Spider Diagrams with Absence

Eocene granitoids in NW Anatolia occurred following the continental collision between Sakarya Continent and Tauride-Anatolide Platform and mark the onset of post-collisional magmatism in the region. One of the representative members of the Eocene granitoids, the Tepelda&#287; pluton crops out as two isolated granitic bodies and is intruded into the Cretaceous blueschist assemblages (Kocasu formation) and ophiolitic rocks within the Izmir-Ankara-Erzincan suture zone (IAESZ). South Tepelda&#287; pluton (STP) is composed mainly of granodiorite with subordinate quartz diorite, which show transitional contacts. Aplitic dykes crosscut the pluton as well as the country rocks. STP includes a number of mafic microgranular enclaves (MME) of gabbro/diorite composition.Geochemically, STP shows distinct I-type affinity with a metaluminous to slightly peraluminous (ASI &#8804;1.02) nature. The samples are medium-K to high-K calc-alkaline in character. They exhibit depletion in HFSE (Ti, Hf, Zr, Nb and Ta) compared to large ion lithophile elements (Rb, Ba, Th, U, K) and presents negative Nb, P, Ti anomalies. STP displays slight negative Eu anomalies (Eu/Eu* = 0.7&#8211;1.2), enrichment in LREE and flat HREE patterns in chondrite-normalized spider diagrams. MELTS modeling (with initial parameters of 1&#8211;3 kbar pressure, 2&#8211;3% water and QFM-NNO oxygen fugacity buffers) indicate that compositional variations in STP samples can be interpreted as a result of open system processes (assimilation fractional crystallization) rather than a reflection of fractional crystallization in the upper crustal magma chamber. All thermodynamic simulations dictate a crustal assimilation, especially in the late stages of the magmatic process, with a MgO, Na2O and Al2O3-rich assimilant similar to the suture zone (IAESZ) rocks.

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Geology, petrology and tectonomagmatic evolution of the plutonic crustal rocks of the Sabzevar ophiolite, NE Iran

Geological Magazine ◽

10.1017/s0016756812000933 ◽

2013 ◽

Vol 150 (5) ◽

pp. 862-884 ◽

Cited By ~ 10

Author(s):

MORTEZA KHALATBARI JAFARI ◽

HASSAN A. BABAIE ◽

MOJTABA MIRZAIE

Keyword(s):

Subduction Zone ◽

Subduction Zones ◽

Island Arc ◽

Magma Chambers ◽

Northern Margin ◽

Crustal Rocks ◽

Microscopic Studies ◽

Element Enrichment ◽

Spider Diagrams ◽

Ocean Ridge

AbstractThe plutonic crustal sequence exposed northeast of Sabzevar is part of the ophiolitic belt of Sabzevar that occurs along the northern margin of the Central Iran micro-continent. The sequence includes olivine and pyroxene gabbro with cumulate characteristics, isotropic gabbro, foliated gabbro and a diabase sheeted dyke complex cut by wehrlite and olivine websterite intrusions, and pegmatite gabbro and plagiogranite as small intrusions and dykes. The sequence is comparable to gabbros in known ophiolite complexes. Microscopic studies show an abundance of the mesocumulate and heteradcumulate textures that represent open system magma chambers, which are common in supra-subduction zones. The olivine → plagioclase → clinopyroxene → ± orthopyroxene → amphibole trend of mineralization in the gabbros, similar to mid-ocean ridge basalt (MORB), and olivine → clinopyroxene → ± orthopyroxene → plagioclase → amphibole, similar to arc rocks, indicate the diversity in the formation of these rocks, and represent petrographic evidence of their formation in a supra-subduction zone. The rocks have calc-alkaline to tholeiitic affinities, and niobium depletion in the spider diagrams of diabase that matches the patterns of island arc magma. These patterns, and the light rare earth element enrichment of the diabase and plagiogranite, suggest the effect and introduction of the fluids, originating from the subducting slab, beneath the mantle wedge. The low titanium compositions, matching those of arc diabase and plagiogranite, plot in the island arc to MORB tectonomagmatic fields, and suggest formation of the Sabzevar ophiolitic plutonic crustal sequence in a supra-subduction zone during Late Cretaceous time.

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On the expressiveness of second-order spider diagrams

Journal of Visual Languages & Computing ◽

10.1016/j.jvlc.2013.07.002 ◽

2013 ◽

Vol 24 (5) ◽

pp. 327-349 ◽

Cited By ~ 4

Author(s):

Peter Chapman ◽

Gem Stapleton ◽

Aidan Delaney

Keyword(s):

Second Order ◽

Spider Diagrams

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Petrogenesis and regional tectonic significance of Late Devonian mafic intrusions in the Meguma Zone, Nova Scotia

Canadian Journal of Earth Sciences ◽

10.1139/e95-145 ◽

1995 ◽

Vol 32 (11) ◽

pp. 1883-1898 ◽

Cited By ~ 22

Author(s):

Marcus C. Tate ◽

D. Barrie Clarke

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Island Arc ◽

Late Devonian ◽

Calc Alkaline ◽

Mafic Intrusions ◽

Heavy Rare Earth Elements ◽

Regional Tectonic ◽

Spider Diagrams ◽

Ocean Lithosphere

Late Devonian (377–368 Ma, 40Ar/39Ar; 376 Ma, U–Pb) mafic intrusions in the Meguma Zone crop out as dykes, plugs, and synplutonic bodies of gabbro, diorite, or lamprophyre. All of the intrusions have similar lithologie characteristics and hydrous ferromagnesian mineral assemblages, and they appear to represent a genetically related series of mafic bodies with similar petrogenetic histories in the crust of the Meguma Zone. The intrusions show wide chemical variation of SiO2 (45.7–65.7 wt.%), Al2O3 (8.9–26.5 wt.%), MgO (2.8–26.5 wt.%), CaO (1.2–11.2 wt.%), and K2O (0.1–4.4 wt.%), and they have calc-alkaline, high-K calc-alkaline, and shoshonitic characteristics. Large-ion lithophile elements (LILE) are present at variable but high concentrations (e.g., Ba = 62–1920 ppm, Sr = 176–2567 ppm) relative to most high field strength element (HFSE) abundances (e.g., Y = 10–37 ppm, Zr = 8–421 ppm), and light rare-earth elements (LREE) have much higher concentrations than heavy rare-earth elements (HREE) (La/Lu = 24–330). Initial Sr isotopic ratios (0.7044–0.7079) and εNd values (−4.36 to 3.69) are highly variable. Scatter on major oxide variation diagrams probably results from the fractionation of all the major modal phases in the intrusions (olivine, augite, hornblende, and (or) plagioclase), and the cumulate characteristics of some bodies support this suggestion. Nevertheless, parallel patterns for the intrusions on mid-ocean ridge basalt (MORB) normalized spider diagrams support the notion of similar mafic parent melts, and Sr–Nd isotopic data identify contamination by continental crust in only one of the intrusions. The most primitive picrite contains approximately basaltic HFSE in conjunction with HREE at 5–11CN, perhaps suggesting that the magmas emanated from depleted peridotite or pyroxenite, but high alkalies, LILE (<60MN), and LREE (10–100CN), and elevated initial Sr ratios in all of the intrusions, also require the existence of an enriched source component. Troughs in the spider diagrams at Ta, Nb, and Ti, and Sr–Nd isotopic values comparable with modern island-arc basalts, suggest that fluids derived from subducted ocean lithosphère metasomatized the mantle. Tectono-magmatic discriminators imply a continental margin arc environment rather than an island arc, and the intrusions record either Early Devonian subduction of Iapetus Ocean lithosphère beneath the Avalon terrane, Middle Devonian subduction of Theic Ocean lithosphère beneath the Meguma terrane, or an inherited subduction signature formed during a much older event.

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Reasoning with spider diagrams

Proceedings 1999 IEEE Symposium on Visual Languages ◽

10.1109/vl.1999.795885 ◽

1999 ◽

Cited By ~ 18

Author(s):

J. Howse ◽

F. Molina ◽

J. Taylor ◽

S. Kent

Keyword(s):

Spider Diagrams

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Spider Diagrams: A Diagrammatic Reasoning System

Journal of Visual Languages & Computing ◽

10.1006/jvlc.2000.0210 ◽

2001 ◽

Vol 12 (3) ◽

pp. 299-324 ◽

Cited By ~ 56

Author(s):

JOHN HOWSE ◽

FERNANDO MOLINA ◽

JOHN TAYLOR ◽

STUART KENT ◽

JOSEPH YOSSI GIL

Keyword(s):

Diagrammatic Reasoning ◽

Reasoning System ◽

Spider Diagrams

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Regularities of distribution of rare-earth elements in the Kivakka olivinite-gabbronorite layered intrusion (Northern Karelia)

Геохимия ◽

10.31857/s0016-7525642145-167 ◽

2019 ◽

Vol 64 (2) ◽

pp. 145-167

Author(s):

Ya. V. Bychkova ◽

D. A. Bychkov ◽

E. A. Minervina ◽

B. A. Ivlev ◽

A. R. Tskhovrebova ◽

...

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Layered Intrusion ◽

Genetic Characteristics ◽

Crystallization Differentiation ◽

Critical Zones ◽

Spider Diagrams ◽

The Stability ◽

Petrographic Description ◽

Residual Melt

This study discusses the presentation of rare-earth elements (REEs) in the rocks of the Kivakka Olivinite-Gabbronorite Layered Intrusion in North Karelia. It aimed to provide a detailed petrographic description of the mineral parageneses that are present in the studied section of the massif. We found that the same minerals can manifest in both intercumulative and cumulative positions, depending on the degree of melt fractionation. At the same time, their quantity, which determines both the petrographic characteristics and the name of the rock, is not a criterion for their presence during the cumulus phases. We analyzed the concentrations of REEs in rocks and rock-forming minerals in the Kivakka massif, considering the REE concentration vertically and in the critical zones of contrast interbedding. In the study area, REEs are present as incoherent elements and accumulate in the residual melt, together with U, Th, Zr, and other incoherent elements, which make them a useful indicator of the degree of melt fractionation. In some cases, they can reflect different structural and genetic characteristics, such as the degree of cumulus density in a specific type of cumulative paragenesis. The presence of hydrothermal changes is best reflected by a change in Ce concentration. The preservation of the stability of the configuration and the slopes of the lines on the spider diagrams for REE indicate that the process of crystallization differentiation took place in a closed system.

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