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Independent magma system underneath micro non-transform discontinuity: geochemical evidence of magma from Daxi area， Carlsberg Ridge

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Journal of Earth Science 2024年

作者： Hang Hu Xiqiu Han Yejian Wang zhongyan qiu Tong Zong Jiqiang Liu Honglin Li Xing Yu Key Laboratory of Submarine Geosciences & Second Institute of Oceanography Ministry of Natural Resources Ocean College Zhejiang University College of Architectural Engineering Weifang University

The discontinuities of a ridge， defined by the geophysical properties， often coincides with geochemical variations in lava， highlighting the relationship between ridge discontinuity and the underlying magmatic system. This study presents bathymetric， geophysical， and basaltic geochemical data from the Daxi-non transform discontinuity (NTD) and adjacent segments. The Daxi-NTD is a typical micro-NTD， with an offset less than 15 km. Within the NTD， a neo-volcanic ridge has emerged， with an active hydrothermal system suggesting an underlying magmatic system. The study examines mantle composition， melting degree， crystallization pressure， and melt extraction processes beneath Daxi-NTD. Comparative analysis reveals that basalts in the Daxi area undergo extensive differentiation， characterized by higher crystallization pressure and lower melting degree compared to the adjacent segments. We propose that Daxi-NTD hosts an independent magmatic system， where melt migrates vertically through the magmatic system rather than laterally from the adjacent segment center. This approach aids in understanding of the magmatism along slow-spreading ridges and provides insights into the geodynamics and tectonic evolution of younger ridge system.

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洋中脊弯折带的构造-岩浆耦合作用:西北印度洋中脊火山锥及断层分布的约束

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岩石学报 2024年第7期40卷 2215-2224页

作者：党牛余星韩喜球吴招才邱中炎王叶剑李洪林自然资源部海底科学重点实验室自然资源部第二海洋研究所杭州310012 福建师范大学地理科学学院福州350007 浙江大学海洋学院舟山316021

洋中脊作为全球火山活动最活跃的区域之一,岩浆以裂隙式喷发为主,同时也存在中心式喷发火山锥。本文基于西北印度洋中脊大洋24航次的船载多波束地形数据,选择具有特殊空间位置和构造属性的北部弯折带作为研究靶区,应用定量地貌学方法分... 详细信息

洋中脊作为全球火山活动最活跃的区域之一,岩浆以裂隙式喷发为主,同时也存在中心式喷发火山锥。本文基于西北印度洋中脊大洋24航次的船载多波束地形数据,选择具有特殊空间位置和构造属性的北部弯折带作为研究靶区,应用定量地貌学方法分析火山锥形态特征与空间分布,探索区域火山作用与构造活动的耦合关系。结果表明,火山锥沿洋脊纵向上的分布主要受控于岩浆供应量,但段内其横向上的分布不仅与岩浆供应量有关,还决定于火山锥岩浆通道的形成。火山锥的分布与断层分布密切相关,断层分布密集,易于火山锥通道的形成。弯折带的洋脊段除了受扩张力外,还受到北东方向的应力作用,使弯折带南翼发育有更密集的断层,更高的火山锥密度。该应力效应的产生与非洲板块的北东向推移、印度板块的逆时针旋转以及弯折带效应本身有关。火山锥形态特征与空间分布,对于理解洋中脊区域构造演化以及火山活动过程具有重要价值。

关键词：火山锥分布特征构造-岩浆背景定量地貌学西北印度洋中脊

Turbidite Events Recorded in Deep-sea Core IR-GC1 off Western Sumatra： Evidence from Grain-size Distribution

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Acta Geologica Sinica(English Edition) 2017年第4期91卷 1448-1456页

作者： qiu zhongyan HAN Xiqiu WANG Yejian Key Laboratory of Submarine Geoseiences Second Institute of Oceanography State Oceanic Administration Hangzhou 310012 China

Sediment core IR-GC1, from the abyssal basin of the Indian Ocean off Sumatra, may provide important information on depositional events related to earthquakes and tsunamis. In this study, based on a combination of grain-size analysis with lithological studies and oxygen isotope stratigraphy, seven deep-sea turbidite layers were identified, corresponding to seven turbidity events that occurred at 128- 130, 105-107, 98-100, 86-87, 50-53, 37-41 and 20-29 ka. The sediments of the turbidite deposits are characterized by coarse grain sizes, poor sorting, wide kurtosis, bimodal frequency distributions and clear depositional variations. Particle size grading is also an important signature of deep-sea turbidite deposits and can be used as an indicator to identify turbidite layers. Possible triggering mechanisms for the turbidite events include tsunamis, earthquakes, volcanic eruptions and sea-level changes.

关键词： grain size turbidite deep-sea core Indian Ocean

Source and nature of ore-forming fluids of the Edmond hydrothermal field,Central Indian Ridge:evidence from He-Ar isotope composition and fluid inclusion study

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Acta Oceanologica Sinica 2017年第1期36卷 101-108页

作者： WANG Yejian HAN Xiqiu qiu zhongyan Key Laboratory of Submarine Geosciences Second Institute of OceanographyState Oceanic AdministrationHangzhou 310012China

To understand the source and nature of the ore-forming fluids of the Edmond hydrothermal field on the Central Indian Ridge, we studied the He-Ar isotope composition and fluid inclusions of the hydrothermal *** results show that the sulfide samples contain noble gases He, Ne, Kr, and Xe with their abundances in between those of air-saturated water（ASW） and mid-ocean ridge basalt（MORB）. The ^3He/^4He ratio varies from1.3 to 8.7 Ra（n=10, average： 5.1 Ra）, whereas the ^40Ar/^36Ar ratio is from 285.3 to 314.7（n=10, average： 294.8）. These results suggest that the He was derived from a mixture of MORB with variable amounts of seawater, but the Ar in the ore-forming fluids trapped in the sulfides is predominantly derived from seawater. The fluid inclusions of barite have a wide range of homogenization temperatures and salinities varying from 163℃ to 260℃ and 2.6 wt%to 8.5 wt% Na Cl equiv., respectively. It is suggested that the ore-forming fluids were produced by phase separation, which agreed with the present-day vent fluid study.

关键词： fluid inclusion helium and argon isotopes phase separation massive sulfides Central Indian Ridge

Tephra records from abyssal sediments off western Sumatra in recent 135 ka: evidence from Core IR-GC1

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Acta Oceanologica Sinica 2014年第12期33卷 75-80页

作者： qiu zhongyan HAN Xiqiu JIN Xianglong WANG Yejian ZHU Jihao Key Laboratory of Submarine Geosciences Second Institute of Oceanography State Oceanic Administration

Three volcanic ash layers were identified in a deep-sea Core IR-GC1 from the north-eastern Indian Ocean, adjacent to western Indonesian arc. They were dominated by glass shards with minor mineral crystals, such as plagioclase, biotite, and hornblende. According to the morphology and major element compositions of the representative glass shards, combined with theδ18O-based age, it is suggested that ash Layer A is cor-related to the youngest Toba tuff （YTT）, Layer B is supposed to be associated with a new eruption of Toba caldera in an age of 98 to 100 ka. Ash Layer C is different the geochemistry characteristics than those of Layer A and Layer B, suggesting that Layer C was not originated from Toba but registered another volcanic erup-tion event.

关键词： geochemistry glass shards youngest Toba tuff abyssal sediment

Fractional crystallization processes of magma beneath the Carlsberg Ridge(57°–65°E)

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Journal of Oceanology and Limnology 2020年第1期38卷 75-92页

作者： ZONG Tong HAN Xiqiu LIU Jiqiang WANG Yejian qiu zhongyan YU Xing Key Laboratory of Submarine Geosciences and Prospection of Ministry of Education Ocean University of ChinaQingdao 266100China Key Laboratory of Submarine Geosciences State Oceanic Administration&Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Ocean College Zhejiang UniversityZhoushan 316021China School of Oceanography Shanghai Jiaotong UniversityShanghai 200030China

Fractional crystallization of basaltic magma at variable depths influences strongly the geochemical compositions of mid-ocean ridge basalts(MORBs),especially at slow-spreading mid-ocean *** Carlsberg Ridge is a typical slow-spreading ridge located in the northwestern Indian *** this study,we conducted petrological,geochemical and modelling studies of MORBs collected along the Carlsberg Ridge from 57°-65°E to understand the fractional crystallization processes of magma and the controls on variations in MORB *** results show that the mantle sources beneath the Carlsberg Ridge are heterogeneous even on the local scale of a segment;such heterogeneity may be ubiquitous beneath the Carlsberg *** heterogeneity may be caused by the enriched components resulting in the"DUPAL"anomaly,whereas the effect of pyroxenite on mantle heterogeneity is *** parental melts experienced crystallization of olivine,plagioclase and clinopyroxene prior to eruption,which played a significant role in the major and trace element variations in MORBs from the Carlsberg *** liquid lines of descent(LLDs),deduced from the forward modelling of three parental magma compositions using the Petrolog3 program at pressures between 1 atm and 10 kbar,demonstrate that clinopyroxene joined the olivine and plagioclase *** over-enrichment in highly incompatible elements relative to LLDs may be caused by the processes of replenishment-tapping-crystallization in magma *** calculated crystallization pressures suggest that parental magmas beneath the Carlsberg Ridge experienced moderateto high-pressure crystallization and that crystallization beneath the slow-spreading Carlsberg Ridge may start at upper mantle depths.

关键词： fractional crystallization crystallization pressure mantle heterogeneity Carlsberg Ridge mid-ocean ridge basalt (MORB)

New discovery of seafloor hydrothermal activity on the Indian Ocean Carlsberg Ridge and Southern North Atlantic Ridge-progress during the 26th Chinese COMRA cruise

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Acta Oceanologica Sinica 2013年第8期32卷 85-88页

作者： TAO Chunhui WU Guanghai DENG Xianming qiu zhongyan HAN Chenhua LONG Yanmei Key Laboratory of Submarine Geosciences Second Institute of Oceanography State Oceanic Administration Key Laboratory of Marine Ecosystem and Biogeochemistry Second Institute of Oceanography State Oceanic Administration State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administration

The 26th Chinese COMRA （China Ocean Mineral Resources Research ＆ Development Association） cruise was an important cruise. The Carlsberg Ridge （CR） of the Northwest Indian Ocean and the North Atlantic Ridge （NAR）, in which less investigation has been carried out for hydrothermal activities, were investigated and studied during the first two legs of the 26th COMRA cruise. During the first leg, we found one hydrother- mal activity field located in the CR at 3.5^-3.8~ N on the Northwest Indian Ocean Ridge （NWIR）, and sampled seafloor polymetallic sulfide deposits where only abnormalities were found before. During the second leg, we found a new hydrothermal anomaly field located in the NAR at 4^-7~N. The discovery of two hydrother- real and anomaly fields filled in the gap of hydrothermal investigation and study in the corresponding re- ~ions for China.

关键词： 26th COMRA cruise Carlsberg Ridge Indian Ocean North Atlantic Ridge seafloor hydrothermal activity

Methane seepages in the northern South China Sea: evidence from in situ measurements

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Journal of Oceanology and Limnology 2018年第5期36卷 1556-1561页

作者：邱中炎韩喜球王叶剑 Key Laboratory of Submarine Geosciences Second Institute of OceanographyState Oceanic Administration

Continental margins in world oceans contain large amounts of marine gas hydrates. Changes in the temperature and pressure of sediment may destabilize the methane hydrate, leading to its release and seepage into the sea. This process would increase the dissolved methane in the ambient seawater. In this study, a methane sensor was used to detect methane anomalies in the water column in southwestern Dongsha and Shenhu, northern slope of the South China Sea. Methane plumes were detected at stations SCS001 and T001 in the southwestern Dongsha area, and station SCS002 in the Shenhu area, respectively. The maximum methane concentrations were 8.8 nmol/L in southwestern Dongsha and 10.1 nmol/L in Shenhu, which are about 4–5 times higher than the background methane concentration. This indicates that there are active methane seepages present in both the southwestern Dongsha and Shenhu areas, which are likely related to a methane hydrate reservoir beneath the seafloor. A methane sensor with a low detection limit is a practical instrument with which to detect methane plumes in oceanic environments and to monitor methane leakage from the seafloor.

关键词：大陆边缘海洋天然气水合物海洋学科普知识

Comparative study on the mineralogy and geochemistry of sediments near active and inactive hydrothermal sites of Wocan hydrothermal field on Carlsberg Ridge, Northwest Indian Ocean

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Comparative study on the mineralogy and geochemistry of sedi...