Several paleoseismic events are recorded in the Neogene Linqu Group, exposed in the Linqu area, Shandong Province, China. The events were interpreted on the basis of fleldwork and laboratory analysis, which showed the...Several paleoseismic events are recorded in the Neogene Linqu Group, exposed in the Linqu area, Shandong Province, China. The events were interpreted on the basis of fleldwork and laboratory analysis, which showed the presence of seismites with plastically deformed soft-sediment deformation structures in the Shanwang Formation, and of seismic volcanic rocks in the Yaoshan Formation which show brittle deformation. The earthquake-triggered soft-sediment deformations in the seismites include load structures, ball-and-pillow structures, flame structures, piUow-like beds, boudinage structures, slump folds, syn-depositional faults, veins of liquefied sand, and dikes of liquefied sandy lime-mud. The seismic activity is also reflected in what might be called ＇brittle seismites＇; these originated when, under the influence of seismic vibrations, semi-consolidated conglomerate was shattered. Moreover, volcanic activity is related to intense earthquakes that affected basalts intercalated with sand layers; these successions are known as ＇seismic volcanic rocks＇, which are characterized by veins of liquefied sand intruding the basalts. AH above traces of paleoseismic activity were left from one single time span of 4 Ma with active seismicity that took place 14-10 Ma. This time span is known as ＇the Linqu Neogene Paleoseismic Active Period＇, which is divided into four paleoseismic episodes, which were responses to tectonic extension and basin rifting in this area. It even includes the activity of the Yishu Fault Zone during the Miocene and the Neogene. The ratios of trace elements in the seismites, w（La）/w（Sc） and w （La）/w（Th） are higher than the average value of the upper crust, but w（Th）/w（Sc） is lower; this is geochemical evidence for the basin rifting that resulted in a high sedimentation rate. The intense and frequent paleo-earthquakes are held responsible for the rapid burial of the Shanwang Biota. Secondary earthquake-induced processes （e.g. slumping of a lake shore and the strongly increased lacustrine sedimentation rate） contributed to the rapid burial of the biota.展开更多
The Shanwang Basin is a small Cenozoic sedimentary basin located in Linqu county, Shandong province.The Shanwang Formation, especially the diatomaceous shale member, contains diverse and finely preserved flora and fau...The Shanwang Basin is a small Cenozoic sedimentary basin located in Linqu county, Shandong province.The Shanwang Formation, especially the diatomaceous shale member, contains diverse and finely preserved flora and fauna fossils （Fig. 1）. Previous paleontological study and radiometric dating show that it was formed in the Miocene. However, on the precise age of the formation, there are such different opinions as Late Miocene, Middle Miocene, Early stage of Middle Miocene, etc.展开更多
Twining stems of plants are very common in extant tropical and subtropical forests, and the climbing growth habit of plants may be an evolutionary innovation and ecological adaptation to either closed, shady or open, ...Twining stems of plants are very common in extant tropical and subtropical forests, and the climbing growth habit of plants may be an evolutionary innovation and ecological adaptation to either closed, shady or open, edge environments. However, the origin of handedness in climbing plants remains unclear. Here we report a Miocene (ca. 16 million years ago) macrofossil from the Shanwang Formation of Shandong Province, Eastern China, unequivocally exhibiting the first direct fossil evidence for a left-handed, stem-twining growth habit in plants. This fossil plant bears a thicker, slightly curved supporting stem (2 - 3.5 mm wide), which is loosely, spirally twined by a thinner stem (1.5 - 2 mm wide), possibly representing part of distal branches from a liana or vine.展开更多
Miocene(16―10 Ma) basalts,together with significantly well-preserved fossils(including animal and plant fossils) in the contemporaneously tephra-rich Maar sediments,are located in Shanwang volcanic region,Shandong Pr...Miocene(16―10 Ma) basalts,together with significantly well-preserved fossils(including animal and plant fossils) in the contemporaneously tephra-rich Maar sediments,are located in Shanwang volcanic region,Shandong Province,China.Distribution area of the basaltic eruption products is about 240 km2.Detailed field observations indicate that most of basaltic rocks are fissure eruptive products and some are central eruptives constrained by linear faults.The well-preserved fossils in the lacustrine deposits have been considered to be a result of mass mortalities.Based on physically volcanologic modeling results,eruption column of the basaltic fissure activities in the Shanwang volcanic region is estimated to have entered the stratosphere.Petrographic observations indicate that the basalts have porphyritic textures with phenocrysts of olivine,pyroxene,plagioclase feldspar and alkali feldspar setting in groundmass of plagioclase feldspar,alkali feldspar,quartz,apatite and glass.Based on observations of tephra,tuff and tuffites collected in the Maar sediments of the Shanwang area,we determined major element oxide concentrations and volatile composition of melt inclusions in phenocrysts and matrix glasses by electron microprobe analysis.Volatile(including S,Cl,F and H2O) concentrations erupted into the stratosphere were estimated by comparing pre-and post-eruptive volatile concentrations.Our determination results show that contents of S,Cl,F and H2O emitted into the stratosphere were 0.18%― 0.24%,0.03%―0.05%,0.03%―0.05% and 0.4%―0.6%,respectively,which was characterized by high-S contents erupted.Amounts of volatiles emitted in the Shanwang volcanic region are much higher than those in eruptions which had a substantial effect on climate and environment.According to the com-positions and amounts of the volatiles erupted from the Miocene basaltic volcanism in Shanwang,we propose a hypothesis that volatile-rich basaltic volcanism could result in the mass mortalities by in-jecting volatiles(e.g.,SO2,H2S,HCl,HF and H2O) into the stratosphere that would have triggered abrupt environmental changes(including formation of acid rain,temperature decline,ozone depletion,etc.) and altered lake chemistry,and subsequently volcanic ash fall buried and covered the dead animals and plants,forming well-preserved fossils in Shanwang Maar sediments.展开更多
基金supported by the National Natural Science Foundation of China (NSFC-41272066)the Program for Changjiang Scholars & Innovative Research Team of the University of China (IRT-13075)
文摘Several paleoseismic events are recorded in the Neogene Linqu Group, exposed in the Linqu area, Shandong Province, China. The events were interpreted on the basis of fleldwork and laboratory analysis, which showed the presence of seismites with plastically deformed soft-sediment deformation structures in the Shanwang Formation, and of seismic volcanic rocks in the Yaoshan Formation which show brittle deformation. The earthquake-triggered soft-sediment deformations in the seismites include load structures, ball-and-pillow structures, flame structures, piUow-like beds, boudinage structures, slump folds, syn-depositional faults, veins of liquefied sand, and dikes of liquefied sandy lime-mud. The seismic activity is also reflected in what might be called ＇brittle seismites＇; these originated when, under the influence of seismic vibrations, semi-consolidated conglomerate was shattered. Moreover, volcanic activity is related to intense earthquakes that affected basalts intercalated with sand layers; these successions are known as ＇seismic volcanic rocks＇, which are characterized by veins of liquefied sand intruding the basalts. AH above traces of paleoseismic activity were left from one single time span of 4 Ma with active seismicity that took place 14-10 Ma. This time span is known as ＇the Linqu Neogene Paleoseismic Active Period＇, which is divided into four paleoseismic episodes, which were responses to tectonic extension and basin rifting in this area. It even includes the activity of the Yishu Fault Zone during the Miocene and the Neogene. The ratios of trace elements in the seismites, w（La）/w（Sc） and w （La）/w（Th） are higher than the average value of the upper crust, but w（Th）/w（Sc） is lower; this is geochemical evidence for the basin rifting that resulted in a high sedimentation rate. The intense and frequent paleo-earthquakes are held responsible for the rapid burial of the Shanwang Biota. Secondary earthquake-induced processes （e.g. slumping of a lake shore and the strongly increased lacustrine sedimentation rate） contributed to the rapid burial of the biota.
基金supported by the National Natural Science Foundation of China(grant 41472092)the Scientific and Technological Innovation Project financially supported by the Qingdao National Laboratory for Marine Science and Technology(No.2016ASKJ13)
文摘The Shanwang Basin is a small Cenozoic sedimentary basin located in Linqu county, Shandong province.The Shanwang Formation, especially the diatomaceous shale member, contains diverse and finely preserved flora and fauna fossils （Fig. 1）. Previous paleontological study and radiometric dating show that it was formed in the Miocene. However, on the precise age of the formation, there are such different opinions as Late Miocene, Middle Miocene, Early stage of Middle Miocene, etc.
文摘Twining stems of plants are very common in extant tropical and subtropical forests, and the climbing growth habit of plants may be an evolutionary innovation and ecological adaptation to either closed, shady or open, edge environments. However, the origin of handedness in climbing plants remains unclear. Here we report a Miocene (ca. 16 million years ago) macrofossil from the Shanwang Formation of Shandong Province, Eastern China, unequivocally exhibiting the first direct fossil evidence for a left-handed, stem-twining growth habit in plants. This fossil plant bears a thicker, slightly curved supporting stem (2 - 3.5 mm wide), which is loosely, spirally twined by a thinner stem (1.5 - 2 mm wide), possibly representing part of distal branches from a liana or vine.
基金Supported by the National Natural Science Foundation of China (Grant Nos 40473023 and 40372045)
文摘Miocene(16―10 Ma) basalts,together with significantly well-preserved fossils(including animal and plant fossils) in the contemporaneously tephra-rich Maar sediments,are located in Shanwang volcanic region,Shandong Province,China.Distribution area of the basaltic eruption products is about 240 km2.Detailed field observations indicate that most of basaltic rocks are fissure eruptive products and some are central eruptives constrained by linear faults.The well-preserved fossils in the lacustrine deposits have been considered to be a result of mass mortalities.Based on physically volcanologic modeling results,eruption column of the basaltic fissure activities in the Shanwang volcanic region is estimated to have entered the stratosphere.Petrographic observations indicate that the basalts have porphyritic textures with phenocrysts of olivine,pyroxene,plagioclase feldspar and alkali feldspar setting in groundmass of plagioclase feldspar,alkali feldspar,quartz,apatite and glass.Based on observations of tephra,tuff and tuffites collected in the Maar sediments of the Shanwang area,we determined major element oxide concentrations and volatile composition of melt inclusions in phenocrysts and matrix glasses by electron microprobe analysis.Volatile(including S,Cl,F and H2O) concentrations erupted into the stratosphere were estimated by comparing pre-and post-eruptive volatile concentrations.Our determination results show that contents of S,Cl,F and H2O emitted into the stratosphere were 0.18%― 0.24%,0.03%―0.05%,0.03%―0.05% and 0.4%―0.6%,respectively,which was characterized by high-S contents erupted.Amounts of volatiles emitted in the Shanwang volcanic region are much higher than those in eruptions which had a substantial effect on climate and environment.According to the com-positions and amounts of the volatiles erupted from the Miocene basaltic volcanism in Shanwang,we propose a hypothesis that volatile-rich basaltic volcanism could result in the mass mortalities by in-jecting volatiles(e.g.,SO2,H2S,HCl,HF and H2O) into the stratosphere that would have triggered abrupt environmental changes(including formation of acid rain,temperature decline,ozone depletion,etc.) and altered lake chemistry,and subsequently volcanic ash fall buried and covered the dead animals and plants,forming well-preserved fossils in Shanwang Maar sediments.
