary and fault ages,we found a strong connection of the Sanying Formation with the Red River and the Jianchuan faults.We therefore propose that activation of the Red River and the Jianchuan faults during the Late Miocene resulted in subsidence of basins in the extensional areas around Eryuan and in the middle to south segments of the Red River fault.The basins were filled with water carried by the Jinsha River and overflow-lakes formed within the basins where the Sanying Formation was deposited.Most of the lakes were dried and sedimentation of the Sanying Formation ceased due to the uplift of the Yunling Mountains,which forced rerouting of the Jinsha River at the beginning of Quaternary.     

云南东川地区昆阳群黑山组凝灰岩锆石SHRIMPU-Pb年龄及其地层学意义

云南东川地区昆阳群的形成时代及地层层序一直令人关注,已获得的一些数据虽然具有参考意义,但高质量的SHRIMP 定年还很缺乏。在东川地区昆阳群黑山组中上段发育的近180m厚的具有地层意义的晶屑、岩屑凝灰岩中采集样品D0202一件,选出锆石百余粒,获得SHRIMP U-Pb加权平均年龄为（1503 ± 17 ）Ma。样品D0202的锆石Th/U大于0.48,并具清晰的振荡环带结构,均为岩浆成因的锆石,表明黑山组形成于中元古代早期。这一年龄表明昆阳群的形成时代至少大于1500Ma,为准确地标定昆阳群的时代和层序提供了新的参考依据。     

白云鄂博陆缘裂谷系沉积物源与超大型稀土矿床含矿白云岩的成因探讨

白云鄂博群尖山组H4岩性段石英砂岩中的碎屑锆石年龄纪录了华北克拉通北缘两期重要的构造岩浆事件,一组年龄集中在新太古代—古元古代初期(2379～2596Ma),另一组年龄集中在古元古代晚期(1761～1946Ma),该结果与白云鄂博地区基底岩石的锆石年龄相吻合。白云鄂博群沉积碳酸盐岩的全岩207Pb-206Pb等时线年龄1649±45Ma,代表了白云鄂博群的沉积时代。白云鄂博地区沉积灰岩、白云岩与含矿白云岩的Pb同位素组成存在非常大的差异,在Pb同位素组成和构造图解中,含矿白云岩都集中在地幔演化线附近,靠近亏损地幔端元[(206Pb/204Pb)i=15.04～16.49,(207Pb/204Pb)i=15.17～15.28,(208Pb/204Pb)i=31.20～36.40],而白云鄂博群中的灰岩、白云岩则位于造山带演化线附近,靠近深海沉积物端元[(206Pb/204Pb)i=17.28～19.35,(207Pb/204Pb)i=15.47～15.69,(208Pb/204Pb)i=36.62～37.12]。