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서북극 척치해의 제4기 후기 해양퇴적층에 대한 퇴적환경 연구

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Alternative Title
Depositional Environment of the Late Quaternary Sediments in the Chukchi Sea, West Arctic
Abstract
In the Arctic Ocean, sediments are deposited by various sedimentary
processes including hemipelagic settling, mass-flow, meltwater plume, iceberg,
and bottom current. Therefore, defining the origins and depositional processes
of the sediments plays an important role in understanding the
paleoenvironment closely associated with paleoclimate changes. In this study,
high-resolution subbottom profile (SBP) and gravity core data are analyzed to
understand origins and depositional processes of the Arctic sediments in the
Chukchi Sea and East Siberian Sea.
Based on clarity and continuity of reflectors (echoes) and seafloor
geometry, 5 echo facies are classified. Echo facies IA is characterized by
continuous sharp bottom echoes and parallel to sub-parallel subbottom echoes.
This echo facies is subdivided into IA-1 and IA-2 types depending on
occurrence of iceberg scours. Echo facies IA-1 is generally attributed to
hemipelagic settling with an influence of fine-grained turbidity current. It
occurs in a great part of the Chukchi Borderland including the Chukchi Shelf,
Chukchi Spur and the deep-sea floor. Echo facies IB includes acoustically
prolonged and relatively flat bottom echo and fuzzy subbottom echo. This
echo facies is restricted to the northern part of the Chukchi Spur, and
interpreted to represent moraines planated by bottom current during the
deglaciation. Echo facies IIB is characterized by overlapping hyperbolae with
hummocky reflectors. This echo facies is further divided into IIB-1 and IIB-2
depending on occurrence of scoured reflectors by iceberg plowing. Type IIB
occurs in the shallow part of the Chukchi Spur (200∼300 m in water depth),
central part of the Chukchi Plateau, and topographic high in the KucherovTerrace. Distribution of echo facies IIB indicates that grounding zone moraines
were formed extensively along the base of the ice sheet (grounding ice)
during the glacial retreat. Echo facies IIC shows tightly overlapping hyperbolic
echoes with acoustically transparent subbottom echoes of lens or wedge shape.
Major part of the steep slopes including the southeastern part of the
Mendeleev Ridge are dominated by echo facies IIC, which is interpreted as
mass-flow deposits or debrites. In the deep-sea floor, lateral change from IIC
to IA-1 indicates that mass flow, debris flow and turbidity current are formed
by influence of ice advance during the glacial stage. Echo facies IIIB is
characterized by acoustically transparent or partially prolonged subbottom
echoes with a high relief (tens of meters). It mainly occurs in the northern
part of the Chukchi Spur. This type echo is interpreted to be characteristic of
the hard rock basement, and the high-relief echoes are interpreted as scour
marks by floating iceberg during the deglaciation.
In the gravity core sediments, 5 sedimentary facies are classified on the
basis of sedimentary structures on X-radiographs and grain texture. Couplets
of thinly laminated mud (TLM) and homogeneous mud (HM) are generally
indicative of fine-grained turbidity current. In the ice-proximal zone (grounding
line), these sedimentary facies can result from subglacial meltwater stream
during the deglaciation. On the other hand, bottom current and turbid
meltwater plume give rise to irregular and indistinct lamination with
bioturbation (ILM). The sedimentary facies ILM/TLM indicate a gradual
change from deglaciation to interglacial stage in the Chukchi Spur.
Structureless or disorganized (gravelly) mud (DM) consists of many ice rafted
debris (IRDs) supported by fine-grained matrix. This sedimentary facies is
interpreted to represent sediments settled from the basal debris zone under thelarge and wide ice shelf during the deglaciation.
The depositional model integrated from the SBP and sediment core analyses
indicates that the Chukchi Borderland was influenced by ice sheet (grouding
ice) and ice shelf during the LGM, which is useful for further paleo-climate
and paleo-oceanographic researches in the Chukchi Sea. The sedimentary
facies suggested in this study will be also helpful to enhancement of
convenience and accuracy for paleoenvironmental researches.
Author(s)
조영진
Issued Date
2014
Awarded Date
2014. 8
Type
Dissertation
URI
http://dcoll.jejunu.ac.kr/jsp/common/DcLoOrgPer.jsp?sItemId=000000006815
Alternative Author(s)
Young Jin Joe
Department
대학원 지구해양과학과
Table Of Contents
제1장 서 론 1
제2장 북극해 지역개관 4
2.1 북극해 해저 지형 4
2.2 북극해 지구조 및 발달사 5
2.3 북극해 해양 순환 7
2.4 빙해양 퇴적환경 9
제3장 연구 자료 및 방법 11
3.1 고해상 해저지층탐사 자료 11
3.2 코어 자료 13
제4장 고해상 탄성파상 18
4.1 탄성파상 분류 18
4.2 탄성파상 분포 23
4.3 탄성파상 해석 29
제5장 퇴적상 32
5.1 코어 기재 32
5.2 퇴적상 분류 및 해석 55
제6장 토 의 62
6.1 척치해 빙해양 퇴적작용 62
6.2 척치해 빙해양 퇴적모델68
6.3 시베리아 빙상 71
제7장 결 론 73
참고 문헌 75
부 록 81
감사의 글 100
요 약 101
Degree
Master
Publisher
제주대학교 대학원
Citation
조영진. (2014). 서북극 척치해의 제4기 후기 해양퇴적층에 대한 퇴적환경 연구
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Faculty of Earth and Marine Convergence > Earth and Marine Science
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