286:
topographically moderate relief flat enough to allow leaching of the products of chemical weathering. A second condition is long periods of tectonic stability; tectonic activity and climate change partially erode the regolith. Weathering rates of 20 m (66 ft) per million years suggest that deep regoliths require several million years to develop. The third condition is humid tropical to temperate climate; higher temperatures enable reactions to occur more rapidly. Deep weathering can occur in cooler climates, but over longer periods of time.
198:
31:
252:
weathered regoliths are widespread in the inter-tropical belt, particularly on the continental landmasses between latitudes 35°N and 35°S. Similar weathered regoliths exist at much higher latitudes – 35–42°S in southeast
Australia (Victoria and Tasmania), 40–45°N in the United States (Oregon and Wisconsin) and 55°N in Europe (Northern Ireland, Germany) – although these are not regionally extensive. In some localities it is possible to
159:
375:. Supergene enrichment occurs near the surface and involves water circulation with its resulting oxidation and chemical weathering. Deep weathering causes the formation of many secondary and supergene ores – bauxite, iron ores, saprolitic gold, supergene copper, uranium and heavy minerals in residual accumulations.
285:
are dominant during the initial phase of weathering under humid conditions. Saprolites form in high rainfall regions which result in chemical weathering and are characterised by distinct decomposition of the parent rock's mineralogy. Conditions for the formation of deeply weathered regolith include a
251:
now occur in a wide variety of climates ranging from warm humid to arid, tropical to temperate, they were formed under similar conditions in the past. In parts of Africa, India, South
America, Australia and southeast Asia, regolith has been forming continuously for over 100 million years. Deeply
328:– are progressively weathered through this zone. Ferromagnesian minerals are the principal hosts for nickel, cobalt, copper and zinc in sulfide-poor mafic and ultramafic rocks, and are retained higher in the profile than sulfide-hosted metals. They are leached from the upper horizons and
181:– regoliths are the loose layer of rocks that rest on the bedrock – saprolite may be overlain by upper horizons of residual laterite; most of the original profile is preserved by residual soils or transported overburden. Weathering formed thin
256:
saprolite by considering that the saprolite must be younger than the parent material and older than any thick cover unit such a lava or sedimentary rock. This principle is useful in some contexts but in others, like certain parts of Sweden where
347:
are of saprolite grit. Poorly weathered saprolite grit aquifers are capable of producing groundwater, often suitable for livestock. Yields depend on the texture of the materials and their depth from which the aquifer is derived.
185:
saprolites 1,000 to 500 million years ago; thick kaolinitic saprolites 200 to 66 million years ago; and medium-thick immature saprolites 5 million years ago in Sweden. The general structure of kaolinite has
166:
Saprolite (from Greek σαπρος = putrid + λιθος = rock) is a chemically weathered rock (literally, it means "rotten rock"). More intense weathering results in a continuous transition from saprolite to
367:, Western Australia, in the top 1 to 2 m (3.3 to 6.6 ft) of the soil profile and locally as deep as 5 m (16 ft). The gold-carbonate association is also apparent in the
236:
compounds are the primary coloring agents in saprolites. At most outcrops the color comes from ferric compounds; the color relates to the mineralogy and particle size. Submicron-sized
104:
of the products of chemical weathering. A second condition is long periods of tectonic stability; tectonic activity and climate change can cause erosion. The third condition is
320:
are highly soluble, especially in acidic environments; the elements hosted by them – calcium, magnesium, manganese and strontium – are strongly leached.
655:
George, Richard J. (January 1992). "Hydraulic properties of groundwater systems in the saprolite and sediments of the wheatbelt, Western
Australia".
589:(2002). "Deep weathering through time in central and northwestern Europe: problems of dating and interpretation of geological record".
243:
Regoliths vary from a few meters to over 150 m (490 ft) thick, depending on the age of the land surface, tectonic activity,
457:"Evolution of Regoliths and Landscapes in Deeply Weathered Terrain – Implications for Geochemical Exploration"
568:
162:
Saprolite is not as weathered as laterite; there is a continuum from the upper layer of saprolite to laterite.
240:
is yellow; coarse goethite is brown. Sub-micron-sized hematite is red; coarse hematite is gray to black.
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17:
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The Use of Index laboratory
Testing to Determine the Engineering Behaviour of Granitic Saprolite
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123:, often suitable for livestock. Deep weathering causes the formation of many secondary and
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247:, climate history and the composition of the bedrock. Although these deeply weathered
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are some of the most unstable minerals in humid, oxidizing environments; many
690:
482:
368:
218:
174:
547:
Hurst, Vernon J. (February 1977). "Visual estimation of iron in saprolite".
324:– oxidized and hydrolized low-silicon, iron- and magnesium-rich oxide
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321:
62:
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120:
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The regolith of a region is the product of its long weathering history;
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compounds. Deeply weathered profiles are widespread on the continental
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with secondary iron-manganese oxides in the mid- to lower saprolite.
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and represent deep weathering of the bedrock surface. In lateritic
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30:
46:; C represents saprolite, a less-weathered regolith; beneath C is
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include a topographically moderate relief flat enough to prevent
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47:
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74:
488:"Palaeosurfaces and associated saprolites in southern Sweden"
387: – Isolated, steep rock hill on relatively flat terrain
624:
Dippenaar, Mattys; Van Rooy, Louis; Croucamp, Leon (2006).
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313:
233:
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35:
569:
10.1130/0016-7606(1977)88<174:VEOIIS>2.0.CO;2
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are closely correlated and documented in the southern
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sulfides are easily leached to deep in the profile.
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455:Butt, C.R.M.; Lintern, M.J.; Anand, R.R. (1997).
92:Conditions for the formation of deeply weathered
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546:
492:Geological Society, London, Special Publications
150:, and heavy minerals in residual accumulations.
61:rock. Saprolites form in the lower zones of
555:(2). Geological Society of America: 174.
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205:(Ireland). Transition from tectonized
173:Saprolites form in the lower zones of
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154:Definition, description and locations
65:and represent deep weathering of the
533:
486:; Olsson, Siv; Olvmo, Mats (1997).
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24:
473:
25:
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269:deposits, it is of little value.
115:Poorly weathered saprolite grit
617:
575:
13:
1:
611:10.1016/S0341-8162(02)00015-2
512:10.1144/GSL.SP.1997.120.01.07
396:
677:10.1016/0022-1694(92)90113-A
361:calcium magnesium carbonates
272:
7:
663:(1–4). Elsevier B.V.: 251.
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10:
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221:with scattered erratics,
119:are capable of producing
27:Chemically weathered rock
587:Lidmar-Bergström, Karna
484:Lidmar-Bergström, Karna
335:
73:, its color comes from
265:rocks and overlain by
230:
217:section is covered by
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351:The distributions of
209:through saprolite to
200:
161:
33:
657:Journal of Hydrology
225:sandy soil and thin
669:1992JHyd..130..251G
603:2002Caten..49...25M
561:1977GSAB...88..174H
504:1997GSLSP.120...95L
194:hydroxide layers.
231:
164:
81:between latitudes
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357:calcium carbonate
345:Western Australia
190:sheets bonded to
110:temperate climate
69:surface. In most
16:(Redirected from
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373:South Australia
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261:is formed from
254:relatively date
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38:; B represents
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631:(Report). IAEG
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597:(1–2): 25–40.
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365:Yilgarn Craton
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106:humid tropical
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702:Sedimentology
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369:Gawler Craton
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330:reprecipitate
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326:igneous rocks
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219:glacial drift
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201:Saprolite at
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175:soil horizons
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138:, saprolitic
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100:and to allow
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63:soil profiles
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49:
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34:A represents
32:
19:
712:Ore deposits
697:Soil science
660:
656:
633:. Retrieved
619:
594:
590:
583:Migoń, Piotr
577:
552:
549:GSA Bulletin
548:
523:. Retrieved
495:
491:
463:. Retrieved
350:
339:
322:Serpentinite
288:
276:
242:
232:
172:
165:
142:, supergene
114:
91:
54:
53:
263:Precambrian
121:groundwater
707:Weathering
691:Categories
397:References
318:Carbonates
306:molybdenum
283:dispersion
267:Quaternary
183:kaolinitic
79:landmasses
525:April 21,
520:129229906
498:(1): 95.
465:April 22,
385:Inselberg
273:Formation
215:weathered
207:quartzite
203:Arranmore
192:aluminium
179:regoliths
136:iron ores
125:supergene
59:weathered
55:Saprolite
722:Regolith
717:Pedology
391:Residuum
379:See also
341:Aquifers
290:Sulfides
279:leaching
249:terrains
238:goethite
223:Holocene
211:laterite
188:silicate
168:laterite
117:aquifers
102:leaching
94:regolith
71:outcrops
44:regolith
40:laterite
665:Bibcode
599:Bibcode
557:Bibcode
500:Bibcode
294:cadmium
245:climate
148:uranium
132:bauxite
98:erosion
67:bedrock
48:bedrock
18:Saprock
635:May 3,
591:Catena
518:
310:nickel
302:copper
298:cobalt
213:. The
144:copper
75:ferric
629:(PDF)
516:S2CID
460:(PDF)
637:2010
527:2010
467:2010
355:and
353:gold
336:Uses
314:zinc
312:and
281:and
259:grus
234:Iron
140:gold
128:ores
87:35°S
85:and
83:35°N
42:, a
36:soil
673:doi
661:130
607:doi
565:doi
508:doi
496:120
359:or
343:in
227:bog
108:to
693::
671:.
659:.
645:^
605:.
595:49
593:.
585:;
563:.
553:88
551:.
535:^
514:.
506:.
494:.
490:.
475:^
405:^
371:,
308:,
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300:,
296:,
170:.
146:,
134:,
130::
112:.
89:.
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20:)
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