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Gokce K Ustunisik

Gokce K Ustunisik
South Dakota School of Mines and Technology/American Museum of Natural History, New York, NY, United States · Department of Geology and Geological Engineering/Department of Earth and Planetary Sciences

PhD in Geochemistry

About

85
Publications
8,406
Reads
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367
Citations
Citations since 2017
27 Research Items
221 Citations
201720182019202020212022202301020304050
201720182019202020212022202301020304050
201720182019202020212022202301020304050
201720182019202020212022202301020304050
Additional affiliations
September 2012 - present
American Museum of Natural History
Position
  • Researcher
August 2012 - August 2016
American Museum of Natural History
Position
  • Faculty for MAT (Master of Arts) in Earth Science Education
September 2009 - August 2012
Stony Brook University
Position
  • Research Associate

Publications

Publications (85)
Article
White micas (muscovite, phengite, paragonite) are widespread in rocks of high-pressure, low-temperature (high P/T) terranes. Metamorphism in these settings occurs over a wide range in pressure and a relatively narrow range in temperature. Pressure increase results in forward progress of the aluminoceladonite exchange (Al-Cel, AlIV + AlVI=SiIV+[Fe²⁺...
Article
Full-text available
A gray-colored sediment from Erzurum/Turkey zone was characterized by scanning electron microscopy, X-ray diffraction, chemical analysis, and thermal analysis techniques. The raw sample contains mainly an amorphous biogenic opal-A as well as opal-CT, smectite, illite, and quartz as impurities. The XRD-pattern of the heated samples at different temp...
Article
Full-text available
Acid activation was carried out by heating muds prepared from Ca-rich bentonite (CaB), sulfuric acid (H 2 SO 4 ) and distilled water, yielding various bleaching earths (BEs). The roles of each of the process variables, namely mass fraction of H 2 SO 4 ( x ) in the dried CaB and pure H 2 SO 4 mixture, heating temperature ( T ) and contact time ( t )...
Article
Surface area (20 m²g⁻¹) and pore volume (0.015 cm³g⁻¹) estimate for the bottom ash of an asphaltite from Şırnak/Turkey deposit, were determined using the nitrogen adsorption/desorption isotherms at -196oC. The shape and location of the adsorption/desorption isotherms of ammonia on the ash at 0, 50, 100, and 200°C revealed that the irreversible chem...
Article
Mineral-hosted melt inclusions have become an important source of information on magmatic processes. As the number of melt inclusion studies increases, so does the need to establish recommended practice guidelines for collecting and reporting melt inclusion data. These guidelines are intended to ensure certain quality criteria are met and to achiev...
Article
Full-text available
Study of melt inclusions (MIs) is a commonly applied method for defining the composition of magmas present at depth prior to mixing, fractionation, and degassing. Our ability to use data from MIs is complicated by post-entrapment processes (PEP) that can modify their composition during transport and eruption. Many of the PEP can be reversed by heat...
Presentation
Full-text available
This file contains the slides from our Goldschmidt 2020 presentation on the utility of plagioclase-hosted inclusions
Article
We determined the mineral-melt partition coefficients (Di’s) and the compositional and/or temperature dependency between grossite, melilite, hibonite, olivine and Ca-, Al-inclusion (CAI)-type liquids for a number of light (LE), high field strength (HFSE), large ion lithophile (LILE), and rare earth (REE) elements including Li, Be, B, Sr, Zr, Nb, Ba...
Article
Full-text available
Apatite-melt partitioning experiments were conducted in a Deltech vertical-quench 1-bar furnace at 0 GPa and 950-1050 °C using an Fe-rich basaltic starting composition. Each experiment had a unique F:Cl ratio to assess the partitioning of F and Cl between apatite and melt, and the oxygen fugacity of all experiments was between IW and IW-1. Apatite-...
Article
Full-text available
Quantitative models of petrologic processes require accurate partition coefficients. Our ability to obtain accurate partition coefficients is constrained by their dependence on pressure temperature and composition, and on the experimental and analytical techniques we apply. The source and magnitude of error in experimental studies of trace element...
Article
Mt. Jefferson is a large composite volcano located in the central Oregon Cascades that has erupted a diverse compositional suite of lavas from basalt to rhyodacite (50-72 wt. % SiO2). Individual eruptive units contain multiple populations of plagioclase, and a variety of mafic textural/mineralogical components often preserved as large cm- to mm-siz...
Article
Experimental degassing of H-, F-, Cl-, C-, and S-bearing species from volatile-bearing magma of lunar composition at low pressure and fO2 close to the quartz-iron-fayalite buffer (QIF) indicates that the composition of the fluid/vapor phase that is lost changes over time. A highly H-rich vapor phase is exsolved within the first 10 min of degassing...
Article
The presence of anorthosite in the lunar highlands containing plagioclase that is compositionally less calcic than plagioclase in the ferroan anorthosites cannot be readily explained by the current lunar paradigm in which lunar anorthosite was produced as a floatation cumulate in the lunar magma ocean. Phase-equilibrium experiments were conducted t...
Conference Paper
Full-text available
Introduction: Ca-, Al-rich inclusions (CAIs) in chondrite meteorites are the oldest crystalline solids in the solar system. Therefore, the variations of trace element concentrations within individual CAIs can provide crucial information into the nature of processes effective in the primitive solar nebula. Despite most CAIs having complex histories...
Article
Trace-element partitioning experiments between grossite and CAI-type melts reveal that REEs, HFSEs (Zr, Nb, Hf, Ta, Th), and LILE (B) are incompatible in grossite.
Article
Full-text available
Although plagioclase is the most abundant mineral in crustal rocks, the factors that control the magnitude of compositional zoning in plagioclase remain poorly constrained. The composition of magmatic plagioclase depends upon physical parameters such as temperature (T) and total pressure (P), as well as the full range of compositional controls, inc...
Conference Paper
Full-text available
Mt. Jefferson is a large composite volcano in the central Oregon Cascades. It is characterized by more diverse lavas than found at Mt. Hood and slightly less diverse compositions than the Three Sisters centers to the south (Conrey et al., 2004). In an attempt to understand the relative roles of the magma mixing, decompression, crystallization and d...
Conference Paper
Full-text available
The variability of chondrule volatile element contents may provide information about the processes that shaped the early solar system and its compositional heterogeneity. An essential observation is that chondrule melts contain very low alkalies and other volatile elements (e.g., Cl). The reason for this depletion is the combined effects of cooling...
Article
Full-text available
Successful synthesis of fluorapatite has been achieved through ion-exchange between NIST hydroxlyapatite SRM 2910a and optical-grade fluorite. Additional intermediate F-OH apatite compositions were made through ion-exchange between the newly synthesized fluorapatite and the original hydroxylapatite. Based on solution calorimetric data collected on...
Conference Paper
Full-text available
Introduction: Vapor-liquid interactions are important in the formation and evolution of the earliest solids including chondrules and Type B (igneous) Ca, Al-rich inclusions (CAIs) in protoplanetary disk environments. The bulk major element and mineral chemistry of CAIs and chondrules closely resembles that of the high temperature (T) solid/liquid a...
Conference Paper
Full-text available
Introduction: The chemical variability of chon-drule volatile element contents may provide a wealth of information on the processes that shaped the early solar system and its compositional heterogeneity. An essential observation is that chondrule melts contain very low alkalis and other volatile elements such as Cl. The primary reason for this depl...
Conference Paper
Full-text available
Introduction: Anorthosites are found in abundance in the Highlands. These rocks are believed to represent some of the earliest crust of the Moon, produced in a Lunar Magma Ocean (LMO) approximately 4.4 billion years ago [1]. While many of these anor-thosites are highly calcic with plagioclase anorthite contents over 95% (>An95), some anorthosite sa...
Article
Cl-free and Cl-bearing heating/degassing experiments ( at <1 bar for 10 min, 4h, 6 h) on Al3509 chondrule melt reveals the systematic role of Cl on alkali volatility.
Article
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Apatite-melt partitioning experiments were conducted and the results put into the context of using apatite to determine H2O abundances in melts/source regions.
Article
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Experimental tests of predicted mineral-liquid equilibria in condensates reveal no perovskite+liq, small olivine+spinel+liq, and large melilite+liquid fields.
Article
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Apatite sensu lato, Ca-10(PO4)(6)(F,OH,Cl)(2), is the tenth most abundant mineral on Earth, and is fundamentally important in geological processes, biological processes, medicine, dentistry, agriculture, environmental remediation, and material science. The steric interactions among anions in the [0,0,z] anion column in apatite make it impossible to...
Article
We equilibrated bulk condensate compositions predicted for specific CI dust enrichments and temperatures to test predicted mineral-liquid equilibria. Predictions are wrong for perovskite CaTiO_3 + CaO-MgO-Al_2O_3-SiO_2 liquid, correct in most other tests.
Conference Paper
Full-text available
Introduction: Condensation models describe the equilibrium distribution of elements between coexisting vapor, solids, and liquid in closed chemical systems at fixed total pressure (P tot) and temperature (T) [1-4]. The VAPORS model [2-4] uses the CaO-MgO-Al 2 O 3-SiO 2 (CMAS) melt model of Berman [5] for liquids at T above the stability field of ol...
Article
During the 2009–2010 school year, 40% of New York City (NYC) Earth science teachers were not certified to teach Earth science [New York State Education Department (NYSED), 2011]. This highlights a longstanding shortage of certified teachers, which persists today and prevents many schools from offering courses on the subject, thus diminishing studen...
Article
Full-text available
Tertiary volcanism (34.3 ± 1.2 Ma and 0.4 ± 0.7 Ma) in NW Turkey produced lead + zinc bearing trachyte, latite, dacite and rhyodacite tuffs, and agglomerates, as well as basaltic andesite, andesite, dacite, and rhyolite lavas. The primary objective of this study is to develop quantitative models for the evolution of magmas that produced these rocks...
Article
Full-text available
Cl-free and Cl-bearing heating/degassing experiments were conducted at <1 bar on a synthetic Al3509 chondrule melt for time intervals of 10 min, 4 hr, and 6 hr.
Article
Experiments were done to test predictions of VAPORS code on constraining mineral-liquid equilibria in dust-enriched systems.
Article
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Fractional crystallization of lunar basalt 14053 with added Cl and F shows evidence of Fe-enrichment and Si-depletion and increasing late liquid density.
Article
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Considerations of plagioclase stability in highlands lithologies suggests that the lunar magma ocean need not have been as alkali depleted as currently thought.
Conference Paper
Full-text available
Introduction: Condensation models describe the equilibrium distribution of elements between coexist-ing phases (solids, liquid, and vapor) in a closed chemical system, where the vapor phase is always present, using equations of state of the phases involved at a fixed total pressure (P tot) and temperature (T) [1]. The VAPORS code of [2] includes th...
Article
The Master of Arts in Teaching (MAT) Program at the American Museum of Natural History is a first-of-its-kind program designed to prepare participants to be world-class Earth Science teachers. The dearth of Earth Science teachers in New York State has resulted in fewer students taking the statewide Earth Science Regents Exam, which negatively affec...
Article
Experiments were conducted as time studies to monitor the changes in relative volatile contents during successive intervals of degassing. The first vapor (after 1 hr) was water-rich; the successive vapor was dry but rich in metal chlorides and fluorides.
Article
Phase equilibria computations have constrained the compositions of parental liquids that can give rise the lithologies observed by M^3 at Moscoviense Basin and indicated evolution of residual melts to rhyolitic compositions.
Article
A variety of studies have focused on redistribution of mantle material by ascent of magmas through the crust, and the nature of these magmas and their compositional evolution (Nekvasil et al. 2009; McCubbin et al. 2009; McCubbin et al. 2010). An additional strong focus has been surface alteration/weathering and redistribution of surface materials b...
Article
Ascending magmas likely played a major role in redistributing material from the martian mantle to the crust, from the crust to the surface, and finally to the atmosphere, particularly during rapid growth of the secondary crust. This redistribution may have involved early loss of dense mineral phases from the magma due to crystal fractionation at th...
Article
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Recent SIMS analysis of water, F, and Cl in lunar apatite suggests significantly higher volatile abundances in lunar magmas than previously considered. However, apatite is commonly a late-crystallizing mineral and its volatile content may reflect late-stage open-system processes that have perturbed the magmatic volatile content and obscured direct...
Article
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During the last 7 Ma, eruptions of the Small Hasandag composite volcano in Central Anatolia, Turkey, have produced calc-alkaline lavas ranging in composition from basalt to rhyolite. Published research on this volcano suggests that crystal fractionation and magma mixing are the two important processes controlling the differentiation of the Small Ha...
Article
Apatite has the potential to retain information on degassing of water, Cl, and F. Lunar apatite records a history of early dehydration followed by loss of a brine during second boiling.
Article
Magmas reaching the low pressure lunar surface have potentially lost volatiles by exsolution of a fluid or vapor + liquid aqueous phases. With the recent SIMS determination of water, F, and Cl abundances in apatite from lunar samples [1-3], of primary interest is the use of these data to estimate volatile abundances in the lunar magmatic source reg...
Article
The recent determination of volatile abundances in apatite from lunar samples [1-3] has opened the door for a new paradigm of lunar evolution, since apatite has the potential to retain information on the water, F, and Cl abundances of crystallizing lunar magmas. For all of the samples investigated, apatite formed late and will therefore, reflect vo...
Article
Experiments on the effect of Cl and S on mineral stability in magma of Backstay composition indicates suppression of olivine, plagioclase, and amphibole stability.
Article
Experimental alteration of a partly crystallized Humphrey basalt by Cl-and S- fluid exsolved from a magma of Backstay composition at mid-crustal levels produced a martian amphibolite.
Article
A question of major relevance to the assessment of habitability of the Martian crust is to what extent hydrothermal activity could have produced the alteration assemblages identified on the surface. This study focuses specifically on the possible role of magmatic fluids in producing these assemblages. Evidence for magmatic fluids is found in melt i...
Article
In many explosively erupting volcanoes geophysical evidence suggests pooling of magma in multiple magma chambers within the crust before eruption. We evaluated the effect of adiabatic uprise of magma followed by isobaric crystallization on plagioclase zoning using the Melts software. A basaltic andesite, parental magma for the explosively erupting...
Article
Full-text available
The composition of plagioclase growing from a melt depends on physical parameters such as changes in temperature (T), total pressure (Ptotal), oxygen fugacity, or water content of the melt (XH2O). The changes in these physical parameters can be modeled under various differentiation scenarios either simulating an isentropic rise of magma between two...
Article
Plagioclase phenocryts in volcanic rocks commonly record various differentiation processes in their magma chambers. A fundamental assumption is that the normal zoning followed by a reverse zoning or oscillatory zoning are either due to the changes in temperature (T) during mixing of two magmas or due to the fluctuations in water pressure (PH2O) and...
Article
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An industrial raw material taken from Sivrihisar (Eskişehir, Turkey) region was heat-treated at different temperatures in the range of 100–1000°C for 2 h. The volumetric percentage of the particles having a diameter below 2 μm after staying in an aqueous suspension of the material was determined as 67% by the particle size distribution analysis. Th...
Article
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An industrial raw material taken from Beypazarı (Ankara, Turkey) region was heated at different temperatures in the 100–1100°C interval for 2 h. The volumetric percentage of particles having diameter below 2 μm in an aqueous suspension of the material held 24 h were determined as 85% by the particle size distribution analysis. The mineralogical com...