Petrological Database of the Ocean Floor

Last updated August 16, 2023

The Petrological Database of the Ocean Floor (PetDB)^[1] is a relational database for global geochemical data on igneous and metamorphic rocks generated at mid-ocean ridges including back-arc basins, young seamounts, and old oceanic crust, as well as ophiolites and terrestrial xenoliths from the mantle and lower crust and diamond geochemistry. These data are obtained by analyses of whole rock powders, volcanic glasses, and minerals by a wide range of techniques including mass spectrometry, atomic emission spectrometry, x-ray fluorescence spectrometry, and wet chemical analyses. Data are compiled from the scientific literature by PetDB data managers, and entered after methodical metadata review. Members of the scientific community can also suggest entry of specific data that has been entered into the EarthChem Library. PetDB is administered by the EarthChem group under the IEDA facility at LDEO headed by K. Lehnert. PetDB is supported by the U.S. National Science Foundation.

About

Developments of PetDB^[2] began in 1995, by Lamont–Doherty Earth Observatory (LDEO)^[3] scientists C. Langmuir (now at Harvard University), W. Ryan, and A. Boulanger, when they realized what impact the World Wide Web and relational databases could have on the use of scientific data in research and in the classroom.

The initial funding phase of PetDB (1996–2001) supported the development of the database structure and population with data values. Renewed funding (2002–2007) permitted the migration of the database into an ORACLE-based environment administered by the Center for International Earth Science Information Network (CIESIN)^[4] of Columbia University,^[5] continued data entry, and enhancement of the web-interface with a more user-friendly design.

PetDB is now maintained by EarthChem and funded by the US National Science Foundation, and is governed by the Interdisciplinary Earth Data Alliance facility as part of an ecosystem of related projects, including The System for Earth Sample Registration (SESAR), and the Astromaterials Data System (AstroMat).

Since its inception, PetDB has supported a wide array of scientific endeavors, providing easy access to a comprehensive global dataset of geochemical data for mid-ocean ridge basalts, abyssal peridotites and also xenolith samples from the Earth's mantle and lower crust.

The relational database structure of PetDB is a sample-based implementation, and designed to accommodate chemical, isotopic and mineralogical data for any type of rock sample, along with essential metadata, which provide information about each sample (e.g. location and time of collection, taxonomy, petrographic description) and the data quality, including analytical procedure, reference standard measurements etc. (Lehnert et al. 2000^[6]).

Initially developed for PetDB and its European counterpart, GEOROC,^[7] this relational data model has demonstrated utility and flexibility by its application in subsequent geochemical database projects including several collaborations that PetDB has also fostered, including EARThD Project, which focuses on tephra samples from the East African Rift; the US Polar Rock Repository housed at Ohio State University, which includes metadata from Antarctic rock samples; and the collaboration with the University of Kansas, which has resulted in the inclusion of North American granitic pluton samples’ data as well. This project evolved from the NAVDAT project.

PetDB has been cited in more than 1500 peer-reviewed scientific articles.^[8]

PetDB is committed to data that follow: FAIR (Findable, Accessible, Interoperable, and Reusable), TRUST (Transparency, Responsibility, User focus, Sustainability and Technology), and CARE principles for Indigenous Data Governance (Collective benefit, Authority to Control, Responsibility, Ethics), and strives to demonstrate the importance of openly available digital resources across all scientific disciplines.

In its current application, PetDB contains and provides on-line access to a complete set of chemical parameters (currently over 250 elements, oxides, isotopes and isotope ratios), as well as petrographic (mode) data through a sophisticated query interface. New data are continuously being added to the database as it is published and submitted to PetDB by authors. Data for a specific sample that is generated by different laboratories or published by various authors are linked and integrated through the use of a unique sample identifier generated by the database application.

Statistics

As of May 15, 2023, PetDB holdings consist of:

References: 3,568
Samples: 136,832
Bulk rock data points: 1,722,849
Minerals: 3,316,363
Volcanic glasses: 911,766
Melt inclusions: 323,365
Total individual values: 6,276,656

Data output

Data from PetDB can be viewed in HTML tables and downloaded in spreadsheets in XLS format. During selection of chemical parameters a user can choose to retrieve data as individual values (each row in the data table contains values measured on the same sample with the same method and linked to the same reference) or in precompiled format. The precompiled format arranges all data associated with a sample in a single row, even when data is sourced from multiple publications. In cases where there is more than one data value for a particular chemical item, the precompilation algorithm selects the most recent analysis and the most precise method available. Links in the HTML table permit the user to access more detailed information about the sample, reference or data value (analytical procedure). The final spreadsheet output contains two worksheets. The first contains queried chemical data, geospatial coordinates, and abridged methods and references, while the second contains metadata on analytical methods and publication information.

Related Research Articles

A lithosphere is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the lithospheric mantle, the topmost portion of the upper mantle that behaves elastically on time scales of up to thousands of years or more. The crust and upper mantle are distinguished on the basis of chemistry and mineralogy.

A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian Traps. Some such volcanic regions lie far from tectonic plate boundaries, while others represent unusually large-volume volcanism near plate boundaries.

<span class="mw-page-title-main">Xenolith</span> Rock inside a rock with a different composition

A xenolith is a rock fragment that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term xenolith is almost exclusively used to describe inclusions in igneous rock entrained during magma ascent, emplacement and eruption. Xenoliths may be engulfed along the margins of a magma chamber, torn loose from the walls of an erupting lava conduit or explosive diatreme or picked up along the base of a flowing body of lava on the Earth's surface. A xenocryst is an individual foreign crystal included within an igneous body. Examples of xenocrysts are quartz crystals in a silica-deficient lava and diamonds within kimberlite diatremes. Xenoliths can be non-uniform within individual locations, even in areas which are spatially limited, e.g. rhyolite-dominated lava of Niijima volcano (Japan) contains two types of gabbroic xenoliths which are of different origin - they were formed in different temperature and pressure conditions.

<span class="mw-page-title-main">Peridotite</span> Coarse-grained ultramafic igneous rock type

Peridotite ( PERR-ih-doh-tyte, pə-RID-ə-) is a dense, coarse-grained igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg²⁺), reflecting the high proportions of magnesium-rich olivine, with appreciable iron. Peridotite is derived from Earth's mantle, either as solid blocks and fragments, or as crystals accumulated from magmas that formed in the mantle. The compositions of peridotites from these layered igneous complexes vary widely, reflecting the relative proportions of pyroxenes, chromite, plagioclase, and amphibole.

Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. The crust overlies the rigid uppermost layer of the mantle. The crust and the rigid upper mantle layer together constitute oceanic lithosphere.

Eclogite is a metamorphic rock containing garnet (almandine-pyrope) hosted in a matrix of sodium-rich pyroxene (omphacite). Accessory minerals include kyanite, rutile, quartz, lawsonite, coesite, amphibole, phengite, paragonite, zoisite, dolomite, corundum and, rarely, diamond. The chemistry of primary and accessory minerals is used to classify three types of eclogite. The broad range of eclogitic compositions has led a longstanding debate on the origin of eclogite xenoliths as subducted, altered oceanic crust.

Isotope geochemistry is an aspect of geology based upon the study of natural variations in the relative abundances of isotopes of various elements. Variations in isotopic abundance are measured by isotope ratio mass spectrometry, and can reveal information about the ages and origins of rock, air or water bodies, or processes of mixing between them.

The Iceland hotspot is a hotspot which is partly responsible for the high volcanic activity which has formed the Iceland Plateau and the island of Iceland.

SedDB was created as an online data management and information system for sediment geochemistry.

Rhenium–osmium dating is a form of radiometric dating based on the beta decay of the isotope ¹⁸⁷Re to ¹⁸⁷Os. This normally occurs with a half-life of 41.6 × 10⁹ y, but studies using fully ionised ¹⁸⁷Re atoms have found that this can decrease to only 33 y. Both rhenium and osmium are strongly siderophilic (iron loving), while Re is also chalcophilic (sulfur loving) making it useful in dating sulfide ores such as gold and Cu-Ni deposits.

Ocean island basalt (OIB) is a volcanic rock, usually basaltic in composition, erupted in oceans away from tectonic plate boundaries. Although ocean island basaltic magma is mainly erupted as basalt lava, the basaltic magma is sometimes modified by igneous differentiation to produce a range of other volcanic rock types, for example, rhyolite in Iceland, and phonolite and trachyte at the intraplate volcano Fernando de Noronha. Unlike mid-ocean ridge basalts (MORBs), which erupt at spreading centers (divergent plate boundaries), and volcanic arc lavas, which erupt at subduction zones (convergent plate boundaries), ocean island basalts are the result of intraplate volcanism. However, some ocean island basalt locations coincide with plate boundaries like Iceland, which sits on top of a mid-ocean ridge, and Samoa, which is located near a subduction zone.

MetPetDB is a relational database and repository for global geochemical data on and images collected from metamorphic rocks from the Earth's crust. MetPetDB is designed and built by a global community of metamorphic petrologists in collaboration with computer scientists at Rensselaer Polytechnic Institute as part of the National Cyberinfrastructure Initiative and supported by the National Science Foundation. MetPetDB is unique in that it incorporates image data collected by a variety of techniques, e.g. photomicrographs, backscattered electron images (SEM), and X-ray maps collected by wavelength dispersive spectroscopy or energy dispersive spectroscopy.

Crustal recycling is a tectonic process by which surface material from the lithosphere is recycled into the mantle by subduction erosion or delamination. The subducting slabs carry volatile compounds and water into the mantle, as well as crustal material with an isotopic signature different from that of primitive mantle. Identification of this crustal signature in mantle-derived rocks is proof of crustal recycling.

<span class="mw-page-title-main">Superswell</span> Large area of anomalously high topography and shallow ocean regions

A superswell is a large area of anomalously high topography and shallow ocean regions. These areas of anomalous topography are byproducts of large upwelling of mantle material from the core–mantle boundary, referred to as superplumes. Two present day superswells have been identified: the African superswell and the South Pacific superswell. In addition to these, the Darwin Rise in the south central Pacific Ocean is thought to be a paleosuperswell, showing evidence of being uplifted compared to surrounding ancient ocean topography.

Provenance in geology, is the reconstruction of the origin of sediments. The Earth is a dynamic planet, and all rocks are subject to transition between the three main rock types: sedimentary, metamorphic, and igneous rocks. Rocks exposed to the surface are sooner or later broken down into sediments. Sediments are expected to be able to provide evidence of the erosional history of their parent source rocks. The purpose of provenance study is to restore the tectonic, paleo-geographic and paleo-climatic history.

An upper mantle body is a geological region where upper mantle rocks (peridotite) outcrop on the surface of the Earth.

<span class="mw-page-title-main">Rarotonga hotspot</span> Volcanic hotspot in the southern Pacific Ocean

The Rarotonga hotspot is a volcanic hotspot in the southern Pacific Ocean. The hotspot is claimed to be responsible for the formation of Rarotonga and some volcanics of Aitutaki but an alternative explanation for these islands most recent volcanics has not be ruled out. Recently alternatives to hotspot activity have been offered for several other intra-plate volcanoes that may have been associated with the Rarotonga hotspot hypothesis.

Emily M. Klein is a professor of geology and geochemistry at Duke University. She studies volcanic eruptions and the process of oceanic crust creation. She has spent over thirty years investigating the geology of mid-ocean ridges and identified the importance of the physical conditions of mantle melting on the chemical composition of basalt.

Stanley Robert Hart is an American geologist, geochemist, leading international expert on mantle isotope geochemistry, and pioneer of chemical geodynamics.

Catherine Chauvel is a geochemist at the Institut de Physique du Globe de Paris known for her research on the impact of volcanic activity on the chemistry of the mantle, continental crust, and island arc geochemistry.

References

↑ "PetDB". Archived from the original on 2008-08-20. Retrieved 2020-05-05.
↑ "PetDB - Home". www.petdb.org. Archived from the original on 20 August 2008. Retrieved 30 June 2022.
↑ "Home". ldeo.columbia.edu.
↑ "Home". ciesin.columbia.edu.
↑ "Home". columbia.edu.
↑ Lehnert, K.; Su, Y.; Langmuir, C. H.; Sarbas, B.; Nohl, U. (2000). "A global geochemical database structure for rocks". Geochemistry, Geophysics, Geosystems. 1 (5): 1012. Bibcode:2000GGG.....1.1012L. doi:10.1029/1999GC000026. S2CID 134706218.
↑ "Geochemical Rock Database-Query".
↑ "EarthChem- Citations for EarthChem Systems".