藏南喜马拉雅北坡色龙地区二叠系基性火山岩的发现及其构造意义

藏南喜马拉雅北坡二叠系基性火山岩位于聂拉木县色龙东山。岩石地球化学特征表明,无论是基龙组火山岩还是色龙群火山岩,都具有大陆拉伸-大陆裂谷环境火山岩系的主、微量元素地球化学特征。据此,判断两套基性火山岩的性质和喷发构造环境相同。该区二叠纪大陆拉伸-裂谷火山活动标志着冈瓦纳超级古大陆开始裂离、解体。     

Petrogenesis of post-collisional A-type granitoids from the Urumieh–Dokhtar magmatic assemblage,Southwestern Kerman,Iran: Constraints on the Arabian–Eurasian continental collision

Three plutons (Deh-Siahan, Bande-Bagh and Baghe-Khoshk Sharghi, collectively referred to as the DBB hereafter) in southwestern Kerman, in the southeastern part of the Urumieh–Dokhtar magmatic assemblage (UDMA) of the Zagros orogenic belt differ from the typical calc-alkaline metaluminous, I-type intrusions of the region. The DBB intrusions have a distinct lithological assemblage varying from diorite through monzogranite and monzonite to alkali feldspar syenite and alkali granite. The DBB granitoids are metaluminous to slightly peraluminous, alkaline to shoshonitic in composition and have high total alkali contents with K₂O > Na₂O, high FeO_T/MgO values, and low CaO and MgO contents. They are enriched in some LILEs (such as Rb and Th) and HFSEs (such as Zr, Y and REEs except Eu) and depleted in Sr and Ba relative to primordial mantle, and have low concentrations of transitional metals. These features along with various geochemical discriminant diagrams suggest that the DBB granitoids are post-collisional A-type granitoids, which had not been recognized previously in the UDMA. The chondrite-normalized REE patterns of the DBB granitoids show slightly enriched light REEs [(La/Sm)_N = 2.26–4.13], negative Eu anomalies [(Eu/Eu*)_N = 0.19–0.74] and flat heavy REE patterns [(Gd/Yb)_N = 0.80–1.87]. The negative Eu anomaly indicates an important role for plagioclase and/or K-feldspar during fractional crystallization. Whole-rock Rb–Sr isotope analysis yields an isochron age of 33 ± 1 Ma with an initial ⁸⁷Sr/⁸⁶Sr value of 0.7049 ± 0.0001. Whole-rock Sm–Nd isotope analysis gives ε_Nd^t values from + 2.56 to + 3.62 at 33 Ma. The positive ε_Nd^t and low I_Sr values of the DBB granitoids together with their T_DM of 0.6–0.7 Ga suggest their formation from partial melting of a lithospheric mantle source, modified by fluids or melts from earlier subduction processes. Melting of lithospheric mantle occurred via a dehydration melting process at pressures below the garnet stability field, as a consequence of lithospheric mantle delamination or break-off of a subducted slab and melting of the lithospheric mantle by upwelling of hot asthenosphere. On the basis of Rb/Sr age dating and the post-collisional geochemical signatures of the DBB granitoids, along with extensive pre-collisional volcanic eruptions in Middle Eocene, we suggest Late Eocene for the time of collision between the Arabian and Central Iranian plates. This also implies that the calc-alkaline I-type intrusions in the southwestern Kerman and in other parts of the UDMA may have formed in a post-collisional context.     

Pattern of abrupt climatic fluctuation in the East Asian Monsoon during the Last Glacial: Evidence from Chinese loess records

Records of two loess sections located in mid-eastern and western margins of the East Asian Monsoon area captured 20 Dansgaard-Oescher events and six Heinrich events. All these suggested that the climate in the East Asian Monsoon area fluctuated rapidly on millennial to century timescales during the whole Last Glacial. We found that these loess-based events of rapid climate fluctuations were generally synchronous with those of GRIP records, but that there were differences between the Shagou loess section in the west and the Wangguan loess section in the east: the former was more sensitive to climate change than the latter. Compared with earlier studies on loess records covering the Last Glacial from neighboring areas, we discovered that the magnitude of Dansgaard-Oeschger cycles decreased gradually from west to east and we suggest that it resulted from the combined effect of the Westerlies and the East Asian Monsoon.     

益阳硐坡金矿地质特征及富集规律初步探讨

益阳岩金矿床的勘查研究表明，该区含金石英脉均受剪切片理化带控制。构造剪切作用形成塑性变形褶皱和糜棱岩化，并使早期石英脉发生塑性变形或脆性碎裂，为成矿提供了构造空间。随着剪切作用的持续进行，派生了里德尔共轭裂隙，再次为金矿化提供了容矿空间。含矿溶液沿裂隙充填或胶结后期糖粒状石英，形成特殊的合会剪切带型金矿。因此，本文提出在北东一近东西向雪峰孤形构造带找金时，应视剪切片理化带为重点靶区，４１８队在硐坡矿段的金矿预测与验证说明，这一认识具有指导意义。     

三角剪切断层传播褶皱在祁连山北缘断裂中的应用:以黑河口断层为例

逆冲断层运动学过程研究可为造山作用和盆地演化提供重要的信息。位于青藏高原东北缘的祁连山北缘逆冲断裂（NFT）是一条主要的边界断裂,控制着祁连山晚新生代以来的隆升变形,但对于该断裂系统的运动学过程缺乏研究。甘肃张掖西南莺落峡附近,黑河口断层（祁连山北缘断裂的一部分）穿过红沙沟并导致其阶地面错断和褶皱变形。为了研究该区域褶皱变形特征和断层运动学过程,我们首先在红沙沟区域进行了详细的野外考察并对变形的地层和阶地面进行了测量,然后通过数值模拟方法来验证褶皱模型。红沙沟保存有9级河流阶地,利用差分GPS对阶地面的高程进行了测量,同时在野外测量了部分地层的产状。多处断层剖面表明该区域变形属于基底卷入的构造类型,另外变形的阶地面在近断层处表现出明显的褶皱形态。结合阶地面变形特征以及地层的变形,三角剪切断层传播褶皱模型被初步用于该区域构造变形的解释。模型模拟得到自T5、T6和T7形成以来断层滑动量分别是 44±7m、59±10m和 164±28m;结合T6年代得到自约9万年以来该断层的平均滑动速率为 0.68±0.19mm/a,垂直分量为 0.58±0.13mm/a。根据地层与阶地变形特征,并结合模型模拟结果,我们认为祁连山山前基底断层卷入的构造中,在断层出露地表之前,断层顶端存在一个分散式的三角形变形区,区域的应力状态控制着下伏地层和上覆地貌面的褶皱变形。     

用新显色剂3-甲氧基-甲亚胺H光度测定海水中的硼

采用新试剂３－甲氧基－甲亚胺Ｈ测定海水中的硼，加入ＥＤＴＡ和酒石酸掩蔽各种干扰离子，不须分离可直接测定，方法简便、快速、准确。     

试论洞庭湖的特征与治理

本文较全面地论述了洞庭湖（区）的特征,治理洞庭湖的必要性、重要性以及可行性。洞庭湖如不治理,少则100年,多则500年,就会因泥沙的淤积而消失。因此作者提出了 “开流节源,治江保湖”,“增秸扩池,治湖保湖”,以及维护和加强防洪工程等治理洞庭湖的设想。     

A study on remote sensing models of sea ice thickness by microwave radiometry

Extrapolating from the propagation theories of electromagnetic waves in a layered medium, a three-layer medium model is deduced in this paper by using microwave radiometric remote sensing technology which is suitable to first-year sea ice condition of the northern part of China seas. Comparison with in situ data indicates that for microwave wavelength of 10 cm, the coherent model gives a quite good fit result for the thickness of sea ice less than 20 cm, and the incoherent model also works well for thickness within 20 to 40 cm. Based on three theoretical models, the inversion soft ware from microwave remote sensing data for calculating the thickness of sea ice can be set up. The relative complex dielectrical constants of different types of sea ice in the Liaodong Gulf calculated by using these theoretical models and measurement data are given in this paper. The extent of their values is (0. 5-4. 0)-j(0. 07~0. 19).     

海水中液-固界面的台阶型动力学曲线 Ⅱ.液膜扩散-递进扩散-界面分级交换反应联合控制的复合模型理论

为定量解释海水中液-固界面的台阶型动力学曲线及其台阶的消长变化规律,在我们已提出的“液膜扩散和递进液膜扩散控制的复合模型”和“海水中液-固界面分级离子/配位子交换理论”基础上,吸取Crank的若干数学处理方法,进而提出适合于非稳态体系的“液膜扩散-递进扩散-界面分级交换反应联合控制的复合模型”。