Kimberlite North America

The distribution of known kimberlites fields clusters isolated occurrences in north america is illustrated in figure 1 heaman and kjarsgaard and zurevinski et al described the geochronology of mesozoic triassic jurassic cretaceous kimberlites in eastern north america and their relationship to the great meteor hotspot track

Deep mantle waves trigger mysterious kimberlite volcanoes a version of this story appeared in science vol 381 issue 6656 forged under extreme temperatures and pressures more than 150 kilometers down in the mantle diamonds ride rockets to reach earth s surface narrow pipes of magma called kimberlite that can erupt at the speed of sound

Kimberlite genesis by edge driven convection has been suggested for cretaceous kimberlites along a north south corridor extending across north america from kansas to somerset island in the

It is tempting to interpret the bimodal peak in kimberlite lag times evident in africa south america and north america fig 1d and extended data figs 3d and 5 to relate to two main phases

We excluded one kimberlite occurrence in its entirety from the literature compilation the triassic jurassic kimberlites from eastern north america 33 these kimberlites show age progressive

Thirty new high precision u pb perovskite and zircon ages from kimberlites in central north america delineate a corridor of mid cretaceous 115 to 92 ma magmatism that extends 4000 km from

Thirty new high precision u pb perovskite and zircon ages from kimberlites in central north america delineate a corridor of mid cretaceous 115 92 ma magmatism that extends 4000 km from somerset island in arctic canada through central saskatchewan to kansas usa

Kimberlites earth s diamond delivery system figure 1 open pit diamond mines in kimberlite rock mining operations remove as much kimberlite as possible and leave deep pits that outline the shape of a kimberlite pipe a the cullinan mine started as an open pit operation and transitioned to underground mining in 1946

Kimberlite and rocks with kimberlitic affinities have a relatively wide distribution throughout the united states they occur in the western margin of the appalachians from new york to tennessee in the central region of the u s including kentucky southern illinois missouri kansas and arkansas and in the western states of montana colorado wyoming and the colorado plateau however

The youngest kimberlites and related rocks are tertiary in age and occur in western north america e g lac de gras n w t and missouri breaks diatremes montana phanerozoic kimberlite magmatism in north america can be broadly subdivided into four geographic regions based on patterns of emplacement fig 1

A simplified tectonic map of central north america with the red box indicating our study area as shown in b with more detail the light steel blue and dark slate gray thick dashed lines represent the great meteor hotspot track inferred by kimberlite occurrences and seismic evidence at a depth of 200 km respectively

North american kimberlites at 80 ma and 60 ma are well known to be distant from llsvps 16 however they are relatively close to isolated rha extended data fig 6e f

The north american jurassic kimberlite magmatism provides some insight into one possible cause of protracted periods of kimberlite magmatism the majority of jurassic kimberlites in north america occur in ontario and follow a nw se trending corridor between the rankin inlet and kirkland lake fields

Over 200 are known in north america of which about 40 occur near the colorado wyoming state line important new discoveries have been made in northern canada in the last decade of the thousands of known kimberlites fewer than about 1 000 contain diamonds and of those only about 50 to 60 have contained enough diamonds to be mined economically

Diamonds found in north america continue to have gemological significance and attract a great amount of interest three notable arkansas diamonds the uncle sam diamond the uncle sam is a 40 23 carat white diamond that stands as the largest diamond ever found in north america

There are numerous diatremes further north in montana and canada the figure at right from schulze et al 2008 shows the locations of some of the noteable kimberlites of the state line region the insert shows the relative position of the archean wyoming craton with the proterozoic mojave and yavapai provinces

Kimberlite from the united states composition forsteritic olivine and carbonate minerals with trace amounts of magnesian ilmenite chromium pyrope almandine pyrope chromium diopside phlogopite enstatite and titanium poor chromite sometimes contains diamonds false color scanning electron microscope image of kimberlite from south africa

Third in addition to containing minerals that crystallized from the ascending magmas kimberlites contain a large assemblage of minerals and xenoliths rock fragments that were collected from

Cretaceous tertiary kimberlite carbonatite magmatism in mid continent north america extends along a n40 w linear trend from louisiana to alberta and occurs in at least four different pulses 109 85 67 64 55 52 and less than 50 ma

The bedrock kimberlite source for the diamonds is unknown but has been presumed to be in northern canada the only area north of wisconsin previously known to contain kimberlites recently a kimberlite pipe here named the lake ellen kimberlite has been found in iron county michigan

From 160 to 120 ma two peaks in kimberlite eruptions correlate with pulses of high slab flux from the subducting farallon plate beneath the americas which plunged 30 35 circ into the

By tim de chant monday may 4 2015 nova next for over a century mineral prospectors have known that a rock known as kimberlite often contains diamonds find kimberlite and you ve got a much

Olivine is the only obvious megacryst mineral present one microdiamond was recovered from caustic fusion of a 45 kg sample upper mantle xenoliths up to 70 cm size are abundant and are some of the largest known garnet peridotite xenoliths in north america the xenolith suite is dominated by dunites and harzburgites containing garnet and or

Kimberlites are never associated of kimberlite generation 1 small scale convection in the upper mantle with subduction zones the dotted line labelled g d indicates the graphite 2

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