Barry Hanan - Academia.edu (original) (raw)

Papers by Barry Hanan

Major Element, trace Element, and isotopic data for samples from Shinkai 6500 Dive Sites and DSDP... more Major Element, trace Element, and isotopic data for samples from Shinkai 6500 Dive Sites and DSDP Sites 447, 458, and 459a. The download also includes dive sites and recovered lithologies. These data are relevant to the study of fore-arc basalts and subduction initiation in the Izu-Bonin-Mariana system.

InterRidge International Workshop Circum-Antarctic Ridges

Lithos, 2015

Near-contemporaneous suites of mafic lavas from Sivas, Central Anatolia record different petrogen... more Near-contemporaneous suites of mafic lavas from Sivas, Central Anatolia record different petrogenetic histories on the eastern and western sides of a major regional suture marked by the Kızılırmak River. The Sivas basaltic suite has major and trace element compositions suggesting derivation from an anhydrous peridotitic mantle source region. Basaltic trachyandesites in this group are related by up to ~65% fractional crystallization of the observed anhydrous mineral phases from a frequently-erupted basaltic parent with ~9 wt.% MgO. Chondrite-normalized Tb/Yb values indicate that the basaltic magmas likely originate from melting peridotite at pressures near the spinel-garnet transition. Clinopyroxene with a range of Al vi /Al iv values suggest multiple stages of mineral growth, consistent with a mantle origin followed by fractional crystallization at shallow crustal levels. In contrast, Sivas basanites have higher abundances of key incompatible elements that suggest a source area in the subcontinental lithosphere with hydrous metasomatic mineral phases. Clinopyroxene in Sivas basanites have Al vi /Al iv values that cluster around 0.25, suggesting the magmas stalled at mid-crustal depths prior to rapid ascent and eruption. High abundances of incompatible major and trace elements in the most magnesian basanites show that the basanite lavas are not related to one another or to the basalt suite by fractionation. The thermal environment that led to formation of parental magmas for both the basalt suite and the basanites likely reflects ascent of asthenospheric material around and through torn slabs beneath Central Anatolia, providing heat to melt both ascending mantle and regionally metasomatized subcontinental lithosphere. This process is enhanced by recent trans-tensional deformation in the Anatolian plate that allows mafic melts to rise to shallow depths on both sides of the Kızılırmak River.

Geochemistry, Geophysics, Geosystems, 2017

Lithos

Abstract Quaternary mafic lavas in Central Anatolia provide geochemical insights into melt genera... more Abstract Quaternary mafic lavas in Central Anatolia provide geochemical insights into melt generation processes following regional delamination of the subducted Tethyan slabs. New geochemical data from the Pleistocene Hasandag Cinder Cone Province (HCCP) and Karapinar Volcanic Field (KVF) record contributions from subduction-modified lithospheric and sub-lithospheric source domains that are distinct from those sampled elsewhere across Anatolia (e.g., Pearce et al., 1990; Aldanmaz et al., 2006; Keskin, 2007; Chakrabarti et al., 2012; Reid et al., 2017). Hasandag cinder cones are primarily basaltic, with subordinate trachybasalt and basaltic trachyandesite; Karapinar lavas comprise basalts and andesites with subordinate basaltic trachyandesite and basaltic andesite. Anomalously high Li, Na, Ti and Zr abundances and Ba/Rb values in these South-Central Anatolian primitive mafic lavas suggest significant contribution from metasomatic phases (i.e., amphibole, zircon and rutile); Dy/Ybn values measured in the mafic volcanics indicate melting in the spinel stability field. Correlation between 87Sr/86Sr and eNd in HCCP and KVF lavas indicate pseudo-binary mixing between enriched and depleted endmembers, while eNd-eHf isotopic values that plot above the terrestrial array extend toward sediment compositions sampled from the eastern Mediterranean Sea (Klaver et al., 2015). Together, trace element chemistry and Sr-Nd-Hf-Pb isotope compositions suggest input from a spatially heterogeneous mantle with contributions from depleted MORB-like and recycled sediment sources. The apparent presence of pyroxenite and hydrous metasomes within the HCCP and KVF source regions, and abundant dense mafic cumulates associated with the adjacent Hasandag stratovolcano, support an unstable small-scale lithospheric density structure in South-Central Anatolia. We suggest regional delamination of the Neotethyan slab on a regional scale caused upwelling asthenosphere to destabilize the remaining Central Anatolian lithosphere and resulted in localized drip melting to produce the mafic volcanism at the HCCP and KVF. Geochemical similarities to Miocene alkali basalts from Galatia and Sivas (Wilson et al., 1997; Varol et al., 2014; Kurkcuoglu et al., 2015) suggest that this mechanism occurred across Central Anatolia subsequent to Tethys subduction, and thus the ages of monogenetic volcanic activity record the descent of the slab beneath Anatolia. We infer that slab foundering played a more important role in this process than lithospheric loss beneath a tectonically shortened orogen (Gogus et al., 2017) although further mapping of sedimentary basins and structures is required to resolve this interpretation.

ABSTRACT The regional neotectonics and volcanism along the margins of the Anatolian microplate (T... more ABSTRACT The regional neotectonics and volcanism along the margins of the Anatolian microplate (Turkey) are broadly well-constrained. The African and Arabian plates currently push Anatolia against the relatively stable Eurasian plate and as a result, Anatolia has had a west-southwest movement for the last 12 Ma in what is called `escape tectonics'. The tectonic environments and their associated volcanism include slab rollback in Western Anatolia (post-Miocene alkaline basalts and basanites) and slab detachment in Eastern Anatolia (mid-Miocene calc-alkaline to Quaternary alkaline). However, the situation in Central Anatolia is less clear: extensional forces govern the neo-tectonic environment and Pliocene-Recent basalts through basaltic andesites and dacites form large stratovolcanoes in extensional basins as well as both small and large basalt fields. The geochemistry of these basalts requires contributions from a poorly-defined mantle source lithology that has been enriched by subduction processes. However, available plate reconstructions indicate that the leading edge of the subducted African plate did not reach Central Anatolia, suggesting that the subduction environment could be related to closure of the neo-Tethyan Ocean in Paleozoic time. Geochemical compositions of mafic lavas along the Central Anatolian Fault Zone (CAFZ) provide new clarity on the question of the extent of lithospheric melting and the influence of the subducting slab. Moving southward along the CAFZ, incompatible trace element compositions of Central Anatolian basalts increase systematically in La/Nb concentrations and other incompatible trace element indicators trend from MORB and OIB signatures to more enriched values. Small negative Nb and no Ta anomalies are present in basalts from the northern CAFZ, and increase to larger negative Nb anomalies and Ta anomalies in the north. The incompatible trace element variations along the CAFZ point to an increase in lithospheric or slab involvement toward the leading edge of the African plate, i.e., to the south. Here we present new Pb and Hf isotopic data on recent (

ABSTRACT The Karakaya Subduction/Accretion Complex consists of various pre-Liassic melange units ... more ABSTRACT The Karakaya Subduction/Accretion Complex consists of various pre-Liassic melange units that record the closing of the Palaeotethys ocean basin. One of these melange units, the Nilufer Unit, is composed of variably metamorphosed (dominantly prehnite-pumpellyite to greenschist facies), mafic rock assemblages that are primarily associated with neritic/pelagic limestones, mudstones and chert. The metabasic rocks are thought to represent oceanic islands/seamounts formed on the Palaeotethyan oceanic crust, fed by a mantle plume. The mafic rocks within the Nilufer Unit have mainly alkaline OIB-type geochemical signature, with marked enrichment in the most incompatible elements, relative to N-MORB. A subset of the mafic rocks are characterized by tholeiitic E-MORB-type signatures. Trace element modelling of elements least effected by metamorphism shows that the mafic rocks have been generated across a source region where garnet- and spinel-facies melts were variably mixed. The Sr isotopic values of the Nilufer mafic rocks are highly variable, indicative of post-magmatic redistribution of Sr and/or Rb. In contrast, the Nd-Hf-Pb systematics provide consistent isotope variations and source affinities in multi-isotope plots. The variations in these rocks cannot be explained solely by a single end-member or binary mixing. Instead, a multi-component mixing between three enriched sources, C-, EM II- and HIMU is required. The modelling suggests an ordered sequence of mixing initially between EM II and HIMU, followed by mixing between the C-like mantle source and the hybrid mantle. In terms of a physical model, the plume may have derived from a heterogeneous deep mantle source, or alternatively, result from the interaction of C-like plume material, upwelling from the margins of the African superplume, with continental lithosphere mantle adjacent to Palaeotethys ocean basin.

Mineralogical Magazine, 1994

Geochemistry, Geophysics, Geosystems, 2009

Ocean intraplate volcanoes (OIVs) are formed in a sequence of stages, from large to small, that i... more Ocean intraplate volcanoes (OIVs) are formed in a sequence of stages, from large to small, that involve a systematic progression in mantle melting in terms of volumes and melt fractions with concomitant distinct mantle source signatures. The Hawaiian volcanoes are the best-known example of this type of evolution, even though they are extraordinarily large. We explore the Pb-Sr-Nd-Hf isotopic evolution of much smaller OIVs in the Fieberling-Guadalupe Seamount Trail (FGST) and small, near-ridge generated seamounts in the same region. In particular, we investigate whether we can extend the Hawaiian models to Jasper Seamount in the FGST, which displays three distinct volcanic stages. Each stage has characteristic variations in Pb-Sr-Nd-Hf isotopic composition and trace element enrichment that are remarkably similar to the systematics observed in Hawaii: (1) The most voluminous, basal ''shield building'' stage, the Flank Transitional Series (FTS), displays slightly isotopically enriched compositions compared to the common component C and the least enriched trace elements (143 Nd/ 144 Nd: 0.512866-0.512909, 206 Pb/ 204 Pb: 18.904-19.054; La/Sm: 3.71-4.82). (2) The younger and substantially less voluminous Flank Alkalic Series (FAS) is comparatively depleted in Sr, Nd, and Hf isotope compositions plotting on the side of C,

Mineralogical Magazine | www.minersoc.org 1803 Seasonal and interannual change in mercury sequest... more Mineralogical Magazine | www.minersoc.org 1803 Seasonal and interannual change in mercury sequestration at Dome Fuji, Antarctica YEONGCHEOL HAN, YOUNGSOOK HUH, SUNGMIN HONG, SOON DO HUR, HIDEAKI MOTOYAMA Seoul National University, Korea, hanlove7@snu.ac.kr (* presenting author), yhuh@snu.ac.kr Inha University, Korea, smhong@inha.ac.kr Korea Polar Research Institute, Korea, sdhur@kopri.re.kr National Institute of Polar Research, Japan, motoyama@nipr.ac.jp

Hydrothermal fluid flow through a sediment hosted volcanic ridge in the Central

Earth and Planetary Science Letters

Peridotite constitutes most of the Earth's upper mantle, and it is therefore unsurprising that mo... more Peridotite constitutes most of the Earth's upper mantle, and it is therefore unsurprising that most mantle-derived magmas exhibit evidence of past equilibrium with an olivine-dominated source. Although there is mounting evidence for the role of pyroxenite in magma generation within upwelling mantle plumes, a less documented non-peridotite source of melts are metasomatic veins (metasomes) within the lithospheric mantle. Here we present major and trace element analyses of 66 lavas erupted from a small Miocene shield volcano located within the Ethiopian flood basalt province. Erupted lavas are intercalated with lahars and pyroclastic horizons that are

Agu Fall Meeting Abstracts, Dec 1, 2006

Hotspot volcanism has long been attributed to mantle plumes, but in recent years suggestions have... more Hotspot volcanism has long been attributed to mantle plumes, but in recent years suggestions have been made that plate tectonic processes, such as extension, can account for all hotspot tracks. This explanation involves a profoundly less dynamic lower mantle, which justifies a critical evaluation before the plume model is dismissed. Such an evaluation has to involve a wide range of

Agu Fall Meeting Abstracts, 2004

South Pacific ocean intraplate volcanoes (OIV's) have formed relatively short, discontinuous ... more South Pacific ocean intraplate volcanoes (OIV's) have formed relatively short, discontinuous chains over the last 140 Ma, in contrast to classic continuous hot spot chains like Hawaii or Louisville. Moreover, its volcanism stands apart by very diverse and radiogenic mantle source regions, defining the South Pacific Isotopic and Thermal Anomaly (SOPITA). Discontinuous SOPITA OIV's form a complex array of crossing