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Reconstruction of paleocoastlines for the northwestern South China Sea since the Last Glacial Maximum 总被引：1，自引：0，他引：1
The range of relative sea level rise in the northwestern South China Sea since the Last Glacial Maximum was over 100 m. As
a result, lowland regions including the Northeast Vietnam coast, Beibu Gulf, and South China coast experienced an evolution
from land to sea. Based on the principle of reconstructing paleogeography and using recent digital elevation model, relative
sea level curves, and sediment accumulation data, this paper presents a series of paleogeographic scenarios back to 20 cal.
ka BP for the northwestern South China Sea. The scenarios demonstrate the entire process of coastline changes for the area
of interest. During the late glacial period from 20 to 15 cal. ka BP, coastline slowly retreated, causing a land loss of only
1×104 km2, and thus the land-sea distribution remained nearly unchanged. Later in 15–10 cal. ka BP coastline rapidly retreated and
area of land loss was up to 24×104km2, causing lowlands around Northeast Vietnam and South China soon to be underwater. Coastline retreat continued quite rapidly
during the early Holocene. From 10 to 6 cal. ka BP land area had decreased by 9×104km2, and during that process the Qiongzhou Strait completely opened up. Since the mid Holocene, main controls on coastline change
are from vertical crustal movements and sedimentation. Transgression was surpassed by regression, resulting in a land accretion
of about 10×104km2.
Supported by Key Laboratory of Marginal Sea Geology, Chinese Academy of Sciences (Grant No. MSGL0711), the Guangdong Natural
Science Foundation (Grant No. 04001309) and Open Fund of the Key Laboratory of Marine Geology and Environment, Chinese Academy
of Sciences (Grant No. MGE2007KG04) 相似文献
2.
Carbon sequestration processes and mechanisms in coastal mariculture environments in China 总被引：1，自引：0，他引：1
YongYu Zhang JiHong Zhang YanTao Liang HongMei Li Gang Li Xiao Chen Peng Zhao ZengJie Jiang DingHui Zou XiaoYong Liu JiHua Liu 《中国科学:地球科学(英文版)》2017,60(12):2097-2107
China is the global leader in mariculture production. Increasing sequestered marine carbon (also known as blue carbon) via mariculture activities is a promising approach for mitigating climate change and promoting the development of a low-carbon economy. Mariculture blue carbon is also considered an important component of China’s “sea granary”. In addition to shellfish and macroalgae yields, which represent carbon removed from mariculture environment, blue carbon also includes other important components, which have been largely neglected in the past, such as the carbon transformed by microbes, dissolved organic carbon (mainly referred to as recalcitrant dissolved organic carbon), and sedimentary particulate carbon. Hence, from different aspects, a comprehensive study on the formation processes and mechanisms of carbon sequestration is of great significance for comprehensively unveiling the carbon sequestration capability in coastal mariculture environment, which will contribute to the sustainable development of the fishery economy and construction of an ecological civilization. Moreover, it may add significant economic benefits to the future carbon-trading market. 相似文献
3.
安徽女山新生代玄武岩中橄榄岩包体矿物的含水性研究 总被引：8，自引：3，他引：8
本文对15个来自安徽女山新生代玄武岩的橄榄岩包体矿物（橄榄石、单斜辉石和斜方辉石）进行了详细的微区傅立叶变换红外光谱（Micro-FTIR）分析。结果显示，所有被测的橄榄石颗粒都没有明显的OH吸收峰，这表明橄榄石要么不舍结构水，要么结构水含量〈2ppm（H2Owt．下同）；所有的单斜辉石和斜方辉石颗粒都含有以OH形式存在的结构水。辉石矿物颗粒内部的结构水含量要么是均一的，要么表现出中心高边缘低的不均一分布。这种不均一分布的特征应该来自于包体上升过程中由于压力降低而引起的H扩散。如果用每个样品多个测定颗粒的中心部位的平均值来代表该样品的话，15个样品的单斜辉石水含量为6～356ppm，斜方辉石水含量6～139ppm。单斜辉石与斜方辉石之间水含量的比值为-2．5，和文献中报道的分配系数吻合，表明女山单斜辉石和斜方辉石之间达到了H平衡。女山的橄榄岩分成低温（〈950℃）和高温（〉1050℃）两组，所有的含角闪石的样品都在低温组。高温组的斜方辉石和单斜辉石表现出H2O含量和Al含量的正相关、和Mg含量的负相关，表明Al^3＋H^←→Si^4＋和Al^＋H^＋←→2Mg^2＋是辉石中H的主要结合机制，同时也表明这些样品有效地保存了其在源区的原始结构水含量。而低温组的辉石偏离了相关趋势，结合该组部分样品含有角闪石的特征，我们提出一个流体（本文中采用广义的概念，即包括熔体和流体）上升交代的模式来解释女山橄榄岩的特征：流体从下向上运移，与高温组（下部）橄榄岩先发生反应，由于水含量较低，既没有影响橄榄岩矿物的原始水含量，也没有能形成角闪石，在上升的过程中由于发生名义上无水矿物（橄榄石，辉石等巨晶）的结晶分离，流体中的水含量不断增加，积累到一定程度，即与低温组（上部）橄榄岩反应时。不仅影响了橄榄岩矿物的原始水含量，也在部分样品中形成了角闪石。 相似文献
4.
安徽女山下地壳麻粒岩包体中的水：红外光谱分析 总被引：7，自引：0，他引：7
运用显微傅立叶变换红外光谱技术，对安徽女山新生代玄武岩中的10个麻粒岩包体的主要组成矿物（单斜辉石、斜方辉石、斜长石）进行了观察。结果显示，这些名义上的无水矿物中都普遍含有以OH一形式赋存的结构水，其含量（H10wt．）分别可以高达～2340ppm（单斜辉石）、～1590ppm（斜方辉石）和～910ppm（斜长石）。不同样品间矿物的结构水含量具有明显的不均一性的分布特点，这很可能是对其原岩性质的一种反映。根据单矿物的水含量和各自的体积分数计算出的全岩水含量为125～963ppm。根据二辉石温度计计算的女山麻粒岩包体的平衡温度为～800～900℃，对应于女山最下部地壳（-25～35km），因此本文数据为大陆下地壳含水与否提供了初步的最直接的证据，并且其水含量可能具有不均一性的分布特点。 相似文献
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贵州三穗龙湾铀矿床地质地球化学特征及成因 总被引：1，自引：1，他引：0
三穗龙湾矿床位于黔中-湘西北铀成矿带内,是近年勘查发现的贵州第一个大型碳硅泥岩型铀矿床。本文对龙湾铀矿床开展了矿物学、地质地球化学及矿床成因等方面研究。结果表明,该矿床矿石中的原生铀矿物主要为沥青铀矿,表生条件下形成的次生铀矿物较发育,主要有硅钙铀矿、硒铅矿、钛铀矿及铀酰磷酸盐矿物等,它们以纳米-微米级粒状(粒径多10μm)、细脉状或隐晶质形式赋存于有机质、粘土矿物等聚铀矿物中;成矿物质主要来源于赋矿层位,可能有少量来自基底岩浆岩,成矿流体为深部流体与大气降水的混合;铀及共伴生元素的富集与炭质泥岩中富含有机质、磷矿物、铁矿物、粘土矿物密切相关;铀矿形成受层位(老堡组)、岩性(炭质泥岩)、构造(三穗向斜及斜切向斜的断层、层间断层)、围岩沉积环境(陆缘裂谷、裂陷的海相还原沉积环境)等因素控制,经历了雪峰期海底喷流作用下形成含矿岩系过程中铀的初始富集→燕山-喜马拉雅期板内伸展构造背景下淋滤、热液叠加改造再富集的成矿过程,后生成矿特征明显,矿床属沉积-热液叠加改造型。本文研究成果对推进黔东地区铀矿成矿预测和找矿勘查,丰富碳硅泥岩型铀矿成矿理论具有重要意义。 相似文献
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