1.Objective,The Luang Prabang(Laos)-Loei(Thailand)metallogenetic belt,located along the northwestern margin of the Indochina Block(Fig.1a)and endowed nearly 200 t of gold and more than 106 t of copper,is one of the mo...1.Objective,The Luang Prabang(Laos)-Loei(Thailand)metallogenetic belt,located along the northwestern margin of the Indochina Block(Fig.1a)and endowed nearly 200 t of gold and more than 106 t of copper,is one of the most important gold-copper metallogenic belts in Indo-China Peninsula.It has undergone tectonic changes during the Early Paleozoic to Mesozoic Proto-Paleo Tethys tectonic evolution,recorded by the Luang Prabang tectonic belt,the Nan-Uttaradit suture,and the Dien Bien Phu-Loei suture.展开更多
Exquisite and ancient Luang Prabang is the capital city of Luang Prabang Province in northern Laos. The city is situated at the meeting of the Nam Khan and the Mekong rivers in an area of less than 10 square kilometer...Exquisite and ancient Luang Prabang is the capital city of Luang Prabang Province in northern Laos. The city is situated at the meeting of the Nam Khan and the Mekong rivers in an area of less than 10 square kilometers on the left bank of the Mekong River. It has a flat terrain and is surrounded by mountains and rivers.展开更多
Forest cover and land use change directly impact biological diversity worldwide, contribute to climate change and affect the ability of biological systems to support human needs by altering ecosystem services. Given t...Forest cover and land use change directly impact biological diversity worldwide, contribute to climate change and affect the ability of biological systems to support human needs by altering ecosystem services. Given the forest land use characteristics and ecosystem types in Luang Namtha Province, Lao PDR, the forest cover and land cover category of Luang Namtha Province were divided into six classes, i.e., current forest （CF）, potential forest （PF）, other wooded areas （OW）, permanent agricultural land （PA）, other non-forest areas （NF） and water （W）. In first instance, earlier geographic information data （GIS data） of forest cover and land use during 1992 and 2002 was obtained from the Ministry of Agriculture and Forestry （MAF）, Lao PDR. Two steps of forest land use change assessment were conducted by the MAF, i.e., plot sampling on satellite image maps （SIMs） to detect the changes of forest cover and land use during 1992 and 2002 for the entire Luang Namtha Province and field verification in order to identify causes of the changes. Secondly, dynamic information of the forest land cover changes during this ten-year period was calculated by means of map algebra in ArcGIS 9.2. Thirdly, based on the theory of ecosystem service functions and the service function values of different global ecosystems, the value of the six forest cover and land use categories in the province was obtained. Finally, ecological environmental effects, produced by the regional land cover changes over the study period, were calculated.展开更多
The Late Paleozoic-Early Mesozoic sedimentary system of the Luang Prabang Paleotethyan back-arc basin in northern Laos is important for investigating sedimentary provenance,paleogeographic patterns,and the tectonic ev...The Late Paleozoic-Early Mesozoic sedimentary system of the Luang Prabang Paleotethyan back-arc basin in northern Laos is important for investigating sedimentary provenance,paleogeographic patterns,and the tectonic evolution of the eastern Paleotethyan Ocean.This study presents systematic stratigraphy,petrology,geochemistry,and detrital zircon U-Pb-Hf isotopic analyses for the Late Carboniferous-Jurassic sedimentary strata on both sides of the Luang Prabang Basin.Based on distinct stratigraphic ages and provenance characteristics,the clastic rock samples can be divided into four groups.The Group 1 Late Carboniferous-Early Permian samples from the western part of the basin yield detrital zircon age-peaks of~348 and~1425 Ma,with correspondingεHf(t)values ranging from-2.0 to+15.5 and+1.5 to+14,respectively.The age spectrum of Group 2 Late Carboniferous-Early Permian samples from the eastern part of the basin shows major age-peaks of~287 and~1860 Ma,withεHf(t)values of-5.9--0.9 and-3.6-+4.2,respectively.Group 3 Late Permian-Triassic samples exhibit age-peaks of~242 and~1853 Ma,along withεHf(t)values of-0.7-+14.4 and-5.4--1.8,respectively.Group 4 Middle-Late Jurassic samples yield agepeaks of~237,~431,~813,~1833,and~2460 Ma,lacking Late Devonian(413-345 Ma)detrital zircons.All these data collectively suggest that the Group 1 sample primarily originated from the Sukhothai arc in western Indochina,Group 2 was from the Kontum and Truong Son in eastern Indochina,and Group 3 has a combined provenance of the Sukhothai,Kontum,and Truong Son.Regional comparisons suggest that the Jurassic provenance was mainly derived from South China,which was imported through the northern river system.Our data,combined with the regional angular unconformities between the Jurassic continental strata and pre-Jurassic marine strata,suggest that the Luang Prabang Basin transformed into a superimposed collisional retroforeland basin during the Jurassic,and the closure of the Luang Prabang BAB occurred before the Late Triassic.展开更多
A field and a household survey, the latter of which included inspections and interviews with the residents of a totalof 1370 properties, were conducted in 2004 in 30 villages of the city of Luang Prabang, Lao PDR, in ...A field and a household survey, the latter of which included inspections and interviews with the residents of a totalof 1370 properties, were conducted in 2004 in 30 villages of the city of Luang Prabang, Lao PDR, in order to assessthe degree of rodent infestation and to identify potential factors influencing infestations. Roof rats, Rattus rattus,and the Polynesian rat, Rattus exulans, were the only rodents found in the city, and trapping results showed a cleardominance of roof rats (80–90% of all individuals). Measurements of rodent activity using tracking patchescorrelated positively with the trapping data, and revealed a significantly higher degree of rat infestation during therainy season (September) than during the dry season (November). If households in the vicinity of the samplinglocations were considered, villagers’ accounts of indoor rodent infestations recorded during the household surveycorrelated positively with measurements of rodent activity. At least every second household reported indoorinfestations. Using explorative statistical analyses (classification trees, factor analysis) we checked the predictiveor explanatory value of up to 28 variables assessed during household inspections for villagers’ observations onrodent infestation as the dependent variable. Trophic factors such as exposed food (indoors) and garbage (outdoors),and structural features such as open ceilings (indoors) and rat harborage in gardens (outdoors) ranked highest asexplanatory variables. Assessment of a small sample of roof rat droppings collected inside houses revealed thepresence of the potential disease agents Salmonella javiana, Cryptosporidium parvum, Giardia duodenalis and theparasitic nematode Calodium hepaticum (syn. Capillaria hepatica). These results underline the need for anappropriate rodent management strategy for the city, whereby simple sanitation and rodent-proofing measurescould be cheap means of reducing rat infestation rates.展开更多
On May 5, 2014, an earthquake with a magnitude of Mw 6.1(the largest earthquake in Thailand so far) occurred in Chiang Rai of the Golden Triangle area in northern Thailand. We had an opportunity to conduct field surve...On May 5, 2014, an earthquake with a magnitude of Mw 6.1(the largest earthquake in Thailand so far) occurred in Chiang Rai of the Golden Triangle area in northern Thailand. We had an opportunity to conduct field survey immediately after the earthquake. Serious damage to buildings and casualties of lives were observed, and the estimated Maximum Mercalli Intensity(MMI) of the earthquake is Ⅷ(evaluated according to the MMI scale of the Chinese Standard). No long continuous ground ruptures were produced during the earthquake, but in the epicenter(commonly within MMI Ⅷ extent), massive small linear ruptures(usually several tens of meters long) developed and displayed intriguing structural features, offsetting many roads several centimeters left laterally on NE trending cracks or offsetting right laterally on NW trending ones. The focal mechanism solution of earthquake shows that this is a pure strike-slip event, and two nodal planes in NW and NE directions had the same motion senses respectively as those of breakage associated with the earthquake. The long axis of the isoseismals and aftershock distributions are in NE direction,which is consistent with the strike of Luang Namtha fault. The 230-km-long Luang Namtha fault which starts from the border of China and Laos, runs through northern Laos, and terminates at Chiang Rai of Thailand is predominated by left-lateral strike-slip and active in late Quaternary, and two earthquakes over Ms 6.0 occurred along the fault in 1925 and 2007 respectively. This Mw 6.1 earthquake occurred at the southwestern end of the fault. All related features such as evident structural rupturing, elongated orientation of MMI and aftershock distribution,as well as the location of the epicenter,suggest that the Luang Namtha fault may be responsible for the 2014 Northern Thailand earthquake.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42102113)the National Key Research and Development Program of China(Grant No.2021YFC2901803)+1 种基金the China Geological Survey Project(Grant No.DD20230579)China Scholarship Council(File No.202108575008).
文摘1.Objective,The Luang Prabang(Laos)-Loei(Thailand)metallogenetic belt,located along the northwestern margin of the Indochina Block(Fig.1a)and endowed nearly 200 t of gold and more than 106 t of copper,is one of the most important gold-copper metallogenic belts in Indo-China Peninsula.It has undergone tectonic changes during the Early Paleozoic to Mesozoic Proto-Paleo Tethys tectonic evolution,recorded by the Luang Prabang tectonic belt,the Nan-Uttaradit suture,and the Dien Bien Phu-Loei suture.
文摘Exquisite and ancient Luang Prabang is the capital city of Luang Prabang Province in northern Laos. The city is situated at the meeting of the Nam Khan and the Mekong rivers in an area of less than 10 square kilometers on the left bank of the Mekong River. It has a flat terrain and is surrounded by mountains and rivers.
文摘Forest cover and land use change directly impact biological diversity worldwide, contribute to climate change and affect the ability of biological systems to support human needs by altering ecosystem services. Given the forest land use characteristics and ecosystem types in Luang Namtha Province, Lao PDR, the forest cover and land cover category of Luang Namtha Province were divided into six classes, i.e., current forest （CF）, potential forest （PF）, other wooded areas （OW）, permanent agricultural land （PA）, other non-forest areas （NF） and water （W）. In first instance, earlier geographic information data （GIS data） of forest cover and land use during 1992 and 2002 was obtained from the Ministry of Agriculture and Forestry （MAF）, Lao PDR. Two steps of forest land use change assessment were conducted by the MAF, i.e., plot sampling on satellite image maps （SIMs） to detect the changes of forest cover and land use during 1992 and 2002 for the entire Luang Namtha Province and field verification in order to identify causes of the changes. Secondly, dynamic information of the forest land cover changes during this ten-year period was calculated by means of map algebra in ArcGIS 9.2. Thirdly, based on the theory of ecosystem service functions and the service function values of different global ecosystems, the value of the six forest cover and land use categories in the province was obtained. Finally, ecological environmental effects, produced by the regional land cover changes over the study period, were calculated.
基金supported by the National Key Research and Development Program of China(No.2023YFF0803701)the National Natural Science Foundation of China(Nos.42330302 and 42472265)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.SML2023SP239)。
文摘The Late Paleozoic-Early Mesozoic sedimentary system of the Luang Prabang Paleotethyan back-arc basin in northern Laos is important for investigating sedimentary provenance,paleogeographic patterns,and the tectonic evolution of the eastern Paleotethyan Ocean.This study presents systematic stratigraphy,petrology,geochemistry,and detrital zircon U-Pb-Hf isotopic analyses for the Late Carboniferous-Jurassic sedimentary strata on both sides of the Luang Prabang Basin.Based on distinct stratigraphic ages and provenance characteristics,the clastic rock samples can be divided into four groups.The Group 1 Late Carboniferous-Early Permian samples from the western part of the basin yield detrital zircon age-peaks of~348 and~1425 Ma,with correspondingεHf(t)values ranging from-2.0 to+15.5 and+1.5 to+14,respectively.The age spectrum of Group 2 Late Carboniferous-Early Permian samples from the eastern part of the basin shows major age-peaks of~287 and~1860 Ma,withεHf(t)values of-5.9--0.9 and-3.6-+4.2,respectively.Group 3 Late Permian-Triassic samples exhibit age-peaks of~242 and~1853 Ma,along withεHf(t)values of-0.7-+14.4 and-5.4--1.8,respectively.Group 4 Middle-Late Jurassic samples yield agepeaks of~237,~431,~813,~1833,and~2460 Ma,lacking Late Devonian(413-345 Ma)detrital zircons.All these data collectively suggest that the Group 1 sample primarily originated from the Sukhothai arc in western Indochina,Group 2 was from the Kontum and Truong Son in eastern Indochina,and Group 3 has a combined provenance of the Sukhothai,Kontum,and Truong Son.Regional comparisons suggest that the Jurassic provenance was mainly derived from South China,which was imported through the northern river system.Our data,combined with the regional angular unconformities between the Jurassic continental strata and pre-Jurassic marine strata,suggest that the Luang Prabang Basin transformed into a superimposed collisional retroforeland basin during the Jurassic,and the closure of the Luang Prabang BAB occurred before the Late Triassic.
文摘A field and a household survey, the latter of which included inspections and interviews with the residents of a totalof 1370 properties, were conducted in 2004 in 30 villages of the city of Luang Prabang, Lao PDR, in order to assessthe degree of rodent infestation and to identify potential factors influencing infestations. Roof rats, Rattus rattus,and the Polynesian rat, Rattus exulans, were the only rodents found in the city, and trapping results showed a cleardominance of roof rats (80–90% of all individuals). Measurements of rodent activity using tracking patchescorrelated positively with the trapping data, and revealed a significantly higher degree of rat infestation during therainy season (September) than during the dry season (November). If households in the vicinity of the samplinglocations were considered, villagers’ accounts of indoor rodent infestations recorded during the household surveycorrelated positively with measurements of rodent activity. At least every second household reported indoorinfestations. Using explorative statistical analyses (classification trees, factor analysis) we checked the predictiveor explanatory value of up to 28 variables assessed during household inspections for villagers’ observations onrodent infestation as the dependent variable. Trophic factors such as exposed food (indoors) and garbage (outdoors),and structural features such as open ceilings (indoors) and rat harborage in gardens (outdoors) ranked highest asexplanatory variables. Assessment of a small sample of roof rat droppings collected inside houses revealed thepresence of the potential disease agents Salmonella javiana, Cryptosporidium parvum, Giardia duodenalis and theparasitic nematode Calodium hepaticum (syn. Capillaria hepatica). These results underline the need for anappropriate rodent management strategy for the city, whereby simple sanitation and rodent-proofing measurescould be cheap means of reducing rat infestation rates.
基金financially supported by National Institute of Natural Hazards,Ministry of Emergency Management of China(Grant No.ZDJ2019-21)the National Science Foundation of China(Grant No.41472204)。
文摘On May 5, 2014, an earthquake with a magnitude of Mw 6.1(the largest earthquake in Thailand so far) occurred in Chiang Rai of the Golden Triangle area in northern Thailand. We had an opportunity to conduct field survey immediately after the earthquake. Serious damage to buildings and casualties of lives were observed, and the estimated Maximum Mercalli Intensity(MMI) of the earthquake is Ⅷ(evaluated according to the MMI scale of the Chinese Standard). No long continuous ground ruptures were produced during the earthquake, but in the epicenter(commonly within MMI Ⅷ extent), massive small linear ruptures(usually several tens of meters long) developed and displayed intriguing structural features, offsetting many roads several centimeters left laterally on NE trending cracks or offsetting right laterally on NW trending ones. The focal mechanism solution of earthquake shows that this is a pure strike-slip event, and two nodal planes in NW and NE directions had the same motion senses respectively as those of breakage associated with the earthquake. The long axis of the isoseismals and aftershock distributions are in NE direction,which is consistent with the strike of Luang Namtha fault. The 230-km-long Luang Namtha fault which starts from the border of China and Laos, runs through northern Laos, and terminates at Chiang Rai of Thailand is predominated by left-lateral strike-slip and active in late Quaternary, and two earthquakes over Ms 6.0 occurred along the fault in 1925 and 2007 respectively. This Mw 6.1 earthquake occurred at the southwestern end of the fault. All related features such as evident structural rupturing, elongated orientation of MMI and aftershock distribution,as well as the location of the epicenter,suggest that the Luang Namtha fault may be responsible for the 2014 Northern Thailand earthquake.
