SMP08-01

会場:A05

時間:5 月 26 日 10:00-10:15

The January 2013 and May 2014 North Aegean Earthquakes Sequence: Their Role in the
Aegean Region
The January 2013 and May 2014 North Aegean Earthquakes Sequence: Their Role in the
Aegean Region
KALAFAT, Dogan1∗ ; KEKOVALI, Kivanc1 ; PINAR, Ali1
KALAFAT, Dogan1∗ ; KEKOVALI, Kivanc1 ; PINAR, Ali1
1
1

B.U. KANDILLI OBSERVATORY &ERI.
B.U. KANDILLI OBSERVATORY &ERI.

Abstract
The North Aegean Sea is one of the most seismically active and deforming region between the Eurasia and Anatolia tectonic
plates. This area is dominated by dextral strike-slip faulting and is characterized by frequent strong earthquakes.
On 8th January 2013 at 14:16 UTC a moderate earthquake (Mw= 5.7) occurred between the south of Gokceada and southwestof Bozcaada Islands. The earthquake was felt at a wide area. The area is defined as the continuation of the branch of North
Anatolian Fault (NAF) inside the Aegean Sea. Fault plane solution determined by this study shows that the earthquake occurred
on NE-SW oriented strike slip fault segment. The aftershocks distribution also supported the rupture of the NE-SW oriented
fault.
Approximately 17 months later, another big earthquake occurred in the same area. On 24th May 2014, at 09:25 UTC, a
powerful Ml=6.7 (Mw=6.8) earthquake hit Greece and Turkey, 87 km west of Canakkale, and totally 350 people injured in
Greece and Turkey. The main-shock occurred on a fault with a NE-SW strike, where the largest portion of the energy was
released towards these directions. Therefore the earthquake was felt strongly in Canakkale, Istanbul and Marmara region. In thisstudy, we calculated CMT solutions for main-shock and important aftershocks (M>4.0). CMT analyses were done for more than
50 important earthquakes. Moment tensor solutions show generally strike-slip faulting. The fault which caused earthquakes, isthought to be a branch of North Anatolian Fault Zone in the North Aegean Sea. Generally, the location of the earthquakes andorientation of the NE-SW nodal planes are consistent with right-lateral faulting within the North Aegean Trough (NAT). The
Aegean Sea is characterized by dextral strike-slip faulting along NE-SW striking faults, along fault zones formed parallel to theNorth Aegean Trough (NAT). Strike slip faulting is changing to oblique, with significant component of extension, as one goesfrom the Aegean to the coastal area of NW and Western Turkey.
The sources region of the North Aegean earthquakes is influenced by both the Aegean extensional regime and the strike-slip
regime in the western part of the North Anatolin Fault Zone.
This study was supported by Bogazici University Research Projects Commission under SRP/BAP project No. 6040 and
MarDIM SATREPS project.

キーワード: North Anatolian Fault, North Aegean Sea, aftershock, strike-slip regime, Moment tensor solution
Keywords: North Anatolian Fault, North Aegean Sea, aftershock, strike-slip regime, Moment tensor solution

1/1

SMP08-02

会場:A05

時間:5 月 26 日 10:15-10:30

Deciphering the Variscan orogeny: HP metamorphism at different temperatures and HT
metamorphism at different pressures.
Deciphering the Variscan orogeny: HP metamorphism at different temperatures and HT
metamorphism at different pressures.
O’BRIEN, Patrick1∗
O’BRIEN, Patrick1∗
1
1

Earth Env Sci, U Potsdam
Earth Env Sci, U Potsdam

The European Variscan belt is well known for its voluminous granites and widespread migmatite complexes. However, thesame short orogenic episode also resulted in the formation of blueschists and numerous bodies of eclogite. The picture is further
complicated by large bodies of felsic granulite (including the type locality for granulite), pods and lenses of mantle-derived garnet
peridotite and, since the beginning of the 20th century, also ultra-high pressure coesite and/or microdiamond-bearing rocks. How
can all these apparently different rocks be created in a single orogen and be exposed so soon after the tectonometamorphic
events (as revealed from post-orogenic conglomerates and sedimentary sequences) in such close proximity? The answer lies indeciphering critical rock types through microanalysis of major and trace elements as well as isotopes. The garnet peridotites,
sometimes enclosing mantle-type eclogite lenses, occur together with the felsic granulites. Detailed investigation has revealed
that these K-feldspar+quartz- rich rocks with minor garnet, kyanite and rutile formed at eclogite facies conditions. Recent studies
have confirmed microdiamond and coesite in such so-called granulites thus confirming UHP conditions i.e. the crustal rocks havebeen subducted to mantle depths and trapped slices of mantle during their exhumation. Geochronological and diffusion studies
have determined a rapid exhumation of these units. These are not the only HP rocks, however. An earlier phase of subductionand exhumation produced eclogites that were in a hanging wall position before exhumation of the hot granulite-peridotite units.
Further away from the final subduction zone the exhuming hot granulite-peridotite bodies flowed to underplate the crust. Locally,
these hot complexes domed upwards and became caught-up and flattened-out in mid- to upper-crustal shear zones. Where
such complexes are exposed today they are bounded by units representing middle and lower crust, locally containing a 3rd
type of eclogite in places together with spinel peridotite. Eclogites in this situation can show a pyroxene-hornfels overprint(olivine-bearing textures) despite preserving omphacite (from the eclogite facies stage) as well as granulite and amphibolitefacies breakdown textures. With the realisation that the eclogites are from different stages of the subduction-collision history,
as deduced by detailed investigation of suitable key samples by multiple microanalytical methods, it is now possible to piece
together this most enigmatic orogenic belt. Is this type of relamination of upper crustal material to the lower crust an example ofwhat is happening in the Himalaya today?
キーワード: Variscan, HP granulite, Garnet peridotite, Eclogite, pyroxene-hornfels
Keywords: Variscan, HP granulite, Garnet peridotite, Eclogite, pyroxene-hornfels

1/1

SMP08-03

会場:A05

時間:5 月 26 日 10:30-10:45

Combined geochronology and P-T pseudosection constrains protracted garnet growth inhigh-pressure eclogite
Combined geochronology and P-T pseudosection constrains protracted garnet growth inhigh-pressure eclogite
CHENG, Hao1∗
CHENG, Hao1∗
11

School of Ocean and Earth Science, Tongji University
School of Ocean and Earth Science, Tongji University

Understanding convergent margin processes requires determination of the onset of subduction, the number and polarity of
subduction zones, and the duration of subduction zone metamorphism. Garnet growth and intracrystalline zonation can be used
to constrain the timing, duration, and kinetics of tectonometamorphic processes. An eclogite from the Huwan shear zone in the
Hong’an orogen was investigated with combined pseudosection analysis and multiple geochronology. The pseudosection analysis
illustrates that garnet growth is continuous and along an early near isothermal trajectory followed by a near isobaric heating pathfrom 1.9 GPa/500 ℃ to 2.4 GPa/575 ℃. 40 Ar/39 Ar dating of amphibole inclusion in garnet from the eclogite yielded age of 310± 5 Ma, which is consistent with the U-Pb age of 302 ± 6 Ma for the metamorphic zircons within uncertainty. Garnet from thesample was crushed to obtain separate core and rim material that produced Lu-Hf ages of 296.9 ± 3.8 Ma and 256.9 ± 3.9 Ma,
the latter is consistent with its Sm-Nd age of 254.3 ± 4.6 Ma for the same aliquots. Similarly limited zircon U-Pb ages of c . 257
Ma were obtained in zircon rims with garnet inclusion. These ages were interpreted to bracket the period of garnet growth andthe difference of up to ∼40 Myr is best explained by protracted garnet growth. We propose that the rocks became detached fromthe downgoing slab and remained in the subduction zone for a long time without much change in P-T conditions until the entryof the continental crust in the subduction zone, which incorporated the rocks into the following subducted and exhumed at sometime later than c . 254 Ma. The increasing observations of protracted garnet growth and long-lived subduction in various orogens
worldwide demand more sophisticated geodynamic models.
キーワード: Lu-Hf, garnet, protracted metamorphism
Keywords: Lu-Hf, garnet, protracted metamorphism

1/1

SMP08-04

会場:A05

時間:5 月 26 日 11:00-11:15

Lawsonite-blueschist in the Hakoishi sub-unit, Kurosegawa belt, Kyushu, Japan, as Water
Carrier Into the mantle.
Lawsonite-blueschist in the Hakoishi sub-unit, Kurosegawa belt, Kyushu, Japan, as Water
Carrier Into the mantle.
平島 崇男 1∗ ; 佐藤 永太郎 1 ; 藤本 善航 1 ; 上村 謙一郎 1
HIRAJIMA, Takao1∗ ; SATO, Eitaro1 ; FUJIMOTO, Yoshikazu1 ; KAMIMURA, Keinichiro1
1
1

京都大学大学院理学研究科地球惑星科学専攻
Division of Earth Planetary Sciences, Kyoto Univ.

Lawsonite blueschist (LBS) is considered to have formed in the past cold subduction system and to be one of the most hydrated
metabasites in the relevant area, with more than 5 wt% of H2O (e.g., Hacker et al., 2003). In these rocks, lawsonite, pumpellyite
and chlorite are major H2O carriers. The dehydration reaction owing to the breakdown of such hydrous minerals is considered
to play the important role as the trigger of arc magmatism, deep intra-slab earthquake and trace element recy-cling in the cold
subduction system.
LBS, almost free from chemical and textural modifications during the exhumation stage, occurs in the Hakoishi sub-unit of theKurosegawa belt, Kyushu, in the outer belt of Southwest Japan. The main constituents of the Hakoishi sub-unit, ex-tending ineast-west trending narrow horst like area of ca. 10 x 1 x at least 1 km3, are metabasites and metachert along with minor amountof metagabbro and metapelite. Our filed mapping cannot detect the significant discontinuity or tectonic contact within the unit,suggesting that the LBS facies metamorphic rocks in Hakoishi sub-unit form a coherent block up to 10 km length originated fromthe upper part of subducting oceanic crust in Paleozoic time.
Following main high-pressure metamorphic minerals are well developed in all types of proto-liths in the sub-unit, such as
lawsonite (Lws), pumpellyite (Pmp), Na-pyroxene (Napx), Na-amphibole (Namp), chlorite (Chl), albite (Ab) and quartz (Qz).
The following westward progres-sive mineral assemblage change is identified even in 10 km horizontal distance in the sub-unit;
Pmp + Namp (Zone1),
Lws + Pmp + Namp (Zone2)
Lws + Napx + Namp (Zone3)
with excess Chl, Qz and Ab.
Jadeite component (XJd) of Napx gradually increases from Zone1 (XJd=0.15) to Zone3 (XJd=0.50). Glaucophane (Gln)component [YAl = Al/(Al + Fe3+)] of Namp also increases from Zone1 (YAl=0.15) to Zone3 (YAl=0.80).
Petrogenetic grid in NCMASH system reveals that the observed mineral assemblages are stable from 0.45 GPa and <300 C
for Zone1 to 0.80 GPa and <300 C for Zone3 and that the following mineral reactions are inferred to define each zone boundary
in NCF3+MASH system;(1) 3.4 Pmp + 2.9 Chl + 12 Ab + 10 Qz + 2.2 hematite (Hem) + 9.5 H2O = 13.5 Lws + 6 Namp
(2) 3.3 Namp + Lws + 0.8 Hem + 2.2 Ab + 1.9 H2O = 9.7 Napx + 1.8 Chl + 10 Qz
These data suggest that the studied rocks were formed under extremely low geothermal gradient (ca. 5-10 C/km).
The above mentioned all metamorphic reac-tions are hydration type. Actually H2O content stored in hydrous minerals instudied blueschists (BS) increases from 2.4-4.2 wt % in Lws-free BS in Zone1 to 5.0-7.0 wt % in Lws-bearing BS in Zone2 andZone3. These data verifies that the LBS in the Hakoishi sub-unit make clear the hydration mechanism in the cold subduction
system.
Estimated P-T condition of the Hakoishi sub-unit well fits to a thermal modeling of the Philippine-sea plate subducting beneath
the Kii Peninsula (Peacock, 2009). Extensive seismic studies were also carried out beneath the Kii Pen-insula. For example,
Kato et al. (2014) found low-velocity areas in three places, inside the arc crust between 5-20km depth, in the mantle wedge
just overlying the Philippine-sea plate between 35-50 km depth, and at the wedge-shaped part between the tip of the mantle
wedge and the Phil-ippine-sea plate. They ascribed the reason of low-velocity to deep fluid activities. In the latter two areas,
H2O-rich fluid released by dehydration reactions are considered to be supplied from the subducting Philippine-sea plate throughthe eclo-gitization of hydrated metabasite at the depth greater than 50 km (Kato et al., 2014).
Our data suggests that LBS-forming reaction should have taken place in the layer 1 and 2 of Philippine-sea plate at the depthof 15-25 km be-neath the Kii Peninsula. We suppose the LBS would carry high water content of 5.0-7.0 wt% to the incipient
depth of the eclogitization at the depth of 30-60 km.
Keywords: Lawsonite, blueschist, cold subduction

1/1

SMP08-05

会場:A05

時間:5 月 26 日 11:15-11:30

Seismic anisotropy from crust to core: a mineral and rock physics perspective
Seismic anisotropy from crust to core: a mineral and rock physics perspective
MAINPRICE, David1∗
MAINPRICE, David1∗
1
1

Geosciences Montpellier,, Universite de Montpellier, France
Geosciences Montpellier,, Universite de Montpellier, France

Since the early work of Hess and co-works for mantle in the 1960s and Poupinet et al. in 1980s for the inner core, we knowthat seismic anisotropy is a global phenomenon. Progress in seismology has led to a much more complete image of the Earth’s
interior in terms of heterogeneity and anisotropy. The interpretation of the seismic anisotropy requires a multidisciplinary effort
to unravel the geodynamic scenario recorded in today’s seismological snapshot. Progress in mineral physics on the experimental
measurement of elastic properties at extreme conditions are now completed by ab initio atomic modelling for the full range oftemperatures and pressures of the Earth’s interior. The new data on the elastic constants of wider range minerals enables more
realistic petrology for seismic anisotropy models. Experimental plastic deformation of polycrystalline samples at deep Earthconditions allows the direct study of crystal preferred orientation (CPO) and these studies are completed by ab initio atomicmodelling of dislocations and other defects that control plasticity. Finally, polycrystalline plasticity codes allow the simulationof CPO reported by experimentalists and the modelling of more complex strain paths required for geodynamic models. The CPOof crustal and mantle rocks from the Earth’s surface or recovered as xenoliths, provides a geological verification of the CPOs
present in the Earth. The systematic use of CPO measured by U-stage for field studies all over the world for last 40 years has
now been intensified in last 15 years by the use of electron back-scattered diffraction (EBSD) to study of CPO and the associateddigital microstructure. It is an appropriate time to analysis CPO databases of olivine and other minerals, which represents thework of our group, both present and former members, as well as collaborating colleagues. It is also interesting to compare thenatural record as illustrated by our databases in the light of recent experimental results. Information on CPO together with single
crystal elastic constants and the equation of state allow the modelling of seismic anisotropy due to plasticity at any PT condition,and the connection with geodynamic processes related to large-scale flow in the deep Earth.
キーワード: seismic anisotropy, upper mantle, inner core, plastic deformation, crystal preferred orientation
Keywords: seismic anisotropy, upper mantle, inner core, plastic deformation, crystal preferred orientation

1/1

SMP08-06

会場:A05

時間:5 月 26 日 11:30-11:45

蛇紋岩メランジェ中のテクトニックブロックの P-T 履歴より類推される沈み込みチャ
ネルのレオロジー
Rheology in subduction channel inferred from P-T paths in tectonic blocks from serpentinite melange
岡本 あゆみ 1 ; 竹下 徹 1∗
OKAMOTO, Ayumi S.1 ; TAKESHITA, Toru1∗
1
1

北海道大学
Hokkaido University

The Kamuikotan metamorphic rocks distributed around the Asahikawa-city have been known as typical high-P/T type metamorphic rocks. Serpentinite melange occupies the stratigraphical highest position of these metamorphic rocks, in which amphibolites tectonic blocks occur (e.g. Ishizuka et al., 1983). These blocks experienced medium to low pressure metamorphism
followed by high pressure metamorphism, while blueschist blocks which did not experience polyphase metamorphism also occur, as explained below. There are three types of compositional zoning in amphibole constituting these tectonic blocks (Okamoto
et al., 2013, Annual Meeting of Geological Society of Japan): Type I, actinolite overgrown by glaucophane; Type II, magnesiohornblende overgrown by actinolite, which is further rimmed by glaucophane; Type III, tschermakite overgrown by glaucophaneor magnesio-riebeckite. While type I zoning occurs in amphiboles from blueschist, type II zoning occur in ones from amphibolites. It is clearly inferred from type II zoning that the rocks were once cooled before they experienced high-P/T type
metamorphism. Amphiboles with type III zoning occur in a garnet-amphibolite sample, for which higher pressure and temperature for formation are inferred from the mineral assemblage than the amphibolites and cooling are also inferred to have occurredin it from the compositional zoning of garnet (Okamoto et al., 2013).
Takeshita et al. (2013, Annual Meeting of Geological Society of Japan) reported quartz c-axis fabric patterns from threemetachert layers intercalated with blueschist. Although all of these show monoclinic symmetry, indicating shear-dominant flow,
the shear direction relative to geographical orientations is unknown because of the occurrence as tectonic blocks. Further, thesequartz c-axis fabric patterns are slightly different, which are characterized by (1) asymmetrical small circle girdles with thehalf-opening angle less than 30o, (2) asymmetrical type I crossed girdle, and (3) a pattern close to type II crossed girdle with a
Y-maximum. The pattern (1), (2) and (3) indicate that basal<a>, basal<a>+rhomb<a>, and basal<a>+prism<a>are dominant slip systems, respectively, and the temperatures for formation are inferred to have increased from (1) to (3), ranging between
300 to 500 oC. Those P-T paths inferred from compositional zoning in amphiboles, and different temperature conditions inferredfrom quartz c-axis fabric patterns could indicate that rocks with different P-T paths could have been juxtaposed in the ancient
subduction channel, and also indicated the cooling of it. These results are in accord with the previous studies that the subduction
responsible for the formation of Kamuikotan metamorphic rocks were initiated at 140 Ma by the jump of trench (Kiminami andKontani, 1983), which was followed by the steady state subduction leading to the cooling of subduction channel and resultant
formation of high P/T type metamorphic rocks. Further, the juxtaposion of tectonic blocks in subduction channel could haveresulted from the weak rheology of sepentinite, as simulated by Gerya et al. (2002). In the present talk, we will demonstratethat the weak rheology in subduction channel could have been also contributed by dissolution-precipitation creep assisted byfracturing in amphibolites and blueschist in addition to the well-known weak serpentine rheology.
Keywords: Kamuikotan metamorphic rocks, P-T paths, quartz c-axis fabric, dissolution-precipitation creep, compositional zoning in amphibole, blueschist

1/1

SMP08-07

会場:A05

時間:5 月 26 日 11:45-12:00

EBSD-measured crystal preferred orientations of Sanbagawa eclogites
EBSD-measured crystal preferred orientations of Sanbagawa eclogites
UR REHMAN, Hafiz1∗ ; MAINPRICE, David2 ; YAMAMOTO, Hiroshi1 ; OKAMOTO, Kazuaki3
UR REHMAN, Hafiz1∗ ; MAINPRICE, David2 ; YAMAMOTO, Hiroshi1 ; OKAMOTO, Kazuaki3
1

Graduate School of Science and Engineering, Kagoshima University, Japan, 2 Geosciences Montpellier, Universite Montpellier
2, France, 3 Saitama University
1
Graduate School of Science and Engineering, Kagoshima University, Japan, 2 Geosciences Montpellier, Universite Montpellier
2, France, 3 Saitama University
Electron backscattered diffraction maps and crystal preferred orientations of the two types of eclogites in the subductionrelated high-pressure/low-temperature type Sanbagawa metamorphic belt, central Shikoku, Japan have been reported. Type 1
eclogite (garnet: 43%, omphacite: 35%, secondary actinolite: 7% and hornblende: 5% with minor quartz, muscovite and rutile),
garnet-rich and dark green, have strong crystal preferred orientations in omphacite and rutile, weak but complex fabric pattern ingarnet suggesting their deformation during peak eclogite facies stage. Type 2 eclogite (omphacite: 41%, garnet: 39%, retrograde
hornblende: 11% with minor quartz, epidote/zoisite, rutile and titanite), omphacite-rich and light green, also show identical fabric to that of type I. Crystal preferred orientations (CPOs) of minerals in both types show that omphacite has the strongest CPO
along [001]-axes and {011}-poles, suggesting intracrystaline flow along [001]{110} and [001](100) slip systems representing
subduction-related deformation rheology at mantle depth. Fabric preserved in rutile (stable at eclogite facies) is identical toomphacite with maxima along [001]-axes also indicate same deformation mechanism. Amphibolite facies minerals (e.g., hornblende and actinolite) exhibit similar CPOs to that of omphacite, indicating homotaxial crystal growth/recrystallization after the
replacement of omphacite during late-stage retrogression. In both type eclogites the deformation was mainly accommodated inomphacite which developed L-type fabric, representing a constrictive stress regime. Based on jadeite content (>0.35 in type 1
and <0.3 in type 2) in the omphacite in both type eclogites there is no clear correlation for the development of L-type fabric in
relation to the cation ordered-disordered structure despite of slightly different equilibration temperatures. Garnet, behaving as
rigid body, exhibit complex CPO and do not show any clear plastic deformation.
キーワード: EBSD, Eclogites, crystal preferred orientations, Sanbagawa
Keywords: EBSD, Eclogites, crystal preferred orientations, Sanbagawa

1/1

SMP08-P01

会場:コンベンションホール

時間:5 月 26 日 18:15-19:30

ボヘミア山塊 Moldanubian 帯 Nove Dvory 産超高圧エクロジャイト中に含まれる 4 種類の Ca 角閃石の起源
4 types of Ca-Amp found from Nove Dvory UHP eclogites and their origin, MoldanubianZone of the Bohemian Massif
安本 篤史 1∗ ; 平島 崇男 1
YASUMOTO, Atsushi1∗ ; HIRAJIMA, Takao1
11

京都大学理学研究科
Graduate School of Science, Kyoto Univ.

Meta-mafic rocks underwent ultra-high pressure (UHP) conditions tend to be anhydrous with bi-mineralic mineral assemblageof garnet and omphacite (Schmidt & Poli, 1998). The studied sample, ND0107, collected at Nove Dvory, Czech Republic, also
comprises mainly of garnet (Grt) and omphacite (Omp) with accessory minerals of rutile (Rt), ilmenite (Ilm), apatite (Apt).
However, 4 types Ca-amphiboles (Amp-Ia, Ib, Ma, and Mb) are identified based on the different modes of occurrence. Amp
grains identified in garnet are named Amp-I and those in the matrix are named Amp-M. Amp-I is subdivided into Amp-Ia and
Amp-Ib. Amp-Ia (40um in long dimension) appears as a member of multi-phase solid inclusions (MSI) which show a sporadic
distribution in garnet, and shows a close association with Omp maintaining UHP stage compositions with/without Rt. Amp-Ib (550um) appears as a member of aligned anhedral inclusions in Grt, associated with diopside (Di) and spinel (Spl), which are stable
at relatively low pressure conditions. Amp-M occurs as a member secondary minerals developed between Grt and Omp, and it issubdivided into Amp-Ma and Amp-Mb based on whether they are associated with Pl or not. Amp-Ma (10um in long dimension)is developed interstitially between Grt and Omp and is not associated with plagioclase (Pl). The incipient stage of Amp-Ma
formation can be represented by the alternation of idiomorphic Amp-Ma interspacing saw-blade shaped rim of garnet, and by
subsequent transformation of saw-blade shaped part of garnet into fine-grained symplectite composed of Di, Spl, and hematite(Hem). Amp-Mb (>5-50um in long dimensions) is also developed interstitially between Grt and Omp but is associated with Pl.
On the garnet-side of Amp-Mb, the fine-grained symplectite composed of Di, Spl, and Hem sometimes appears. The outlineof the fine-grained symplectite resembles the saw-blade shaped rim of garnet which is interspaced by Amp-Ma, suggesting that
Amp-Mb was formed at later stage of exhumation than Amp-Ma. Four types of Amp are mainly classified as pargasite (Prg).
Amp-Ia and Ma are almost K-free but Amp-Ib and Mb contains up to 0.3pfu of K. Mg# ascends in the order of Amp-Ib, Ia,
Mb, and Ma (70-82, 77-85, 80-93, 87-92, respectively). All types of Amp contain F as shown as follows; Ia: 0.07-0.2pfu; Ib:
0.02-0.28pfu; Ma: 0.10-0.16pfu; Mb: 0.05-0.16pfu, but a significant amount of Cl is identified only in Amp-Ib (0.10-0.30pfu).
Modes of occurrence of Amp and compositions of neighboring Grt and Omp suggest that Amp-Ib, Ma, and Mb were generated
by later stage fluid activity accompanying with decompositions of Grt and Omp. Since the studied eclogite is bi-mineralic at the
UHP stage, K, F, and Cl in secondary Amp should be supplied by the infiltrated fluids. In contrast, Amp-Ia seems like to beequilibrated with Grt and Omp rather than to be generated by decomposition of Grt and Omp. The maximum pressure limit of
Prg is known to be 2-3GPa (Gilibert, 1969), but it expands to higher pressures by incorporation of F in Prg (Holloway & Ford,
1975). High XF (= F/(F+Cl+OH) >0.4) is required for Prg to be stable at the peak metamorphic conditions of Nove Dvory.
However, Amp-Ia yields low XF (<0.1), and thus is considered to be a prograde relict.
キーワード: 超高圧, エクロジャイト, 角閃石, 流体
Keywords: UHP, eclogite, amphibole, fluid

1/1