华南晚二叠世碳酸盐岩碳同位素旋回对海平面变化的响应

华南晚二叠世的碳同位素变化曲线是逐渐降低的,与全球海平面变化趋势相一致。华南晚二叠世碳酸盐岩碳同位素旋回可分为两个三级旋回,与两个三级海平面变化响应,其中吴家坪晚期和长兴期组成了一个三级旋回。华南长兴期识别出了三个四级碳同位素地层旋回可能与四级海平面变化旋回相对应。华南晚二叠世碳同位素旋回记录了全球海平面变化的信息:高值区和高海平面相对应,而低值区和低海平面相对应。     

Numerical Analysis on the Effects of Submerged Depth of the Grid and Direction of Incident Wave on Gravity Cage

In this paper,the numerical model of the net cage with the grid mooring system in waves is set up by the lumped mass method and rigid kinematics theory,and then the motion equations of floating system,net system,mooring system,and floaters are solved by the Runge-Kutta fifth-order method.For the verification of the numerical model,a series of physical model tests have been carried out.According to the comparisons between the simulated and experimental results,it can be found that the simulated and experimental results agree well in each condition.Then,the effects of submerged depth of grid and direction of incident wave propagation on hydrodynamic behaviors of the net cage are analyzed.According to the simulated results,it can be found that with the increase of submerged depth of grid,the forces acting on mooring lines and bridle lines increase,while the forces on grid lines decrease;the horizontal motion amplitudes of floating collar decrease obviously,while the vertical motion amplitudes of floating collar change little.When the direction of incident wave propagation changes,forces on mooting lines and motion of net cage also change accordingly.When the propagation direction of incident wave changes from 0° to 45°,forces on the main ropes and bridle ropes increase,while the forces on the grid ropes decrease.With the increasing propagation direction of incident wave,the horizontal amplitude of the forces collar decreases,while the vertical amplitude of the floating collar has little variation.     

碟形网箱水动力特性的研究

根据物模实验得到碟形网箱在不同海况条件下的受力并给出了其估算方法和公式及其相关系数的取值,同时总结了碟形网箱的运动特性。     

华南二叠系长兴阶层型剖面碳酸盐岩的碳氧同位素地层

华南长兴阶层型剖面４０多米厚的地层主要由泥晶灰岩组成,从中系统采集了１５９个碳酸盐岩样品进行碳氧同位素地层学研究,清楚地识别出同位素的变化规律,划分出８个序列和３个旋回。３个碳氧同位素地层旋回由上至下为：长兴早期的Ｐａｌａｅｏｆｕｓｕｌｉｎａｍｉｎｉｍａ旋回,长兴中期的Ｃｒｕ－ｒｉｔｈｙｒｉｓ－Ｇｅｉｎｉｔｚｉｎａ－Ｃｌａｒｋｉｎａｓｕｂｃａｒｉｎａｔａ旋回,长兴晚期的Ｐａｌａｅｏｆｕｓｕｌｉｎａｓｉｎｅｎｓｉｓ旋回。碳酸盐岩碳同位素的异常变化与有机碳的贮藏和氧化相关,而这些变化可能具同时性,记录于整个古华南海水中,从而成为地层对比的良好标志。长兴阶高分辨率碳氧同位素地层的建立,提高了地层的划分精度,为长兴阶进一步的精细地层对比提供了可能。     

海底管线上波浪力的大涡模拟及三步有限元数值模拟

应用三步有限元法结合大涡模拟方法(LES)离散非定常不可压流动的Navier-Stokes方程,模拟了波浪场中海底管线周围流场及其受力情况,并把数值模拟的结果与物理实验的实测结果进行了比较,两者符合较好。为了检验三维效应的影响,同时进行了二维和三维流场的数值模拟。     

波流共同作用下水平杆件上的力谱

本文根据波流共同作用下的修正Morison公式和等效线性化方法,近似地求得了水平杆件上波流作用力的相关函数,并通过傅里叶变换,求得了波面谱与波力谱间的传递函数和力谱函数,文中还将本方法与实验结果做了比较,最后利用本方法做了部分计算实例。     

中国南方二叠-三叠纪过渡时期的碳同位素旋回地层与突变事件

在中国南方晚二叠世至早三叠世初碳酸盐岩的Ｃ 同位素演化基础上, 考察了长兴阶层型剖面的高分辨率Ｃ 同位素旋回地层,发现长兴阶有三个Ｃ 同位素四级旋回,与吴家坪阶晚期的一个四级旋回共同组成了一个完整的三级旋回。与这种缓慢变化形成强烈对比的是：Ｐ／ Ｔ 界线上在１ ．５ ～２．６ 万ａ 左右的地球年时间中δ１３ Ｃ 突变为高负值, 形成剧烈负异常, 其中生物集群绝灭因素可能占２／３ 以上,变负幅度约５‰～６ ‰。二叠纪末生物集群绝灭的原因可能与大规模的火山爆发引起的气体增加和缺氧事件有关。     

An improved numerical simulation mode of nonlinear wave with consideration of high order terms

In this paper the 0-1 combined BEM is adopted to subdivide the computational domain boundary,and to discretize the Green’s integral expression based on Laplace equation.The FEM is used to subdivide the wave surface and deduce the surface equation which satisfies the nonlinear boundary conditions on the surface.The equations with potential function and wave surface height as an unknown quantity by application of Taylor expansion approach can be solved by iteration within the time step.In m-time iteration within the computational process of time step(n-1)Δt to nΔt,the results of the previous iteration are taken as the initial value of the two-order unknown terms in the present iteration.Thus,an improved tracking mode of nonlinear wave surface is established,and numerical results of wave tank test indicate that this mode is improved obviously and is more precise than the previous numerical model which ignored the two-order unknown terms of wave surface location and velocity potential function in comparison with the theoretical values.     

华南二叠系长兴阶灰岩的碳同位素地层对比

以浙江长兴煤山长兴阶层型剖面、江西上高七宝山剖面、陕西汉中梁山剖面为代表的华南长兴阶碳酸盐岩碳同位素地层,清楚地显示出长兴阶顶、底为碳同位素低值区,其中Ｐ－Ｔ界线附近的碳同位素出现强烈负异常事件。在长兴阶内部两次碳同位素低值异常区,将长兴阶碳同位素演化曲线由下至上明显分为３个旋回,其中长兴阶顶,也即Ｐ－Ｔ界线,碳同位素强烈负异常与生物绝灭事件有关,时间短,变化幅度大,是全球界线对比的重要标志。而其它碳同位素负漂移和由此构成的３个旋回,在华南可以追踪对比。上旋回与长兴阶上段煤山段相当;而中、下旋回则与下段葆青段相当,并将其两分。碳同位素地层对比表明江西上高地区长兴组的中、上部可能属长兴阶,而下部厚约９０ｍ的含Ｇａｌｏｗａｙｉｎｅｌａ灰岩可能属吴家坪晚期。     

太行山南段洪山岩体中粗面斑岩地球化学特征及LA-ICP-MS锆石U-Pb定年

在详细野外调研的基础上,对位于太行山南段洪山岩体中粗面斑岩的岩石学、地球化学和年代学特征进行了研究。该区斑岩中Si O2含量为63.57%~67.85%,平均为65.19%;里特曼指数σ值为5.6~8.2;K2O/Na2O为1.00~1.74,平均为1.24;A12O3为16.75%~18.77%,平均为18.21%。铝饱和指数A/CNK为1.00~1.06,属于碱性正长岩类岩石。岩石稀土元素总量(∑REE)为33.75×10-6~144.30×10-6,(La/Yb)N=9.18~33.28,呈现轻稀土元素(LREE)富集、重稀土元素(HREE)相对亏损的特点。δEu=0.99~1.16,有微弱正Eu异常。在原始地幔标准化微量元素蜘蛛图解中,样品均显示强烈富集大离子亲石元素(LILEs)、相对亏损高场强元素(HFSEs)的特征。同时,在该地区获得的粗面斑岩LA-ICP-MS锆石U-Pb年龄为128.6±1.0Ma。锆石εHf(t)值为-16.0~-11.4,对应的地壳模式年龄(TDM)为1258~1432Ma。这些数据表明,洪山粗面斑岩与洪山其他中生代侵入岩是同期岩浆作用的产物,形成于早白垩世由造山挤压环境向伸展环境转变期,是EM1型富集地幔部分熔融形成富碱的岩浆上升侵位,并受古老下地壳物质混染形成的。华北规模庞大的中生代岩浆作用可能与部分熔融并消耗富集岩石圈地幔层有关,这可能也是岩石圈地幔减薄的重要方式之一。