Activities of titanite (Ttn, CaTiSiO5) and ⁄or rutile (Rt, TiO2) phase components were calculated for 45 well-characterized natural titaniteor rutile-undersaturated epidote–amphibolites by using the equilibria: (i) 3 anorthite + 2 zoisite ⁄ clinozoisite + rutile + quartz = 3 anorthite + titanite + water (referred to as TZARS) and (ii) anorthite + 2 titanite = grossular + 2 rutile + quartz (refe...

INTRODUCTION Experimental studies were carried out to evaluate phase relations involving titanite–F–Al-titanite solid solution in the system CaSiO3– Geological background Al2SiO5–TiO2–CaF2. The experiments were conducted at Titanite is a common accessory mineral in mafic, pelitic 900–1000°C and 1·1–4·0 GPa. The average F/Al ratio in and granitic rocks from many geological environments titanite ...

Microbial corrosion textures in volcanic glass from Cenozoic seafloor basalts and the corresponding titanite replacement microtextures in metamorphosed Paleoarchean pillow lavas have been interpreted as evidence for a deep biosphere dating back in time through the earliest periods of preserved life on earth. This interpretation has been recently challenged for Paleoarchean titanite replacement ...

The Omai intrusion-centred Au-quartz vein system, the largest Au producer presently operating in the Guyana Shield, was sampled for detailed U-Pb and Pb-Pb geochronology and petrological investigation. The age of a metavolcanic/sub-volcanic unit in the host rock sequence is 212092 Ma. Zircon analyses from the main body dioritic rocks give U-Pb ages of 209496, 2092911 and 2096+11/−10 Ma. Magmati...

We have explored the diffusivity characteristics of radiogenic He in titanite (sphene) and have developed analytical techniques for (U–Th)/He dating of this mineral. Results of incremental He outgassing experiments performed on titanites from a variety of geological environments suggest a thermally activated volume diffusion mechanism with an activation energy of 44.6 6 3.4 (2s) kcal/mol and a ...

[1] Recent calibration studies have expanded the range of target minerals suitable for cosmogenic He dating to include U and Th‐rich phases such as zircon, apatite, and titanite. These minerals often contain large amounts of radiogenic He that present several analytical challenges for precise and accurate He determinations. In this paper we document the abundance sensitivity and changes in the ...

Fe-doped titanite (TiCaSiO5) and quasi-titanite (Ti0.5CaSi1.5O5) compositions were synthesized by the ceramic method. For each structure, two samples with 0.1 mol% and 0.2 mol% Fe were used. The synthesized samples were homogenized using a planetary ball mill in 2-ethylhexyl stearate solvent and then printed on the ceramic with screen printing system....

Craton cores far from plate boundaries have traditionally been viewed as stable features that experience minimal vertical motion over 100–1000 Ma time scales. Here we show that the Fennoscandian Shield in southeastern Sweden experienced several episodes of burial and exhumation from ~1800 Ma to the present. Apatite, titanite, and zircon (U-Th)/He ages from surface samples and drill cores constr...

The Beemerville alkaline complex, New Jersey, occurs at the western end of the CortlandtBeemerville magmatic belt. The eastern end of the belt is defined by the Cortlandt complex, New York, which largely consists of ultramafic and mafic rocks. Between these two intrusive centers is a linear almost east-west trending zone of lamprophyre and felsic dikes. The Beemerville complex consists of two l...