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https://bereket-haileab.geology.sites.carleton.edu/files/original/16a6b44c6f8d0f868a1b2bce65506053.jpg
0fb784792f82bb3b720d73511314d360
Dublin Core
The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/.
Title
A name given to the resource
Igneous Rocks
Subject
The topic of the resource
This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites.
Creator
An entity primarily responsible for making the resource
Bereket Haileab
Source
A related resource from which the described resource is derived
Housed in Anderson Hall, Carleton College.
Format
The file format, physical medium, or dimensions of the resource
Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples).
Thin section and hand sample
Dublin Core
The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/.
Title
A name given to the resource
BH250-129
Subject
The topic of the resource
Gabbro
Description
An account of the resource
Major Minerals: plagioclase, clinopyroxene, orthopyroxene<br />Minor Minerals: pyrite, biotite, iron-titanium oxide<br />Alteration: Chlorite, sericite, <br />
<p data-start="196" data-end="578">BH250-129 is a sample from the Duluth Gabbro near Nickel Lake, Minnesota, part of the Duluth Complex—one of the largest mafic layered intrusions in the world, formed during the Midcontinent Rift. These rocks provide critical insights into magmatic differentiation, crystal settling, and the large-scale evolution of rift-related magmatism.</p>
<p data-start="580" data-end="1067">The rock is mineralogically dominated by plagioclase, clinopyroxene, and orthopyroxene, consistent with a typical gabbroic composition. However, what makes this sample particularly significant is the extensive alteration observed. The plagioclase feldspars show clear evidence of fluid interaction, indicating that hydrothermal fluids passed through the rock after crystallization. These fluids altered the primary minerals and introduced new chemical components into the system.</p>
<p data-start="1069" data-end="1508">This fluid activity is directly linked to the presence of sulfide mineralization, represented by pyrite in the sample. The sulfides likely formed as metals were mobilized and concentrated by these fluids, either during late-stage magmatic processes or subsequent hydrothermal circulation. Texturally, this may be expressed as alteration halos, replacement textures, or sulfide grains associated with fractures and grain boundaries.</p>
<p data-start="1510" data-end="1956">Although the Duluth Complex is globally significant for its nickel, copper, and platinum-group element (PGE) deposits, the Nickel Lake area itself is considered relatively weakly mineralized. This makes BH250-129 especially useful as a teaching example: it captures the processes of fluid-driven alteration and early-stage sulfide formation, even in areas where economic concentrations were not fully developed.</p>
<p data-start="1958" data-end="2303">Overall, this sample highlights the important link between magmatic systems and hydrothermal processes. It demonstrates how primary igneous minerals can be modified by later fluids and how these interactions can lead to the redistribution and concentration of metals, key steps in the formation of ore deposits within large igneous complexes.</p>
<br /><iframe width="1800" height="100" src="https://docs.google.com/spreadsheets/d/e/2PACX-1vS4nyqCmZQGn3t6vX4g4nhDPwHMBaKrigt1LaY2pykWbBGXB1wNb6FYArx625I-JTtD7lyg4uz1OS1r/pubhtml?gid=956375385&single=true&widget=true&headers=false"></iframe>
Coverage
The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant
Location: Nickel Lake, Minnesota, USA
GPS Coordinates: 93°27'43.79"W, 47°36'27.23"N
Date
A point or period of time associated with an event in the lifecycle of the resource
Spring 2017
Source
A related resource from which the described resource is derived
From the rock collection of Bereket Haileab. Sample 129. Housed at Carleton College in Minnesota.
Contributor
An entity responsible for making contributions to the resource
Bereket Haileab
Type
The nature or genre of the resource
Thin section and hand sample
Relation
A related resource
<iframe width="100%" height="600" style="border: 0;" src="https://carleton.maps.arcgis.com/apps/instant/media/index.html?appid=83adfb73d7884a948b03f94a0e55a73e" frameborder="0" allowfullscreen="allowfullscreen">iFrames are not supported on this page.</iframe><br />View on ArcGIS Online <a href="https://carleton.maps.arcgis.com/home/item.html?id=83adfb73d7884a948b03f94a0e55a73e">here</a><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1JvLdi2luGSV-toQwPogZEhazwO8S4d76/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1eLtukPknydSOX4l36fbtzMklWKNLW4wX/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1l7oG0pBtMjBeinxSsjv0j-eLgK9kUFLn/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1LiFBFnlEG3hWBbV_OrbOoFz6iZaYDqew/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1j07lJevyuTgLlkg9plOTgKtFyqtQHtBX/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1l4nFk64K_r3QMXlZGbju_T-nRZ_fMtCu/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1EyL5gdXXQpCOE7hLSoNSS5yRYfcgNwjP/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1XNuvl7o1jMjPmYhkaJ6lpNGZ9PET3x8P/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1GN81nhVyQ_1gfhquN52vPFEv5oj6jDoK/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1pTu0xjankS7GRDfpGX_Gy4dM0tDAbeCz/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1AtzrKtNk7i_VnmHzc-FvohvTAiskR0I7/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/15786u8qzlkCNVtIykUH_nlWrcyHrkzLe/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1busNZCYlJLvy_2XnDr5On-8dKbtAX4o7/preview" allow="autoplay"></iframe><br />TAS diagram of sample BH250-129.
Creator
An entity primarily responsible for making the resource
Bereket Haileab
alteration textures
Base metal deposits
Clinopyroxene
Copper mineralization
Duluth Complex
Duluth Gabbro
fluid alteration indicator
fluid pathways
Fluid-rock interaction
gabbro
Hydrothermal alteration
igneous
mafic
Mafic Intrusive Rock
Mafic layered intrusion
mafic minerals
Magmatic Differentiation
metasomatism
Midcontinent Rift
Minnesota geology
Nickel Lake
Nickel mineralization
Orthopyroxene
Plagioclase
plagioclase alteration
Platinum-group elements (PGE)
plutonic
Pyrite
replacement texture
sulfide mineralization
Sulfide minerals