scholarly journals “Influences of temperature and the meteoric water δ18O value on a stalagmite record in the last deglacial to middle Holocene period from southwestern Japan”

2021 ◽  
Vol 253 ◽  
pp. 106746
Author(s):  
Hirokazu Kato ◽  
Shota Amekawa ◽  
Masako Hori ◽  
Chaun-Chou Shen ◽  
Yoshihiro Kuwahara ◽  
...  
1991 ◽  
Vol 35 (3-Part1) ◽  
pp. 427-437 ◽  
Author(s):  
W. Geoffrey Spaulding

AbstractPackrat middens from the McCullough Range, in the southeastern Mojave Desert of Nevada, record vegetation conditions during the periods 6800 to 5060 yr B.P. and 1250 yr B.P. to present. Their age and location are ideal to test for middle Holocene aridity; the period between 6800 and 5060 yr B.P. does appear to have been more arid than during the late Holocene period of record. This agrees with other evidence for middle Holocene aridity from the Southwest. Arguments for strengthened middle Holocene monsoons in the region are based chiefly on packrat midden samples older than 7500 yr B.P., or on samples that are younger than 5500 yr B.P. Simulations of 6000 yr B.P. climate that fail to show strong subtropical flow into the Southwest are therefore supported by evidence for enhanced aridity in that region.


2012 ◽  
Vol 8 (5) ◽  
pp. 4357-4399 ◽  
Author(s):  
G. Siani ◽  
M. Magny ◽  
M. Paterne ◽  
M. Debret ◽  
M. Fontugne

Abstract. Holocene paleohydrology reconstruction was derived combining planktic and benthic stable oxygen and carbon isotopes, sea surface temperatures (SSTs) and oxygen isotope composition of seawater (δ18Ow) from a high sedimentation core collected in the south Adriatic sea (SAS). Chronology of core is based on 10 AMS 14C measures on planktic foraminifera and tephra markers. Results reveal two contrasted paleohydrological periods that reflect (i) a marked lowering of δ 18Ow/salinity during the early to middle Holocene (11.5 ka to 6.3 ka), including the two-steps sapropel S1 deposition, followed during the middle to upper Holocene by (ii) a prevailed period of increased salinity and enhanced arid conditions in the south Adriatic basin. Superimposed on these trends, short-term centennial-scale hydrological events punctuated the Holocene period in the SAS. During the Early to Middle Holocene, a short-term SST cooling together with a prominent δ 18Ow/salinity lowering, more pronounced than during the sapropel S1 phase, delineates the sapropel S1 interruption. This short interval, coeval to the 8.2 ka event, is also distinguished by a resumption of deep-water convection in the SAS as indicated by stable isotope reconstruction on benthic forminifera. After 6 ka, centennial-scale δ18Ow and G. bulloides δ13C lowering, mostly centered between 3 to 0.6 ka, reflect short term hydrological changes related to a more intensive Po river runoff. These short-term events, even of lesser amplitude compared to the early to middle Holocene period, may have induced a lowering of sea surface density and consequently reduced and/or inhibited the formation of deep bottom waters in the SAS. Comparison of the emerging centennial to millennial-scale hydrological record with previous climatic records from the central Mediterranean area and north of the Alps revealed possible synchronicities (within the radiocarbon-dating uncertainty) between phases of lower salinity in SAS and periods of wetter climatic conditions around the north-central Adriatic Sea. Finally, wavelet analyses provide new clues about the potential origin of climate variability in the SAS confirming the evidence for a mid-Holocene transition in the Central Mediterranean climate and the dominance of a ~ 1700 yr periodicity after 6 ka that reflects a plausible connection with the North Atlantic climate system.


SPAFA Journal ◽  
2021 ◽  
Vol 5 ◽  
Author(s):  
Suryatman ◽  
◽  
Fakhri ◽  
Budianto Hakim ◽  
Yinika Perston ◽  
...  

Since the recent discovery of Late Pleistocene rock art in Island Southeast Asia was announced, evidence for symbolic behaviour in the region has become a focus of international archaeological interest. South Sulawesi is one region that hold much evidence for this important human activity. In addition to the cave paintings, several engraved stone artefacts have also been recovered in the same area, nearly all of which date back to the Late Pleistocene. However, while cave use by ‘hunter-gatherer’ societies continued into the Holocene period, archaeological evidence for symbolic expression during this Toalean period is extremely rare. Here, we report for the first time on engraved stone artefacts from the Middle Holocene period, associated with six human burials. Of ten incised artefacts recovered, eight are stone flakes and two are stone plaquettes, all made of hematite material. Our study suggests that unlike comparative Pleistocene engraved stones, the incisions on the Cappalombo artefacts are more likely the result of use-wear that occurs from producing red pigment powder than portable artworks. As no Toalean-age cave art has yet been identified, it is suspected that pigment powder was applied to the corpses as part of a burial practice or perhaps smeared on the body of the person/s performing the ceremony itself as part of a symbolic ritualistic activity. Sejak penemuan gambar cadas Pleistosen Akhir terbaru diumumkan di Pulau Asia Tenggara, bukti perilaku simbolis di wilayah tersebut telah menjadi fokus kajian arkeologis internasional. Sulawesi Selatan adalah salah satu wilayah yang menyimpan banyak bukti aktivitas manusia yang penting ini. Selain lukisan gua, beberapa artefak batu berukir juga telah ditemukan di daerah yang sama, hampir semuanya berasal dari Pleistosen Akhir. Namun, ketika penggunaan gua oleh masyarakat 'pemburu-pengumpul' berlanjut hingga periode Holosen, bukti arkeologis untuk ekspresi simbolis selama periode Toalean ini sangat langka. Di sini, kami melaporkan untuk pertama kalinya tentang artefak batu berukir dari periode Holosen Tengah, yang terkait dengan enam penguburan manusia. Dari sepuluh artefak gores yang ditemukan, delapan berupa serpihan batu dan dua berupa plakat batu, semuanya terbuat dari bahan hematit. Studi kami menunjukkan bahwa tidak seperti batu terukir Pleistosen, sayatan pada artefak Cappalombo lebih mungkin hasil dari penggunaan yang terjadi dari memproduksi bubuk pigmen merah daripada karya seni portabel. Karena seni gua periode Toalean belum dapat diidentifikasi, diduga bubuk pigmen dioleskan pada mayat sebagai bagian dari praktik penguburan atau mungkin dioleskan pada tubuh orang yang melakukan upacara itu sendiri sebagai bagian dari aktifitas ritual simbolis.


Author(s):  
Ksenya V. Poleshchuk ◽  
Zinaida V. Pushina ◽  
Sergey R. Verkulich

The diatom analysis results of sediment samples from Dunderbukta area (Wedel Jarlsberg Land, West Svalbard) are presented in this paper. The diatom flora consists of four ecological groups, which ratio indicates three ecological zones. These zones show environmental changes of the area in early–middle Holocene that is demonstrating periods of regression and temperature trends.


2020 ◽  
Vol 11 (1) ◽  
pp. 230
Author(s):  
Hoil Lee ◽  
Jin-Young Lee ◽  
Seungwon Shin

We obtained a 15 m drill core from Deukryang Bay on the southwest coast of Korea, which is now an area of reclaimed land used for agriculture. We investigated changes in the depositional environment and hydrological climate responses to sea level changes using sedimentary facies, radiocarbon ages, grain-size analysis, total organic carbon (TOC), total sulfur (TS), and stable carbon isotopes (δ13C). Sediment deposition began at 12,000 cal yr BP and was divided into four stages based on changes from fluvial to intertidal environments related to Holocene marine transgression events. Stage 1 (>10,000 cal yr BP) is represented by fluvial sediments; Stage 2 (10,000–7080 cal yr BP) is represented by the deposition of mud facies in an intertidal zone in response to sea level rise; Stage 3 (7080–3300 cal yr BP) was a period of gradually descending sea level following the Holocene maximum sea level and is characterized by gradual changes in TOC, TS, and C/S ratios compared with the mud facies of Stage 2. Stage 4 (3300 to present) was deposited in a supratidal zone and contains low TS and an abundance of TOC. Based on our TS and C/S ratio results, the south coast of Korea was mainly affected by sea level rise between 7000 and 3000 cal yr BP, during the middle Holocene. At 3000 cal yr BP, sea level began to stabilize or gradually decrease. In addition, changes in δ13C values are clearly observed since ca. 5000 cal yr BP, in particular, large hydrological changes via freshwater input are confirmed in 4000–3000 cal yr BP. We consider these shifts in freshwater input indicators of an increased influence of El Niño and La Niña conditions, related to the weakening of the East Asian Summer Monsoon (EASM) and changes in sea surface temperature (SST) of the Western Pacific Ocean during the middle Holocene climatic optimum (between 7800 and 5000 cal yr BP). The cooling periods of SST in East Asia between 8400 and 6600 cal yr BP reported from the west coast of Korea are related closely to changes in vegetation (as evidenced by δ13C) from 7700 cal yrs BP to the present in the southwest coast of Korea. We interpret the freshwater input events at 4000–3000 cal yr BP to be related to changes in SST in response to the weakening of the EASM on the southwest coast of Korea. However, additional research is needed to study the southward migration effect of the westerly jet related to SST and atmospheric circulation controlling terrestrial climate in the middle Holocene.


The Holocene ◽  
2021 ◽  
pp. 095968362110332
Author(s):  
Tingli Yan ◽  
Kefu Yu ◽  
Rui Wang ◽  
Wenhui Liu ◽  
Leilei Jiang

Beachrock is considered a good archive for past sea-levels because of its unique formation position (intertidal zone). To evaluate sea-level history in the northern South China Sea, three well-preserved beachrock outcrops (Beigang, Gongshanbei, and Hengling) at Weizhou Island, northern South China Sea were selected to examine their relative elevation, sedimentological, mineralogical, and geochemical characteristics. Acropora branches with well-preserved surface micro-structures were selected from the beachrocks and used to determine the ages of these beachrocks via U-series dating. The results show that the beachrocks are composed of coral reef sediments, terrigenous clastics, volcanic clastics, and various calcite cements. These sediments accumulated in the intertidal zone of Weizhou Island were then cemented in a meteoric water environment. The U-series ages of beachrocks from Beigang, Gongshanbei, and Hengling are 1712–768 ca. BP, 1766–1070 ca. BP, and 1493–604 ca. BP (before 1950 AD) respectively. Their elevations are 0.91–1.16 m, 0.95–1.24 m, and 0.82–1.17 m higher than the modern homologous sedimentary zones, respectively. Therefore, we concluded that the sea-level in the Meghalayan age (1766–604 ca. BP) was 0.82–1.24 m higher than the present, and that the sea-level over this period showed a declining trend.


Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2791
Author(s):  
Pengyan Su ◽  
Mingjun Zhang ◽  
Deye Qu ◽  
Jiaxin Wang ◽  
Yu Zhang ◽  
...  

As a species for ecological restoration in northern China, Tamarix ramosissima plays an important role in river protection, flood control, regional climate regulation, and landscape construction with vegetation. Two sampling sites were selected in the hillside and floodplain habitats along the Lanzhou City, and the xylems of T. ramosissima and potential water sources were collected, respectively. The Bayesian mixture model (MixSIAR) and soil water excess (SW-excess) were applied to analyze the relationship on different water pools and the utilization ratios of T. ramosissima to potential water sources in two habitats. The results showed that the slope and intercept of local meteoric water line (LMWL) in two habitats were smaller compared with the global meteoric water line (GMWL), which indicated the existence of drier climate and strong evaporation in the study area, especially in the hillside habitat. Except for the three months in hillside, the SW-excess of T. ramosissima were negative, which indicated that xylems of T. ramosissima are more depleted in δ2H than the soil water line. In growing seasons, the main water source in hillside habitat was deep soil water (80~150 cm) and the utilization ratio was 63 ± 17% for T. ramosissima, while the main water source in floodplain habitat was shallow soil water (0~30 cm), with a utilization ratio of 42.6 ± 19.2%, and the water sources were different in diverse months. T. ramosissima has a certain adaptation mechanism and water-use strategies in two habitats, and also an altered water uptake pattern in acquiring the more stable water. This study will provide a theoretical basis for plant water management in ecological environment protection in the Loess Plateau.


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