https://repository.kopri.re.kr/handle/201206/5466 2026-04-18T17:17:43Z https://repository.kopri.re.kr/handle/201206/8553 Title: Sources and Levels of Ambient Ocean Sound near the Antarctic Peninsula Authors: Robert P. Dziak; David K. Mellinger; Joseph H. Haxel; Tai-Kwan Lau; Matt J. Fowler; Lee, Won Sang; Minkyu Park; Haruyoshi Matsumoto; Kathleen M. Stafford; DelWayne R. Bohnenstiehl Abstract: Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (Antarctic Peninsula region) from 2005 to 2009 to record ambient ocean sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the ocean soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapid disintegration also releases significant acoustic energy, equivalent to large-scale geophysical events. Overall ambient sound levels can be as much as ~10？20 dB higher in the open, deep ocean of the Scotia Sea compared to the relatively shallow Bransfield Strait. Noise levels become lowest during the austral winter, as sea-ice cover suppresses wind and wave noise. Ambient noise levels are highest during austral spring and summer, as surface noise, ice cracking and biological activity intensifies. Vocalizations of blue (Balaenoptera musculus) and fin (B. physalus) whales also dominate the long-term spectra records in the 15？28 and 89 Hz bands. Blue whale call energy is a maximum during austral summer-fall in the Drake Passage and Bransfield Strait when ambient noise levels are a maximum and sea-ice cover is a minimum. Fin whale vocalizations were also most common during austral summer-early fall months in both the Bransfield Strait and Scotia Sea. The hydrophone data overall do not show sustained anthropogenic sources (ships and airguns), likely due to low coastal traffic and the typically rough weather and sea conditions of the Southern Ocean. 2015-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/6292 Title: Calcified microbial reefs in Cambrian Series 2, North China Platform: Implications for the evolution of Cambrian calcified microbes Authors: Lee, Jeong-Hyun; Woo, Jusun; Chough, S. K.; Chen, Jitao; Lee, Hyun Suk Abstract: This study focuses on the microbial reefs of the Zhushadong Formation (Cambrian Series 2) in Shandong Province, China in order to understand the evolution of calcified microbes in the North China Platform during the Cambrian Series 2 and 3. The microbial reefs occur in a thin unit, ca. 3 m thick, over an area of 1 km2. They consist of three types of thrombolite based on their mesostructures: rimmed, grainstone-patch, and dendritic. The thrombolites mainly occur in various coarse-grained carbonate facies, including crudely stratified oolitic grainstone, stromatolitic grainstone, and disorganized limestone conglomerate. Calcified microbes in the thrombolites include Epiphyton, Kordephyton, a tubiform microbe, Bija, Tarthinia, Renalcis, Amgaina, and Razumovskia. The Zhushadong thrombolites were formed within a grainstone shoal, and experienced repeated burial and exposure. The rimmed thrombolite and grainstone-patch thrombolite experienced abundant input of carbonate grains (forming grainstone patches). In contrast, the dendritic thrombolite formed solely by calcification of microbes that mainly include Epiphyton, Tarthinia, and the tubiform microbe. The outer crusts of the rimmed thrombolite were formed by Amgaina, under high energy conditions. The diverse calcified microbes of the Zhushadong Formation form the earliest assemblage of their type in the North China Platform. Their descendants, mostly Epiphyton, subsequently thrived, forming a ca. 180 m thick microbialite？oolite-dominated succession during the Cambrian Series 3 (Zhangxia Formation). Although the reefs in the Zhushadong Formation are much smaller than those of the overlying Zhangxia Formation, their calcified microbes are more diverse. This most likely reflects changes in depositional environments (e.g., abundant siliciclastic input and tidal effects vs. those of a stable carbonate platform), and/or global changes within reef environments (e.g., end-Cambrian Series 2 extinction of archaeocyaths and calcified microbes). A decrease in diversity of calcified microbes in the North China Platform, where archaeocyaths were absent, may help to account for evolutionary trends in calcified microbes that occurred independently of archaeocyath influence. 2014-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/6255 Title: Recent changes in the flow of the Ross Ice Shelf, West Antarctica Authors: C. L. Hulbe; T. Haran; J. Bohlander; Lee, Choon-Ki; T. A. Scambos Abstract: Comparison of surface velocities measured during the Ross Ice Shelf Geophysical and Glaciological Survey (RIGGS, 1973 to 1978) and velocities measured via feature tracking between two Moderate-resolution Imaging Spectroradiometer (MODIS) mosaics (compiled from 2003/4 and 2008/9 images) reveals widespread slowing and minor areas of acceleration in the Ross Ice Shelf (RIS) over the approximately 30 year interval. The largest changes (？ 13 ma？ 2？ 13 ma？ 2) occur near the Whillans and Mercer Ice Streams grounding line in the southernmost part of the ice shelf. Speed has increased over the interval (up to 5 ma？ 25 ma？ 2) between the MacAyeal Ice Stream grounding line and the shelf front, and along the eastern shelf front. Changes in ice thickness computed using ICESat laser altimetry are used together with a well-tested model of the ice shelf to investigate underlying causes of change in the flow of the ice shelf over time. The observed transients represent a combination of recent forcings and ongoing response to ice stream discharge variations over the past millennium. While evidence of older events may be present, the modern signal is dominated by shorter time scale events, including the stagnation of Kamb Ice Stream about 160 years ago, recent changes in basal drag on the Whillans Ice Stream ice plain and, perhaps, iceberg calving. Details in embayment geometry, for exampsaics (compiled from 2003/4 and 2008/9 images) reveals widespread slowing and minor areas of acceleration in the Ross Ice Shelf (RIS) over the approximately 30 year interval. The largest changes (？ 13 ma？ 2？ 13 ma？ 2) occur near the Whillans and Mercer Ice Streams grounding line in the southernmost part of the ice shelf. Speed has increased over the interval (up to 5 ma？ 25 ma？ 2) between the MacAyeal Ice Stream grounding line and the shelf front, and along the eastern shelf front. Changes in ice thickness computed using ICESat laser altimetry are used together with a well-tested model of the ice shelf to investigate underlying causes of change in the flow of the ice shelf over time. The observed transients represent a combination of recent forcings and ongoing response to ice stream discharge variations over the past millennium. While evidence of older events may be present, the modern signal is dominated by shorter time scale events, including the stagnation of Kamb Ice Stream about 160 years ago, recent changes in basal drag on the Whillans Ice Stream ice plain and, perhaps, iceberg calving. Details in embayment geometry, for examp 2013-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/6647 Title: Geological history and stratigraphy of northern Victoria Land Authors: Woo, Jusun; Cheo, Moon Young; Kim, Young-Hwan G.; Kim, Tae Hoon; Lee, Mi Jung; Lee, Jong Ik; Park, Tae-Yoon S. Abstract: Sedimentary successions in the central Transantarctic Mountains (CTAM) and Victoria Land can be subdivided into two representative units. The first unit formed by the early Paleozoic tectonic processes of the Ross Orogeny with the Precambrian metamorphic rocks being the basement. The Beardmore and Byrd groups which consist of shallow marine sandstone, mudstone, and lesser amounts of carbonates represent the early Paleozoic units in the CTAM. On the other hand, the early Paleozoic Ross Orogeny-related successions in the Northern Victoria Land (NVL) are characterized by accretionary complexes of three terranes: Wilson, Bowers,Robertson Bay terranes, from inboard to outboard. The Wilson Terrane consists of high-grade metasedimentary rocks and granitoids. The Bowers Terrane comprises low-grade metasedimentary rocks of siliciclastics, volcanics,and carbonates. The outermost Robertson Bay Terrane consists predominantly of flysch deposits of deep-sea turbidite. No early Paleozoic succession occurs in the Southern Victoria Land (SVL). Afterwards, the late Paleozoic to Triassic Beacon Supergroup (siliciclastics including coal seams) formed over the deformed early Paleozoic strata,bounded below by a regional unconformity. There are minor unconformities within the Beacon Supergroup in the CTAM, the hiatus and resulting unconformities increase in frequency and duration toward NVL. Both the Devonian Taylor and Permian-Triassic Victoria groups occur in the SVL, but only the Victoria Group occurs in the NVL. The Victoria Group consists of shallow marine, fluvial, and volcaniclastic successions. The deposition in the Pacific margin of the Gondwana stopped after the formation of the Victoria Group. Afterwards, the geological processes in the TAM were dominated by regional development of volcanics and lava flow units of Ferrar Group. It is effusive and eruptive tholeiitic volcanics which formed thick succession of volcaniclastics, lava flow units, dykes, and sills.These volcanics are related to the rifting in the early stage of the breakup of the Gondwana. 2013-01-01T00:00:00Z