Geologic Domains eologic g a a l regions where rocks share similar b s o u t r i

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rock type Compiled by m MGS (sedimentary, igneous, metamorphic) Linda Murphy and Anders Carlson fishing or age. 1928 , Tadoule Lake, spring water beaches 600 wilderness Hudson Bay NEJANILINI MUDJADIC Quaternary geologists study the most recent eroded and deposited rocks. Erratics are boulders Erratic plucked from bedrock and transported by glacier action. When the glacier melted, the boulders are Lennox for scale WOLLASTON deposited. Large rivers can form high energy currents within a melting glacier and transport boulders. GREAT ISLAND Dene-Tzi Marble Churchill As the energy of the current slows, large then smaller sediment such as cobbles, gravel and sand is deposited forming the eskers at Tadoule Lake. The process of erosion helps deposit the sand from Duck Lake Post the eskers to beaches along the lakeshore. SOUTHERN HUDSON INDIAN BAY BASIN well rounded 1200 boulders A geologic map uses symbols and colors that represent rock types and geologic structures. Each bedrock picture is labeled with a colored square eroded scheduled air service corresponding to a rock type in the legend. roads on eskers Churchill 651 7584N 560 100E Tadoule Lake A turbidity current is gravity- Younging Stony Lake Legend Pelitic to psammitic greywacke driven sediment-laden water compacted to rock Sedimentary Calc-silicate quartzite that flows downward along the Summer Camp Tadoule Lake Arkose, arenite bottom of a deep-water sea or (Sayisi Dene First Nation) Tonalite gneiss lake. The sediment then Granitoid rocks compacted into mudstone- graded beds Tadoule Lake sandstone. A turbidite in sandy shoreline exhibits a recognizable series deposited of rock called a Bouma Bedding North Knife Ryan Lake Lake sequence. The rock in the top Lennox, George and John picture show flame structures at summer camp (silt pushes upward into redeposited heavier sand). The rock in the The Sayisi Dene First Nation were dislocated from their traditional lands and lifestyle in 1956 (above). sandy esker bottom picture show graded Younging Sayisi Dene The community is now re-established on the shore of Tadoule Lake (below). beds, pebbles to fine sand.

505 124E 505 10 km The pebbles in the rock were artists have used raw material imported from 647 6931N originally clay and have Bedrock in the Ryan Lake and Tadoule Lake area is metamorphosed into a Bedding Lac Brochet, Churchill, Thompson and rock found underlying younger glacial deposits. mineral called sillimanite. 554984E 6524949N to produce and export a variety of Shethanei Lake Stony Lake traditional sculpture, carvings, paintings and beadwork. Intrusive Younging direction of sedimentary rocks is interpreted using the Principle of Uniformitarianism (the present is the key to the

Leucogabbro past). Heavy rocks and pebbles are found toward the bottom of a stratigraphic sequence and the grains become finer toward

Negassa Granodiorite, pegmatite the top. Evidence for younging can be found in the scour bottom of a crossbed in the arkosic rock. These conglomerates, Lake Granite+/-syeno-granite dikes; arkoses and sandstones originally formed in lake, river and delta environments, similar to the lake and river where they are now pegmatite; arkosic inclusions found today. High quality marble sculptures are rare in Manitoba, and

Metasedimentary Mudstone with pebbly sandstone The plane where different the Dene-Tzi Marble represents an opportunity for the interbeds Sericite-hematite ? Talented Tadoule rocks meet is called a Quartzofeldspathic garnet-bearing Younging artists biotite-muscovite schist and arkose Bedding contact. Relative age is Sayisi Dene First Nation to Quartz-arenite ? determined using contact Cobble conglomerate and quartz- arenite Dextral shear relationships. This is an develop and promote Lake Geological contacts (defined, intrusive contact. approximate) Arenite Younger pegmatite part of their traditional land. Mapping Program 20092009 TadouleTadoule LakeLake Faults intruded older mudstone. Limit of mapping The mudstone has Chert metamorphosed into a The Community Mapping Program promotes relationship-building and 0 10 kilometres 6480029N 525027E garnet-bearing rock. geological-information sharing between Manitoba First Nations and the Igneous rocks form in a melt deep in the earth where minerals Manitoba Geological Survey (MGS). The work creates partnerships that crystalize and cool slowly. Large-sized crystals may form during the enhance local and provincial economic development, assist mineral cooling process or may form during metamorphism in a later event. exploration, contribute to the Manitoba geological database and encourages Plagioclase These intrusive rocks are felsic. land-use resolution. By working together, the program provides a balanced perspective of land-use issues. igneous MGS staff and participants geologically mapped the shoreline at Tadoule Lake in the first part of the program in 2009. The second part of the four- Magnetite week geological mapping course assessed a marble occurrence at Ryan Hornblende Lake in 2010.

20102010 RyanRyan LakeLake Some igneous rocks are mafic. Gabbro contains dark coloured The goals of the program are to: minerals such as pyroxene and forms deeper in the crustal melt than - increase awareness of the region's geology felsic igneous rocks. Leuco means light therefore the leucogabbro - provide basic skills needed to work in a mineral exploration camp contains more light coloured minerals such as plagioclase. - foster information-sharing between First Nations and the MGS 510000E The uniformly Laminated

laminated marble marble pods The authors thank 2009-2010 participants J. Thorassie, G. Yassie, J.J. 6495000N may have formed may represent Jawbone, L. Bussidor, M. Powderhorn, D. Summerville and S. Cutlip metamorphism Granite through growth of laminae small conical for taking time to learn how the MGS conducts mapping projects and for large stromatolitic stromatolites teaching us about the Sayisi Dene First Nation. The project benefited from bioherms in a that grew when the help and support of the Chief and Council, the Sayisi Dene Land Claims quiescent platform chert the ocean office and insightful discussions with Tadoule Lake residents. environment at the habitat became photic level below less stable. wave-base. Field equipment Paragneiss Fieldwork Fieldwork Classroom Data collection Pebbly Tectonic processes related to ca. 1.85-1.77 Ga Trans- Ryan Lake dolomitic Hudsonian orogeny buried the sedimentary limestone, carbonate chert 67 carbonate- dolostone and sandstone sequence. Amphibolite grade 90 40 46 quartz sand metamorphism recrystallized the carbonate rocks into and silty beds 57 Marble dolomitic, impure marble. During this process, cyanobacterial Thin brown chert stringers mark Dene Hand Game suggest mats were recrystallized into laminated metamorphosed bedding in layered and podiform deposition in tremolite and diopside sediment largely composed of tremolite, diopside, phlogopite laminae marble. The brown colour is from Chipewyan a higher and hematite. Subsequent uplift exposed the marble at Ryan phlogopite. In places the chert 0 1000 Granite 6490000N energy 1 mm metres Lake to erosion, weathering, and coverage by glacial terminates the red laminae. environment. sediment. 515000E Abundant thin red to brown The marble bedding represents repetitious sedimentation of clastic, Dolomitic carbonate-quartz matrix run laminae is found throughout the quartz-rich continental sources and carbonate platform growth. The concordant and slightly oblique to the marble marble. It is straight in the Ryan Lake marble is interpreted to be an amphibolite-grade Outcrop washing bedding planes and surround individual pods in layered marble and draped within metamorphosed stromatolite bioherm that formed during the Early poorly exposed marble at Ryan Lake: the breccia beds. Natural growth or sea-level each pods in the brecciated Proterozoic in a shallow marine platform environment. Fossil evidence before, during and after regression may have brought the bioherm within marble. The colour may be from of stromatolite development has been found in rock records throughout or above wave base, where periodic storms hematite. Earth's history, from Archean to Proterozoic to and grow in modern-day caused disturbance and brecciation of ocean environments. Stromatolites are organosedimentary chert stromatolites. The smaller, broken pods were structures that form by the growth of photosynthesizing cyanobacteria, 1 cm infilled with carbonate, quartz sand and chert, which induce carbonate precipitation. Expansive algal mats capture resulting in a matrix-supported stromatolitic nutrients and collect sediment from the water column.