https://repository.kopri.re.kr/handle/201206/9853 2026-04-17T22:13:18Z 2026-04-17T22:13:18Z Yi, Sang-Bong Lee, Mi Jung Park, Sung Hyun Han, Seung Hee Yang, Yun Seok Choi, Hakkyum https://repository.kopri.re.kr/handle/201206/10871 2022-03-24T07:14:07Z 2019-08-01T00:00:00Z

Title: Occurrence of ice-rafted erratics and the petrology of the KR1 seamount trail from the Australian-Antarctic Ridge Authors: Yi, Sang-Bong; Lee, Mi Jung; Park, Sung Hyun; Han, Seung Hee; Yang, Yun Seok; Choi, Hakkyum Abstract: A multi-disciplinary study of the KR1 segment of the Australian-Antarctic Ridge has been conducted since 2011. We present geochemical and age dating results for samples dredged from three sites on the KR1 seamount trail. The majority of the samples are alkaline ocean island basalts with subdominant enriched tholeiites. The samples from the DG05 bathymetric depression include ice-rafted erratics from Antarctica, which consist of gabbro, diabase, various granitoids, volcanic rocks such as trachyte and rhyolite and deformed or undeformed sedimentary rocks. The main provenance of glacial erratics is considered to be the the Ross Sea region. However, Carboniferous to Cretaceous ages of erratics indicate that some of these may originate from the western regions of West Antarctica. Based on the size and topography of the volcanic features and geochemical characteristics of the alkaline ocean island basalts (La/SmN = 2.62-3.88; Tb/YbN = 1.54-2.67) and the enriched tholeiites, the KR1 seamount trail is interpreted to be a submarine hotspot chain that is the product of alkaline volcanic eruption and seafloor spreading.

2019-08-01T00:00:00Z Park, Sung Hyun Langmuir, Charles H. Sims, Kenneth W. W. Blichert-Toft, Janne Kim, Seung-Sep Scott, Sean R. Lin, Jian Choi, Hakkyum Yang, Yun Seok Michael, Peter J. https://repository.kopri.re.kr/handle/201206/9662 2022-03-24T07:14:04Z 2019-03-01T00:00:00Z

Title: An isotopically distinct Zealandia？Antarctic mantle domain in the Southern Ocean Authors: Park, Sung Hyun; Langmuir, Charles H.; Sims, Kenneth W. W.; Blichert-Toft, Janne; Kim, Seung-Sep; Scott, Sean R.; Lin, Jian; Choi, Hakkyum; Yang, Yun Seok; Michael, Peter J. Abstract: The mantle sources of mid-ocean ridge basalts beneath the Indian and Pacific oceans have distinct isotopic compositions with a long-accepted boundary at the Australian？Antarctic Discordance along the Southeast Indian Ridge. This boundary has been widely used to place constraints on large-scale patterns of mantle flow and composition in the Earth's upper mantle. Sampling between the Indian and Pacific ridges, however, has been lacking, especially along the remote 2,000？km expanse of the Australian？Antarctic Ridge. Here we present Sr, Nd, Hf and Pb isotope data from this region that show the Australian？ Antarctic Ridge has isotopic compositions distinct from both the Pacific and Indian mantle domains. These data define a separate Zealandia？Antarctic domain that appears to have formed in response to the deep mantle upwelling and ensuing volcanism that led to the break-up of Gondwana 90？million years ago, and currently persists at the margins of the Antarctic continent. The relatively shallow depths of the Australian？Antarctic Ridge may be the result of this deep mantle upwelling. Large offset transforms to the east may be the boundary with the Pacific domain.

2019-03-01T00:00:00Z Park, Sung Hyun Lee, Kyeong Yong Hauff, Folkmar Lee, Sang-Mook Kamenov, George D. Michael, Peter J. https://repository.kopri.re.kr/handle/201206/9521 2022-03-24T07:14:14Z 2018-09-01T00:00:00Z

Title: Petrogenesis of basalts along the eastern Woodlark spreading center, equatorial western Pacific Authors: Park, Sung Hyun; Lee, Kyeong Yong; Hauff, Folkmar; Lee, Sang-Mook; Kamenov, George D.; Michael, Peter J. Abstract: Seafloor spreading in the Woodlark Basin is taking place on pre-existing arc crust that was produced by the sub- duction of the Indo-Australian Plate into the Pocklington Trough (now inactive) to the south during the Paleo- gene. The Woodlark Basin has a unique tectonic setting characterized by two surrounding subduction zones. To the east, a spreading ridge is also currently being subducted beneath the Solomon Arc. Moreover, long-term subduction ofthe Pacific Plateoccurredinthisarea,which was halted by thecollision of theOntong？Java Plateau withtheVitiazTrench atca.10 Ma.Any oneofthesesubductionzonescouldhaveinfluencedthemantlebeneath the Woodlark Basin. In this study, basalts from the eastern Woodlark Basin spreading center (EWLB; eastern WoodlarkBasinbasalts) wereanalyzedfor majorand trace element compositions and Sr-Nd-Pb isotopiccompo- sitionsto investigate themelting processes andmantleheterogeneity inthis unusualtectonic setting. Our results show that theEWLB canbeclassifiedintothreetypes basedonmajorand trace elements, and Sr？Nd？Pb isotopic characteristics: normal EWLB (N-EWLB), very depleted EWLB (VD-EWLB), and ultra-depleted EWLB (UD-EWLB). N-EWLB are similar to normal mid-ocean ridge basalts (N-MORB) and comprise most of the EWLB. The EWLB formed from local mantle, which is similar to depleted MORB mantle. VD-EWLB are more de- pleted than N-EWLB and have a weak subduction fingerprint. These rocks are characterized by increasing Nb/La with increasing Sm/La, which is a trend that is not produced by peridotite melting. As such, VD-EWLB may have formed by melting of a source containing residual eclogite that had previously undergone low-degree partial melting during subduction, leaving residual rutile in the source. UD-EWLB are extremely depleted relative to globalMORB,haveelevatedH 2 O/CeandBa/Nb ratios similartoback-arcbasinbasalts (BABB),andlower concen- trations of H 2 O and Ba than N-MORB. We propose that UD-EWLB was derived from sub-arc residual mantle that wasenrichedbyfluidandthenexperiencedmeltdepletion.ThesubductionfingerprintsintheVD-andUD-EWLB are not related to the current ridge subduction or earlier, long-term subduction of the Pacific Plate in the northeast of the basin, as they are geochemically distinct from the Solomon Arc, which was strongly influenced by both these subduction systems. Instead, we suggest that the subduction fingerprint of the VD- and UD-EWLB was produced during Paleogene subduction of the Indo-Australian Plate to the south.

2018-09-01T00:00:00Z Choi, Hakkyum Kim, Seung-Sep Park, Sung Hyun https://repository.kopri.re.kr/handle/201206/12381 2022-03-24T07:15:11Z 2018-01-01T00:00:00Z

Title: Morphological characteristics of off-axis volcanism in the vicinity of the easternmost segment of the Australian-Antarctic Ridge Authors: Choi, Hakkyum; Kim, Seung-Sep; Park, Sung Hyun Abstract: The Australian-Antarctic Ridge (AAR) is an intermediate spreading system positioned to the east of the Southeast Indian Ridge (SEIR) and extending to the Macquarie Triple Junction (MTJ) of Australian-Antarctic-Pacific plates. The KR1 and KR2, the easternmost segments of the AAR system, are separated by the Balleny Fracture Zone (FZ) stretching NNW-SSE direction. During the recent oceangoing surveys of R/VIB Araon, we identified 3 volcanic seamount chains aligned roughly perpendicular to the KR1 ridge axis. The high-resolution shipboard bathymetric data show that each seamount chain consists of several isolated volcanic constructs. Height of the seamounts varies from a few hundreds of meters up to ~2 km; the largest seamount has a volume of ~300 km3. The seamounts situated in the western and eastern ends of the KR1 are significantly larger in height and volume compared to the seamounts stretching southward in the central KR1. In addition, we estimated the age of seamount formation using the forward magnetic modeling. As a result, the seamount chains were formed within the last ~3 Myrs; each edifice of the seamounts had been constructed by volcanic activity lasted approximately for 250~600 kyrs. As we can assume a seamount is constructed after the seafloor is formed at ridge axis, comparison of the geomagnetic polarity of the given seamount with the polarity of the pre-existing seafloor can be used to constrain its formation age. The forward magnetic model shows that each seamount chain has at least one seamount having the polarity reversed from that of the pre-existing seafloor. Furthermore, the model indicates that the formation of all the seamounts surveyed in the area appears to be concentrated on ~0.52 Ma, ~1.02 Ma, ~1.86 Ma, and ~2.45 Ma. Here we present the morphological characteristics of these seamounts and discuss their tectonic implications based on their magnetic properties.

2018-01-01T00:00:00Z