Skaergaard 암체에서 layering의 기원과 그의 마그마 대류와의 관계

장윤득 대한자원환경지질학회 2001 자원환경지질 Vol.34 No.6

At least two distinct types of layering are present in the middle zone of the Skaergaard intrusion; alternating plagioclase-rich and pyroxene-rich, macro-rhythmic layers, and smaller scale, modally-graded, rhythmic layers. The macro-rhythmic layers are ubiquitous in the middle zone of the Layered Series, but are not observed in the lower and upper zone of the Layered Series or in the wall or roof series of the intrusion. They range from 0.3 to 3.3 m in thichiess, have sharp upper and lower boundaries, and can be traced laterally for over 2 km in outcrop. Although individual macro-rhythmic layers are not internally graded, many contain smaller-scale, modally-graded layers. Modally-graded, rhythmic layers are a common feature of the Layered Series but are not abundant in either the Upper Border Series or the MarginalBorder Series. They range in thickness from 1 to 50 cm and can be traced laterally in outcrop for up to 100 m. Their lateral termination ranges from abrupt to gradational, and they are often associated with cut and fill structures and cross-bedding suggestive of current activity. They are characterized by sharp lower and gradational upper contacts, and by strong intra-layer modal grading with olivine, ilmenite, and magnetite concentrated at the base, pyroxene concenoated above the base, and plagioclase concentrated at the top. The layers are also grain-size graded with the maximum size for each phase occurring at the horizon in the layer where the phase is most abundant. Modally-graded, rhythmic layers in the middle zone of the Layered Series occur within both plagioclase-rich and pyroxene-rich macro-rhythmic layers. Two sequences of modally-graded layering from the Middle Zone have been investigated in detail, one from a plagioclase-rich, macro-rhythmic layer and one from a pyroxene-rich, macro-rhythmic layer. In general, the compositions of individual minerals do not vary systematically within the layers, except for K₂O and Ba in plagioclase, and MgO and FeO in pyroxene, ilmenite, and magnetite. The compositions of pyroxene, ilmenite, and magnetite are all richer in MgO and poorer in FeO at the base of layers where ilmenite, and magnetite are abundant. This compositional variation appears to be the result of reaction between early-formed crystals and interstitial Fe-rich melt. Samples at the base of the layers undergo less re-equilibration than samples higher up in the layers suggesting reaction with interstitial melt percolating down through the layer from above. There does not appear to be a direct correlation between the abundance of an indiyidual phase or the pyroxene-oxide ratio and the degree of reequilibration. Compared to plagioclase in the pyroxene-rich layers, plagioclase in the plagioclase-rich layers has lower K2O contents and lower Eu/sm, similar to plagioclase in the UBS, suggesting that the plagioclase-rich layers haye accumulated excessplagioclase transported from the roof zone of the intrusion. The plagioclase-rich layers may have formed during periodsof conyection, while the pyroxene-rich layers formed during periods of stagnation. The K₂O-poor plagioclase in theplagioclase-rich layers appears to haye reequilibrated with a K₂O-rich liquid percolating downward through the layer. The K₂O-rich plagioclase in the pyroxene-rich macro layers, which is belieyed to haye initially crystallized on the floorof the intrusion, is in equilibrium with the interstitial liquid and shows no reequilibration. Modally-graded, rhythmiclayers appear to be the result of interaction between density currents or density plumes and a zone of in-situcrystallization on the floor of the Skaergaard magma chamber.

Skaergaard 암체의 희토류의 분화경향

장윤득 대한자원환경지질학회 2001 자원환경지질 Vol.34 No.6

Skaeigaard 암체는 광범한 in situ 화성분화작용을 격은 층상관입암의 대표적인 예로 널리 알려져 있다. 따라서 이암체는 폐쇄계에서 미량원소변이를 modeling 할 수 있는 적지가 될 것이다. 그러나, 기존의 연구에 의하면 본 암체의 전암및 광물의 희토류는 폐쇄계로서의 예상된 경향을 보이지 않는다(Haskin and Haskin, 1965; Paster et al., 1974). 발표된 분배계수, 공존광물들의 mode, 그리고 전암 및 광물의 미량원소함량을 사용한 미량원소 modeling에 의하면 Skaergaard 암체의 희토류는 분화후기에 일어난 광범한 인회석 결정작용에 크게 영향을 받았음을 보여준다. 미량원소 modeling은 Upper Border Series에서 간헐적으로 나타나는 인회석이 기존에 주장되어 온 바와 같은 liquidur상이 아니라 진화하는 magma의 미량원소함량에는 영향을 끼칠 수 없는 interstitial phase임을 시사한다. 분화작용 말기에 Skaeigaard 마그마가 대류를 멈추거나 소규모로 대류를 할 때, 마그마 암장의 상부에 축적되는 휘발성분에 기인한 증가된 PH₂O가 인회석이 UBS에서 정출 되는 것을 방해하였을 것이다. 이와 같은 인회석의 특성을 고려해서 Skaergaard 분화작용을 modeling하면 희토류는 폐쇄계로서의 예상된 경향을 따른다. 이와 같은 결과는 최종 20% 분화작용기간 중에 양적으로 상당한 양의 마그마의 주입이나 분출을 수반하는 그 어떤 Skaergaard 암체의 분화model을 배격한다. The Skaergaard intrusion is widely considered a type example of a strongly fractionated, layered intrusion that has undergone extensive in situ igneous difffrentiation. The intrusion, therefore, should be a good locality for modeling trace element variation in a closed system. Previous studies (Haskin and Haskin, 1968; Paster et al., 1974), however, have suggested that the rare earth elements in whole rocks and mineral separates from the intrusion did not follow the expected trend for closed system crystallization. Trace element modeling using published disoibution coefficients, modal abundances of the coexisting minerals, and the concentration of trace elements in whole rocks and mineral separates from the Skaergaard intrusion, reveals that the rare earth elements were significantly influenced by the crystallization of abundant apatite in the Layered Series during the final stages of crystallization. The results of trace element modeling also suggests that apatite, which appears sporadically in the UBS, is not a primary liquidus phase in these samples as previously suggested (Naslund, 1984) but an interstitial phase that did not directly effect trace element abundances in the evoIving magma. As the Skaergaard magma ceased convection, or convected as small isolated cells during the final stages of difffrentiation, an elevated PH₂O induced by accumulation of volatile elements near the roof of the magma chamber inhibited or delayed the precipitation of primary apatite in the UBS. If the Skaergaard differentiation is modeled assuming primary apatite crystallization in the upper part of the LS where abundant modal apatite is present, and only late stage crystallization of apatite in the UBS where apatite is less abundant, rare earth elements abundances follow a closed system variation trend. These results rule out any differentiation model for the Skaergaard intrusion that includes volumetrically significant injections or discharges of magma into or out of the chamber during the final 20% of the crystallization history.

울릉도-독도의 세계지질공원으로서의 가치와 추진전략

장윤득,임지현,황상구,김정진 대한지질학회 2009 대한지질학회 학술대회 Vol.2009 No.

良浦, 牟浦一帶에 分布하는 新生代 火山活動에 對한 考察

張閏得 慶北大學校 自然科學大學 地質學科 地質學硏究會 1988 伏賢地質 Vol.- No.10

The Tertiary strata in study area are mainly composed of pyroclastic deposits and associated with the Tertiary volcanics and Yeongil Basalt in space and time. Volcanic rocks divided into three groups; Rhyolitic (or Dacitic), andesitic, and Basaltic rocks. Magmatic series was inferred by chemical analyses and several variation diagrams; SiO_2-Oxide, SiO_2 - D. I., Alkalilime index, AFM etc., and belonged to calc - alkali series.

월성동 구석기 유적 출토 흑요석제 석기의 암석 및 광물학적 연구를 통한 원산지 추정

장윤득,박태윤,이상목,김정진 한국지구과학회 2007 한국지구과학회지 Vol.28 No.6

Petrological, mineralogical, and geochemical analyses were carried on the paleolithic obsidian implementsexcavated at Wolseongdong, Daegu, Korea. The obsidians has a homogeneous glassy texture that can be observed in atypical obsidian formed from a rapid cooling of silicic magma. Major element composition of the obsidians representcalc-alkaline series. Comparing those with other obsidians from domestic local excavation sites, Mt. Baekdu, and Kyusuof Japan, the Wolseongdong obsidians show similar element distribution pattern with others in spite of small diference intrace and rare Earth element contents. Sr isotopes of the obsidians considerably differ from those of the obsidians fromMt. Baekdu (10 Ma). Therefore, considering the characteristics of obsidians found in the Korean Peninsula includingmineralogy, petrology, trace element, and isotopes chronology, the obsidians can be divided into four groups: Mt. Baekdu,southern part of Korea (Kyusu of Japan), midle part of Korea, and Wolseongdong region. These groups suggest apossibility of more than four different origins of the obsidians found in the Korean Peninsular.......... mineral, obsidian, stone implement, paleolithic, origin. . : .. ... .. ... ... ... .. , .. . ..... .... ..... .... ..

상용 보존처리제의 암종에 따른 특성 연구

우엄식,이아름,정홍윤,장윤득,김정진 한국암석학회 2011 한국암석학회 학술발표회 논문집 Vol.2011 No.5

단층비지의 입도분포 특징 및 단층구성광물의 암석광물학적 기원: 경주시 양북면

장윤득 ( Yun Deuk Jang ),장천중 ( Cheon Jung Chang ),이정민 ( Jeong Min Lee ),송수정 ( Soo Jeong Song ),추창오 ( Chang Oh Choo ) 대한지질공학회 2011 대한지질공학회 학술발표회논문집 Vol.2011 No.-

Compositional Variation in Olivine in the Skaergaard Intrusion

Yun-Deuk Jang(장윤득) 한국암석학회 2003 암석학회지 Vol.12 No.3

Syenite from Ulleung Island : As a Window for Pre-eruptive Shallow Alkaline Magma Dynamics

Yun Deuk Jang(장윤득) 한국암석학회 2019 한국암석학회 학술발표회 논문집 Vol.2019 No.5

옥천화강암 주변의 다중변형구조

이현우,장윤득 대한지질학회 2003 대한지질학회 학술대회 Vol.2003 No.