Calculations, according to some open-system models, point out that while a statistically significant discrepancy between the results of two U-series methods, 230Th/234U and 227Th/230Th (or 231Pa/235U), attests a relat...Calculations, according to some open-system models, point out that while a statistically significant discrepancy between the results of two U-series methods, 230Th/234U and 227Th/230Th (or 231Pa/235U), attests a relatively recent and important uranium migration,concordant dates cannot guarantee closed-system behavior of a sample. The results of 20 fossil bones from 10 Chinese sites, 19 of which are determined by two U-series methods, are given.Judging from independent age controls, 8 out of the 11 concordant age sets are unacceptable.The results in this paper suggest that uranium may cycle into or out of fossil bones, such geochemical events may take place at any time and no known preserving condition may securely protect them from being affected. So for the sites we have studied, the U-series dating of fossil bones is of limited reliability.展开更多
From Ganqian (Tubo) Cave a total of 17 hominid teeth attributed to late Homo sapiens has been collected along with an abundance of mammalian fossils. The fossiliferous deposits are bracketed by the capping and second ...From Ganqian (Tubo) Cave a total of 17 hominid teeth attributed to late Homo sapiens has been collected along with an abundance of mammalian fossils. The fossiliferous deposits are bracketed by the capping and second flowstone layers, which yielded 230 Th/ 234 U dates of ～93 and ～220 ka, marking the minimum and maximum age of the hominid teeth respectively. Two U series methods performed on two mammalian teeth gave dates in the range of 85 and 139 ka, lending support to the stratigraphic order of the depositional sequence. The results presented in this paper point to an occurrence of modern Homo sapiens in southern China much earlier than has been thought, which is supported by the dating of nearby Liujiang and Bailiandong hominid sites. Taken together, these data suggest that China should not be considered as a backwater in recent human evolution where all the previous populations were replaced.展开更多
The ideology of being ready to make innovation and keeping abreast of the times is a defining feature of the Chinese civilization.IN several of his recent speeches President Xi Jinping stressed that the Chinese civili...The ideology of being ready to make innovation and keeping abreast of the times is a defining feature of the Chinese civilization.IN several of his recent speeches President Xi Jinping stressed that the Chinese civilization has the tradition of discarding the outdated in favor of the new and moving ahead with the times.In exploring a new philosophy that is suitable for governing China in the new era,China draws on its fine traditional culture to find ways of abolishing outdated ideas and making theoretical,practical,and institutional innovations,thus staying abreast of the time to create a better future.展开更多
Using the isotopic diluting and thermal ionization mass spectrometric (TIMS) technique, the U-series dating procedure was established on the basis of measurement of national standard GBW04412. With this highly precise...Using the isotopic diluting and thermal ionization mass spectrometric (TIMS) technique, the U-series dating procedure was established on the basis of measurement of national standard GBW04412. With this highly precise technique the Holocene corals from the South China Sea were dated. Comparison between this method and α-spectrometry was made. The results show that a thriving period of corals in the South China Sea appeared at 6 800—5 800 a BP, during which the paleosea level was the higher than at present in the Holecene.展开更多
In order to provide fundamental data to speleological researchers and tourists, 50 dating data of speleothems dated by our laboratory in recent years are reported in this note. Among them, 18 are from Beijing area, 17...In order to provide fundamental data to speleological researchers and tourists, 50 dating data of speleothems dated by our laboratory in recent years are reported in this note. Among them, 18 are from Beijing area, 17 from Guizhou Province, 4 from Zhejiang Province, 3 from Hunan Province, 2 from Yunnan Province, 2 from Hubei Province, 2 from Guangxi Province and 2 from Sichuan Province. The method of U-series elating has been discussed in another paper, so it will not be covered in this note. The 232U—228Th spike was distributed by the organizer of USIP conferences Ⅱ and Ⅲ. The appraised results to the spike are presented in Refs. [1—3].展开更多
The U-series component-dating method has been employed to date the sediment core B-194 from Balikun Lake. 230Th/ 232Th and 234U/ 232Th ratios in various components of the samples dissolved in different concentration a...The U-series component-dating method has been employed to date the sediment core B-194 from Balikun Lake. 230Th/ 232Th and 234U/ 232Th ratios in various components of the samples dissolved in different concentration acids were measured respectively. The results indicate that there is a good relationship of the isotopic ratios between the solutions and the residues, and that uranium and thorium isotopic fractionations did not occur during acid leaching. Based on the U-series ages obtained by using component-dating method, a 144-ka time sequence was established corresponding to the upper 25-m interval of the B-194 core, which is in agreement with palaeomagnetic dating results. The fact that the palaeoclimatic and palaeoenvironmental record labeled with U-series ages is correlative with the deep-sea δ 18O SPECMAP also demonstrates that the U-series component-dating method can be used to date lake sediments.展开更多
1.Objective Three stages of Mesozoic magmatic activity have been identified in the Jiaodong area,namely early magmatic emplacement,the magmatic emplacement prior to mineralization,and magmatic activity post-mineraliza...1.Objective Three stages of Mesozoic magmatic activity have been identified in the Jiaodong area,namely early magmatic emplacement,the magmatic emplacement prior to mineralization,and magmatic activity post-mineralization,from early to late.展开更多
The cultural deposits at pits T1 and T2 in Zhangkou Cave are intercalated with several flowstone lay- ers. U-series dates show that the capping and 2nd flowstone layers are Holocene of age. The 4th and 5th flowstone l...The cultural deposits at pits T1 and T2 in Zhangkou Cave are intercalated with several flowstone lay- ers. U-series dates show that the capping and 2nd flowstone layers are Holocene of age. The 4th and 5th flowstone layers are ca. 55 and 110 ka old respectively. The lithic artifacts bracketed by them provide unequivocal evidence for hominid presence during this time interval. The “temporal gap” of hominid fossil, widely quoted as in support of the out-of-Africa hypothesis, is most probably an artifact due to systematic errors of dating techniques. The infillings under 6th flowstone layer date to >300 ka, much older than the previous estimate at 15 ka based on classical 14C dating of fossil bones, providing one more example of the limited reli- ability of this chronometer. With rich relics and favorable conditions for precise dating, this site is promising for fur- ther multidisciplinary studies to address issues concerning recent human evolution in China.展开更多
The ages of coral reef samples from several shallow drill holes in the South China Sea are determined by ESR and U-series (230Th/234U) methods. The experimental results show ideal agreement between ESR and U-series ag...The ages of coral reef samples from several shallow drill holes in the South China Sea are determined by ESR and U-series (230Th/234U) methods. The experimental results show ideal agreement between ESR and U-series ages and that the coral reefs were formed in the early Holocene. In the determination of natural total dose of coral reef by use of the additive dose method good results can be obtained by exponential fitting, no matter how the effect of dose saturation is. It was found that the ratio of the natural ESR signal intensity ( I0) to the ESR signal intensity at dose saturation ( Imax) of sample can reflect the significance of a irradiation efficiency-k value. Using the k value of sample determined by the formula given in this paper, the precision of ESR dating of marine carbonates can be improved.展开更多
samples of lava and pumice from the cone of Changbaishan Tianchi Volcano, Jiling, China, were dated by using high precision U-series TIMS method. We conclude that the bottom of the cone formed before 350 ka, the middl...samples of lava and pumice from the cone of Changbaishan Tianchi Volcano, Jiling, China, were dated by using high precision U-series TIMS method. We conclude that the bottom of the cone formed before 350 ka, the middle part in 70～80 ka, the upper during 20～1ka, and the top less than 1ka, and the age based periods of the volcano eruption since Late Pleistocene is given as follows: >350ka,70ka,18～25ka,10ka, 4C5ka, 1～0.75ka, which may offer the basis for the study of volcanic disaster in future. In addition, the principle of dating young volcanic rocks by using U-series TIMS method is introduced briefly. Differentiation characteristics of U and Th in different minerals of the volcanic rocks are discussed, and the ability producing isochrons, based on U and Th differentiation, are discussed. In the last part of the paper, the closure of samples to the elements U and Th, which is important for age results, is discussed by using ( 234 U/ 238 U) radioactivity ratio which can be used to monitor if the samples have been weathered or eroded or leached since the time they formed. In this study, all samples have ( 234 U/ 238 U) activity ratios within 1% of secular equilibrium (( 234 U/ 238 U) radioactivity ratios are unity), indicating no disturbance of the 234 U～ 238 U system. All of these discussions show that the TIMS method is good to date Tianchi volcanics and the results are reliable.展开更多
DEAR EDITOR,Biogeography is a scientific field dedicated to the investigation of the origins and distribution patterns of organisms,as well as predicting future alterations in their geographical distributions(Cox&...DEAR EDITOR,Biogeography is a scientific field dedicated to the investigation of the origins and distribution patterns of organisms,as well as predicting future alterations in their geographical distributions(Cox&Moore,2005).However,the majority of conclusions drawn within the field of biogeography are hypothetical.Rigorous testing of these biogeographic hypotheses remains a considerable challenge.This paper presents the concept of“integrative biogeography”,which emphasizes the experimental testing of biogeographic hypotheses through studies on geological history,as well as biotic and abiotic factors(Figure 1).展开更多
The invasive insect pest, red palm weevil (RPW), Rhynchophorus ferrugineus, poses a significant threat to date production, causing substantial economic damage. If uncontrolled, RPW leads the severely infested host tre...The invasive insect pest, red palm weevil (RPW), Rhynchophorus ferrugineus, poses a significant threat to date production, causing substantial economic damage. If uncontrolled, RPW leads the severely infested host tree to collapse and eventually die. The symbiotic associations with microorganisms and RPW in their gut may help their host insects’ establishment, development, nutrition assimilation, and survival. The objective of this research was the molecular characterization of the microbiome of RPW. In this study, the microbiome was compared among different tissues in females and males of RPW of three different morphs and larvae collected from date palm plantations in the Kingdom of Bahrain. A 251-bp segment of bacterial 16S rRNA was amplified by PCR, sequenced, and processed using the bioinformatics platform QIIME2. One ASV, corresponding to the obligate weevil symbiont Nardonella, predominated in adult female samples, constituting 56 ± 7% of total reads, but was less dominant in male samples (12 ± 3%) and larval samples (2.6 ± 1.9%). For females, samples that included reproductive tissues were almost entirely composed of Nardonella (88% - 99%). When Nardonella was excluded from analyses, there were no differences between adult females and adult males, but larval samples were more species-rich and differed in microbial composition from adults. There were no consistent differences in the microbiomes among morphs. Several specimens showed evidence of infection with host-specific strains of Spiroplasma-like members of the Entomoplasmatales, which are often pathogens or vertically transmitted symbionts. Such close microbial associates deserve additional attention as potential routes to control this destructive date palm pest.展开更多
1.Objective The Gejiu-Bozhushan-Laojunshan tin-tungsten polymetallic metallogenic belt is located in southeastern Yunnan.It is bounded by the Mile-Shizong Fault and the Yangzi Plate to the north and west,respectively,...1.Objective The Gejiu-Bozhushan-Laojunshan tin-tungsten polymetallic metallogenic belt is located in southeastern Yunnan.It is bounded by the Mile-Shizong Fault and the Yangzi Plate to the north and west,respectively,while the Honghe Fault represents its southwestern boundary.It is adjacent to the Ailaoshan Fault,and extends to Guangxi and Vietnam to the southeast(Fig.1a;Liu JP et al.,2021).展开更多
1.Objective The Altay Orogenic Belt in Xinjiang,China is located in the west of the Central Asian Orogenic Belt and in the transition zone between the Siberian Plate and the Kazakhstan-Junggar Plate,extending approxim...1.Objective The Altay Orogenic Belt in Xinjiang,China is located in the west of the Central Asian Orogenic Belt and in the transition zone between the Siberian Plate and the Kazakhstan-Junggar Plate,extending approximately 500 km in northern Xinjiang,China(Fig.1a).The Altay Orogenic Belt has undergone two-way accretion of the Paleozoic crust and the Meso-Cenozoic intracontinental orogeny,leading to the formation of large numbers of intermediate-acid intrusions.More than 100000 pegmatite veins have been discovered in the intermediate-acid intrusions,and they constitute an important rare metal metallogenic belt of China(Fig.1b).展开更多
1.Objective Pegmatite hosts important resource of rare metals,e.g.,lithium(Li)and beryllium(Be).In recent years,increasingly more studies were dedicated to characterize and unravel the formation of pegmatite-type depo...1.Objective Pegmatite hosts important resource of rare metals,e.g.,lithium(Li)and beryllium(Be).In recent years,increasingly more studies were dedicated to characterize and unravel the formation of pegmatite-type deposits,for which accurate dating of pegmatite formation and mineralization is essential.The Songpan-Ganzi orogenic belt is a major rare metal metallogenic belt in China,hosting many important pegmatite-type Li deposits,including the Lijiagou,Dangba,Jiajika,Yelonggou,Cuola,and Declalongba.Radiometric age data(mica Ar-Ar and zircon/cassiterite U-Pb)from these Li deposits are sparse,ranging from 210 to 152 Ma.However,obtaining reliable zircon U-Pb dates can be a challenge due to the strong decidualization in pegmatites.As a result,the formation and mineralization ages of these rare metal pegmatites remain controversial,which hampers the development of pegmatite-type metallogenic model for the Songpan-Ganzi orogenic belt.展开更多
Permian sedimentary successions,widely distributed in the eastern Junggar Basin,may record key details on the closure of the Paleo-Asian Ocean in this region.Results of boreholes show that Permian strata is mainly com...Permian sedimentary successions,widely distributed in the eastern Junggar Basin,may record key details on the closure of the Paleo-Asian Ocean in this region.Results of boreholes show that Permian strata is mainly composed of mudstone,sandy mudstone,siltstone,sandstone,sandy conglomerate,dolomite,and limestone.Detrital zircon U-Pb dating results of three sandstone samples yielded the calculated maximum ages of 296 Ma,278 Ma and 293 Ma,indicating they possibly deposited during the Early Permian.Permian strata in the eastern Junggar Basin show similar rock associations and detrital zircon age data distribution patterns.Our new and compiled age data for sandstone samples in the eastern Junggar Basin and Bogda region yield predominant Paleozoic ages,close to their sedimentary ages.Such detrital zircon age data distribution patterns support the hypothesis that these Early Permian meta-clastic rocks in the eastern Junggar Basin and Bogda region were deposited in a subduction-related basin,and indicate an Early Permian Ocean prevented Precambrian detritus from the Central Tianshan block from depositing in the eastern Junggar Basin and Bogda region.展开更多
The Hesar pluton in the northern Urumieh-Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves(MMEs).Whole rock geochemistry,mineral chemistry,zircon U-Pb and Sr-Nd isotopes were measured.It is suggested th...The Hesar pluton in the northern Urumieh-Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves(MMEs).Whole rock geochemistry,mineral chemistry,zircon U-Pb and Sr-Nd isotopes were measured.It is suggested that the rocks are metaluminous(A/CNK=1.32-1.45),subduction-related I-type calc-alkaline gabbro to diorite with similar mineral assemblages and geochemical signatures.The host rocks yielded an U-Pb crystallization age of 37.3±0.4 Ma for gabbro-diorite.MMEs have relatively low SiO_(2) contents(52.9-56.6 wt%)and high Mg^(#)(49.8-58.7),probably reflecting a mantle-derived origin.Chondrite-and mantle-normalized trace element patterns are characterized by LREE and LILE enrichment,HREE and HFSE depletion with slight negative Eu anomalies(Eu/Eu^(*)=0.86-1.03).The host rocks yield(^(87)Sr/^(86)Sr)_(i) ratios of 0.70492-0.70510,positive ε_(Nd)(t)values of+1.55-+2.06 and T_(DM2)of 707-736 Ma,which is consistent with the associated mafic microgranular enclaves((^(87)Sr/^(86)Sr)_(i)=0.705014,ε_(Nd)(t)=+1.75,T_(DM2)=729 Ma).All data suggest magma-mixing for enclave and host rock formation,showing a complete equilibration between mixed-mafic and felsic magmas,followed by rapid diffusion.The T_(DM1)(Nd)and T_(DM2)(Nd)model ages and U-Pb dating indicate that the host pluton was produced by partial melting of the lower continental crust and subsequent mixing with injected lithospheric mantlederived magmas in a pre-collisional setting of Arabian-Eurasian plates.Clinopyroxene composition indicates a crystallization temperature of~1000℃ and a depth of~9 km.展开更多
Efficient and high-quality estimation of key phenological dates in rice is of great significance in breeding work. Plant height(PH) dynamics are valuable for estimating phenological dates. However, research on estimat...Efficient and high-quality estimation of key phenological dates in rice is of great significance in breeding work. Plant height(PH) dynamics are valuable for estimating phenological dates. However, research on estimating the key phenological dates of multiple rice accessions based on PH dynamics has been limited. In 2022, field traits were collected using unmanned aerial vehicle(UAV)-based images across 435 plots, including 364 rice varieties. PH, dates of initial heading(IH) and full heading(FH), and panicle initiation(PI), and growth period after transplanting(GPAT) were collected during the rice growth stage. PHs were extracted using a digital surface model(DSM) and fitted using Fourier and logistic models. Machine learning algorithms, including multiple linear regression, random forest(RF), support vector regression, least absolute shrinkage and selection operator, and elastic net regression, were employed to estimate phenological dates. Results indicated that the optimal percentile of the DSM for extracting rice PH was the 95th(R^(2) = 0.934, RMSE = 0.056 m). The Fourier model provided a better fit for PH dynamics compared with the logistic models. Additionally, curve features(CF) and GPAT were significantly associated with PI, IH, and FH. The combination of CF and GPAT outperformed the use of CF alone, with RF demonstrating the best performance among the algorithms. Specifically, the combination of CF extracted from the logistic models, GPAT, and RF yielded the best performance for estimating PI(R^(2) = 0.834, RMSE = 4.344 d), IH(R^(2) = 0.877, RMSE = 2.721 d), and FH(R^(2) = 0.883, RMSE = 2.694 d). Overall, UAV-based rice PH dynamics combined with machine learning effectively estimated the key phenological dates of multiple rice accessions, providing a novel approach for investigating key phenological dates in breeding work.展开更多
Early on the morning of 11 September 2023,floodwaters that were up to 7 m deep surged down the normally dry riverbed that cuts through the city of Derna in eastern Libya[1].Two nearby dams,both built in the 1970s from...Early on the morning of 11 September 2023,floodwaters that were up to 7 m deep surged down the normally dry riverbed that cuts through the city of Derna in eastern Libya[1].Two nearby dams,both built in the 1970s from clay,rock,and dirt to forestall just this scenario,had ruptured after heavy rainfall from a near-hurricane strength storm(Fig.1)[2].According to Libyan government statistics,more than 4500 people died after the deluge inundated much of the city[3].展开更多
Poor fruit and vegetable consumption is one of the 10 major risk factors for mortality.There is a misconception regarding the consumption of dates among patients with diabetes.This manuscript assessed the effects of d...Poor fruit and vegetable consumption is one of the 10 major risk factors for mortality.There is a misconception regarding the consumption of dates among patients with diabetes.This manuscript assessed the effects of date consumption on fasting and postprandial blood glucose,glycated hemoglobin,total cholesterol,triglycerides,low-density lipoproteins,high-density lipoproteins,and microbial markers.Four literature databases were searched for relevant articles.Of the 595 studies retrieved,24 assessed the effects of dates on glycemic control and lipids.Overall,the evidence suggests that dates have a lowering effect on blood glucose.Dates reduce total cholesterol and triglyceride levels and increase high-density lipoprotein levels.Dates also promote the abundance of beneficial gut microbiota.Therefore,patients with diabetes and dyslipidemia can consume dates to reduce their blood glucose,cholesterol,and triglycerides.展开更多
文摘Calculations, according to some open-system models, point out that while a statistically significant discrepancy between the results of two U-series methods, 230Th/234U and 227Th/230Th (or 231Pa/235U), attests a relatively recent and important uranium migration,concordant dates cannot guarantee closed-system behavior of a sample. The results of 20 fossil bones from 10 Chinese sites, 19 of which are determined by two U-series methods, are given.Judging from independent age controls, 8 out of the 11 concordant age sets are unacceptable.The results in this paper suggest that uranium may cycle into or out of fossil bones, such geochemical events may take place at any time and no known preserving condition may securely protect them from being affected. So for the sites we have studied, the U-series dating of fossil bones is of limited reliability.
文摘From Ganqian (Tubo) Cave a total of 17 hominid teeth attributed to late Homo sapiens has been collected along with an abundance of mammalian fossils. The fossiliferous deposits are bracketed by the capping and second flowstone layers, which yielded 230 Th/ 234 U dates of ～93 and ～220 ka, marking the minimum and maximum age of the hominid teeth respectively. Two U series methods performed on two mammalian teeth gave dates in the range of 85 and 139 ka, lending support to the stratigraphic order of the depositional sequence. The results presented in this paper point to an occurrence of modern Homo sapiens in southern China much earlier than has been thought, which is supported by the dating of nearby Liujiang and Bailiandong hominid sites. Taken together, these data suggest that China should not be considered as a backwater in recent human evolution where all the previous populations were replaced.
文摘The ideology of being ready to make innovation and keeping abreast of the times is a defining feature of the Chinese civilization.IN several of his recent speeches President Xi Jinping stressed that the Chinese civilization has the tradition of discarding the outdated in favor of the new and moving ahead with the times.In exploring a new philosophy that is suitable for governing China in the new era,China draws on its fine traditional culture to find ways of abolishing outdated ideas and making theoretical,practical,and institutional innovations,thus staying abreast of the time to create a better future.
文摘Using the isotopic diluting and thermal ionization mass spectrometric (TIMS) technique, the U-series dating procedure was established on the basis of measurement of national standard GBW04412. With this highly precise technique the Holocene corals from the South China Sea were dated. Comparison between this method and α-spectrometry was made. The results show that a thriving period of corals in the South China Sea appeared at 6 800—5 800 a BP, during which the paleosea level was the higher than at present in the Holecene.
文摘In order to provide fundamental data to speleological researchers and tourists, 50 dating data of speleothems dated by our laboratory in recent years are reported in this note. Among them, 18 are from Beijing area, 17 from Guizhou Province, 4 from Zhejiang Province, 3 from Hunan Province, 2 from Yunnan Province, 2 from Hubei Province, 2 from Guangxi Province and 2 from Sichuan Province. The method of U-series elating has been discussed in another paper, so it will not be covered in this note. The 232U—228Th spike was distributed by the organizer of USIP conferences Ⅱ and Ⅲ. The appraised results to the spike are presented in Refs. [1—3].
文摘The U-series component-dating method has been employed to date the sediment core B-194 from Balikun Lake. 230Th/ 232Th and 234U/ 232Th ratios in various components of the samples dissolved in different concentration acids were measured respectively. The results indicate that there is a good relationship of the isotopic ratios between the solutions and the residues, and that uranium and thorium isotopic fractionations did not occur during acid leaching. Based on the U-series ages obtained by using component-dating method, a 144-ka time sequence was established corresponding to the upper 25-m interval of the B-194 core, which is in agreement with palaeomagnetic dating results. The fact that the palaeoclimatic and palaeoenvironmental record labeled with U-series ages is correlative with the deep-sea δ 18O SPECMAP also demonstrates that the U-series component-dating method can be used to date lake sediments.
基金This paper was supported by the geological researchprojects of the Shandong Yantai Xintai Gold Mining Co.,Ltd.under China National Gold Group Corporation(Grant Nos.XY-DZ2020081,WTDZ2022001,XY-DZ20210161,and XY-DZ2022183)。
文摘1.Objective Three stages of Mesozoic magmatic activity have been identified in the Jiaodong area,namely early magmatic emplacement,the magmatic emplacement prior to mineralization,and magmatic activity post-mineralization,from early to late.
基金This work was jointly supported by the National Natural Science Foundation of China(Grant No.40073020)the Wen-ner-Gren Foundation(Gr.6975).
文摘The cultural deposits at pits T1 and T2 in Zhangkou Cave are intercalated with several flowstone lay- ers. U-series dates show that the capping and 2nd flowstone layers are Holocene of age. The 4th and 5th flowstone layers are ca. 55 and 110 ka old respectively. The lithic artifacts bracketed by them provide unequivocal evidence for hominid presence during this time interval. The “temporal gap” of hominid fossil, widely quoted as in support of the out-of-Africa hypothesis, is most probably an artifact due to systematic errors of dating techniques. The infillings under 6th flowstone layer date to >300 ka, much older than the previous estimate at 15 ka based on classical 14C dating of fossil bones, providing one more example of the limited reli- ability of this chronometer. With rich relics and favorable conditions for precise dating, this site is promising for fur- ther multidisciplinary studies to address issues concerning recent human evolution in China.
文摘The ages of coral reef samples from several shallow drill holes in the South China Sea are determined by ESR and U-series (230Th/234U) methods. The experimental results show ideal agreement between ESR and U-series ages and that the coral reefs were formed in the early Holocene. In the determination of natural total dose of coral reef by use of the additive dose method good results can be obtained by exponential fitting, no matter how the effect of dose saturation is. It was found that the ratio of the natural ESR signal intensity ( I0) to the ESR signal intensity at dose saturation ( Imax) of sample can reflect the significance of a irradiation efficiency-k value. Using the k value of sample determined by the formula given in this paper, the precision of ESR dating of marine carbonates can be improved.
文摘samples of lava and pumice from the cone of Changbaishan Tianchi Volcano, Jiling, China, were dated by using high precision U-series TIMS method. We conclude that the bottom of the cone formed before 350 ka, the middle part in 70～80 ka, the upper during 20～1ka, and the top less than 1ka, and the age based periods of the volcano eruption since Late Pleistocene is given as follows: >350ka,70ka,18～25ka,10ka, 4C5ka, 1～0.75ka, which may offer the basis for the study of volcanic disaster in future. In addition, the principle of dating young volcanic rocks by using U-series TIMS method is introduced briefly. Differentiation characteristics of U and Th in different minerals of the volcanic rocks are discussed, and the ability producing isochrons, based on U and Th differentiation, are discussed. In the last part of the paper, the closure of samples to the elements U and Th, which is important for age results, is discussed by using ( 234 U/ 238 U) radioactivity ratio which can be used to monitor if the samples have been weathered or eroded or leached since the time they formed. In this study, all samples have ( 234 U/ 238 U) activity ratios within 1% of secular equilibrium (( 234 U/ 238 U) radioactivity ratios are unity), indicating no disturbance of the 234 U～ 238 U system. All of these discussions show that the TIMS method is good to date Tianchi volcanics and the results are reliable.
基金supported by the National Natural Science Foundation of China(32070423)Third Xinjiang Scientific Expedition Program(2021xjkk0600)。
文摘DEAR EDITOR,Biogeography is a scientific field dedicated to the investigation of the origins and distribution patterns of organisms,as well as predicting future alterations in their geographical distributions(Cox&Moore,2005).However,the majority of conclusions drawn within the field of biogeography are hypothetical.Rigorous testing of these biogeographic hypotheses remains a considerable challenge.This paper presents the concept of“integrative biogeography”,which emphasizes the experimental testing of biogeographic hypotheses through studies on geological history,as well as biotic and abiotic factors(Figure 1).
文摘The invasive insect pest, red palm weevil (RPW), Rhynchophorus ferrugineus, poses a significant threat to date production, causing substantial economic damage. If uncontrolled, RPW leads the severely infested host tree to collapse and eventually die. The symbiotic associations with microorganisms and RPW in their gut may help their host insects’ establishment, development, nutrition assimilation, and survival. The objective of this research was the molecular characterization of the microbiome of RPW. In this study, the microbiome was compared among different tissues in females and males of RPW of three different morphs and larvae collected from date palm plantations in the Kingdom of Bahrain. A 251-bp segment of bacterial 16S rRNA was amplified by PCR, sequenced, and processed using the bioinformatics platform QIIME2. One ASV, corresponding to the obligate weevil symbiont Nardonella, predominated in adult female samples, constituting 56 ± 7% of total reads, but was less dominant in male samples (12 ± 3%) and larval samples (2.6 ± 1.9%). For females, samples that included reproductive tissues were almost entirely composed of Nardonella (88% - 99%). When Nardonella was excluded from analyses, there were no differences between adult females and adult males, but larval samples were more species-rich and differed in microbial composition from adults. There were no consistent differences in the microbiomes among morphs. Several specimens showed evidence of infection with host-specific strains of Spiroplasma-like members of the Entomoplasmatales, which are often pathogens or vertically transmitted symbionts. Such close microbial associates deserve additional attention as potential routes to control this destructive date palm pest.
基金supported by Yunnan Major Scientific and Technological Projects(202202AG050006)National Natural Science Foundation of China(42362010)Bozhushan Late Yanshanian magmatic metallogenic system and metallogenic regularity project(202202AG05006-2)。
文摘1.Objective The Gejiu-Bozhushan-Laojunshan tin-tungsten polymetallic metallogenic belt is located in southeastern Yunnan.It is bounded by the Mile-Shizong Fault and the Yangzi Plate to the north and west,respectively,while the Honghe Fault represents its southwestern boundary.It is adjacent to the Ailaoshan Fault,and extends to Guangxi and Vietnam to the southeast(Fig.1a;Liu JP et al.,2021).
基金Supported by the Natural Science Foundation of Shaanxi Province(2024JC-ZDXM-22,2020JM-311)the Project of China Geological Survey(DD20240128,DD20230284,DD20221636)。
文摘1.Objective The Altay Orogenic Belt in Xinjiang,China is located in the west of the Central Asian Orogenic Belt and in the transition zone between the Siberian Plate and the Kazakhstan-Junggar Plate,extending approximately 500 km in northern Xinjiang,China(Fig.1a).The Altay Orogenic Belt has undergone two-way accretion of the Paleozoic crust and the Meso-Cenozoic intracontinental orogeny,leading to the formation of large numbers of intermediate-acid intrusions.More than 100000 pegmatite veins have been discovered in the intermediate-acid intrusions,and they constitute an important rare metal metallogenic belt of China(Fig.1b).
基金financially supported by the Geological Survey Project of China Geological Survey(DD20230341)the National Natural Science Funds Integration Project(92262302)。
文摘1.Objective Pegmatite hosts important resource of rare metals,e.g.,lithium(Li)and beryllium(Be).In recent years,increasingly more studies were dedicated to characterize and unravel the formation of pegmatite-type deposits,for which accurate dating of pegmatite formation and mineralization is essential.The Songpan-Ganzi orogenic belt is a major rare metal metallogenic belt in China,hosting many important pegmatite-type Li deposits,including the Lijiagou,Dangba,Jiajika,Yelonggou,Cuola,and Declalongba.Radiometric age data(mica Ar-Ar and zircon/cassiterite U-Pb)from these Li deposits are sparse,ranging from 210 to 152 Ma.However,obtaining reliable zircon U-Pb dates can be a challenge due to the strong decidualization in pegmatites.As a result,the formation and mineralization ages of these rare metal pegmatites remain controversial,which hampers the development of pegmatite-type metallogenic model for the Songpan-Ganzi orogenic belt.
基金supported by China Petroleum&Chemical Corporation Key Scientific and Technological Projects(P22078,P22128,and 22079).
文摘Permian sedimentary successions,widely distributed in the eastern Junggar Basin,may record key details on the closure of the Paleo-Asian Ocean in this region.Results of boreholes show that Permian strata is mainly composed of mudstone,sandy mudstone,siltstone,sandstone,sandy conglomerate,dolomite,and limestone.Detrital zircon U-Pb dating results of three sandstone samples yielded the calculated maximum ages of 296 Ma,278 Ma and 293 Ma,indicating they possibly deposited during the Early Permian.Permian strata in the eastern Junggar Basin show similar rock associations and detrital zircon age data distribution patterns.Our new and compiled age data for sandstone samples in the eastern Junggar Basin and Bogda region yield predominant Paleozoic ages,close to their sedimentary ages.Such detrital zircon age data distribution patterns support the hypothesis that these Early Permian meta-clastic rocks in the eastern Junggar Basin and Bogda region were deposited in a subduction-related basin,and indicate an Early Permian Ocean prevented Precambrian detritus from the Central Tianshan block from depositing in the eastern Junggar Basin and Bogda region.
基金supported by the Iran National Science Foundation(INSF)(Grant No.98012578)projects from the National Natural Science Foundation of China(Grant Nos.41473033,41673031)。
文摘The Hesar pluton in the northern Urumieh-Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves(MMEs).Whole rock geochemistry,mineral chemistry,zircon U-Pb and Sr-Nd isotopes were measured.It is suggested that the rocks are metaluminous(A/CNK=1.32-1.45),subduction-related I-type calc-alkaline gabbro to diorite with similar mineral assemblages and geochemical signatures.The host rocks yielded an U-Pb crystallization age of 37.3±0.4 Ma for gabbro-diorite.MMEs have relatively low SiO_(2) contents(52.9-56.6 wt%)and high Mg^(#)(49.8-58.7),probably reflecting a mantle-derived origin.Chondrite-and mantle-normalized trace element patterns are characterized by LREE and LILE enrichment,HREE and HFSE depletion with slight negative Eu anomalies(Eu/Eu^(*)=0.86-1.03).The host rocks yield(^(87)Sr/^(86)Sr)_(i) ratios of 0.70492-0.70510,positive ε_(Nd)(t)values of+1.55-+2.06 and T_(DM2)of 707-736 Ma,which is consistent with the associated mafic microgranular enclaves((^(87)Sr/^(86)Sr)_(i)=0.705014,ε_(Nd)(t)=+1.75,T_(DM2)=729 Ma).All data suggest magma-mixing for enclave and host rock formation,showing a complete equilibration between mixed-mafic and felsic magmas,followed by rapid diffusion.The T_(DM1)(Nd)and T_(DM2)(Nd)model ages and U-Pb dating indicate that the host pluton was produced by partial melting of the lower continental crust and subsequent mixing with injected lithospheric mantlederived magmas in a pre-collisional setting of Arabian-Eurasian plates.Clinopyroxene composition indicates a crystallization temperature of~1000℃ and a depth of~9 km.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFD2300700)the Open Project Program of the State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute (Grant No.2023ZZKT20402)+1 种基金the Agricultural Science and Technology Innovation Program, the Central Public-Interest Scientific Institution Basal Research Fund, China (Grant No.CPSIBRF-CNRRI-202119)the Zhejiang ‘Ten Thousand Talents’ Plan Science and Technology Innovation Leading Talent Project, China (Grant No.2020R52035)。
文摘Efficient and high-quality estimation of key phenological dates in rice is of great significance in breeding work. Plant height(PH) dynamics are valuable for estimating phenological dates. However, research on estimating the key phenological dates of multiple rice accessions based on PH dynamics has been limited. In 2022, field traits were collected using unmanned aerial vehicle(UAV)-based images across 435 plots, including 364 rice varieties. PH, dates of initial heading(IH) and full heading(FH), and panicle initiation(PI), and growth period after transplanting(GPAT) were collected during the rice growth stage. PHs were extracted using a digital surface model(DSM) and fitted using Fourier and logistic models. Machine learning algorithms, including multiple linear regression, random forest(RF), support vector regression, least absolute shrinkage and selection operator, and elastic net regression, were employed to estimate phenological dates. Results indicated that the optimal percentile of the DSM for extracting rice PH was the 95th(R^(2) = 0.934, RMSE = 0.056 m). The Fourier model provided a better fit for PH dynamics compared with the logistic models. Additionally, curve features(CF) and GPAT were significantly associated with PI, IH, and FH. The combination of CF and GPAT outperformed the use of CF alone, with RF demonstrating the best performance among the algorithms. Specifically, the combination of CF extracted from the logistic models, GPAT, and RF yielded the best performance for estimating PI(R^(2) = 0.834, RMSE = 4.344 d), IH(R^(2) = 0.877, RMSE = 2.721 d), and FH(R^(2) = 0.883, RMSE = 2.694 d). Overall, UAV-based rice PH dynamics combined with machine learning effectively estimated the key phenological dates of multiple rice accessions, providing a novel approach for investigating key phenological dates in breeding work.
文摘Early on the morning of 11 September 2023,floodwaters that were up to 7 m deep surged down the normally dry riverbed that cuts through the city of Derna in eastern Libya[1].Two nearby dams,both built in the 1970s from clay,rock,and dirt to forestall just this scenario,had ruptured after heavy rainfall from a near-hurricane strength storm(Fig.1)[2].According to Libyan government statistics,more than 4500 people died after the deluge inundated much of the city[3].
文摘Poor fruit and vegetable consumption is one of the 10 major risk factors for mortality.There is a misconception regarding the consumption of dates among patients with diabetes.This manuscript assessed the effects of date consumption on fasting and postprandial blood glucose,glycated hemoglobin,total cholesterol,triglycerides,low-density lipoproteins,high-density lipoproteins,and microbial markers.Four literature databases were searched for relevant articles.Of the 595 studies retrieved,24 assessed the effects of dates on glycemic control and lipids.Overall,the evidence suggests that dates have a lowering effect on blood glucose.Dates reduce total cholesterol and triglyceride levels and increase high-density lipoprotein levels.Dates also promote the abundance of beneficial gut microbiota.Therefore,patients with diabetes and dyslipidemia can consume dates to reduce their blood glucose,cholesterol,and triglycerides.
