Island arc tholeiite to boninitic melt evolution of the Cretaceous Kizildag (Turkey) ophiolite: Model for multi-stage early arc–forearc magmatism in Tethyan subduction factories

Lithos ◽  
2009 ◽  
Vol 113 (1-2) ◽  
pp. 68-87 ◽  
Author(s):  
Yildirim Dilek ◽  
Peter Thy
Keyword(s):  
Island Arc ◽  
Multi Stage ◽  
Melt Evolution

scholarly journals Polymineralic Inclusions in Megacrysts as Proxies for Kimberlite Melt Evolution—A Review

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 530 ◽  
Author(s):  
Bussweiler
Keyword(s):  
Chemical Properties ◽  
Major Question ◽  
Secondary Alteration ◽  
Origin And Evolution ◽  
Multi Stage ◽  
Kimberlite Magma ◽  
Physical And Chemical ◽  
Melt Evolution ◽  
And Chemical Properties

Polymineralic inclusions in megacrysts have been reported to occur in kimberlites worldwide. The inclusions are likely the products of early kimberlite melt(s) which invaded the pre‐existing megacryst minerals at mantle depths (i.e., at pressures ranging from 4 to 6 GPa) and crystallized or quenched upon emplacement of the host kimberlite. The abundance of carbonate minerals (e.g., calcite, dolomite) and hydrous silicate minerals (e.g., phlogopite, serpentine, chlorite) within polymineralic inclusions suggests that the trapped melt was more volatile‐rich than the host kimberlite now emplaced in the crust. However, the exact composition of this presumed early kimberlite melt, including the inventory of trace elements and volatiles, remains to be more narrowly constrained. For instance, one major question concerns the role of accessory alkali‐halogen‐phases in polymineralic inclusions, i.e., whether such phases constitute a common primary feature of kimberlite melt(s), or whether they become enriched in late‐stage differentiation processes. Recent studies have shown that polymineralic inclusions react with their host minerals during ascent of the kimberlite, while being largely shielded from processes that affect the host kimberlite, e.g., the assimilation of xenoliths (mantle and crustal), degassing of volatiles, and secondary alteration. Importantly, some polymineralic inclusions within different megacryst minerals were shown to preserve fresh glass. A major conclusion of this review is that the abundance and mineralogy of polymineralic inclusions are directly influenced by the physical and chemical properties of their host minerals. When taking the different interactions with their host minerals into account, polymineralic inclusions in megacrysts can serve as useful proxies for the multi‐stage origin and evolution of kimberlite melt/magma, because they can (i) reveal information about primary characteristics of the kimberlite melt, and (ii) trace the evolution of kimberlite magma on its way from the upper mantle to the crust.

Rodingitization of mafic rocks from Central Evia (Greece) associated with serpentinite exhumation: Evidence from Petrological, Geochemical and Isotopic data 

2021 ◽  
Author(s):  
Christos Karkalis ◽  
Andreas Magganas ◽  
Petros Koutsovitis ◽  
Theodoros Ntaflos
Keyword(s):  
Late Stage ◽  
Island Arc ◽  
Calc Alkaline ◽  
Isotopic Data ◽  
Metasomatic Process ◽  
Multi Stage ◽  
Thrust Sheets ◽  
Reaction Zones ◽  
Data Points ◽  
Element Transfer

<p>In Central Evia island (Aegean-Greece) serpentinized ultramafic rocks appear as elongated thrust sheets or in the form of olistostromes incorporated within Maestrichtian-Paleocene flysch. These are crosscut by well-developed rodingite dykes that were derived from four main protoliths that include i) Boninites, ii) Island-arc Tholeiitic Basalts and Gabbros, iii) Alkaline basalts and iv) Calc-alkaline basalts. They mainly comprise of minerals that include (hydro)garnet + chlorite + clinopyroxene ± vesuvianite. Accessory minerals include spinel ± calcite ± prehnite ± amphibole ± orthopyroxene ± olivine ± quartz ± opaque Fe-Ti oxides. Rodingites that were formed at the expense of boninites and island-arc tholeiitic rocks were likely formed within a single rodingitization stage, since garnet is mainly grossular-rich and relict primary clinopyroxene has been preserved. The rodingitization of the alkaline and calc-alkaline basalts seems to have occurred as a multi-stage metasomatic process that occurred during the exhumation of the mafic-ultramafic mantle wedge complex. This resulted in the development of late-stage andradite, vesuvianite and in some cases of chlorite during derodingitization. In this case, successive reaction zones with variability in the participating mineral phases were developed.  Geochemical results reveal remarkable rare earth element (REE) enrichments, especially in the inner zones, likely being the result of successive diffusion and element transfer. Few rodingites are characterized as calcite-bearing, whose stable <sup>13</sup>C-<sup>18</sup>O isotopic data points to the restricted involvement of late-stage mixed hydrothermal and seawater-related carbonation processes.</p>

Triassic sponges (Sphinctozoa) from Hells Canyon, Oregon

1988 ◽  
Vol 62 (03) ◽  
pp. 419-423 ◽  
Author(s):  
Baba Senowbari-Daryan ◽  
George D. Stanley
Keyword(s):  
Endemic Species ◽  
Upper Triassic ◽  
Island Arc ◽  
Tropical Island ◽  
The Family ◽  
Wallowa Terrane ◽  
Unique Condition ◽  
Hells Canyon

Two Upper Triassic sphinctozoan sponges of the family Sebargasiidae were recovered from silicified residues collected in Hells Canyon, Oregon. These sponges areAmblysiphonellacf.A. steinmanni(Haas), known from the Tethys region, andColospongia whalenin. sp., an endemic species. The latter sponge was placed in the superfamily Porata by Seilacher (1962). The presence of well-preserved cribrate plates in this sponge, in addition to pores of the chamber walls, is a unique condition never before reported in any porate sphinctozoans. Aporate counterparts known primarily from the Triassic Alps have similar cribrate plates but lack the pores in the chamber walls. The sponges from Hells Canyon are associated with abundant bivalves and corals of marked Tethyan affinities and come from a displaced terrane known as the Wallowa Terrane. It was a tropical island arc, suspected to have paleogeographic relationships with Wrangellia; however, these sponges have not yet been found in any other Cordilleran terrane.

Volcanoes of the southwestern extension of the active Mariana island arc: New swath-mapping and geochemical studies

Island Arc ◽  
1998 ◽  
Vol 7 (3) ◽  
pp. 596-607
Author(s):  
F RYER ◽  
S UJIMOTO ◽  
S EKINE ◽  
J OHNSON ◽  
K ASAHARA ◽  
...  
Keyword(s):  
Island Arc ◽  
Swath Mapping ◽  
Geochemical Studies ◽  
Mariana Island Arc

Planning and Search in Multi-Stage Risky Decision Making

2011 ◽  
Author(s):  
Jared Hotaling ◽  
Jerry Busemeyer ◽  
Richard Shiffrin
Keyword(s):  
Decision Making ◽  
Risky Decision Making ◽  
Risky Decision ◽  
Multi Stage

Effects of Cooking Oil Subsidy Removals on Related Markets in Malaysia: A Comparative Static, Multicommodity, Multi Stage Production Approach

2011 ◽  
Author(s):  
Jamal Othman ◽  
Yaghoob Jafari
Keyword(s):  
Equilibrium Model ◽  
Comparative Statics ◽  
Partial Equilibrium ◽  
Cooking Oil ◽  
Multi Stage ◽  
Supply Factor ◽  
Partial Equilibrium Model ◽  
Factor Markets ◽  
Input Markets ◽  
Production Approach

Malaysia is contemplating removal of most of her subsidy support measures including subsidies on cooking oil which is largely palm oil based. This paper aims to examine the effects of cooking oil subsidy removals on the competitiveness of the oil palm subsector and related markets. This is done by developing and applying a comparative static, multi-commodity, partial equilibrium model with multi-stages of production function for the Malaysian perennial crops subsector which explicitly links different stages of production, primary and intermediate input markets, trade, and policy linkages. Results partly suggest that export of cooking oil will increase by 0.2 per cent due to a 10 per cent cooking oil subsidy reduction, while domestic output of cooking oil may eventually see a net decline of 1.97 per cent. The results clearly point out that the effect of reducing cooking oil subsidies is relatively small at the upstream levels and therefore it only induces minute effects on factor markets. Consequently, the market for other agricultural crops is projected to change very marginally.   Keywords: Multicomodity, comparative statics, partial equilibrium model, output supply-factor markets linkages, effects of cooking oil subsidy removals.

IMPACT ASSESSMENT OF AGRICULTURAL TRANSFORMATION PROJECT ON PRODUCTIVITY AND POVERTY AMONG RICE FARMERS IN KANO STATE, NIGERIA.

2020 ◽  
Vol 4 (2) ◽  
pp. 392-400
Author(s):  
O. S. Balogun ◽  
M. A. Damisa ◽  
O. Yusuf ◽  
O. L. Balogun
Keyword(s):  
Sampling Method ◽  
Insect Pests ◽  
Study Data ◽  
Average Treatment Effect ◽  
Descriptive Statistics ◽  
Rice Farmers ◽  
Agricultural Transformation ◽  
Multi Stage ◽  
Significant Difference ◽  
Late Model

The study was carried out to examine the effect of agricultural transformation on the beneficiary’s productivity and poverty of rice farmers in Kano State Nigeria. A multi-stage sampling method was employed to select 571 respondents for the study. Data were collected through structured questionnaires on respondent’s income, input and output quantities as well as their expenditures. Data were analysis using descriptive statistics, Foster-Greer-Thorbecke (FGT), Propensity score matching and LATE model. Results from the study shows that respondents productivity revealed a significant difference of about 127 kg/ha in rice productivity between participants and non-participants. Also, the LATE estimates revealed an average treatment effect ATE0 of about 222.98kg/ha. Furthermore, the project had a significant effect N11, 321.4 on the participant’s consumption expenditure than the non-participants N9980.60. Moreover, participants were, able to increase their household total expenditures by N34780 per annum. Fluctuations of input/output prices insect pests and inadequate extension visits were all the major constraints faced by the farmers. It was recommended that farmers’ information and sensitization system should be overhauled and improved. Also, attention should be given to well organize extension visits for the farmers from stake holders

Radiofrequency ablation of colorectal liver metastases

2019 ◽  
Vol 98 (10) ◽  
Keyword(s):  
Radiofrequency Ablation ◽  
Liver Resection ◽  
Liver Metastases ◽  
Colorectal Liver Metastases ◽  
Survival Rates ◽  
Postoperative Mortality ◽  
Disease Free Survival ◽  
Female Ratio ◽  
Liver Resections ◽  
Multi Stage

Introduction: Radical liver resection is the only method for the treatment of patients with colorectal liver metastases (CLM); however, only 20–30% of patients with CLMs can be radically treated. Radiofrequency ablation (RFA) is one of the possible methods of palliative treatment in such patients. Methods: RFA was performed in 381 patients with CLMs between 01 Jan 2001 and 31 Dec 2018. The mean age of the patients was 65.2±8.7 years. The male to female ratio was 2:1. Open laparotomy was done in 238 (62.5%) patients and the CT-navigated transcutaneous approach was used in 143 (37.5%) patients. CLMs <5 cm (usually <3 cm) in diameter were the indication for RFA. We used RFA as the only method in 334 (87.6%) patients; RFA in combination with resection was used in 36 (9.4%), and with multi-stage resection in 11 (3%) patients. We performed RFA in a solitary CLM in 170 (44.6%) patients, and in 2−5 CLMs in 211 (55.6%) patients. We performed computed tomography in each patient 48 hours after procedure. Results: The 30-day postoperative mortality was zero. Complications were present in 4.8% of transcutaneous and in 14.2% of open procedures, respectively, in the 30-day postoperative period. One-, 3-, 5- and 10-year overall survival rates were 94.8, 66.8, 43.9 and 16.6%, respectively, in patients undergoing RFA, and 90.6, 69.1, 52.8 and 39.2%, respectively, in patients with liver resections. Disease free survival was 63.2, 30.1, 18.4 and 13.1%, respectively, in the same patients after RFA, and 71.1, 33.3, 22.8 and 15.5%, respectively, after liver resections. Conclusion: RFA is a palliative thermal ablation method, which is one of therapeutic options in patients with radically non-resectable CLMs. RFA is useful especially in a non-resectable, or resectable (but for the price of large liver resection) solitary CLM <3 cm in diameter and in CLM relapses. RFA is also part of multi-stage liver procedures.

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