甲烷厌氧氧化作用（Anaerobic Oxidation of Methane,简称AOM）是海洋沉积物早期成岩过程中常见的地质作用,记录了沉积物埋藏压实期间海水下渗与沉积流体上涌过程中发生的硫酸盐还原和甲烷厌氧氧化等生物地球化学反应,形成了一套独特的...甲烷厌氧氧化作用（Anaerobic Oxidation of Methane,简称AOM）是海洋沉积物早期成岩过程中常见的地质作用,记录了沉积物埋藏压实期间海水下渗与沉积流体上涌过程中发生的硫酸盐还原和甲烷厌氧氧化等生物地球化学反应,形成了一套独特的自生矿物.通过实例分析东北太平洋IODP311航次U1328站位和南海北部陆坡GMGS2航次08站位的钻孔岩芯沉积物中自生矿物的类型和稳定碳、氧、硫同位素组成等,在U1328站位浅表层及约219m深度位置和在GMGS2-08站位15mbsf、60mbsf和84mbsf位置发现了AOM成因的自生碳酸盐类矿物,其δ13C值分别低至-41.50‰（VPDB）和-57.89‰（VPDB）,并且出现了富集的黄铁矿及其正偏硫稳定同位素组成,其δ34S值分别高达32.49‰（VCDT）和20.80‰（VCDT）.认为现代海洋沉积物中AOM成因的自生矿物能有效地记录海洋的甲烷异常渗漏事件,其矿物组合和稳定同位素组成可用于探索地史时期古海洋的甲烷渗漏事件.新元古代＂雪球地球＂结束后陡山沱组＂盖帽＂碳酸盐岩中极低碳稳定同位素的特征和扇状重晶石等自生矿物特征,指示了新元古代冰后期古海洋中曾经出现异常的甲烷渗漏事件,可能造成了古海洋环境和吉气候的突变.根据＂将今论古＂原理,利用AOM成因的自生矿物探索深时地球重大转折期古海洋的甲烷异常渗漏事件具有广阔的应用前景.展开更多
古地理重建是研究地质历史时期地表构造过程、海陆格局和地貌环境特征的一项综合研究,并通过绘制表达海洋和大陆的古代轮廓以及重要的地形和地表环境的地图来呈现,是还原地球演化历史、预测能源矿产分布、认识生命和气候演变的基础性工...古地理重建是研究地质历史时期地表构造过程、海陆格局和地貌环境特征的一项综合研究,并通过绘制表达海洋和大陆的古代轮廓以及重要的地形和地表环境的地图来呈现,是还原地球演化历史、预测能源矿产分布、认识生命和气候演变的基础性工作。随着大数据时代的到来,数字化方法的应用为古地理图快速更新和友好呈现提供了方便。目前,全球有多个团队发布了数字化的全球古地理重建模型以及相关的数据和方法,如EarthByte、PaleoMap、UNIL、Deep Time Maps等团队。笔者研究团队基于“深时数字地球(Deep-time Digital Earth,DDE)”国际大科学计划提出的数据-知识-模型驱动的古地理重建思想,提出基于数字化方法驱动的升级更新全球古地理图的新流程,并通过不断尝试地球科学与信息科学的交叉融合,从知识图谱、大数据分析和机器学习技术等方面开发了多项古地理重建应用技术。以东特提斯域中二叠世—中三叠世的古地理重建为例,首先在GPlates软件平台上重建了板块构造框架,再利用岩相古地理图自动生成地形地貌图并结合人工校正,最后在GPlates软件通过图层叠加实现了中二叠世—中三叠世东特提斯域的动态数字综合古地理重建。本用例与广泛使用的Scotese(2021)的古地理图对比,在成图效率、数据丰富性和可追溯性、模型准确性等方面都有明显提升,并为该时期板块运动、冰期消亡、大洋缺氧和生物灭绝等重大地质事件的研究提供新的约束和启示。展开更多
自2018年以来,国际地层委员会的工作取得了一系列进展,完成了换届工作,成立了新的时间标尺校准分会(Subcommission on Timescale Calibration),作为创始会员共同发起了国际地科联首个国际大科学计划——深时数字地球,完成了以下5个全球...自2018年以来,国际地层委员会的工作取得了一系列进展,完成了换届工作,成立了新的时间标尺校准分会(Subcommission on Timescale Calibration),作为创始会员共同发起了国际地科联首个国际大科学计划——深时数字地球,完成了以下5个全球界线层型的确立工作:第四系千叶阶(ChibanianStage)、古近系普利亚本阶(PriabonianStage)、白垩系康尼亚克阶(ConiacianStage)、白垩系欧特里夫阶(HauterivianStage)及侏罗系钦莫利阶(Kimmeridgian Stage)。在此基础上,国际地层委员会发布了新的《国际年代地层表》(2021/07版)。展开更多
Using seismic data of about one year recorded by 18 broadband stations of ASCENT project, we obtained 2547 receiver func- tions in the northeastern Tibetan Plateau. The Moho depths under 14 stations were calculated by...Using seismic data of about one year recorded by 18 broadband stations of ASCENT project, we obtained 2547 receiver func- tions in the northeastern Tibetan Plateau. The Moho depths under 14 stations were calculated by applying the H-x domain search algorithm. The Moho depths under the stations with lower signal-noise ratio （SNR） were estimated by the time delay of the PS conversion. Results show that the Moho depth varies in a range of -40--60 kin. The Moho near the Haiyuan fault is vague, and its depth is larger than those on its two sides. In the Qinling-Qilian Block, the Moho becomes shallower gradually from west to east. To the east of 105~E, the average depth of the Moho is 45 km, whereas the west is 50 km or even deeper. Combining our results with surface wave research, we suggest a boundary between the Qinling and the Qilian Mountains at around 105~E. S wave velocities beneath 15 stations have been obtained through a linear inversion by using Crust2.0 as an ini- tial model, and the crustal thickness that was derived by H-x domain search algorithm was also taken into account. The results are very similar to the results of previous active source studies. The resulting figure indicates that low velocity layers devel- oped in the middle and lower crust beneath the transition zone of the Tibet Block and western Qinling, which may be related to regional faults and deep earth dynamics. The velocity of the middle and lower crust increases from the Songpan Block to the northeastern margin of Tibetan Plateau. Based on the velocity of the crust, the distribution of the low velocity zone and the composition of the curst （Poisson＇s ratio）, we infer that the crust thickening results from the crust shortening along the direc- tion of compression.展开更多
文摘甲烷厌氧氧化作用（Anaerobic Oxidation of Methane,简称AOM）是海洋沉积物早期成岩过程中常见的地质作用,记录了沉积物埋藏压实期间海水下渗与沉积流体上涌过程中发生的硫酸盐还原和甲烷厌氧氧化等生物地球化学反应,形成了一套独特的自生矿物.通过实例分析东北太平洋IODP311航次U1328站位和南海北部陆坡GMGS2航次08站位的钻孔岩芯沉积物中自生矿物的类型和稳定碳、氧、硫同位素组成等,在U1328站位浅表层及约219m深度位置和在GMGS2-08站位15mbsf、60mbsf和84mbsf位置发现了AOM成因的自生碳酸盐类矿物,其δ13C值分别低至-41.50‰（VPDB）和-57.89‰（VPDB）,并且出现了富集的黄铁矿及其正偏硫稳定同位素组成,其δ34S值分别高达32.49‰（VCDT）和20.80‰（VCDT）.认为现代海洋沉积物中AOM成因的自生矿物能有效地记录海洋的甲烷异常渗漏事件,其矿物组合和稳定同位素组成可用于探索地史时期古海洋的甲烷渗漏事件.新元古代＂雪球地球＂结束后陡山沱组＂盖帽＂碳酸盐岩中极低碳稳定同位素的特征和扇状重晶石等自生矿物特征,指示了新元古代冰后期古海洋中曾经出现异常的甲烷渗漏事件,可能造成了古海洋环境和吉气候的突变.根据＂将今论古＂原理,利用AOM成因的自生矿物探索深时地球重大转折期古海洋的甲烷异常渗漏事件具有广阔的应用前景.
文摘古地理重建是研究地质历史时期地表构造过程、海陆格局和地貌环境特征的一项综合研究,并通过绘制表达海洋和大陆的古代轮廓以及重要的地形和地表环境的地图来呈现,是还原地球演化历史、预测能源矿产分布、认识生命和气候演变的基础性工作。随着大数据时代的到来,数字化方法的应用为古地理图快速更新和友好呈现提供了方便。目前,全球有多个团队发布了数字化的全球古地理重建模型以及相关的数据和方法,如EarthByte、PaleoMap、UNIL、Deep Time Maps等团队。笔者研究团队基于“深时数字地球(Deep-time Digital Earth,DDE)”国际大科学计划提出的数据-知识-模型驱动的古地理重建思想,提出基于数字化方法驱动的升级更新全球古地理图的新流程,并通过不断尝试地球科学与信息科学的交叉融合,从知识图谱、大数据分析和机器学习技术等方面开发了多项古地理重建应用技术。以东特提斯域中二叠世—中三叠世的古地理重建为例,首先在GPlates软件平台上重建了板块构造框架,再利用岩相古地理图自动生成地形地貌图并结合人工校正,最后在GPlates软件通过图层叠加实现了中二叠世—中三叠世东特提斯域的动态数字综合古地理重建。本用例与广泛使用的Scotese(2021)的古地理图对比,在成图效率、数据丰富性和可追溯性、模型准确性等方面都有明显提升,并为该时期板块运动、冰期消亡、大洋缺氧和生物灭绝等重大地质事件的研究提供新的约束和启示。
文摘自2018年以来,国际地层委员会的工作取得了一系列进展,完成了换届工作,成立了新的时间标尺校准分会(Subcommission on Timescale Calibration),作为创始会员共同发起了国际地科联首个国际大科学计划——深时数字地球,完成了以下5个全球界线层型的确立工作:第四系千叶阶(ChibanianStage)、古近系普利亚本阶(PriabonianStage)、白垩系康尼亚克阶(ConiacianStage)、白垩系欧特里夫阶(HauterivianStage)及侏罗系钦莫利阶(Kimmeridgian Stage)。在此基础上,国际地层委员会发布了新的《国际年代地层表》(2021/07版)。
基金financially supported by National Natural Science Foundation of China(Grant No.40930317)CHINARE2012-02-02+1 种基金Project SinoProbe-02-03the NSFC Innovation Research Group Fund(Grant No.41021001)
文摘Using seismic data of about one year recorded by 18 broadband stations of ASCENT project, we obtained 2547 receiver func- tions in the northeastern Tibetan Plateau. The Moho depths under 14 stations were calculated by applying the H-x domain search algorithm. The Moho depths under the stations with lower signal-noise ratio （SNR） were estimated by the time delay of the PS conversion. Results show that the Moho depth varies in a range of -40--60 kin. The Moho near the Haiyuan fault is vague, and its depth is larger than those on its two sides. In the Qinling-Qilian Block, the Moho becomes shallower gradually from west to east. To the east of 105~E, the average depth of the Moho is 45 km, whereas the west is 50 km or even deeper. Combining our results with surface wave research, we suggest a boundary between the Qinling and the Qilian Mountains at around 105~E. S wave velocities beneath 15 stations have been obtained through a linear inversion by using Crust2.0 as an ini- tial model, and the crustal thickness that was derived by H-x domain search algorithm was also taken into account. The results are very similar to the results of previous active source studies. The resulting figure indicates that low velocity layers devel- oped in the middle and lower crust beneath the transition zone of the Tibet Block and western Qinling, which may be related to regional faults and deep earth dynamics. The velocity of the middle and lower crust increases from the Songpan Block to the northeastern margin of Tibetan Plateau. Based on the velocity of the crust, the distribution of the low velocity zone and the composition of the curst （Poisson＇s ratio）, we infer that the crust thickening results from the crust shortening along the direc- tion of compression.
