# Reinhardt Adolfo Fuck

Reinhardt Adolfo Fuck (/ˈfʊk/, rhyming with "hook") is a Brazilian geologist and professor emeritus at the University of Brasília. Fuck specializes on geochronology and petrology, having written extensively on Precambrian geology.

## Biography

Born in April 1940 in Linha Serraria, Piratuba, Santa Catarina, he pursued his early education in remote villages in Santa Catarina and Rio Grande do Sul, following his father, a schoolteacher and occasional accountant. After completing secondary studies in Panambi and Ijuí, he attended the School of Geology at the University of Rio Grande do Sul, where he began his research. Graduating as a geologist in 1963, he was employed by the Government of Ceará for geological surveys and groundwater well exploration. This later led to him meeting his future wife, Isaurinha.
In August 1964, he joined the Paraná Geological Chart Commission, a collaboration between the State Government and the Federal University of Paraná. Working alongside many other geologists he participated in the systematic survey of eastern Paraná. The data collected contributed to numerous publications that advanced the understanding of Paraná's Precambrian and Palaeozoic geology.
In 1969 he graduated from the Escola de Geologia de Porto Alegre (UFRGS) in Brazil. In 1973 he got his doctorate in the University of São Paulo in Brazil. In 1975 he carried out postdoctoral research in geology and petrology in the Department of Geological Sciences at the University of Durham in England. His research lines are geochronology, petrology and lithogeochemistry, high-grade metamorphism, greenstone belts, Proterozoic double belts. He is an author of a large number of Precambrian-geology-related scientific papers.
In 2010, he was awarded the Brazilian honour called the National Order of Scientific Merit.

## Ophiolitic Mélange of the Neoproterozoic Brasília Belt

Alongside fellow researchers Matthew T. Brown and Elton L. Dantas he published an article in 2019 titled Isotopic age constraints and geochemical results of disseminated ophiolitic assemblage from Neoproterozoic mélange, Central Brazil.
The study that the article is written about investigates an ophiolitic mélange within the Neoproterozoic Brasília Belt in central Brazil, part of the West Gondwana assembly, contains an ophiolitic mélange comprising metamafic and ultramafic rocks within a meta-sedimentary matrix. U-Pb geochronology and isotopic data suggest these rocks formed in a back-arc basin environment approximately 800–760 Ma. The mélange's metamafic components exhibit Mid Ocean Ridge Basin characteristics, while associated garnet-mica schists indicate sedimentary deposition within the same tectonicsetting. This mélange provides key evidence for understanding the tectonic and geochemical evolution of the Neoproterozoic Brasília Belt.

## Evidence of a Palaeoproterozoic SLIP, northern Amazonian Craton, Brazil

This article published along with Nazaré A. Barbosa, Valmir Souza, Elton L Dantes, and Stélio Tavares gives insight into how one of the most significant ignimbrite eruption events in the world during the Palaeoproterozoic is represented by the Orocaima volcano-plutonism. The Orocaima SLIP is a large area consisting of acid-intermediate volcanic-plutonic rocks. It may correspond to one of the world's oldest silicic Lips, the Amazonian Craton in Brazil.
The creation of these volcanic rocks was due to explosive eruptions through low eruptive columns, between 2.0 and 1.98 Ga. It generated ignimbrites.
To determine this Palaeoproterozoic SLIP, a method called the U-Pb analysis was carried out with the use of a Thermo Finnigan Neptune MulticollectorICP-MS mass spectrometer. Researchers selected zircon grains using a binocular microscope to ensure they obtained fractions that were similar in size, shape, and color. For the U-Pb analysis, the zircon grains were hand-selected, and mounted on epoxy and polished supports. When choosing the points for analysis, the focus was placed on the rims and nuclei to check for any overlapping geological events. The zircon grains were placed in a chamber with a flow rate of He between 0.35 and 0.45 per minute. Passing the gas through gas tubes containing quarts and gold particles allowed for the removal of Hg in the He. Once transported through the argon plasma, the vaporized material was placed in the detector area. The pattern and samples were then analyzed. The bracketing technique was applied.
Another analysis was undergone, called the Sm-Nd isotopic analysis. In this, the total rock samples were pulverized, homogenized, and later dissolved in steel-coated Teflon pumps with the addition of more Sm and Nd combined with isotopic tracers. The separation of Sm from Nd was carried out and deposited to then be analyzed. The analytical banks measured for Sm and Nd and it was found that the 143/144 isotopic ratios were constant and held higher values when compared to the values obtained for the standard rock BHVO-1.

## Fluid Escape from Diamond Caught-in-the-Act: Towards the Composition and Origin of Diamond-Forming Fluids

This article, which was published alongside Luísa Diniz Vilela de Carvalho, Thomas Stachel, Robert W. Luth, Andrew J. Locock, Graham Pearson, Matthew Steele-MacInnis, Richard A. Stern, Fabrizio Nestola, Ricardo Scholz, and Tiago Jalowitzki, examines how diamonds form through interactions between carbon-rich fluids and mantle rocks. The study highlights a unique case of fluid escape from a diamond from Brazil, offering insights into the composition and origin of diamond-forming fluids.
Minerals trapped within the diamond during growth were found to provide clues about the fluids involved in its formation. The geochemical signatures of the inclusions, such as hydrous Mg-silicates and olivine, suggest that the diamond originated from partially dehydrated peridotitic rocks in Earth's upper mantle.
After the diamond broke, needle-like crystals began to form on its surface. These were identified as hydrated potassium-magnesium carbonates, indicative of high-density fluids (HDFs) playing a role in diamond formation. These HDFs, enriched in magnesium and potassium, are linked to carbonatitic fluids from peridotitic sources.
The diamond also contained both fluid and mineral inclusions, which point to interactions between hydrothermally altered oceanic crust and mantle fluids. Isotopic analyses of carbon and nitrogen within the diamond revealed a mixture of crustal and mantle materials, supporting the idea of a combined source for diamond-forming fluids.

## Geological History of the São Francisco Craton and the Patos Shear System

This study provides a detailed account of the geological evolution of the São Francisco Craton, highlighting the complex interplay between magmatism, crustal reworking, and subduction. The findings offer valuable insights into the tectonic processes that shaped one of Earth's key geological regions over billions of years.
The article, authored alongside Frankie J.S. Fachetti, Rodrigo S. Marimon, Alanielson Ferreira, Ana C.D. da Costa, and Chris J. Hawkesworth, investigates the geological history of the São Francisco Craton and the Patos Shear System (PSS) in northeastern Brazil. It utilizes data from U-Pb, Lu-Hf, and Sm-Nd isotopic analyses to uncover the magmatic and metamorphic processes that shaped the basement rocks over billions of years.
The study finds that the São Francisco Craton underwent significant high-grade metamorphism approximately 2.1–2.0 billion years ago, during a continental collision event. This metamorphism contributed to the formation of the craton and neighboring orogens. Earlier magmatic activity, occurring between 3.1 and 2.6 billion years ago, involved both the addition of new material from the mantle and the reworking of older crust. Isotopic data suggest that the magmas from this period originated from a mantle source with a CHUR-like isotopic signature and mixed with older crustal material, pointing to a tectonic environment characterized by simultaneous juvenile magmatism and crustal reworking.
Reinhardt A. Fuck provided key insights into the tectonic models of the region. He argued that isotopic data for Paleoarchean rocks support a stagnant-lid tectonic model, where mantle plumesplayed a central role. He noted that the lack of typical “reworking arrays” in these ancient rocks suggests that magma from a depleted mantle mixed with older crust, rather than undergoing extensive reworking. For the Paleoproterozoic, he proposed that the juvenile material observed in magmatism likely resulted from subduction processes beneath the Archean core of the craton.