东马努斯弧后盆地中酸性火山岩岩浆演化中的锂同位素特征

通过分析东马努斯海盆中酸性火山岩的全岩主量、微量元素以及锂同位素组成,并结合前人数据,讨论盆地岩浆体系的演化过程.分析数据显示,东马努斯海盆主、微量元素与SiO2含量之间呈线性变化关系,表明岩浆结晶分异过程控制东马努斯海盆岩浆演化过程.东马努斯弧后盆地火山岩富集流体相关元素,指示东马努斯弧后盆地岩浆源区可能经历了俯冲流...     

东马努斯海盆PACMANUS热液区Cu的物质来源：质量守恒模拟证据

东马努斯海盆位于巴布亚新几内亚的俾斯麦海域,是一个正在扩张的弧后盆地,与其活动热液喷口相关的热液产物,是现代海底系统中富含铜最丰富的矿产资源之一。火山岩与这种成矿作用有着密切的关系,然而通过海水对火山岩的淋滤作用是否可以为富含Cu的硫化物提供充足的Cu元素。PACMANUS热液区位于东马努斯海盆,质量守恒模拟在该热液系统的应用表明,由于水岩反应中较低的淋滤、转移和沉淀效率,通过热液流体对稳定反应区（0.144 km³）的简单淋滤无法满足硫化物矿床中Cu的需求。即使在100%的淋滤、转移和沉淀效率条件下,为了满足PACMANUS热液区硫化物中Cu的总量,仍需要0.166 km³体积的火山岩参与淋滤作用。
形成富含金属元素的岩浆流体的关键在于金属元素可以在挥发分中富集。首先,俯冲物质对地幔楔的交代作用,导致了东马努斯海盆地区生成的岩浆具有较高的氧逸度,进而使其岩浆房中富集Cu元素。其次,Pual Ridge的安山岩包裹体的气泡中富含Cu元素,进一步证实了在东马努斯海盆,Cu元素通过岩浆脱气作用向挥发分中运移。数值模拟结果显示,每1 km³体积的岩浆就可能向热液系统中运移0.236 Mt Cu。因此,岩浆脱气作用可能比淋滤作用更显著。     

马努斯海盆东部裂谷岩浆演化过程——火山岩中斜长石斑晶的启示

岩浆岩中斜长石矿物的结构、成分特征记录了岩浆演化过程的重要信息。本文对马努斯海盆东部裂谷(East Rift, ER)火山岩中的斜长石斑晶进行了详细的矿物学研究,结果表明:在玄武质安山岩中,斜长石斑晶具正环带结构,核-幔部属高An值(斜长石中钙长石分子百分数)斜长石(An值大于80,最大为87),而边缘的An值骤降(最小为63);而在英安岩中,大多数斜长石斑晶的成分从核部到边部变化较小, An值逐渐缓慢降低,呈现正环带结构,少量为韵律环带。结合火山岩斑晶矿物形成的温压条件计算结果,ER地区岩浆演化过程为:地幔源区发生部分熔融产生玄武质岩浆(温度～1300℃);在岩浆活动早期,由于岩浆供应充足,岩浆上升过程中速度较快,仅发生很小程度的分离结晶,形成少量斑晶矿物,并以较高的速度、温度(～1 100℃)直接喷出海底后形成玄武岩-玄武质安山岩;至岩浆活动晚期,岩浆供应量减少,岩浆在岩浆房(3～10km)停留较长时间,岩浆温度已经明显下降(960～1 020℃),发生强烈的分离结晶作用,岩浆喷出海底形成酸性火山岩;而在整个岩浆演化过程中,未有明显的岩浆混合作用发生。     

滇西腾冲新生代火山岩岩石地球化学特征

腾冲新生代火山岩位于印度板块和欧亚板块碰撞带附近,但是喷发时大洋已经闭合,属于大陆板内火山岩。对其进行地球化学研究,可以用来划分构造属性和推测岩浆来源。采用XRF和ICP-MS对典型岩石样品进行了较系统的岩石地球化学研究,结果表明,岩石类型有玄武质粗面安山岩、粗面安山岩和玄武安山岩,属高钾钙碱性系列;岩石化学显示高K2O、CaO和低TiO2,Mg#较高,平均约为46;稀土元素分布呈右倾,显示明显的Eu负异常;相对于原始地幔富集大离子亲石元素和高场强元素,并具有明显的Th正异常;地球化学组成总体上与岛弧岩浆岩相似,推测其成因与印度板块向欧亚板块俯冲引发的岩浆活动有关。特征元素比值显示岩浆可能来源于与俯冲作用相关的EMⅠ型地幔。     

西太平洋弧后盆地的热液系统及其岩浆环境研究

研究海底热液系统及其岩浆环境,可为了解西太平洋流固界面跨圈层物质与热交换过程,揭示板块俯冲过程的岩浆活动和资源环境效应提供研究支撑。为此,研究了冲绳海槽热液活动的岩浆环境、马努斯海盆的热液柱以及弧后盆地和洋中脊背景下的硫化物与玄武岩的同位素组成,对冲绳海槽热液区附近玄武岩、安山岩、粗安岩、英安岩、流纹岩及其基性岩浆包体进行了岩相学、矿物学以及主量元素、微量元素和同位素组成分析,对马努斯海盆PACMANUS和Desmos热液区的热液柱及海水进行了测量,在海底热液区岩浆混合过程及时间尺度、透视冲绳海槽深部岩浆房及岩浆演化过程和岩浆对热液系统物质贡献研究方面获新进展,揭示了俯冲蛇纹岩对琉球构造带南部岩浆活动的影响,论证了熔体包裹体对弧后盆地岩浆演化的指示,获得了冲绳海槽玄武质岩浆来源新证据,揭示了弧后盆地与洋中脊硫化物和玄武岩中铁、铜、锌的来源及其同位素在硫化物形成和岩浆活动过程中的分馏情况,明确了热液柱的物理、化学空间结构与物质组成特征,以及热液柱的扩散受深度和底流流速的影响,且热液柱扩散过程中溶解铁浓度异常比溶解锰的维持时间更长。未来,发展非传统稳定同位素和挥发份测试技术,进一步了解西太平洋板块俯冲环境下热液活动与岩浆作用的关系,将有助于海底热液系统及其成矿过程研究获得新进展。     

西太平洋典型弧后盆地的地质构造、岩浆作用与热液活动

研究了西太平洋典型弧后盆地冲绳海槽和马努斯海盆的区域地质背景、岩浆岩、喷口流体、热液柱、沉积物以及多金属硫化物。结果表明,冲绳海槽在构造和地球物理特征上南北分异,从北向南地壳厚度减薄,南部重力异常变化大,发育条带状磁异常,中部则具有最高的热流值。马努斯海盆的重力异常变化较小,磁力异常呈东西向展布,海底扩张中心附近出现磁异常条带。马努斯海盆已出现洋壳,冲绳海槽的地壳属于过渡性地壳,在中南部的地堑中可能已出现洋壳。 冲绳海槽与马努斯海盆玄武岩的岩浆是由地幔源区部分熔融产生的原始岩浆与板块俯冲组分混合构成。中酸性岩与基性岩具有相同的岩浆物质来源,是玄武质岩浆结晶分异的产物。与马努斯海盆火山岩相比,冲绳海槽火山岩存在不同程度的地壳混染。 冲绳海槽的喷口流体为富含金属元素（Mn、Fe、Zn、Pb）的酸性高温（高达320 °C）流体,其热液柱中的Zn2 、Cd2 、Pb2 、Cu2 离子浓度明显高于正常海水。马努斯海盆的热液柱呈现出CH4、Mn、Al、δ3He正异常及pH负异常的特征。与马努斯海盆PACMANUS热液区的喷口流体（220–276 °C、pH = 2.5–3.5）相比,DESMOS热液区的喷口流体温度（≥88–120 °C）相对较低,酸性更强（pH ≤ 2.1）,二者较低的δ34SH2S和δD值表明岩浆演化过程中有酸性挥发分进入岩浆流体。冲绳海槽与马努斯海盆含金属沉积物的分布及其元素含量特征具有差异,相应地,两个弧后盆地含金属沉积物中的微生物群落也不同。冲绳海槽和马努斯海盆热液区均具富Zn型、Ba-Pb-Zn型、Si-硫化物型和Si-硫化物-硫酸盐型热液产物。与冲绳海槽的多金属硫化物相比,马努斯海盆中多金属硫化物的Pb和Au含量较低。     

西太平洋典型弧后盆地的地质构造、岩浆作用与热液活动

本文研究了西太平洋典型弧后盆地冲绳海槽和马努斯海盆的区域地质背景、岩浆岩、喷口流体、热液柱、沉积物及多金属硫化物。结果表明,冲绳海槽在构造和地球物理特征上南北分异,从北向南地壳厚度减薄,南部重力异常变化大,发育条带状磁异常,中部则具有最高的热流值。马努斯海盆的重力异常变化较小,磁力异常呈东西向展布,海底扩张中心附近出现磁异常条带。马努斯海盆已出现洋壳,冲绳海槽的地壳属于过渡性地壳,在中南部的地堑中可能已出现洋壳。冲绳海槽与马努斯海盆玄武岩的岩浆是由源区地幔部分熔融产生的原始岩浆与板块俯冲组分混合构成。中酸性岩与基性岩具有相同的岩浆物质来源,是玄武质岩浆结晶分异的产物。与马努斯海盆火山岩相比,冲绳海槽火山岩存在不同程度的地壳混染。冲绳海槽的喷口流体为富含金属元素(Mn、Fe、Zn、Pb)的酸性高温(高达320°C)流体,其热液柱中的Zn~(2+)、Cd~(2+)、Pb~(2+)、Cu~(2+)离子浓度明显高于正常海水。马努斯海盆的热液柱呈现出CH_4、Mn、Al、δ~3He正异常及pH负异常的特征。与马努斯海盆PACMANUS热液区的喷口流体(220~276°C、pH=2.5~3.5)相比,DESMOS热液区的喷口流体温度(88~120°C或120°C以上)相对较低,酸性更强(pH≤2.1),二者较低的δ~(34)S_(H_2S)和δD值表明,岩浆演化过程中有酸性挥发分进入岩浆流体。冲绳海槽与马努斯海盆含金属沉积物的分布及其元素含量特征具有差异,相应地,两个弧后盆地含金属沉积物中的微生物群落也不同。冲绳海槽和马努斯海盆热液区均具富Zn型、Ba-Pb-Zn型、Si-硫化物型和Si-硫化物-硫酸盐型热液产物。与冲绳海槽的多金属硫化物相比,马努斯海盆中多金属硫化物的Pb和Au含量较低。     

东太平洋海隆近赤道区玄武岩岩石地球化学与地幔源区特征

本文对东太平洋海隆赤道地区北部和南部的9件玄武岩样品进行了详细的岩相学和主量、微量元素及Sr-Nd-Pb同位素分析研究,结果表明:MgO含量为7.32%~10.22%,Na_2O为3.03%~3.59%,K_2O为0.23%~0.57%,CaO为10.96%~12.39%,Al_2O_3为11.40%~13.76%,该区玄武岩均属于亚碱性玄武岩,具有MORB型的稀土及微量元素特点,原始岩浆均经历了橄榄石和斜长石的分离结晶。轻重稀土元素含量均较低,LREE/HREE比值为0.61~0.97,(La/Yb)N比值为0.72~1.76,(La/Sm)N比值为0.60~1.30,(Gd/Yb)N为0.99~1.16。Sr-Nd-Pb同位素特征更接近NMORB,其中,87Sr/86Sr和143 Nd/144 Nd比值更接近DM源区,而Pb的三种同位素比值要明显高于DM源区,更为接近EM源区。研究表明岩浆起源于尖晶石橄榄岩区,来源于较为亏损的地幔,NEPR玄武岩可能混有HIMU源区,SEPR玄武岩除了混合有HIMU成分外,可能还有少量的EMⅡ成分。     

东马努斯盆地热液蚀变火山岩元素迁移特征及影响因素

本文选择东马努斯盆地的5个新鲜火山岩和1个蚀变火山岩作为研究对象,对样品进行全岩主微量及斜长石电子探针分析,并对蚀变岩石与新鲜火山岩之间的化学成分进行对比,深入探究了蚀变火山岩的元素迁移特征及影响因素。结果显示,蚀变火山岩的硫化物以黄铜矿、方铅矿和闪锌矿为主,为富Cu型热液硫化物。岩石蚀变区的SiO2含量极高,为硅化蚀变。蚀变岩石的化学成分约为同区玄武质安山岩和英安岩成分总含量的平均值,原岩可能为安山岩。在热液蚀变的过程中,蚀变岩石的质量增加了150%,其中元素Cu、Zn、Ga、Sr、Cd、Ba和Pb超强烈富集,Ti、V、Mn、Co、Ni、Mo和U强烈富集,Si和Fe中等富集;Sc、Cr、Nb、Ta、W和Bi轻微富集;Be和Ca超强烈亏损;Li、Na、Mg、K、Rb、REE和Y强烈亏损;Zr、Cs和Th轻微亏损;Al、P和Hf稳定不变。推测影响蚀变岩石元素迁移的因素有3种:成矿作用、交代作用(绿泥石化、硅化)和元素在流体中的活动性。     

西北印度洋中脊玄武岩源区地幔特征

利用全球岩石地球化学数据库(Pet DB)中有关卡尔斯伯格洋脊(CR)、北中印度洋脊(NCIR)及南中印度洋脊(SCIR)玄武岩的微量元素及同位素组成数据,分析了玄武岩的元素地球化学特征及其沿脊轴的变化,旨在探讨玄武岩源区地幔的(不)均一性及岩浆作用过程的差异。初步研究结果表明:CR、NCIR及SCIR玄武岩组成相近,仅在个别脊段表现有微量稀土元素和同位素组成上的差异,玄武岩整体与N-MORB组成特征相近,与先前通常认为的典型印度洋中脊玄武岩不同。玄武质岩浆主要源自尖晶石二辉橄榄岩地幔的熔融,岩浆源区主要由两个地幔端元构成,即以亏损型地幔(DMM)为主(69%),其次为富集型地幔(EMⅡ,27%)。富集组分可能源自古老陆壳物质的混染。自CR经NCIR到SCIR整个印度洋中脊西北分支玄武岩的Sr、Nd及Pb同位素组成表现出均一性,表明岩浆源区地幔组成相近。在SCIR 19°S附近脊段岩浆源区地幔存在有不均一性,有EMⅡ型地幔端元混入的迹象。在CR 3.5°N附近脊段,玄武岩明显富集K、Ba、La及U等微量元素,但由于缺少同位素数据,源区地幔特征有待进一步研究。在上述研究成果的基础上,提出了该区大比例尺的调查填图及密集采样和精细室内分析是CR深入研究的基础,同时加强Sr、Nd、Pb及Re、Os、Be等同位素分析测试,可提供揭示CR地幔不均一性的可靠依据,而厘清印度洋型地幔对CR的影响程度则有助于深入认识地幔不均一性的成因及地幔动力学过程。     

基于独立成分分析的马里亚纳弧后地幔源区特征研究

对采自太平洋洋中脊(277组)、印度洋洋中脊(159组)、马里亚纳海槽(53组)、马里亚纳岛弧(39组)、中南劳海盆(72组)共600组玄武岩数据进行了独立成分分析,从Sr-Nd-Pb五维同位素比值空间提取出占样本方差99％的3个独立成分(IC1,IC2,IC3),并利用这3个独立成分(ICs)与微量元素比值之间的相关...     

冲绳海槽中部伊平屋脊火山岩地球化学和Sr-Nd-Pb同位素组成：对岩石成因和地幔源区的指示

As an active back-arc basin, the Okinawa Trough is located in the southeastern region of the East China Sea shelf and is strongly influenced by the subduction of the Philippine Sea Plate. Major element, trace element and Sr-NdPb isotopic composition data are presented for volcanic rocks from the Iheya Ridge(IR), the middle Okinawa Trough. The IR rocks record large variations in major elements and range from basalts to rhyolites. Similar trace element distribution characteristics together with small variations in ~(87)Sr/~(86)Sr(0.703 862–0.704 884), ~(144)Nd/~(143)Nd(0.512 763–0.512 880) and Pb isotopic ratios, demonstrate that the IR rocks are derived from a similar magma source. The fractional crystallization of olivine, clinopyroxene, plagioclase, and amphibole, as well as accessory minerals, can reasonably explain the compositional variations of these IR rocks. The simulations suggest that approximately 60% and 75% fractionation of an evolved basaltic magma can produce trace element compositions similar to those of the intermediate rocks and acid rocks, respectively. The analysis of their Sr-Nd-Pb isotopic content ratios suggest that the source of the rocks from the IR is close to the depleted mantle(DM) but extends to the enriched mantle(EMII), indicating that the mantle source of these rocks is a mixture between the DM and EMII end members. The simulations show that the source of the IR volcanic rocks can be best interpreted as the result of the mixing of approximately 0.8%–2.0% subduction sediment components and 98.0%–99.2% mantlederived melts.     

冲绳海槽火山岩地球化学特征及岩浆源区地幔性质探讨

冲绳海槽是因菲律宾海板块俯冲于欧亚板块之下,在陆壳上发育起来的一个初始的弧后盆地,是研究弧后扩张作用早期盆地演化、岩浆作用和壳幔过程的天然实验室.尽管迄今对冲绳海槽已经做了大量的调查研究工作,但仍存在一些颇有争议或亟待解决的科学问题,如:冲绳海槽酸性浮岩与基性玄武岩之间的成因联系,冲绳海槽不同区段构造背景对岩浆作用的控...     

Mantle source heterogeneity and magmatic evolution at Carlsberg Ridge (3.7°N): constrains from elemental and isotopic (Sr,Nd, Pb) data

We present new major element, ICP-MS trace element, and Sr–Nd–Pb isotope data of basalts from four locations along the Carlsberg Ridge (CR), northern Indian Ocean. The basalts are low-K tholeiites with 7.52–9.51 wt% MgO, 49.40–50.60 wt% SiO₂, 0.09–0.27 wt% K₂O, 2.55–2.90 wt% Na₂O, and 0.60–0.68 Mg^#. Trace element contents of the basalts show characteristics similar to those of average normal MORB, such as LREE depleted patterns with (La/Sm)_N ratio of 0.55–0.69; however, some samples are enriched in large-ion lithophile elements such as K and Rb, suggesting probable modification of the mantle source. Poor correlations between the compatible elements [e.g. Ni, Cr, and Sr (related to olivine, clinopyroxene and plagioclase, respectively)] and the incompatible elements (e.g. Zr and Y), and positive correlations in the Zr versus Zr/Y and Nb versus Nb/Y plots suggest a magmatic evolution controlled mainly by mantle melting rather than fractional crystallization. Our results extend the CR basalt range to higher radiogenic Pb isotopes and lower ¹⁴³Nd/¹⁴⁴Nd. These basalts and basalts from the northern Indian Ocean Ridge show lower ¹⁴³Nd/¹⁴⁴Nd and higher ⁸⁷Sr/⁸⁶Sr values than those of the depleted mantle (DM), defining a trend towards pelagic sediment composition. The Pb isotopic ratios of basalts from CR 3–4°N lie along the compositional mixing lines between the DM and the upper continental crust. However, the low radiogenic Pb of basalts from CR 9–10°N lie on the mixing line between the DM and lower continental crust. Since the Pb isotopic ratio of MORB would decrease if the source mantle was contaminated by continental lithospheric mantle, we suggest that CR contains continental lithospheric material, resulting in heterogeneous mantle beneath different ridge segments. The continental lithospheric material was introduced into the asthenosphere before or during the breakup of the Gondwana. These results support the long-term preservation of continental material in the oceanic mantle which would significantly influence the isotopic anomaly of the Indian Ocean MORB.     

Evolution of the basalts from three back-arc basins of southwest Pacific

Petrography, petrochemistry, and mineral chemistry of basalts from the Woodlark, Manus, and Lau basins from the southwest Pacific, have been studied to understand their magmatic evolution. Basalt from the western Woodlark Basin (Dobu Seamount) indicates mixing of a near-primitive magma with fractionated basaltic melt in shallow magma chambers. Basalts from Manus Basin and Central Lau Spreading Center (Lau Basin) are typical N-MORBs, and they exhibit olivine fractionation under high oxidizing conditions while basalts from Mangatolu Triple Junction (Lau Basin) are enriched in Al₂O₃, K₂O, and Zr indicative of a contribution from a subducting plate.     

Evolution of the basalts from three back-arc basins of southwest Pacific

 Petrography, petrochemistry, and mineral chemistry of basalts from the Woodlark, Manus, and Lau basins from the southwest Pacific, have been studied to understand their magmatic evolution. Basalt from the western Woodlark Basin (Dobu Seamount) indicates mixing of a near-primitive magma with fractionated basaltic melt in shallow magma chambers. Basalts from Manus Basin and Central Lau Spreading Center (Lau Basin) are typical N-MORBs, and they exhibit olivine fractionation under high oxidizing conditions while basalts from Mangatolu Triple Junction (Lau Basin) are enriched in Al₂O₃, K₂O, and Zr indicative of a contribution from a subducting plate. Received: 4 August 1998 / Revision received: 19 February 1999     

白垩纪以来太平洋上地幔组成和温度变化

The geological evolution of the Earth during the mid-Cretaceous were shown to be anomalous, e.g., the pause of the geomagnetic field, the global sea level rise, and increased intra-plate volcanic activities, which could be attributed to deep mantle processes. As the anomalous volcanic activities occurred mainly in the Cretaceous Pacific, here we use basalt chemical compositions from the oceanic drilling(DSDP/ODP/IODP) sites to investigate their mantle sources and melting conditions. Based on locations relative to the Pacific plateaus, we classified these sites as oceanic plateau basalts, normal mid-ocean ridge basalts, and near-plateau seafloor basalts. This study shows that those normal mid-ocean ridge basalts formed during mid-Cretaceous are broadly similar in average Na8, La/Sm and Sm/Yb ratios and Sr-Nd isotopic compositions to modern Pacific spreading ridge(the East Pacific Rise). The Ontong Java plateau(125–90 Ma) basalts have distinctly lower Na8 and143Nd/144 Nd, and higher La/Sm and 87Sr/86 Sr than normal seafloor basalts, whereas those for the near-plateau seafloor basalts are similar to the plateau basalts, indicating influences from the Ontong Java mantle source. The super mantle plume activity that might have formed the Ontong Java plateau influenced the mantle source of the simultaneously formed large areas of seafloor basalts. Based on the chemical data from normal seafloor basalts, I propose that the mantle compositions and melting conditions of the normal mid-ocean ridges during the Cretaceous are similar to the fast spreading East Pacific Rise. Slight variations of mid-Cretaceous normal seafloor basalts in melting conditions could be related to the local mantle source and spreading rate.     

冲绳海槽中部岩心沉积物中浮岩的物理性质和地球化学特征差异及其对岩浆活动的指示

为进一步了解冲绳海槽浮岩的物理性质和地球化学特征差异,对冲绳海槽中部岩心沉积物S9中的浮岩进行了微观结构和地球化学组成分析。结果显示,冲绳海槽中部存在白色、灰白色及棕色3种浮岩,其中灰白色浮岩又可以根据构造特征分为气孔构造和流动构造浮岩两个亚类。浮岩的地球化学组成表明白色、灰白色及棕色浮岩都是由玄武质岩浆经过充分的分离结晶作用形成的流纹质或流纹英安质火山岩。玄武质岩浆在演化的过程中发生了斜长石、角闪石、辉石、Fe-Ti氧化物、磷灰石等矿物的结晶分离。结合有孔虫14C年龄,认为浮岩是冲绳海槽中部距今13.1 ka左右的长英质火山活动的产物。演化程度相对较低的棕色浮岩具有比白色浮岩高的TiO2, Al2O3, Fe2O3, MgO, CaO含量,且棕色浮岩具有相对低的稀土总量和轻稀土总量。根据浮岩的物理性质及地球化学组成差异推测,岩浆的黏度和压力是影响浮岩构造特征的主要因素。黏度大、连续减压的岩浆易于形成具有流动构造和密集气孔的浮岩,黏度小、阶段性减压的岩浆易于形成气孔大而疏松的浮岩。     

冲绳海槽浮岩中碳、氢同位素组成特征

利用分阶段热解释放气体质谱分析法研究了冲绳海槽浮岩热解释放气中CO₂和H₂O的碳、氢同位素组成,结果显示:浮岩中原生CO₂和H₂O主要释放于400～1 000℃,CO₂的碳同位素组成介于-6.7×10-3～-22.7×10-3,H₂O的氢同位素组成从-45×10-3变到-71×10-3,均落入幔源火山岩的变化范围,而且浮岩的氢同位素组成与海槽区玄武岩的氢同位素组成非常接近,这表明冲绳海槽浮岩与玄武岩之间具有密切的成因联系,浮岩岩浆和玄武岩岩浆是同源岩浆不同程度结晶分异的产物.另外,这些浮岩较洋中脊玄武岩要贫13C,并富集D,同时具有从洋中脊玄武岩向岛弧玄武岩变化的趋势,这表明浮岩岩浆在形成或上升过程中可能受到俯冲板块释放流体的影响.