Growth performance of larval and juvenile manila clam (<Emphasis Type="Italic">Ruditapes philippinarum</Emphasis>) from divergently selected individuals of a full-sib family

In this study, the method of divergent selection was employed to test the larval and juvenile growth performance within a full-sib family of Manila clam Ruditapes philippinarum. The 10% largest and 10% smallest clam individuals (on the basis of shell length) of a full-sib family were selected as parents for the fast and slow growing lines, respectively. The difference in shell length was significant among the three lines (fast, control, and slow) tested. The sequence of shell length were fast line > control line > slow line. The responses to selection, realized heritability, and genetic gain were 0.06%–0.81%, 0.04%–0.47% and 0.58%–18.89% in the fast direction, respectively; and were 0.14%–1.27%, 0.08%–0.73%, and 0.31%–49.03% in the slow direction, respectively. The results suggested that there was a large portion of additive genetic variance affecting the growth in the full-sib family. Selection in the fast direction within the full-sib family would greatly improve the growth of R. philippinarum.     

Depth classification of underwater targets based on complex acoustic intensity of normal modes

In order to solve the problem of depth classification of the underwater target in a very low frequency acoustic field, the active component of cross spectra of particle pressure and horizontal velocity (ACCSPPHV) is adopted to distinguish the surface vessel and the underwater target. According to the effective depth of a Pekeris waveguide, the placing depth forecasting equations of passive vertical double vector hydrophones are proposed. Numerical examples show that when the sum of depths of two hydrophones is the effective depth, the sign distribution of ACCSPPHV has nothing to do with horizontal distance; in addition, the sum of the first critical surface and the second critical surface is equal to the effective depth. By setting the first critical surface less than the difference between the effective water depth and the actual water depth, that is, the second critical surface is greater than the actual depth, the three positive and negative regions of the whole ocean volume are equivalent to two positive and negative regions and therefore the depth classification of the underwater target is obtained. Besides, when the 20 m water depth is taken as the first critical surface in the simulation of underwater targets (40 Hz, 50 Hz, and 60 Hz respectively), the effectiveness of the algorithm and the correctness of relevant conclusions are verified, and the analysis of the corresponding forecasting performance is conducted.     

The Impact of Large-Scale Reclamation on Hydro-Dynamic Environment——A Case Study of Xinghua Bay

A hydro-dynamic model is established on basis of MIKE21 FM to simulate the hydro-dynamic characteristics of Xinghua Bay and investigate the influence of reclamation project on the tidal elevation and tidal currents. Tidal elevation data was obtained at the six tide gauge stations around the Xinghua Bay, and another six current stations were established to observe the tidal current velocity and direction. Validation shows that the model-simulated tidal elevation and tidal currents agree well with observations made at different stations. Predictions are made according to the reclamation project proposed in the regional marine planning of Hanjiang Industrial Park around the port in Putian City. The variations of hydro-dynamic factors, such as tide, current velocity and direction and tidal influx are obtained, and the adverse effect of reclamation on marine environment is discussed. It is shown that the tidal level inside the Xinghua Bay during high tide decreases after the reclamation project is completed. The tidal currents during flooding tide generally decrease in the southeast of the reclamation region, with the maximum decreasing amplitude reaching 0.44 m s^-1. On the other hand, the tidal currents during flooding tide increase around the southeast and southwest corners of the reclamation region. The tidal currents during ebb tide increase around the southeast and southwest corners of the reclamation region, with the maximum increasing amplitude attaining 0.18 m s^-1. The results in this paper can give some guidance for the marine environment management and the effective utilization of land in Putian.     

渤海湾海岸带地区~(137)Cs参考剖面——意义、方法及初步结果

海岸带地区近百年来的现代地质过程重建必须以精确的年代学研究为基础,~(137)Cs时标法和~(210)Pb_(exc)测年法是目前广泛应用的方法。由于易受到河流沉积物供给变化、潮位状况、极端天气事件等的影响,海岸带现代过程的定量研究一直是高分辨率研究的瓶颈。区域性参考剖面可以提升现代沉积物测年方法在海岸带应用中的可靠性。因此,建立区域性的~(210)Pb_(exc)和~(137)Cs比活度-深度参考剖面,将改善对海岸带及邻近海区实测数据的解释。以渤海湾海岸带为研究区,选取沉积环境相对稳定、水平搬运作用较小的地区,采用人工探坑、Eijkelkamp槽型取样器获取了2个柱状岩心,通过γ能谱仪对样品进行~(210)Pb、~(226)Ra及~(137)Cs比活度测试,绘制剖面图,结合研究区已有数据,总结出6类海岸带常见的~(210)Pb_(exc)和~(137)Cs比活度-深度剖面类型,并重建了渤海湾海岸带~(137)Cs区域性参考剖面。结果显示,~(137)Cs在渤海湾地区的最大峰值指示1963年,可以作为区域性主要参考时标。但是,最大峰值上部的次峰在不同区域指示不同的时标,S4和S5两个站位该峰值指示的并非1986年时标。     

津冀海岸线现状、变化特征及保护建议

根据覆盖全区的3期遥感影像和实地调查,以及对滨海新区和滦河口2个典型区更深入的案例研究(包括回溯至1870年、1950年的基准岸线及逐年遥感信息),对津冀沿海海岸线现状进行解译和分类,并分析岸线变化特征及成因。津冀沿海现状岸线总长度894km,可以划分为自然岸线、半开发岸线和人工岸线3类,长度分别为90km、329km和475km。1950年以前为自然因素主导的岸线变化,1950年以后变为人类活动主导的岸线向海推进,逐渐加强的人类活动至2010年达到顶峰。在全球海面上升和区域地面下沉的大背景下,海岸线的自然演化趋势应该是向陆蚀退,但是人类活动主导的岸线变化却表现为违反自然趋势的向海推进。今后,向海推进最前沿的围海造陆区将受到来自海洋越来越强烈的影响,亟需加强监测和防护。兼顾环境保护与开发两方面的长远需求,建议赋予海岸线新的定义与内涵,划定岸线保护红线,恢复部分岸线的自然属性。     

莱州湾南岸全新世相对海平面变化重建

在对莱州湾南岸8个钻孔沉积物沉积结构及有孔虫特征分析基础上,识别相关海面标志层位,辅以加速器质谱AMS14C测年,重建了全新世相对海面变化历史,并讨论了海面变化的沉积响应及控制因素。约9200cal BP以前,海面快速上升,研究区海侵时海面于-21.5m左右;9200~8400cal BP海面上升速率减缓至约2mm/a;8400~8000cal BP海面由-14m快速上升至-5.5m,速率约为33mm/a;8000~7600cal BP,海面持续数百年停滞或微弱下降;7600~7000cal BP海面由-5.5m快速上升至0m以上,速率至少约为13mm/a;7000~6000cal BP海面缓慢上升至+2~+3m位置,速率约为3mm/a;约6000cal BP以后海面缓慢下降至现今水平。约9200cal BP以前、8400~8000cal BP、7600~7000cal BP时期的3次海面快速上升,是MWP-1C融水脉冲、诱发8.2ka冷事件的融水脉冲,以及MWP-2融水脉冲的中纬度地区响应。中全新世全球冰融趋于停滞后,由于研究区沉积盆地沉降速度较慢,在冰川均衡调整效应下,使+2~+3m的相对高海面得以呈现。     

On the problem of the scale and composition of Paleozoic and Mesozoic granitoid magmatism in the Khilok–Vitim fold belt of Central Transbaikalia

The paper presents a study of the gneissic granitoids of the Malkhan Complex and the intruisve granitoids of the Daur and Bichur complexes developed within the Khilok–Vitim fold belt of Central Transbaikalia. In the state geological map, these complexes have been attributed to the Early and Late Paleozoic. New ⁴⁰Ar/³⁹Ar geochronological data indicate that these rocks are Mesozoic rather than Paleozoic in age, which suggests the much broader manifestation of the Mesozoic granitoid complexes in this area. The studied Mesozoic granitoid massifs exhibit temporal and compositional zoning reflected in a westward decrease in age (from Early to Late Mesozoic) and increase in total alkalinity and potassium content at the appropriate trace-element characteristics. The obtained results of study of the Khilok–Vitim Belt are interpreted in the framework of the model of the formation of domal–cupola structures by the multiple activity of deep thermochemical plumes.     

Problems of Paleogene–Neogene stratigraphy of the Zerkal’naya depression,East Sikhote Alin

The Paleogene–Neogene stratigraphic scale of the Zerkal’naya River basin is modified with account for new isotopic and paleobotanical data. It is established that the Tadushi Formation and underlying volcanics, which were previously considered as representing transitional Cretaceous–Paleocene strata, are separated in the section of the Ustinovka quarry by a significant stratigraphic hiatus. According to the new data, the volcanics and the Tadushi Formation are established as Campanian and Late Paleocene in age, respectively. The Bogopol Formation in the type section is dated back to the Middle–Late Paleocene. The Svetlyi Formation is now considered to be Early Eocene in age, rather than Late Eocene–Oligocene as previously thought. A new variant of the stratigraphic scale is proposed for the Paleogene–Neogene deposits of the Zerkal’naya depression.     

Petrophysical features of the tectonic structures of the Okhotsk continent–ocean transition zone

Petrophysical characteristics are determined for the rock complexes of the Okhotsk margin within the continent–ocean transition zone. Petrophysical maps showing the major inhomogeneities of the main tectonic elements of the studied area are constructed. Petrophysical inhomogeneities and the corresponding geophysical field anomalies are compared. A relationship between the magnetic field anomalies and subsurface rock complexes is revealed. The gravity field anomalies are related to deep inhomogeneities and are almost independent of the subsurface rock complexes of relatively low thickness.     

Tectonics and metallogeny of the Khakandzha ore district in the Okhotsk–Chukotka volcanic belt

The data on the structure, geodynamics, and metallogeny of the Khakandzha ore district in northwestern Okhotsk region are analyzed and the two main factors responsible for the localization of ore deposits are defined. The magmatic factor controls the confinement of the ore district to the tectono-magmatic structure of the central type (source of ore matter), which determines the concentric zoning patterns in the distribution of ore mineralization. The tectonic factor determines the confinement of the ore districts, deposits, and ore occurrences of the region to the meridional left-lateral shear structure, which controls the magma and fluid distribution. Local extension (transtension) in this structure against the background of general lateral compression (transpression) provided tectonic environments most favorable for ore accumulation.