利用漫反射光谱技术得到湖光岩玛珥湖沉积物的叶绿素a浓度.通过与TOC、Sr/Rb比值和磁化率的对比发现,叶绿素a浓度能够忠实地反映湖泊初级生产力的变化,较高的叶绿素a浓度代表季风较强、降雨量较高,反之亦然.湖光岩玛珥湖沉积物多环境代...利用漫反射光谱技术得到湖光岩玛珥湖沉积物的叶绿素a浓度.通过与TOC、Sr/Rb比值和磁化率的对比发现,叶绿素a浓度能够忠实地反映湖泊初级生产力的变化,较高的叶绿素a浓度代表季风较强、降雨量较高,反之亦然.湖光岩玛珥湖沉积物多环境代用指标分析结果显示,湛江地区早全新世季风强盛,中全新世季风迅速衰退.这种全新世季风演化模式与北半球季风区的很多地质记录以及北纬30°变化趋势相似,反映了太阳辐射是湛江地区千年尺度季风演化的主要驱动因素,但是湛江地区的季风演化滞后于太阳辐射变化大约2200 a.叶绿素a浓度记录显示6000 a BP左右季风迅速减弱,这与其他记录显示的季风渐变模式不同.一方面,太阳辐射渐变激发了湛江地区植被-大气圈的负反馈作用,这可能是造成6000 a BP左右气候迅速变干的原因之一;另一方面,沉积速率增加导致的稀释作用放大了叶绿素a浓度下降的趋势.3600 a BP以来的沉积环境可能受到了人类活动的影响.展开更多
From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target a...From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target area since the terminal Late Miocene was recovered. The vertical section changes of microstructure and chemical composition are consistent in the studied crust, which indicate three major accretion periods and corresponding paleoenvironment evolution of the crust. The bottom crust zone was formed in the terminal Late Miocene (5.6 Ma) with loose microstructure, high detritus content and high growth rate. Reductions of mineral element content, accretion rate and positive Ce-anomaly degree at 4.6 Ma indicate temporal warming, which went against the crust accretion and finally formed an accretion gap in the terminal Middle Pliocene (2.8―2.7 Ma). The more active Antarctic bottom sea-waters in the Late Pliocene (2.7 Ma) facilitated the fast transfer to the top pure crust zone. Hereafter, with the further apart of volcanic source and the keeping increase of eolian material (1.0 Ma), although surrounding conditions were still favorable, mineral element content still shows an obvious reducing trend. It thereby offers new carrier and data for the unclear paleoceanographic research of the target area since the terminal Late Miocene.展开更多
Organic matter is the basis for oil and gas generation,and the depositional environment controls its enrichment.The first member of the Qingshankou Formation(K_(2)qn^(1))in Songliao Basin has a thick organic-rich shal...Organic matter is the basis for oil and gas generation,and the depositional environment controls its enrichment.The first member of the Qingshankou Formation(K_(2)qn^(1))in Songliao Basin has a thick organic-rich shale and so is an important target section for shale oil exploration and development.In the Gulong Sag,shale samples from this unit were collected over the full length of the section.The characterization of the environments of deposition(EOD)of K_(2)qn^(1)was improved by utilizing lithological characteristics,thin section observations,elemental compositions,and organic carbon concentrations.Combined with the normalization coefficients proposed in this paper,an organic matter correlation model was established to elucidate the factors that influence organic matter enrichment.From the bottom to the top of K2qn1,the lake depth gradually becomes shallower,the primary productivity first decreases and then increases,the reducing conditions become stronger and then weaker,the water salinity gradually decreases,the climate first becomes semi-humid and then warm and humid,and the input of terrigenous debris first decreases and then increases.A major marine transgression at the base of the K_(2)qn^(1)᾽s brought in nutrients to increase primary productivity,and the density-stratified reducing environment preserved and enriched organic matter.High primary productivity occurred during the middle of the deposition of the K_(2)qn^(1),while terrigenous input is low.Organic matter is preserved in reduced deep lake environments,resulting in organic matter-rich black shale.The lake became shallower,and the salinity decreased in the upper part of K_(2)qn^(1).Benthic organisms rapidly multiplied,consuming large amounts of oxygen and destroying the previously depositional environment,resulting in a reducing environment disturbed by benthic organisms with poor preservation conditions and the lowest organic matter content.展开更多
On the basis of lacustrine sedimentary profile of Ebinur Lake,sequences of evolution of paleoclimate and paleoenvironment in Ebinur Lake area have been rebuilt by analysing the sedimentary stratigraphy,bio-stratigraph...On the basis of lacustrine sedimentary profile of Ebinur Lake,sequences of evolution of paleoclimate and paleoenvironment in Ebinur Lake area have been rebuilt by analysing the sedimentary stratigraphy,bio-stratigraphy and gepochemistry as well as the chronological records.The results show that,during the last 10 ha years,the general change trends of the paleoclimate in Ebinur Lake area can be divided into three stages: (1) 10. 2-8.3 ka B. P., a warm-cool dry climate stage;(2) 8.3-3.5 ka B.P.,a warmer moist climate stage (specially,7.3-6. 4 ka B. P.,a relatively stable humid temperate stage);(3) 3. 5 ka B. P.-present, adraught temperate climate stage,similar to the present climate. In addition,there existed clearly several times of secondary undulations of dry-humid climate,i.e. 8.3 ka and 7.3 ka for dry climate展开更多
Paleontologists search the fossil record for evidence of age, ancient environments, phylogenetic reconstructions and ancient communities. Cenozoic foraminifera preserve evidence for all of these simultaneously from th...Paleontologists search the fossil record for evidence of age, ancient environments, phylogenetic reconstructions and ancient communities. Cenozoic foraminifera preserve evidence for all of these simultaneously from the water column and from at, above and below the sediment/water interface. As our understanding of foraminiferal assemblages and their place in the strata （biofacies） becomes more sophisticated, so are foraminiferal biofacies challenged to contribute to more subtle problems in Cenozoic earth and life history. Progress is described as a series of five ＂integrations＂. （Ⅰ） The quantification of foraminiferal biofacies was an advance on simple presences and absences of species meeting such questions as marine or nonmarine, or shallow or deep. （Ⅱ） Foraminiferal shells carry geochemical signals especially isotopes of oxygen （temperature, ice volume）, carbon （nutrition and the carbon cycle）, and strontium （seawater ratios through time）. （Ⅲ） From modern foraminiferal biology we have lifestyle insights leading to a model of oceans and paleo-oceans called the trophic resource continuum, a valuable way into greenhouse-icehouse comparisons and contrasts. （Ⅳ） Biofacies changes in space and time are sometimes abrupt with little evidence of diachrony, and sometimes gradual. These patterns are clarified in the context of sequence stratigraphy （which they enrich in turn）. （Ⅴ） The paleobiological counterpart of sequence stratigraphy is evolutionary paleoecology, reconstructing communities in deep time. The foraminifera are perfectly suited to investigate the possibility （or likelihood） that global environmental shifts have controlled community turnover in the pelagic, neritic and terrestrial realms.展开更多
The Hongzuisi Section in Lanzhou area is used to infer the paleoclimate since the late glacial epoch. Through combined analysis of organic carbon isotope and CaCO3 content, paleoenvironment evolution of Hongzuisi Sect...The Hongzuisi Section in Lanzhou area is used to infer the paleoclimate since the late glacial epoch. Through combined analysis of organic carbon isotope and CaCO3 content, paleoenvironment evolution of Hongzuisi Section since the late glacial epoch is discussed. There were changes in both dry-moist and warm-cold. Especially the climate changes can be compared with synchronous sections of other areas, which provides useful information for our future forecast.展开更多
文摘利用漫反射光谱技术得到湖光岩玛珥湖沉积物的叶绿素a浓度.通过与TOC、Sr/Rb比值和磁化率的对比发现,叶绿素a浓度能够忠实地反映湖泊初级生产力的变化,较高的叶绿素a浓度代表季风较强、降雨量较高,反之亦然.湖光岩玛珥湖沉积物多环境代用指标分析结果显示,湛江地区早全新世季风强盛,中全新世季风迅速衰退.这种全新世季风演化模式与北半球季风区的很多地质记录以及北纬30°变化趋势相似,反映了太阳辐射是湛江地区千年尺度季风演化的主要驱动因素,但是湛江地区的季风演化滞后于太阳辐射变化大约2200 a.叶绿素a浓度记录显示6000 a BP左右季风迅速减弱,这与其他记录显示的季风渐变模式不同.一方面,太阳辐射渐变激发了湛江地区植被-大气圈的负反馈作用,这可能是造成6000 a BP左右气候迅速变干的原因之一;另一方面,沉积速率增加导致的稀释作用放大了叶绿素a浓度下降的趋势.3600 a BP以来的沉积环境可能受到了人类活动的影响.
基金the Key Program of the National Natural Science Foundation of China (Grant No. 90411014)the National Natural Science Foundation of China (Grant Nos. 40576032 and 40506016).
文摘From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target area since the terminal Late Miocene was recovered. The vertical section changes of microstructure and chemical composition are consistent in the studied crust, which indicate three major accretion periods and corresponding paleoenvironment evolution of the crust. The bottom crust zone was formed in the terminal Late Miocene (5.6 Ma) with loose microstructure, high detritus content and high growth rate. Reductions of mineral element content, accretion rate and positive Ce-anomaly degree at 4.6 Ma indicate temporal warming, which went against the crust accretion and finally formed an accretion gap in the terminal Middle Pliocene (2.8―2.7 Ma). The more active Antarctic bottom sea-waters in the Late Pliocene (2.7 Ma) facilitated the fast transfer to the top pure crust zone. Hereafter, with the further apart of volcanic source and the keeping increase of eolian material (1.0 Ma), although surrounding conditions were still favorable, mineral element content still shows an obvious reducing trend. It thereby offers new carrier and data for the unclear paleoceanographic research of the target area since the terminal Late Miocene.
基金funded by the National Natural Science Foundation of China(Grant Nos.42072147 and 41922015)the Fundamental Research Funds for the Central Universities(No.22CX07001A).
文摘Organic matter is the basis for oil and gas generation,and the depositional environment controls its enrichment.The first member of the Qingshankou Formation(K_(2)qn^(1))in Songliao Basin has a thick organic-rich shale and so is an important target section for shale oil exploration and development.In the Gulong Sag,shale samples from this unit were collected over the full length of the section.The characterization of the environments of deposition(EOD)of K_(2)qn^(1)was improved by utilizing lithological characteristics,thin section observations,elemental compositions,and organic carbon concentrations.Combined with the normalization coefficients proposed in this paper,an organic matter correlation model was established to elucidate the factors that influence organic matter enrichment.From the bottom to the top of K2qn1,the lake depth gradually becomes shallower,the primary productivity first decreases and then increases,the reducing conditions become stronger and then weaker,the water salinity gradually decreases,the climate first becomes semi-humid and then warm and humid,and the input of terrigenous debris first decreases and then increases.A major marine transgression at the base of the K_(2)qn^(1)᾽s brought in nutrients to increase primary productivity,and the density-stratified reducing environment preserved and enriched organic matter.High primary productivity occurred during the middle of the deposition of the K_(2)qn^(1),while terrigenous input is low.Organic matter is preserved in reduced deep lake environments,resulting in organic matter-rich black shale.The lake became shallower,and the salinity decreased in the upper part of K_(2)qn^(1).Benthic organisms rapidly multiplied,consuming large amounts of oxygen and destroying the previously depositional environment,resulting in a reducing environment disturbed by benthic organisms with poor preservation conditions and the lowest organic matter content.
文摘On the basis of lacustrine sedimentary profile of Ebinur Lake,sequences of evolution of paleoclimate and paleoenvironment in Ebinur Lake area have been rebuilt by analysing the sedimentary stratigraphy,bio-stratigraphy and gepochemistry as well as the chronological records.The results show that,during the last 10 ha years,the general change trends of the paleoclimate in Ebinur Lake area can be divided into three stages: (1) 10. 2-8.3 ka B. P., a warm-cool dry climate stage;(2) 8.3-3.5 ka B.P.,a warmer moist climate stage (specially,7.3-6. 4 ka B. P.,a relatively stable humid temperate stage);(3) 3. 5 ka B. P.-present, adraught temperate climate stage,similar to the present climate. In addition,there existed clearly several times of secondary undulations of dry-humid climate,i.e. 8.3 ka and 7.3 ka for dry climate
文摘Paleontologists search the fossil record for evidence of age, ancient environments, phylogenetic reconstructions and ancient communities. Cenozoic foraminifera preserve evidence for all of these simultaneously from the water column and from at, above and below the sediment/water interface. As our understanding of foraminiferal assemblages and their place in the strata （biofacies） becomes more sophisticated, so are foraminiferal biofacies challenged to contribute to more subtle problems in Cenozoic earth and life history. Progress is described as a series of five ＂integrations＂. （Ⅰ） The quantification of foraminiferal biofacies was an advance on simple presences and absences of species meeting such questions as marine or nonmarine, or shallow or deep. （Ⅱ） Foraminiferal shells carry geochemical signals especially isotopes of oxygen （temperature, ice volume）, carbon （nutrition and the carbon cycle）, and strontium （seawater ratios through time）. （Ⅲ） From modern foraminiferal biology we have lifestyle insights leading to a model of oceans and paleo-oceans called the trophic resource continuum, a valuable way into greenhouse-icehouse comparisons and contrasts. （Ⅳ） Biofacies changes in space and time are sometimes abrupt with little evidence of diachrony, and sometimes gradual. These patterns are clarified in the context of sequence stratigraphy （which they enrich in turn）. （Ⅴ） The paleobiological counterpart of sequence stratigraphy is evolutionary paleoecology, reconstructing communities in deep time. The foraminifera are perfectly suited to investigate the possibility （or likelihood） that global environmental shifts have controlled community turnover in the pelagic, neritic and terrestrial realms.
文摘The Hongzuisi Section in Lanzhou area is used to infer the paleoclimate since the late glacial epoch. Through combined analysis of organic carbon isotope and CaCO3 content, paleoenvironment evolution of Hongzuisi Section since the late glacial epoch is discussed. There were changes in both dry-moist and warm-cold. Especially the climate changes can be compared with synchronous sections of other areas, which provides useful information for our future forecast.
