南极陆缘天然气水合物特征及资源前景

首先,根据地震反射剖面的似海底反射特征、深海钻探计划(DSDP)和大洋钻探计划(ODP)钻孔沉积物的高甲烷含量、高有机碳含量以及孔隙水盐度、氯离子浓度和硫酸根离子浓度异常等地球物理和地球化学证据推测,南极陆缘有7个潜在的天然气水合物分布区,它们分别为南设得兰陆缘、南极半岛的太平洋陆缘、罗斯海陆缘、威尔克斯地陆缘、普林斯湾陆缘、里瑟-拉森海陆缘和南奥克尼群岛东南陆缘等。其次,从气源条件、沉积条件、热流及温压条件和地质构造条件等对南极陆缘天然气水合物的成藏条件进行了分析,认为该陆缘具备天然气水合物形成和赋存的有利地质条件。最后,对南极陆缘天然气水合物的资源前景进行了探讨,认为其资源量非常可观。     

广西钦州板城晚泥盆世硅质岩地球化学特征及沉积环境探讨

广西钦州小董——板城地区发育较好的晚泥盆世至晚二叠世含放射虫硅质岩,剖面连续。本文对板城地区石梯水库晚泥盆世含放射虫硅质岩进行了主量元素、微量元素和稀土元素的分析,指示这些硅质岩形成于大陆边缘与深海盆地之间的过渡地带,说明在晚泥盆世钦州地区不存在大洋,与当时在华南板块与扬子板块之间发育古特提斯洋不符。     

层析方法在印度科拉拉-康坎（Kerala-Konkan）地区天然气水合物调查中的应用

地震层析是根据多道地震数据估算速度结构的有效方法。本次研究针对海上科拉拉-康坎（Kerala—Konkan）地区一条以前识别出似海底反射（BSR）的地震测线东段的多道地震数据,采用2D方法得到可能的速度场结构,并推测气体水合物,游离气的存在。层析模拟由反射相识别和不同源-接收器位置的走时拾取组成。利用这些拾取采用射线追踪技术进行正演和反演来得到2D速度场。本次模拟调查区的模型第一次显示出细微速度结构。2D模拟揭示了速度场沿地震线研究段的横向发生的变化。结果表明薄层沉积物盖层（约50—60m）的速度为1770至1850m／s。在海底之下具高P波速度（1980—2100m／s）的沉积物层被解释为水合物层,水合物层的厚度在110—140m之间变化。在水合物层底部有一低速层,速度为1660—1720m／s,被解释为游离气层,厚度在50—100m之间。本次调查表明在海上科拉拉-康坎（Kerala—Konkan）局部地区水合物之下存在游离气。     

参量阵浅地层剖面仪在海底羽状流探测中的应用——以ATLAS P70在马克兰海域调查为例

海底渗漏的羽状流是沉积层赋存天然气水合物的重要证据之一,基于非线性水声学原理的参量阵浅地层剖面仪作为海洋探测的重要设备,对于获得羽状流在水体中的物性特征和渗漏点的浅地层信息有着重大意义.本文根据ATLAS P70浅地层剖面仪在马克兰海域调查中得到的浅地层剖面数据,结合多道地震数据、多波束数据以及地质样品等资料,刻画了研究区内羽状流形态特征,分析了羽状流区海底地层流体运移的通道以及近海底微地形地貌特征.通过研究发现在羽状流区伴随泥火山喷发,自生碳酸盐岩发育,剥蚀海底松散沉积物形成大小不一的麻坑,滋生生物群落等特征.反映在浅剖初始高频(20 kHz)数据界面上羽状流表现为柱状浑浊反射异常,形态呈火焰状,高度由80 m到1500 m不等;对应在次级低频(4 kHz)信号界面可以清晰显示流体渗漏的浅地层结构特征,从中不仅可以识别出流体的运移通道,如泥火山和管状通道等,而且揭示了流体逸散的残留地貌,如麻坑构造和海底滑坡等.本文依托参量阵浅地层剖面数据,对巴基斯坦马克兰海域羽状流有了较全面的认识,为天然气水合物的研究垫定了基础.     

冷泉系统甲烷气体渗漏的声学特征及潜在环境效应

The amount of methane leaked from deep sea cold seeps is enormous and potentially affects the global warming,ocean acidification and global carbon cycle. It is of great significance to study the methane bubble movement and dissolution process in the water column and its output to the atmosphere. Methane bubbles produce strong acoustic impedance in water bodies, and bubble strings released from deep sea cold seeps are called "gas flares"which expressed as flame-like strong backscatter in the water column. We characterized the morphology and movement of methane bubbles released into the water using multibeam water column data at two cold seeps. The result shows that methane at site I reached 920 m water depth without passing through the top of the gas hydrate stability zone(GHSZ, 850 m), while methane bubbles at site II passed through the top of the GHSZ(597 m) and entered the non-GHSZ(above 550 m). By applying two methods on the multibeam data, the bubble rising velocity in the water column at sites I and II were estimated to be 9.6 cm/s and 24 cm/s, respectively. Bubble velocity is positively associated with water depth which is inferred to be resulted from decrease of bubble size during methane ascending in the water. Combined with numerical simulation, we concluded that formation of gas hydrate shells plays an important role in helping methane bubbles entering the upper water bodies, while other factors, including water depth, bubble velocity, initial kinetic energy and bubble size, also influence the bubble residence time in the water and the possibility of methane entering the atmosphere. We estimate that methane gas flux at these two sites is 0.4×10~6–87.6×10~6 mol/a which is extremely small compared to the total amount of methane in the ocean body, however, methane leakage might exert significant impact on the ocean acidification considering the widespread distributed cold seeps. In addition, although methane entering the atmosphere is not observed, further research is still needed to understand its potential impact on increasing methane concentration in the surface seawater and gas-water interface methane exchange rate, which consequently increase the greenhouse effect.     

大洋中脊热液硫化物矿床分布及矿物组成

海底热液硫化物是继大洋多金属结核、富钴结壳外的又一种新型海底多金属矿物资源，富含Cu，Zn，Fe，Mn，Pb，Ba，Ag，Au，Co，Mo等金属和稀有金属。多金属硫化物矿床是热液活动的产物，主要分布在大洋中脊、年轻和成熟的弧后盆地、岛弧以及海山等。本文总结了热液硫化物矿床在大洋中脊的分布特征及矿物组成，探讨不同扩张速度条件下的热液硫化物矿床的差异，有助于我们今后在大洋中脊环境中勘查和寻找新的大型热液硫化物矿床。     

骑田岭花岗岩~(40)Ar/~(39)Ar同位素年龄及其地质意义

报道骑田岭岩体长石~(40)Ar/~(39)Ar定年的结果.~(40)Ar/~(39)Ar方法定年在骑田岭岩体还是首次应用.测定的3个正长石样品~(40)Ar/~(39)Ar坪年龄(Ma)分别为(139.57±2.79)(2KL 17),(140.55±2.81)(99LQ-2),(144.91土2.90)(2KL-31),上述年龄反映了骑田岭岩体主体芙蓉和菜岭超单元岩浆冷却到正长石Ar-Ar封闭的年龄.可以认为这是岩体形成的最小年龄.其中2KL-31样品采自前人划为菜岭超单元的印支期花岗岩.菜岭超单元和芙蓉超单元年龄相近,与两单元地球化学特征与岩石结构的相似性以及正长石斑晶在几乎全岩体中呈NW-SE定向排列的地质事实相吻合.表明芙蓉与菜岭两个超单元岩体是晚侏罗世同源岩浆分异的产物.对骑田岭岩体和千里山岩体进行了对比讨论.     

40Ar/39Ar isotopic ages of Qitianling granite and their geologic implications

This paper has reported the first application of 40Ar/39Ar dating to orthoclase from Qitianling granite. The resultant plateau ages yielded by three orthoclase specimens 2KL-17, 99LQ-2 and 2KL-31 (Note: The last one was taken from the part of granite which had been attributed to Cailing super-unit of the Indosinian Period by the former researchers) collected from the said granite are (139.57±2.79) Ma, (140.55±2.81) Ma and (144.91±2.90) Ma respectively. The above-mentioned ages represent the closed 40Ar/39Ar age of the orthoclase. The consistency in age dating results, the similarity in geochemical characteristics and rock textures, and the NW-SE orientation of orthoclase phenocrysts almost throughout the granite, provide evidence for the intimate relationship between the Furong super-unit and the Cailing super-unit that form the main part of the granite, suggesting that they are products of comagmatic conjugate differentiation during the Late Jurassic. This paper also makes a comparison between the Qitianling granite and the Qianlishan granite.     

南极大陆及其周缘海域重、磁异常特征及区域构造分析

许多国家和组织在南极地区开展了大量的重、磁调查工作,并依据调查成果开展了区域地质构造等相关学科的研究,而中国此方面调查和研究工作很少.本文收集了南极地区最新的重、磁异常数据,首次对其进行了重、磁异常对应分析处理,详细描述了重、磁异常特征及对应分析特征.在此基础上,对区域构造进行了初步分析和解释,指出了东南极克拉通存在东、西深部构造差异,并对几个深大断裂进行了划分,探讨了东南极太古宙陆核的分布,对西南极及其周缘海域岩浆岩分布进行了初步划分.