심 해 퇴 적 물 고 기 후 지 시 자 를 이 용 한 북 태평양순환류 변동성 연구

해양 퇴적물의 고기후 지표를 이용한 북태평양 해양 순환 변동성에 관한 연구. 또한, 현생 플랑크톤 유공충 종의 구성에 관한 연구와 비교하면, 동태평양 적도 해역은 상대적으로 차갑고, LGM부터 홀로세까지 용승이 활발했고, 이후 홀로세 동안 따뜻해졌다.

탐사지역

탐사장비

심해저에서 긴 퇴적물 시료를 보다 간단하고 효율적으로 수집하여 고해양 환경의 특성을 이해하는 것이 가능합니다. 수분함량이 높은 표층퇴적물을 교란하지 않고 잘 보존된 상태로 수집할 수 있는 장치로 1회에 8개의 코어를 사용할 수 있다.

탐사내용

트리거 해제 메커니즘: 철판, 암. 6) 다중 코어. 라이너 접합부 15cm 분리, 교란 없는 부표본 수집, 별도 보관, 지자기 시료.

Table 2-2. NPG1301-1 주상시료 채취정점 위치 , 심도 및 주상시료 길이

초록

서론

그러나 퇴적물 공급의 급격한 변화(화산재 흐름 등)로 인해 지자기장 정보를 기록하는 자성광물에 큰 변화가 있는 경우에는 연대측정이 불가능하다. 즉, 지자기장의 세기 변화는 퇴적층의 연대뿐만 아니라 기후변화에 관한 중요한 정보를 제공한다.

시료 및 연구방법

지자기장 방향 변화 기록을 추출한 후 시료에 인공자기장을 인가하여 무이력잔류자화(ARM) 및 등온잔류자화(IRM) 검색 실험을 수행하였다. 또한, 포화 등온 잔류 자화 값(포화 IRM, SIRM)은 시료에 1 T의 강한 DC 자기장을 인가한 후 측정한 값을 사용하였다.

Fig. 3-1. Sediment core locations recovered by a piston corer.

결과 및 토의

지자기 역전 (geomagnetic reversal) 을 이용한 연대측정
지자기 회유 (geomagnetic excursion) 를 이용한 연대측정
지자기 강도 (paleomagnetic intensity) 를 이용한 연대측정
대자율 (magnetic susceptibility) 을 이용한 연대측정

경사각의 변화가 경사각의 변화보다 더 두드러지며 약 370cm 깊이까지 양성자극이 유지되고 그 후 Maturama chron에 해당하는 역자극이 약 500cm까지 나타난다. 잔류 자화 성분의 이러한 부분적 오염은 자극이 안정화됨에 따라 점진적으로 제거됩니다(방향 대칭으로 MAD 값 감소).

Fig. 3-2. Down core variation of paleomagnetic directions in NPGP1301-3A and correlation with the reference geomagnetic polarity time scale (GPTS).

결론

참고문헌

Kim, Flux and grain size 23 variation of eolian dust as a proxy tool for the paleoposition of the Intertropical Convergence Zone in the northeast Pacific. Lee, Magnetic evaluation of sediment provenance in the northern East China Sea using fuzzy c-means.

서론

또한, 엘니뇨 기간 동안 서풍의 강화로 인해 쿠로시오 해류가 남쪽으로 이동하고, 라니냐 기간 동안 쿠로시오 해류가 북쪽으로 이동하는 변화는 적도 해역과 북태평양 해류 면적 사이의 먼 상관관계를 나타냅니다. 야마모토 등, 2005). 따라서 본 연구에서는 중앙태평양 적도 지역과 북서태평양 지역에서 생산되는 폐렴구균 유공충을 이용하여 LGM 이후의 고해양 환경을 재구성하고, 두 지역 간의 시기별 기후 상관관계를 규명하는 것을 목적으로 한다.

연구지역

쿠로시오 확장역

쿠로시오 해류와 오야시오 해류가 만나는 천이대에서는 수온과 염도가 수직으로 변합니다. Kuroshio와 Oyashio가 북위 35°에서 만나는 천이대에서 G.

Table 4-1. Details of core samples collected in Kuroshio Extension area and Central Equatorial Pacific area.

중앙태평양 적도해역

연구방법

시료채취 및 처리
유공충 군집해석
탄산염 용해지수 분석
표층 수온 복원

저서 유공충의 비율은 저서 유공충이 플랑크톤 유공충에 비해 상대적으로 분해에 저항한다는 사실에만 근거합니다. 따라서 저서성 유공충 비율이 용해에 미치는 영향을 정확히 이해할 필요가 있다.

Table 4-2. Several indices estimating degree of calcium carbonate dissolution of planktic foraminifera.

결과

부유성 유공충 군집

쿠로시오 확장역
중앙태평양 적도해역

반면, G.는 중앙태평양 적도해역에 가장 많이 서식하는 종이다. G.

Table 4-4. List of planktic foraminifera obtained from NPGM/P 1302-1B and MC 090301. Foraminifera species of each core are listed in the order of abundaces

탄산염의 용해가 종조성 변화에 미치는 영향성

탄산수 쿠로시오 확장지역에 서식하는 일종의 플랑크톤 유공충이다. 그러나 LGM 이후 지금까지 F의 용해율은 높았으나 foraminifera G에서는 용해율이 높았습니다.

Fig. 4-6. Comparison of CaCO 3 (a), CSF (b), B (c), and FDX/Res (d) with fragmentation (F LS ) in NPGM/P1302-1B core

토의

표층 수온 변화

장주기 온도변화
단주기 온도변화

단기적인 기온변화에도 불구하고 쿠로시오 확장지역과 중앙태평양 적도지역에서는 반대되는 기온변화가 나타난다(그림 4-8). 첫 번째는 적도수렴대 북쪽과 남쪽을 따라 난수대의 위치 변화이다.

Fig. 4-8. Variation of sea surface temperature since LGM in the study areas based on warm water species (Rögl and Bolli, 1973) and SST (Berger, 1969).

결론

참고문헌

Maximum: Results from a coupled atmosphere-ocean general circulation model. and Corselli, C., 2004, Late Quaternary Planctonic Foraminiferal Distributions: Problems Related to Size Fraction. ed.), Proceedings of the First Italian Meeting on Environmental Micropaleontology, Grzybowski Foundation Special Publication, pp. Proceedings of the Ocean Drilling Program: Scientific results, The Program, p. and Röhl, U., 2001, Southward Migration of the Intertropical Convergence Zone through the Holocene.

국문 요약

Abstract

The results of this study contradict the prevailing view that direct dust transport by the spring EAWM winds dominates the annual stream of aeolian dust in the Northwest Pacific.

Introduction

Thus, the relative contribution of these potential sources warrants further investigation using multiple source indicators [e.g. Ferrat et al., 2011]. Zhang et al., 1999], it is possible that the contribution of potential dust sources and transport mechanisms has changed over longer periods of time.

Fig. 5-1. Location of core PC 631 (solid gray circle, this study) and aerosol samples (open diamonds) collected during the Moana Wave cruise [Arnold et al., 1998], ADIOS cruise [Arnold et al., 1998], and a series of Deep Sea Drilling Project cruises (L ser

Materials and Methods

They were then treated with a hot solution of sodium citrate-sodium dithionite buffered with sodium bicarbonate to remove ferromanganese oxides and hydroxides. The solid residue was then sieved at 63 μm to remove coarse biogenic components and finally treated with Na2CO3 solution to remove biogenic silica.

Fig. 5-2. Locations of possible dust source regions (i.e., Chinese deserts, Luzon Island, and the Mariana Islands) and their reported ε Nd compositions [Chen et al., 2007; Defant et al., 1990; Dixon and Stern, 1983; Honda et al., 2004; Nakano et al.,2004;

Results

For consistency, the clay mineral compositions of aerosol and sediments have been reported by Arnold et al. Down-core variations in (a) stable oxygen isotope composition of benthic foraminifera in the LR04 stack and PC 631, (b) radiogenic isotope compositions (87Sr/86Sr and εNd ), and (c) clay mineral composition of the <4 μm fraction of aeolian dust.

Fig. 5-3. Down-core variations in (a) stable oxygen isotope composition of benthic foraminifera in the LR04 stack and PC 631, (b) radiogenic isotopic compositions ( 87 Sr/ 86 Sr and ε Nd ), and (c) clay mineral composition of the <4 μ m fraction of eoli

Discussion

Dust from EAD and CAD have distinct values of illite/kaolinite (I/K) and kaolinite/chlorite (K/C) (Figs. 5-6) [Shen et al., 2005], which enables an assessment of the relative contribution of these two major Asian dust source regions in the dust budget of the study area. Dust from CADs is thought to travel to the study site via the prevailing westerly winds, and then via the northeast trade winds, as depicted in the dust transport trajectories in Fig.

Fig. 5-4. (a) 87 Sr/ 86 Sr versus ε Nd arrays of dust samples measured in this study with a compilation of sediment samples from literature [Grousset et al., 1998; Hyeong et al., 2011; Nakai et al., 1993; Pettke et al., 2000;

Conclusions

Nishimura (1995), Asian Continental Nature of 87Sr/86Sr Ratios in North Central Pacific Sediments, Earth and. 1965), Mineralogy and Sedimentation of Recent Deep-Sea Clays of the Atlantic and Adjacent Seas and Oceans, Geological Society of. Wang (1997), Origin and significance of clay minerals in the last Mesozoic loess of the Lanzhou area, north-central China, Marine Geology and Quaternary Geology.

국문요약

6장 중기 홍적세 전환기 동안 적도 수렴대의 위치 변화로 인한 적도 중앙 태평양의 대기 및 해양 순환의 변화.

Abstract

These changes can be explained by the southward movement of the Intertropical Convergence Zone (ITCZ) and the North Equatorial Countercurrent (NECC) and the direct influence of these features on the country after 0.8 Ma. Our results, together with previously published Atlantic data, suggest a northward position of the ITCZ between 1.1 and 0.9 Ma, and a southward position thereafter.

Introduction

Because this cooling was recorded in both the equatorial Atlantic and Pacific Oceans, it can be seen as one of the most important tropical responses to climate forcing during the MPT. -2(a) Map of surface currents, surface winds and mean positions of the seasonal ITCZ over the tropical Pacific.

Fig. 6-1. Long-term trends in paleoceanographic and paleoclimatic proxies during the middle to late Pleistocene

Study Site and Analytical Methods

The radiogenic isotope composition of the aeolian dust fraction in the studied samples was measured to investigate its source region. MAR is the product of the linear sedimentation rate (LSR) and the dry bulk density (DBD) of the sample.

Results

To understand temporal changes in local hydrology of the study site, stable oxygen isotope compositions (δ18O) of the planktic foraminifera Globigerinoides sacculifer (without definitive sac) in the 250-355 µm size fraction were determined using a Finnigan MAT 251 mass spectrometer at the University of Michigan at Ann Arbor , USA. The relative content of each component to the bulk sediment was further converted to the mass accumulation rate (MAR) for the more accurate estimation of the influx of each component.

Fig. 6-3. (a) Geomagnetic chrons used to define depositional age, (b) Stable oxygen isotope composition ( δ 18O) of planktic foraminifera G

Discussion

The predominance of SH dust at the study site prior to 0.8 Ma suggests that the ITCZ was north of the study site at that time. Accordingly, the observed changes in the source signal can best be explained by a southward migration of the southern boundary of the ITCZ to the study site at 0.8 Ma.

Conclusions

This proposed cooling history supports the suggestion that the NH ice sheet has significantly expanded and stabilized since 0.9 Ma [ Clark et al ., 2006 ; Clark and Pollard, 1998; Hernández-Almeida et al., 2012;.

Gibbard (2005), Early-Middle Pleistocene Transitions: a review and recommendation for the defining boundary, in Early-Middle Pleistocene Transitions: The Land-Ocean Evidence, edited by M. 1-18, The Geological Society of London, London, UK . 1995), Late Cenozoic Atmospheric Circulation Intensity and Climatic History Recorded by Aeolian Deposition in the Eastern Equatorial Pacific Ocean, Leg 138Rep., 615-625 pp, Ocean Drilling Program, College Station, TX. Hathorne (2014), Nd and Sr isotope compositions of different phases of surface sediments in the South Pacific: seawater signature extraction, boundary exchange, and detrital/dust origin, Geochemistry, Geophysics, Geosystems doi GC005443.

국문요약

Abstract

In contrast, those for the upper thermocline were increased as high as 3°C during the last deglaciation period between 18 and 12 ka and have declined and maintained at present levels since 12 ka. This suggests a possibility that the study site, now under the control of the ITCZ-North Equatorial Countercurrent, had been located north of the ITCZ and under the direct influence of the northeast trade winds and the NEC during the last deglaciation period.

Introduction

The central equatorial Pacific Ocean near the International Date Line is currently characterized by the ITCZ's narrowest seasonal migration belt. This study reports high-resolution proxy data for the first time for the last 23 kyrs in the central equatorial Pacific region and also addresses the displacement of the ITCZ during the last deglaciation period and the consequent response of the upper water column in the.

Study Site and Analytical Methods

Southeasterly trade winds cause upwelling and bring nutrients to the surface at the equator, resulting in higher primary production than in the WPWP and NECC regions [ Eldin and Rodier , 2003 ; Le Bouteiller et al., 2003]. According to the depth habitats of these three species assessed in the WPWP region by Sagawa et al.

Results

Mg/Ca ratios were determined using an inductively coupled plasma optical emission spectrophotometer (ICP-OES) (Perkin-Elmer Optima 3300 DV) at the Korean Institute of Ocean Science and Technology, Ansan, Korea. For Mg/Ca measurements, 20–30 monospecific tests were crushed and homogenized, and then cleaned with methanol (removal of clay), NaOH-buffered hydrogen peroxide (removal of organic matter), and a weak acid (removal of of high-Mg calcite) after Barker et al.

Discussion

Simultaneous increases in SSTs are also reported in the upwelling areas of the East Equatorial Pacific (EEP) [Koutavas et al., 2002;. The early warming of SH high latitudes relative to its NH counterpart [see Denton et al., 2010 and references therein].

Fig. 7-2. Analytical results of foraminiferal (a) δ 18 O and (b) Mg/Ca compositions of three foraminifera species, and (c) Mg/Ca-derived calcification temperatures converted using equations provided in Sadekov et al

Conclusions

This interpretation leads to the conclusion that the ITCZ was south of the study site during the last deglaciation and that the study site was influenced by the northeasterly trade winds prevailing north of the ITCZ.

Gagan (2002), Seasonal change in foraminiferal production in the western equatorial Pacific warm pool:. evidence from sediment trapping experiments, Deep Sea Research Part II:. Kuwae (2012), Shoaling of the western equatorial Pacific thermocline during the last glacial maximum inferred from multispecies temperature reconstruction of planktonic foraminifera, Paleogeography, Paleoclimatology, Paleoecology doi:10.1016/j.palaeo.

국문요약

Abstract

It was proposed that the increase in alkenone-derived SSTs during the early Pleistocene would be influenced by the 23kyr period of precession (orbital precession).

Introduction

These factors create discrepancies between export and sedimentary siliceous fluxes on a global scale (Nelson et al., 1995). The resistance to degradation and good retention of algal biomarkers in sediments has long been used to assess the sources of ocean phytoplankton biomass (Volkman et al., 1998).

Geochemical background of proxies

Sediment traps have been shown to have good correlation between organic carbon fluxes and carbonate flux under certain conditions (Ruhlemann et al., 1996). The distribution of long-chain diols is basically controlled by temperature, salinity and nutrient concentrations in aquatic environments (Versteegh et al., 2001;

Geographical and geological settings

The SST distribution exhibits a dominant equatorial cold tongue centered along ∼1ºS and a strong frontal zone extending from the equator to ∼5ºN, almost always present with a strength that varies both seasonally and on an interannual time scale (Wallace et al., 1989). The interannual variability in this region is dominated by the El Niño/Southern Oscillation (ENSO) phenomenon which is clearly defined during the cold season (Wallace et al., 1989).

Materials and methods

Surface water conditions in the equatorial Pacific Ocean are characterized by strong E-W gradients in SST (~6 ºC and thermocline depth (~50 m) in the eastern equatorial Pacific Ocean, with a thermocline and nutricline generally closely associated in a tropical system) (Cane, 2005; Turk et al., 2001; Bolton et al., 2010b) Annual mean SST data from the 2013 World Ocean Atlas are shown as gray outlines [Boyer et al., 2013].

Fig. 8-1. (a) Map of surface currents, surface winds and mean positions of the seasonal ITCZ over the tropical Pacific

Results and Discussion

CaCO 3 and biogenic silica as a proxy for lysocline fluctuation
Stable carbon isotope ( δ 13 C)andoxygenisotope( δ 18O)offoraminifera
Lipid biomarker: phytoplankton productivity and community structure
High latitude influence on oceanography of the equatorial Pacific

Shown in (Fig. 8-3a, Fig. 8-3b), the opal MAR and CaCO3 MAR data appear to have a similar profile during the early Pleistocene. The diol index record from PC 932 showed a distinct trend; values were low in the early Pleistocene and increased at the Matuyama-Brunhes boundary (Figs. 8-9d).