Geochemical and physical investigations such as 13 C isotope ratio, carbon/nitrogen (C/N) ratio, ... more Geochemical and physical investigations such as 13 C isotope ratio, carbon/nitrogen (C/N) ratio, magnetic susceptibility (MS), and particle size analyses were carried out on the estuarine tidal flat sediments from the west coast of Korea in order to reconstruct the East Asian summer monsoon variability during the late Pleistocene and Holocene. Our results indicated that the summer monsoon probably peaked around 7,700-7,800 yr BP and then started to decline about 7,400 yr BP in the Korean peninsular, and that the monsoon was relatively weak between 24,000-24,500 yr BP but relatively strong between 18,500-19,500 yr BP during the Last Glacial Maximum. Our estuarine geochemical data have proven to be valuable as a new proxy for detecting the shifts in monsoon strength. This new evidence will be helpful, especially for Korean paleoenvironmental studies with few proxy data archives.
We analyzed two radiocarbon-dated lagoonal sediment cores from Cheonjinho and Ssangho using vario... more We analyzed two radiocarbon-dated lagoonal sediment cores from Cheonjinho and Ssangho using various biogeochemical methods. As a result, the start times of rice agriculture are estimated to be AD 780 for Cheonjinho and 100 BC for Ssangho. There is a large temporal difference in the beginning of rice agriculture between two study sites even though they are closely located on the coast. This result indicates that pollen records are not sufficient to approximate the start time of rice agriculture accurately. A temporal lag seems to exist between the time when rice agriculture was first introduced and the time when full-scale rice agriculture began in the Yeongdong region, probably because of low agricultural productivity. In both study sites, rice agriculture intensified and slope erosion increased 250 years after full-scale agriculture began. This suggests that intensified rice agriculture resulted in an increased number of inhabitants, settlement expansion to hilly areas, and the consequent deforestation.
The pollen record from Woljeong-ri in southwestern Korea reveals a vegetation history with high t... more The pollen record from Woljeong-ri in southwestern Korea reveals a vegetation history with high temporal resolution over the period from ca. 1950 BC to AD 310. The pollen profile is divided into four phases: zone 1 (ca. 1950e1220 BC), zone 2a (ca. 1220 BCeAD 200), zone 2b (ca. AD 200e290) and zone 2c (ca. AD 290e310). The abundance of Quercus (Lepidobalanus) and Carpinus, and the paucity of Artemisia, Cyperaceae and Poaceae in the initial stage suggest the dominance of deciduous broadleaved forest with little evidence of human interference. The reduction of deciduous broadleaved trees, particularly of Quercus and Alnus, and the abundance of herbaceous plants and cultivated Poaceae indicate increasing anthropogenic disturbance in the surrounding vegetation after ca. 1220 BC, which is probably attributable to agricultural expansion and the construction of rice paddy fields. This change temporally corresponds to the transition from the Neolithic to the Bronze Age across the region. The dominance of cultivated Poaceae continues in the subsequent period, and its amount increases markedly after ca. AD 200, along with the increase of Pinus. This implies that rice agriculture and anthropogenic disturbance on vegetation may have intensified at least a century earlier than the presumed emergence of state-level societies. The decline in rice agriculture, which is possibly related to the advent of drier climatic conditions, is suggested in the current pollen record after ca. AD 290.
a b s t r a c t Millennial-and centennial-scale climate and vegetation changes during the last de... more a b s t r a c t Millennial-and centennial-scale climate and vegetation changes during the last deglaciation from Hanon Maar paleolake on Jeju Island, South Korea were reconstructed by high-resolution multi-proxy data (pollen, Anhysteretic Remanent Magnetization [ARM], Total Organic Carbon [TOC], Total Nitrogen [TN], Carbon/Nitrogen [C/N] ratio, carbon and nitrogen isotope compositions (d 15 N and d 13 C), major element
Orbital-and millennial-scale climate and vegetation changes between 32.5 and 6.9k cal a BP from H... more Orbital-and millennial-scale climate and vegetation changes between 32.5 and 6.9k cal a BP from Hanon Maar paleolake on Jeju Island, Korea, were demonstrated by high-resolution multi-proxy data (pollen, magnetic susceptibility, total organic carbon, carbon/nitrogen ratios and sediment grain size). High-resolution pollen records provided detailed information on the vegetation response to climate change. The Thalictrum pollen percentage, which corresponded to the magnetic susceptibility data, and the first principal component of principalcomponent analysis of pollen data were good indicators of the orbital-and millennial-scale dry/wet cycle in the study area. Hanon pollen and magnetic susceptibility records suggested that colder and drier conditions were prevalent between 25.2 and 17.6k cal a BP in the study area due to a precession-induced decrease in summer insolation. Hanon multi-proxy data were correlated with oxygen isotope records from Greenland and Hulu cave, suggesting the possible teleconnection of millennial-scale climate oscillations between North Atlantic and East Asian regions. According to our results, Heinrich-like cold events probably occurred around 31.1, 25.2 and 16.7k cal a BP, and the warm intervals observed around 30.7 and 29.9k cal a BP may have corresponded to Dansgaard-Oeschger warm events 4 and 3, respectively.
An overview is presented of the analysis of wood remains at 11 archaeological sites in the southw... more An overview is presented of the analysis of wood remains at 11 archaeological sites in the southwestern region of the Korean Peninsula, and the results are used to shed light on the changes in wood-resource selection around the villages over the periods of c. 1500-300 bc and ad 1-700. Pollen research on swamps of the region has previously revealed that oak (Quercus), alder (Alnus), and pine (Pinus) were the major woodland components, and that pine became increasingly prevalent after c. 1500 bc under the influence of agricultural expansion and climatic changes. Agricultural activities are represented by the dominance of grasses (Poaceae) in the pollen records. The wood collection underwent changes over time but not in direct response to the regional vegetation change. Wood was not randomly collected during the Mumun Period (c. 1500-300 bc), with oak being preferentially selected despite the increasing dominance of pine. Chestnut tree (Castanea crenata Siebold & Zucc.) was routinely used during and after the Proto-Three-Kingdoms Period (c. ad 1-300) and was used almost exclusively at some sites. Such abundance suggests that the site occupants managed the neighboring forests and promoted the propagation of chestnut trees. Pinewood rarely appears in the retrieved samples, which suggests that the versatile use of pinewood is a relatively recent tradition in the Holocene history.
This paper presents multiproxy (pollen, magnetic susceptibility, sediment chemistry) records from... more This paper presents multiproxy (pollen, magnetic susceptibility, sediment chemistry) records from two maar crater lakes in the Valle de Santiago of Guanajuato, Mexico: Hoya San Nicolá s and Hoya Rincon de Parangueo. Sediment cores from the two sites have basal dates of ca 11,600 and 9600 cal yr BP, respectively. The San Nicolá s results show that the lake desiccated several times during the Holocene, and this resulted in the selective destruction of the less resistant pollen types. A comparative analysis of data from both sites indicates that during the earliest Holocene (ca 11,600-9000 cal yr BP) there were short term oscillations of wetter and drier climate; during the early Holocene (ca 9000-5700 cal yr BP) it was on average wetter; during the middle Holocene (ca 5700-3800 cal yr BP) drier; and during the middle to late Holocene (ca 3800-2200 cal yr BP) wetter. Increasing human disturbance during the late Holocene of environment obscures the climatic record. Agricultural activities in the area began as early as ca 5700 cal yr BP and intensified around 2400 cal yr BP.
We present a record of Holocene environmental change on the east coast of Korea, inferred using p... more We present a record of Holocene environmental change on the east coast of Korea, inferred using pollen, carbon-isotopic composition (d 13 C), total organic carbon, total sulfur, carbon/nitrogen ratios, particle size analysis and major element geochemistry in a sediment core from Soonpogae Lagoon. A multiproxy paleoenvironmental approach had not previously been applied in Korea and allowed us to reconstruct climate and vegetation change, sea-level rise, lagoon development, and human impact on the east coast of Korea over the last 8,000 years. Evidence from Soonpogae Lagoon supports the following three conclusions: (1) As a drying trend prevailed on the east coast of Korea after *5,900 cal yr BP, chemical weathering weakened and herbaceous plants became more important than during the previous humid phase (Holocene Climate Optimum), (2) Sea-level rise on the east coast slowed dramatically about 6,800 cal yr BP, resulting in low rates of sedimentation in Soonpogae Lagoon, and (3) Soonpogae Lagoon was almost completely isolated from the sea by sand barriers when human impact intensified *2,100 BP.
Three up to 520-cm-long sediment cores from Hoya San Nicolas in Guanajuato, Mexico, were analysed... more Three up to 520-cm-long sediment cores from Hoya San Nicolas in Guanajuato, Mexico, were analysed for various magnetic properties in order to better define a palaeomagnetic secular curve for Central Mexico. The results-magnetic susceptibility, hysteresis cycles, anhysteretic and isothermal remanent magnetization-suggest that the remanent magnetization of the sediments is controlled by ferrimagnetic minerals (pseudo-single domain magnetite), which are suitable recorders of the geomagnetic field. The age-depth model indicates average deposition rates of 0.32 (interval 146-198 cm) and 0.45 mm yr −1 (interval 200-520 cm) and a basal age of about 11 600 calibrated years BP (cal. yr BP).
We present varve chronologies for sediments from two maar lakes in the Valle de Santiago region (... more We present varve chronologies for sediments from two maar lakes in the Valle de Santiago region (Central Mexico): Hoya La Alberca (AD 1852(AD -1973 and Hoya Rincón de Parangueo (AD 1839(AD -1943. These are the first varve chronologies for Mexican lakes. The varved sections were anchored with tephras from Colima (1913) and Paricutín (1943Paricutín ( /1944 and 210Pb ages. We compare the sequences using the thickness of seasonal laminae and element counts (Al, Si, S, Cl, K, Ti, Mn, Fe, and Sr) determined by micro X-ray fluorescence spectrometry. The formation of the varve sublaminae is attributed to the strongly seasonal climate regime. Limited rainfall and high evaporation rates in winter and spring induce precipitation of carbonates (high Ca, Sr) enriched in 13C and 18O, whereas rainfall in summer increases organic and clastic input (plagioclase, quartz) with high counts of lithogenic elements (K, Al, Ti, and Si). Eolian input of Ti occurs also in the dry season. Moving correlations (5-yr windows) of the Ca and Ti counts show similar development in both sequences until the 1930s. Positive correlations indicate mixing of allochthonous Ti and autochthonous Ca, while negative correlations indicate their separation in sublaminae. Negative excursions in the correlations correspond with historic and reconstructed droughts, El Niño events, and positive SST anomalies. Based on our data, droughts (3-7 year duration) were severe and centred around the following years: the early 1850s, 1865, 1880, 1895, 1905, 1915 and the late 1920s with continuation into the 1930s. The latter dry period brought both lake systems into a critical state making them susceptible to further drying. Groundwater overexploitation due to the expansion of irrigation agriculture in the region after 1940 induced the transition from calcite to aragonite precipitation in Alberca and halite infiltration in Rincón. The proxy data indicate a faster response to increased evaporation for Rincón, the lake with the larger maar dimensions, solar radiation receipt and higher conductivity, whereas the smaller, steeper Alberca maar responded rapidly to increased precipitation.
Geochemical and physical investigations such as 13 C isotope ratio, carbon/nitrogen (C/N) ratio, ... more Geochemical and physical investigations such as 13 C isotope ratio, carbon/nitrogen (C/N) ratio, magnetic susceptibility (MS), and particle size analyses were carried out on the estuarine tidal flat sediments from the west coast of Korea in order to reconstruct the East Asian summer monsoon variability during the late Pleistocene and Holocene. Our results indicated that the summer monsoon probably peaked around 7,700-7,800 yr BP and then started to decline about 7,400 yr BP in the Korean peninsular, and that the monsoon was relatively weak between 24,000-24,500 yr BP but relatively strong between 18,500-19,500 yr BP during the Last Glacial Maximum. Our estuarine geochemical data have proven to be valuable as a new proxy for detecting the shifts in monsoon strength. This new evidence will be helpful, especially for Korean paleoenvironmental studies with few proxy data archives.
We analyzed two radiocarbon-dated lagoonal sediment cores from Cheonjinho and Ssangho using vario... more We analyzed two radiocarbon-dated lagoonal sediment cores from Cheonjinho and Ssangho using various biogeochemical methods. As a result, the start times of rice agriculture are estimated to be AD 780 for Cheonjinho and 100 BC for Ssangho. There is a large temporal difference in the beginning of rice agriculture between two study sites even though they are closely located on the coast. This result indicates that pollen records are not sufficient to approximate the start time of rice agriculture accurately. A temporal lag seems to exist between the time when rice agriculture was first introduced and the time when full-scale rice agriculture began in the Yeongdong region, probably because of low agricultural productivity. In both study sites, rice agriculture intensified and slope erosion increased 250 years after full-scale agriculture began. This suggests that intensified rice agriculture resulted in an increased number of inhabitants, settlement expansion to hilly areas, and the consequent deforestation.
The pollen record from Woljeong-ri in southwestern Korea reveals a vegetation history with high t... more The pollen record from Woljeong-ri in southwestern Korea reveals a vegetation history with high temporal resolution over the period from ca. 1950 BC to AD 310. The pollen profile is divided into four phases: zone 1 (ca. 1950e1220 BC), zone 2a (ca. 1220 BCeAD 200), zone 2b (ca. AD 200e290) and zone 2c (ca. AD 290e310). The abundance of Quercus (Lepidobalanus) and Carpinus, and the paucity of Artemisia, Cyperaceae and Poaceae in the initial stage suggest the dominance of deciduous broadleaved forest with little evidence of human interference. The reduction of deciduous broadleaved trees, particularly of Quercus and Alnus, and the abundance of herbaceous plants and cultivated Poaceae indicate increasing anthropogenic disturbance in the surrounding vegetation after ca. 1220 BC, which is probably attributable to agricultural expansion and the construction of rice paddy fields. This change temporally corresponds to the transition from the Neolithic to the Bronze Age across the region. The dominance of cultivated Poaceae continues in the subsequent period, and its amount increases markedly after ca. AD 200, along with the increase of Pinus. This implies that rice agriculture and anthropogenic disturbance on vegetation may have intensified at least a century earlier than the presumed emergence of state-level societies. The decline in rice agriculture, which is possibly related to the advent of drier climatic conditions, is suggested in the current pollen record after ca. AD 290.
a b s t r a c t Millennial-and centennial-scale climate and vegetation changes during the last de... more a b s t r a c t Millennial-and centennial-scale climate and vegetation changes during the last deglaciation from Hanon Maar paleolake on Jeju Island, South Korea were reconstructed by high-resolution multi-proxy data (pollen, Anhysteretic Remanent Magnetization [ARM], Total Organic Carbon [TOC], Total Nitrogen [TN], Carbon/Nitrogen [C/N] ratio, carbon and nitrogen isotope compositions (d 15 N and d 13 C), major element
Orbital-and millennial-scale climate and vegetation changes between 32.5 and 6.9k cal a BP from H... more Orbital-and millennial-scale climate and vegetation changes between 32.5 and 6.9k cal a BP from Hanon Maar paleolake on Jeju Island, Korea, were demonstrated by high-resolution multi-proxy data (pollen, magnetic susceptibility, total organic carbon, carbon/nitrogen ratios and sediment grain size). High-resolution pollen records provided detailed information on the vegetation response to climate change. The Thalictrum pollen percentage, which corresponded to the magnetic susceptibility data, and the first principal component of principalcomponent analysis of pollen data were good indicators of the orbital-and millennial-scale dry/wet cycle in the study area. Hanon pollen and magnetic susceptibility records suggested that colder and drier conditions were prevalent between 25.2 and 17.6k cal a BP in the study area due to a precession-induced decrease in summer insolation. Hanon multi-proxy data were correlated with oxygen isotope records from Greenland and Hulu cave, suggesting the possible teleconnection of millennial-scale climate oscillations between North Atlantic and East Asian regions. According to our results, Heinrich-like cold events probably occurred around 31.1, 25.2 and 16.7k cal a BP, and the warm intervals observed around 30.7 and 29.9k cal a BP may have corresponded to Dansgaard-Oeschger warm events 4 and 3, respectively.
An overview is presented of the analysis of wood remains at 11 archaeological sites in the southw... more An overview is presented of the analysis of wood remains at 11 archaeological sites in the southwestern region of the Korean Peninsula, and the results are used to shed light on the changes in wood-resource selection around the villages over the periods of c. 1500-300 bc and ad 1-700. Pollen research on swamps of the region has previously revealed that oak (Quercus), alder (Alnus), and pine (Pinus) were the major woodland components, and that pine became increasingly prevalent after c. 1500 bc under the influence of agricultural expansion and climatic changes. Agricultural activities are represented by the dominance of grasses (Poaceae) in the pollen records. The wood collection underwent changes over time but not in direct response to the regional vegetation change. Wood was not randomly collected during the Mumun Period (c. 1500-300 bc), with oak being preferentially selected despite the increasing dominance of pine. Chestnut tree (Castanea crenata Siebold & Zucc.) was routinely used during and after the Proto-Three-Kingdoms Period (c. ad 1-300) and was used almost exclusively at some sites. Such abundance suggests that the site occupants managed the neighboring forests and promoted the propagation of chestnut trees. Pinewood rarely appears in the retrieved samples, which suggests that the versatile use of pinewood is a relatively recent tradition in the Holocene history.
This paper presents multiproxy (pollen, magnetic susceptibility, sediment chemistry) records from... more This paper presents multiproxy (pollen, magnetic susceptibility, sediment chemistry) records from two maar crater lakes in the Valle de Santiago of Guanajuato, Mexico: Hoya San Nicolá s and Hoya Rincon de Parangueo. Sediment cores from the two sites have basal dates of ca 11,600 and 9600 cal yr BP, respectively. The San Nicolá s results show that the lake desiccated several times during the Holocene, and this resulted in the selective destruction of the less resistant pollen types. A comparative analysis of data from both sites indicates that during the earliest Holocene (ca 11,600-9000 cal yr BP) there were short term oscillations of wetter and drier climate; during the early Holocene (ca 9000-5700 cal yr BP) it was on average wetter; during the middle Holocene (ca 5700-3800 cal yr BP) drier; and during the middle to late Holocene (ca 3800-2200 cal yr BP) wetter. Increasing human disturbance during the late Holocene of environment obscures the climatic record. Agricultural activities in the area began as early as ca 5700 cal yr BP and intensified around 2400 cal yr BP.
We present a record of Holocene environmental change on the east coast of Korea, inferred using p... more We present a record of Holocene environmental change on the east coast of Korea, inferred using pollen, carbon-isotopic composition (d 13 C), total organic carbon, total sulfur, carbon/nitrogen ratios, particle size analysis and major element geochemistry in a sediment core from Soonpogae Lagoon. A multiproxy paleoenvironmental approach had not previously been applied in Korea and allowed us to reconstruct climate and vegetation change, sea-level rise, lagoon development, and human impact on the east coast of Korea over the last 8,000 years. Evidence from Soonpogae Lagoon supports the following three conclusions: (1) As a drying trend prevailed on the east coast of Korea after *5,900 cal yr BP, chemical weathering weakened and herbaceous plants became more important than during the previous humid phase (Holocene Climate Optimum), (2) Sea-level rise on the east coast slowed dramatically about 6,800 cal yr BP, resulting in low rates of sedimentation in Soonpogae Lagoon, and (3) Soonpogae Lagoon was almost completely isolated from the sea by sand barriers when human impact intensified *2,100 BP.
Three up to 520-cm-long sediment cores from Hoya San Nicolas in Guanajuato, Mexico, were analysed... more Three up to 520-cm-long sediment cores from Hoya San Nicolas in Guanajuato, Mexico, were analysed for various magnetic properties in order to better define a palaeomagnetic secular curve for Central Mexico. The results-magnetic susceptibility, hysteresis cycles, anhysteretic and isothermal remanent magnetization-suggest that the remanent magnetization of the sediments is controlled by ferrimagnetic minerals (pseudo-single domain magnetite), which are suitable recorders of the geomagnetic field. The age-depth model indicates average deposition rates of 0.32 (interval 146-198 cm) and 0.45 mm yr −1 (interval 200-520 cm) and a basal age of about 11 600 calibrated years BP (cal. yr BP).
We present varve chronologies for sediments from two maar lakes in the Valle de Santiago region (... more We present varve chronologies for sediments from two maar lakes in the Valle de Santiago region (Central Mexico): Hoya La Alberca (AD 1852(AD -1973 and Hoya Rincón de Parangueo (AD 1839(AD -1943. These are the first varve chronologies for Mexican lakes. The varved sections were anchored with tephras from Colima (1913) and Paricutín (1943Paricutín ( /1944 and 210Pb ages. We compare the sequences using the thickness of seasonal laminae and element counts (Al, Si, S, Cl, K, Ti, Mn, Fe, and Sr) determined by micro X-ray fluorescence spectrometry. The formation of the varve sublaminae is attributed to the strongly seasonal climate regime. Limited rainfall and high evaporation rates in winter and spring induce precipitation of carbonates (high Ca, Sr) enriched in 13C and 18O, whereas rainfall in summer increases organic and clastic input (plagioclase, quartz) with high counts of lithogenic elements (K, Al, Ti, and Si). Eolian input of Ti occurs also in the dry season. Moving correlations (5-yr windows) of the Ca and Ti counts show similar development in both sequences until the 1930s. Positive correlations indicate mixing of allochthonous Ti and autochthonous Ca, while negative correlations indicate their separation in sublaminae. Negative excursions in the correlations correspond with historic and reconstructed droughts, El Niño events, and positive SST anomalies. Based on our data, droughts (3-7 year duration) were severe and centred around the following years: the early 1850s, 1865, 1880, 1895, 1905, 1915 and the late 1920s with continuation into the 1930s. The latter dry period brought both lake systems into a critical state making them susceptible to further drying. Groundwater overexploitation due to the expansion of irrigation agriculture in the region after 1940 induced the transition from calcite to aragonite precipitation in Alberca and halite infiltration in Rincón. The proxy data indicate a faster response to increased evaporation for Rincón, the lake with the larger maar dimensions, solar radiation receipt and higher conductivity, whereas the smaller, steeper Alberca maar responded rapidly to increased precipitation.
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Papers by Jungjae Park