275:
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.
187:
20:
241:
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
148:
364:. 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.
274:
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
240:
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
317:– 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
170:– 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
245:
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
336:
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.
174:
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
155:
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
356:, 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
225:
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
93:
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
309:
are highly soluble, especially in acidic environments; the elements hosted by them – calcium, magnesium, manganese and strontium – are strongly leached.
644:
George, Richard J. (January 1992). "Hydraulic properties of groundwater systems in the saprolite and sediments of the wheatbelt, Western
Australia".
578:(2002). "Deep weathering through time in central and northwestern Europe: problems of dating and interpretation of geological record".
232:
Regoliths vary from a few meters to over 150 m (490 ft) thick, depending on the age of the land surface, tectonic activity,
446:"Evolution of Regoliths and Landscapes in Deeply Weathered Terrain – Implications for Geochemical Exploration"
557:
151:
Saprolite is not as weathered as laterite; there is a continuum from the upper layer of saprolite to laterite.
229:
is yellow; coarse goethite is brown. Sub-micron-sized hematite is red; coarse hematite is gray to black.
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318:
575:
472:
615:
The Use of Index laboratory
Testing to Determine the Engineering Behaviour of Granitic Saprolite
690:
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112:, often suitable for livestock. Deep weathering causes the formation of many secondary and
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236:, 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
679:
471:
357:
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163:
536:
Hurst, Vernon J. (February 1977). "Visual estimation of iron in saprolite".
313:– oxidized and hydrolized low-silicon, iron- and magnesium-rich oxide
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51:
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109:
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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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35:; 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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55:
36:
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477:"Palaeosurfaces and associated saprolites in southern Sweden"
376: – Isolated, steep rock hill on relatively flat terrain
613:
Dippenaar, Mattys; Van Rooy, Louis; Croucamp, Leon (2006).
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128:
24:
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10.1130/0016-7606(1977)88<174:VEOIIS>2.0.CO;2
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are closely correlated and documented in the southern
570:
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sulfides are easily leached to deep in the profile.
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444:Butt, C.R.M.; Lintern, M.J.; Anand, R.R. (1997).
81:Conditions for the formation of deeply weathered
677:
535:
481:Geological Society, London, Special Publications
139:, and heavy minerals in residual accumulations.
50:rock. Saprolites form in the lower zones of
544:(2). Geological Society of America: 174.
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194:(Ireland). Transition from tectonized
162:Saprolites form in the lower zones of
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143:Definition, description and locations
54:and represent deep weathering of the
522:
475:; Olsson, Siv; Olvmo, Mats (1997).
392:
13:
462:
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722:
258:deposits, it is of little value.
104:Poorly weathered saprolite grit
606:
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1:
600:10.1016/S0341-8162(02)00015-2
501:10.1144/GSL.SP.1997.120.01.07
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666:10.1016/0022-1694(92)90113-A
350:calcium magnesium carbonates
261:
7:
652:(1–4). Elsevier B.V.: 251.
367:
10:
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210:with scattered erratics,
108:are capable of producing
16:Chemically weathered rock
576:Lidmar-Bergström, Karna
473:Lidmar-Bergström, Karna
324:
62:, its color comes from
254:rocks and overlain by
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206:section is covered by
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40:
340:The distributions of
198:through saprolite to
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22:
646:Journal of Hydrology
214:sandy soil and thin
658:1992JHyd..130..251G
592:2002Caten..49...25M
550:1977GSAB...88..174H
493:1997GSLSP.120...95L
183:hydroxide layers.
220:
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70:between latitudes
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346:calcium carbonate
334:Western Australia
179:sheets bonded to
99:temperate climate
58:surface. In most
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362:South Australia
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250:is formed from
243:relatively date
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27:; B represents
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5:
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620:(Report). IAEG
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586:(1–2): 25–40.
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354:Yilgarn Craton
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95:humid tropical
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691:Sedimentology
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358:Gawler Craton
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319:reprecipitate
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208:glacial drift
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190:Saprolite at
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164:soil horizons
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127:, saprolitic
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89:and to allow
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52:soil profiles
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38:
34:
30:
26:
23:A represents
21:
701:Ore deposits
686:Soil science
649:
645:
622:. Retrieved
608:
583:
579:
572:Migoń, Piotr
566:
541:
538:GSA Bulletin
537:
512:. Retrieved
484:
480:
452:. Retrieved
339:
328:
311:Serpentinite
277:
265:
231:
221:
161:
154:
131:, supergene
103:
80:
43:
42:
252:Precambrian
110:groundwater
696:Weathering
680:Categories
386:References
307:Carbonates
295:molybdenum
272:dispersion
256:Quaternary
172:kaolinitic
68:landmasses
514:April 21,
509:129229906
487:(1): 95.
454:April 22,
374:Inselberg
262:Formation
204:weathered
196:quartzite
192:Arranmore
181:aluminium
168:regoliths
125:iron ores
114:supergene
48:weathered
44:Saprolite
711:Regolith
706:Pedology
380:Residuum
368:See also
330:Aquifers
279:Sulfides
268:leaching
238:terrains
227:goethite
212:Holocene
200:laterite
177:silicate
157:laterite
106:aquifers
91:leaching
83:regolith
60:outcrops
33:regolith
29:laterite
654:Bibcode
588:Bibcode
546:Bibcode
489:Bibcode
283:cadmium
234:climate
137:uranium
121:bauxite
87:erosion
56:bedrock
37:bedrock
624:May 3,
580:Catena
507:
299:nickel
291:copper
287:cobalt
202:. The
133:copper
64:ferric
618:(PDF)
505:S2CID
449:(PDF)
626:2010
516:2010
456:2010
344:and
342:gold
325:Uses
303:zinc
301:and
270:and
248:grus
223:Iron
129:gold
117:ores
76:35°S
74:and
72:35°N
31:, a
25:soil
662:doi
650:130
596:doi
554:doi
497:doi
485:120
348:or
332:in
216:bog
97:to
682::
660:.
648:.
634:^
594:.
584:49
582:.
574:;
552:.
542:88
540:.
524:^
503:.
495:.
483:.
479:.
464:^
394:^
360:,
297:,
293:,
289:,
285:,
159:.
135:,
123:,
119::
101:.
78:.
668:.
664::
656::
628:.
602:.
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218:.
39:.
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