Brine-driven destruction of clay minerals in Gale crater, Mars

Science ◽  
2021 ◽  
Vol 373 (6551) ◽  
pp. 198-204
Author(s):  
T. F. Bristow ◽  
J. P. Grotzinger ◽  
E. B. Rampe ◽  
J. Cuadros ◽  
S. J. Chipera ◽  
...  
Keyword(s):  
Magnesium Sulfate ◽  
Clay Minerals ◽  
Sedimentary Rock ◽  
Sedimentary Rocks ◽  
Silicate Minerals ◽  
Gale Crater ◽  
Rock Record ◽  
Spatial Differences ◽  
Rock Strata ◽  
Globally Distributed

Mars’ sedimentary rock record preserves information on geological (and potential astrobiological) processes that occurred on the planet billions of years ago. The Curiosity rover is exploring the lower reaches of Mount Sharp, in Gale crater on Mars. A traverse from Vera Rubin ridge to Glen Torridon has allowed Curiosity to examine a lateral transect of rock strata laid down in a martian lake ~3.5 billion years ago. We report spatial differences in the mineralogy of time-equivalent sedimentary rocks <400 meters apart. These differences indicate localized infiltration of silica-poor brines, generated during deposition of overlying magnesium sulfate–bearing strata. We propose that destabilization of silicate minerals driven by silica-poor brines (rarely observed on Earth) was widespread on ancient Mars, because sulfate deposits are globally distributed.

scholarly journals Extraformational sediment recycling on Mars

Geosphere ◽  
2020 ◽  
Vol 16 (6) ◽  
pp. 1508-1537
Author(s):  
Kenneth S. Edgett ◽  
Steven G. Banham ◽  
Kristen A. Bennett ◽  
Lauren A. Edgar ◽  
Christopher S. Edwards ◽  
...  
Keyword(s):  
Calcium Sulfate ◽  
Sedimentary Rock ◽  
Sedimentary Rocks ◽  
Fundamental Aspect ◽  
Geological Record ◽  
Physical Weathering ◽  
Gale Crater ◽  
Weathering Processes ◽  
Curiosity Rover

Abstract Extraformational sediment recycling (old sedimentary rock to new sedimentary rock) is a fundamental aspect of Earth’s geological record; tectonism exposes sedimentary rock, whereupon it is weathered and eroded to form new sediment that later becomes lithified. On Mars, tectonism has been minor, but two decades of orbiter instrument–based studies show that some sedimentary rocks previously buried to depths of kilometers have been exposed, by erosion, at the surface. Four locations in Gale crater, explored using the National Aeronautics and Space Administration’s Curiosity rover, exhibit sedimentary lithoclasts in sedimentary rock: At Marias Pass, they are mudstone fragments in sandstone derived from strata below an erosional unconformity; at Bimbe, they are pebble-sized sandstone and, possibly, laminated, intraclast-bearing, chemical (calcium sulfate) sediment fragments in conglomerates; at Cooperstown, they are pebble-sized fragments of sandstone within coarse sandstone; at Dingo Gap, they are cobble-sized, stratified sandstone fragments in conglomerate derived from an immediately underlying sandstone. Mars orbiter images show lithified sediment fans at the termini of canyons that incise sedimentary rock in Gale crater; these, too, consist of recycled, extraformational sediment. The recycled sediments in Gale crater are compositionally immature, indicating the dominance of physical weathering processes during the second known cycle. The observations at Marias Pass indicate that sediment eroded and removed from craters such as Gale crater during the Martian Hesperian Period could have been recycled to form new rock elsewhere. Our results permit prediction that lithified deltaic sediments at the Perseverance (landing in 2021) and Rosalind Franklin (landing in 2023) rover field sites could contain extraformational recycled sediment.

scholarly journals Impact generated porosity in Gale crater and implications for the density of sedimentary rocks in lower Aeolis Mons

Icarus ◽  
2021 ◽  
pp. 114539
Author(s):  
B.C. Johnson ◽  
R.E. Milliken ◽  
K.W. Lewis ◽  
G.S. Collins
Keyword(s):  
Sedimentary Rocks ◽  
Gale Crater

A metasedimentary source of gold in Archean orogenic gold deposits

Geology ◽  
2021 ◽  
Author(s):  
Iain K. Pitcairn ◽  
Nikolaos Leventis ◽  
Georges Beaudoin ◽  
Stephane Faure ◽  
Carl Guilmette ◽  
...  
Keyword(s):  
Sedimentary Rock ◽  
Sedimentary Rocks ◽  
Gold Deposits ◽  
Metamorphic Grade ◽  
Orogenic Gold ◽  
Metal Source ◽  
Main Metal ◽  
Metasedimentary Rocks ◽  
Orogenic Gold Deposits ◽  
Archean Orogenic Gold Deposits

The sources of metals enriched in Archean orogenic gold deposits have long been debated. Metasedimentary rocks, which are generally accepted as the main metal source in Phanerozoic deposits, are less abundant in Archean greenstone belts and commonly discounted as a viable metal source for Archean deposits. We report ultralow-detection-limit gold and trace-element concentrations from a suite of metamorphosed sedimentary rocks from the Abitibi belt and Pontiac subprovince, Superior Province, Canada. Systematic decreases in the Au content with increasing metamorphic grade indicate that Au was mobilized during prograde metamorphism. Mass balance calculations show that over 10 t of Au, 30,000 t of As, and 600 t of Sb were mobilized from 1 km3 of Pontiac subprovince sedimentary rock metamorphosed to the sillimanite metamorphic zone. The total gold resource in orogenic gold deposits in the southern Abitibi belt (7500 t Au) is only 3% of the Au mobilized from the estimated total volume of high-metamorphic-grade Pontiac sedimentary rock in the region (25,000 km3), indicating that sedimentary rocks are a major contributor of metals to the orogenic gold deposits in the southern Abitibi belt.

The Sedimentary Cycle on Early Mars

2019 ◽  
Vol 47 (1) ◽  
pp. 91-118 ◽  
Author(s):  
Scott M. McLennan ◽  
John P. Grotzinger ◽  
Joel A. Hurowitz ◽  
Nicholas J. Tosca
Keyword(s):  
Plate Tectonics ◽  
Sedimentary Rock ◽  
First Order ◽  
Sedimentary Environments ◽  
Source To Sink ◽  
Rock Record ◽  
Mineral Assemblages ◽  
Sedimentary Cycle ◽  
Early Mars ◽  
Over Time

Two decades of intensive research have demonstrated that early Mars ([Formula: see text]2 Gyr) had an active sedimentary cycle, including well-preserved stratigraphic records, understandable within a source-to-sink framework with remarkable fidelity. This early cycle exhibits first-order similarities to (e.g., facies relationships, groundwater diagenesis, recycling) and first-order differences from (e.g., greater aeolian versus subaqueous processes, basaltic versus granitic provenance, absence of plate tectonics) Earth's record. Mars’ sedimentary record preserves evidence for progressive desiccation and oxidation of the surface over time, but simple models for the nature and evolution of paleoenvironments (e.g., acid Mars, early warm and wet versus late cold and dry) have given way to the view that, similar to Earth, different climate regimes on Mars coexisted on regional scales and evolved on variable timescales, and redox chemistry played a pivotal role. A major accomplishment of Mars exploration has been to demonstrate that surface and subsurface sedimentary environments were both habitable and capable of preserving any biological record. ▪ Mars has an ancient sedimentary rock record with many similarities to but also many differences from Earth's sedimentary rock record. ▪ Mars’ ancient sedimentary cycle shows a general evolution toward more desiccated and oxidized surficial conditions. ▪ Climatic regimes of early Mars were relatively clement but with regional variations leading to different sedimentary mineral assemblages. ▪ Surface and subsurface sedimentary environments on early Mars were habitable and capable of preserving any biological record that may have existed.

Effect of rock strength on exhumation and the thermochronologic record: The south-central Colorado example

2021 ◽  
Author(s):  
Sabrina Kainz ◽  
Lon Abbott ◽  
Rebecca Flowers ◽  
James Metcalf
Keyword(s):  
Low Temperature ◽  
Sedimentary Rock ◽  
Rock Strength ◽  
Sedimentary Rocks ◽  
Sedimentary Basins ◽  
Crystalline Basement ◽  
Precambrian Basement ◽  
The West ◽  
South Central ◽  
Sangre De Cristo

&lt;p&gt;Past work has used the Southern Rocky Mountains (SRM) in the U.S. state of Colorado to illustrate the important role that rock strength plays in the histories recorded by the apatite fission track (AFT) and apatite (U-Th)/He (AHe) low-temperature thermochronometers (Flowers &amp; Ehlers, 2018). The SRM were initially raised during the Laramide Orogeny, ca. 70-45 Ma, but consensus exists that the region also experienced a later, post-Laramide exhumation event. Flowers &amp; Ehlers (2018) pointed to the low erosion potential of the Precambrian crystalline basement rocks that crop out in most SRM ranges as a primary reason for the abundance of 55-70 Ma &amp;#8220;Laramide&amp;#8221; AFT and AHe dates in the region, compared to a paucity of younger dates that would presumably be produced through erosion triggered by the post-Laramide exhumation event. South-central Colorado offers a test of this hypothesis, due to lateral variations in rock erodibility provided by the presence here of both sedimentary and crystalline Laramide ranges and adjacent sedimentary basins. The combination of our ongoing AHe study with previous south-central Colorado AFT and AHe work reveals kilometer-scale post-Laramide (Oligo-Miocene) exhumation has occurred in areas that possess thick sedimentary rock sequences whereas exhumation has been negligible where crystalline basement comprises the land surface.&amp;#160;&lt;/p&gt;&lt;p&gt;South-central Colorado&amp;#8217;s Sangre de Cristo Mountains consist of an imbricate stack of thrust sheets composed of Permian sedimentary rock. About 30 km farther east stand the Wet Mountains, another Laramide range &amp;#8211; but one composed of Precambrian basement rock. The Raton Basin, a SRM foreland basin filled with 2 km of synorogenic fill underlain by a thick sequence of marine shale, lies south and east of the two ranges. The Wet Mountains thus form a peninsula of strong crystalline rock surrounded by more erodible sedimentary rocks to the west, south, and east.&amp;#160;&lt;/p&gt;&lt;p&gt;Our study and that of Landman (2018) records at least 2 km of erosion in the Raton Basin east and south of the Wet Mountains since 25 Ma. Lindsey et al (1986) obtained 24-15 Ma AFT dates from the Paleozoic sedimentary rocks of the Sangre de Cristo Mountains, demonstrating that kilometer-scale Oligo-Miocene exhumation occurred just west of the Wet Mountains. By contrast, Kelley and Chapin (2004) obtained only pre-Laramide AFT ages between 228-110 Ma for 17 samples of Precambrian basement from the crest of the Wet Mountains. A 32 Ma ash flow tuff unconformably overlies Precambrian basement on Greenhorn Mountain, the Wet Mountains&amp;#8217; highest and southernmost peak. Its presence reinforces the conclusion, based on the AFT dates, that Oligo-Miocene erosion of the Wet Mountain massif has been minimal simultaneous with kilometer-scale exhumation to the west, south, and east. These results illustrate the important role that rock strength plays in determining the dates recorded in low-temperature thermochronologic studies.&lt;/p&gt;

3. Sedimentary rocks

2016 ◽  
pp. 29-50
Author(s):  
Jan Zalasiewicz
Keyword(s):  
Sedimentary Rock ◽  
Chemical Weathering ◽  
Sedimentary Rocks ◽  
Chemical Environment ◽  
Combined Effects ◽  
Star System ◽  
The Earth ◽  
Different Types ◽  
Physical And Chemical

The Earth has the greatest abundance and variety of sedimentary strata in our star system, dating back some 3.8 billion years. ‘Sedimentary rocks’ describes the processes that create different types of sedimentary rocks, which form a key guideline in reconstructing Earth’s history. Particles are created by both physical and chemical weathering. These particles are then moved by different modes of transport and sorted by size, which affect the resulting sedimentary rock. Sedimentary layers can remain as soft muds or loose sands for millions of years, but most buried sedimentary layers harden and turn into rock, under the combined effects of increasing heat and pressure, and of changes in chemical environment.

Enigmatic provenance signature of sandstone from the Okwa Group, Botswana

2020 ◽  
Vol 123 (3) ◽  
pp. 331-342
Author(s):  
T. Andersen ◽  
M.A. Elburg ◽  
J. Lehmann
Keyword(s):  
South Africa ◽  
Detrital Zircon ◽  
Sedimentary Rock ◽  
Age Distribution ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Significant Shift ◽  
Zircon Age ◽  
Three Samples ◽  
Isotope Distributions

Abstract Detrital zircon grains from three samples of sandstone from the Tswaane Formation of the Okwa Group of Botswana have been dated by U-Pb and analysed for Hf isotopes by multicollector LA-ICPMS. The detrital zircon age distribution pattern of the detrital zircons is dominated by a mid-Palaeoproterozoic age fraction (2 000 to 2 150 Ma) with minor late Archaean – early Palaeoproterozoic fractions. The 2 000 to 2 150 Ma zircon grains show a range of epsilon Hf from -12 to 0. The observed age and Hf isotope distributions overlap closely with those of sandstones of the Palaeoproterozoic Waterberg Group and Keis Supergroup of South Africa, but are very different from Neoproterozoic deposits in the region, and from the Takatswaane siltstone of the Okwa Group, all of which are dominated by detrital zircon grains younger than 1 950 Ma. The detrital zircon data indicate that the sources of Tswaane Formation sandstones were either Palaeoproterozoic rocks in the basement of the Kaapvaal Craton, or recycled Palaeoproterozoic sedimentary rocks similar to the Waterberg, Elim or Olifantshoek groups of South Africa. This implies a significant shift in provenance regime between the deposition of the Takatswaane and Tswaane formations. However, the detrital zircon data are also compatible with a completely different scenario in which the Tswaane Formation consists of Palaeoproterozoic sedimentary rock in tectonic rather than depositional contact with the other units of the Okwa Group.

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