珠江口盆地白云凹陷渐新世/中新世地质事件的碎屑组分响应

南海北部渐新世/中新世之交发生了物源突变地质事件。利用珠江口盆地白云凹陷渐新统珠海组和中新统珠江组砂岩薄片镜下计点法统计技术,详细研究了碎屑组分的变化特征。结果表明:珠海组砂岩碎屑组分中,岩屑以深成的岩浆岩屑占绝对优势,长石和沉积岩屑含量也相对较高,与该期物源主要来自华南沿海近源以燕山期花岗岩为主的母岩区相一致;而珠江组砂岩中,岩屑以变质岩屑占优势,同时也含有一定量的岩浆岩屑、沉积岩屑和较多的长石,显示珠江组具有更多的物源供给区。随着渐新世/中新世之交各种地质事件发生,尤其是伴随青藏高原隆升引起的大陆风化及侵蚀程度增强,珠江口盆地沉积物源区向华南古陆内部古老的沉积-变质岩区和青藏高原东麓扩展,碎屑组分变化应该是该期各种地质事件的综合作用结果。     

河南洛宁太华变质杂岩区早元古代变质作用P-T-t轨迹及其大地构造意义

太华变质杂岩广泛出露于华北克拉通南缘,总体呈SW-NE向展布.在河南洛宁地区,太华变质杂岩以TTG片麻岩、斜长角闪片麻岩和变泥质片麻岩为主.斜长角闪片麻岩中可识别出三个阶段的变质矿物组合:进变质阶段矿物组合(M1)为石榴子石变斑晶内部的包裹体矿物组合( Amp1+ Pl1+Qtz),变质高峰期矿物组合(M2)为石榴子石变斑晶边部和基质矿物组合( Grt2+ Amp2+ Pl2+ Qtz),退变质阶段矿物组合(M3)为“白眼圈”状后成合晶组合(Amp3+ Pl3+ Qtz).运用矿物温度计与压力计估算三个阶段的P-T条件分别为:进变质阶段约600 ～ 680℃/7.0～ 7.6kbar,变质高峰期为680 ～ 790℃/9.5 ～10.7kbar,退变质阶段为580～720℃/6.5 ～7.6kbar.变泥质片麻岩中保留了进变质阶段(M1)包裹体矿物组合(Bt1+Pl1+Qtz)和峰期变质阶段(M2)矿物组合(Grt2 +Bt2+Pl2 +Qtz)两个阶段.其中未发现后期退变质反应结构,石榴子石中也未发现成分环带.P-T条件估算结果分别为:M1阶段620 ～ 710℃/4.9 ～5.6kbar,M2阶段710～760℃/7.3～8.3kbar.洛宁地区太华变质杂岩记录了顺时针的近等温降压型的P-T轨迹,可能经历了与华北中部造山带其它杂岩类似的变质演化过程,推测其形成于华北克拉通东部陆块和西部陆块沿中部造山带的拼合过程中.SIMS与ICP-MS锆石U-Pb定年表明,斜长角闪片麻岩记录了1938～1967Ma的变质事件,比华北中部造山带其它变质杂岩区所广泛记录的～1850Ma变质事件早了约100Ma,暗示中部造山带的拼合可能是一个长期的、复杂的过程.     

超高压岩石中变质脉的研究

超高压岩石中的变质脉体是示踪变质流体活动的重要途径之一。高压-超高压岩石中不仅出露"纯"的石英脉(石英含量>98%),还出露了具有不同复杂矿物组合的"不纯"脉。最近的研究成果表明,对各种类型变质脉的观察和研究有助于深化对大陆碰撞造山带中变质流体/熔体性质以及元素迁移行为的认识。目前主要解决的科学问题包括:(1)确认形成各种类型脉的流体/熔体性质;(2)获得成脉过程中主微量元素(特别是流体不活动性HREE和HFSE)发生迁移的尺度和规模,探讨流体/熔体性质对超高压变质条件下元素地球化学行为的影响;(3)获得各种类型变质脉形成的确切时代。     

A Metamorphic Core Complex Model for the Host of Uranium Mineralization in the Khoshoumi Mountain,Central Iran

A metamorphic core complex model is proposed for Khoshoumi Mountain uranium mineralization located in the Bafq–Saghand metallogenic zone of central Iran. Uranium mineralization occurred in the Chapedoni metamorphic complex. Detailed structural analysis of the complex leads to the interpretation that the mineralization is spatially concentrated in a low angle shear zone of mylonitized migmatite, the lower ductile part of the Chapedoni metamorphic complex. The shear zone that has top to the NE sense of shear in the northeastern and southeastern parts of the mountain and top to the WNW sense of shear in the southwestern part is a detachment zone to the Chapedoni Metamorphic Core Complex (CMCC). The Eocene granite is the plutonic core to the CMCC. The shear zone is cut by several NE‐trending left‐lateral strike‐slip faults. This later faulting is interpreted to account for the significant enrichment of uranium in the southern part of the mountain. The bimodal distribution of radiometric data gathered from exploratory drill holes in this part of the mountain constrains this interpretation. That is, the lower value is from the shear zone across the area but the higher value is from the places that the shear zone is cut by the transverse faults.     

中国地震事件沉积研究的若干问题探讨

地震事件沉积已经成为当今沉积地质学的一个热点领域.文中通过回顾国内震积岩的研究历史,总结了中国震积岩研究的成果及其存在的问题,重点讨论了地震引起的软沉积物变形、地震事件沉积的时序、地震事件沉积的空间分布和地震事件沉积序列等.按照地震对沉积物改造的时间,将软沉积物变形划分为同生、准同生、后生变形3类,并对地震同生断裂、准...     

新旧气候态的差异及其对江西气候业务的影响

利用1961—2022年江西74个气象站平均气温、最高气温、最低气温、降水量、相对湿度、平均风速和日照时数资料,对比分析了1991—2020年和1981—2010年新、旧气候态下气象要素差异,探讨气候平均值改变对气候影响评价和预测业务的影响。结果表明：新气候态下,江西省三类气温的年和季节平均值均上升,年降水量总体增加将弱化气温偏高、降水偏多的变化特征。年和季节平均风速距平山区减小而平原地区增大;年日照时数距平总体增加。极端高温年份减少,极端低温年份增多,其中平均气温和最低气温的极端高（低）温年发生概率的降幅（增幅）比最高气温更大。极端强降水年发生概率在赣西北、赣中大部、赣南西北部等地区夏季减少,赣南中南部地区冬季增大。全省历年极端日高温、低温和强降水事件发生站次总体减少。新、旧气候态的更替会对气候业务产生影响,如冬季气温偏冷的年份增加,偏暖的年份减少,需对冷、暖冬事件进行重新评估,夏季降水增多的变化特征减弱,将导致夏季降水预测量级和趋势发生改变。     

游标法事件计时器

根据游标法事件计时器的设计原理，给出基于现场可编门阵列(FPGA)的设计方案，并对实现游标法事件计时器的技术难点进行相关分析。     

豫西狮子坪地区秦岭群中的斜长角闪岩-大理岩组

在河南卢氏狮子坪地区的秦岭群中出露一套变质地层,其组成特点与各地已知的秦岭群明显不同,主要岩石类型为斜长角闪岩、透辉斜长变粒岩和含石墨大理岩。在构造迭置关系上这套变质地层位于秦岭群条带状长英质片麻岩层和云母片岩层之上,原始接触关系已不明朗,内部也难以逐层恢复层序,但内部三部分的迭置关系是明确的。作者提出这套变质地层应当作为一个独立的填图单位,进而建立岩组,并认为这可能是一套迭置于秦岭群之上的较新地层,但曾与秦岭群一道遭受了变质变形改造。     

Late Weichselian fluvio‐aeolian sands and coversands of the type locality Grubbenvorst (southern Netherlands): sedimentary environments,climate record and age

The Weichselian Late Pleniglacial and Lateglacial aeolian stratigraphy (Older Coversand I, Beuningen Gravel Bed, Older Coversand II, Younger Coversand I, Usselo Soil, Younger Coversand II) in the southern Netherlands has been reinvestigated in its type locality (Grubbenvorst). Sedimentary environments have been reconstructed and related to their climatic evolution based on periglacial structures. In addition, 22 optically stimulated luminescence (OSL) ages have been determined that provide an absolute chronology for the climatic evolution and environmental changes of the coversand area. From this work it appears that, prior to 25 ka fluvial deposition by the Maas dominated. After 25 ka fluvial activity reduced and deposition occurred in a fluvio‐aeolian environment with continuous permafrost (Older Coversand I). This depositional phase was dated between 25.2 ± 2.0 and 17.2 ± 1.2 ka. The upward increase of aeolian activity and cryogenic structures in this unit is related to an increase of climatic aridity and a decrease in sedimentation rate during the Last Glacial Maximum (LGM). The Beuningen Gravel Bed, that results from deflation with polar desert conditions and that represents a stratigraphic marker in northwestern Europe, was bracketed between 17.2 ± 1.2 and 15.3 ± 1.0 ka. Based on this age result a correlation with Heinrich event H1 is suggested. Permafrost degradation occurred at the end of this period. Optical ages for the Older Coversand II unit directly overlying the Beuningen Gravel Bed range from 15.3 ± 1.0 ka at the base to 12.7 ± 0.9 ka at the top. Thus this regionally important Older Coversand II unit started at the end of the Late Pleniglacial and continued throughout the early Lateglacial. Its formation after the Late Pleniglacial (LP) maximum cold and its preservation are related to rapid climatic warming around 14.7 ka cal. BP. The Allerød age of the Usselo Soil was confirmed by the optical ages. Copyright © 2007 John Wiley & Sons, Ltd.     

Controls on runoff components on a forested slope and implications for N transport

Transfer of atmospheric N deposition on shallow‐soil forested basins on the Canadian Shield to receiving water bodies may be enhanced by rapid preferential flow along the soil–bedrock interface (BR runoff) on basin slopes. Controls on BR runoff, partitioning of event and pre‐event water contributions to this flow, and implications of this partitioning for N fluxes in BR runoff were studied under natural and artificial inputs to an instrumented slope. BR runoff as a fraction of water inputs to the slope increased with antecedent soil wetness and input depth. Event water contributions to BR runoff initially increased with antecedent soil wetness, but then declined at large antecedent soil wetness. Export of applied NH₄⁺ from the slope was maximized when event water contributions containing large NH₄⁺ concentrations dominated BR runoff; however, there was no relationship between the fraction of NO₃^? application transported in BR runoff and either application input or the event water fraction of that runoff. The applicability of our results to other shallow‐soil areas of the Canadian Shield is limited by artificial N inputs to the slope in excess of natural loads and by low rates of N mineralization and negligible nitrification in the slope's soils. Nevertheless, the study reinforces the need to consider how the hydrologic, geometric and pedologic properties of forest slopes interact with biotic and abiotic soil processes to control N transport and transformation. Copyright © 2001 John Wiley & Sons, Ltd.