Sand Mineralogy Research Articles

Sand-silt Petrology and Sediment Dispersal in the Gulf of Alaska

ABSTRACT Variations in the heavy and light mineralogy of Pliocene-Quaternary sands and coarse silts in Deep Sea Drilling Project holes in the Gulf of Alaska and eastern Aleutian Trench have been studied. Diagenesis is unimportant. Grain size has a strong influence on both heavy and light mineralogy. Pyroxene and volcanic lithic fragments are concentrated in coarser sands; amphibole and coarser crystalline lithic fragments in finer sands. This variation is partly provenance dependent. The sands are derived from two sources. Coarse pyroxene rich sands, with lithic fragments of volcanic and sedimentary rocks, have been transported by ice rafting from the Alaskan Peninsula and south-central Alaska. An amphibole-altered grain assemblage, associated with a wide range of lithic fragments, including m tamorphic and plutonic rocks, is transported by turbidity currents from south-eastern and south-central Alaska. The ice-rafted material is of lesser importance in Pliocene sediments, but is present in substantial amounts through the Pleistocene.

Mineralogy, Petrography and Derivation of Sands and Silts of the Continental Slope, Rise and Abyssal Plain of the Gulf of Mexico

ABSTRACT Sand and silt interbeds in cores from the continental slope, rise and abyssal plain of the Gulf of Mexico, may be composed of either detrital or carbonate sediments. Because of the insensitivity of the detrital minerals to transport distance and environment, the sand and silt interbeds from the deep portions of the Gulf may be related to specific source areas on the continental shelf. These source areas include (1) the Mississippi, (2) the Rio Grande, and (3) the rivers of northeast Mexico. Vertical variations in mineralogy show no significant trend with increasing depth in any core, indicating that relative contributions from each source remained constant. Carbonate sands and silts of the abyssal plain were derived from the shallow waters of the Campeche Shelf. Transportation along t e axis of the Campeche Canyon carried these shelf carbonates northward into deeper water areas. in some instances through the medium of turbidity currents.

A reconnaissance study of the mineralogy of sand fractions from East Pakistan sediments and soils

Two main sand provinces comprising nearly all the sediments of East Pakistan can be recognized on the basis of their sand mineralogy. One province contains most of the folded Tertiary sedimentary formations bordering East Pakistan in the north, east and southeast as well as old clays, “Madhupur clay”, which occupy extensive terrace-like areas in the centre and west. These sediments are characterized by low contents of feldspars and micas and by high contents of epidote, zircon, tourmaline, kyanite, staurolite and sillimanite in the heavy sand fraction. Except perhaps for the youngest sedimentary formations of this group which are of Pliocene-Early Pleistocene age, the sediments of this main province probably mainly originated from the crystalline rocks of the old Indian peninsula. The second main sand province comprises the recent and subrecent floodplain deposits of the Brahmaputra, Ganges, Meghna, Tista and some smaller rivers. The sand fractions from this unit are characterized by relatively high contents of feldspars, micas and amphiboles. They have probably mainly been derived from crystalline rocks in the Himalayas. This sand province can be subdivided into a number of smaller provinces on the basis of the relative importance of different heavy minerals. Each of these sub-provinces generally corresponds with one or more physiographic units recognized during soil surveys carried out in East Pakistan (Brammer, in preparation). Soil formation and weathering have had little influence on the composition of the sand fraction of East Pakistan soils. Even in the oldest soils sampled which are young, latosolic soils developed in Madhupur clay deposits, relatively easily weatherable minerals such as feldspars occur in similar amounts as in the unweathered parent material. Biotite is the only mineral which shows clear signs of weathering in most soils. Rapid weathering resulting in the complete destruction of this mineral appears to take place in seasonally flooded or puddled plough layers of both floodplain and terrace soils used for rice cultivation. Similar weathering processes may have taken place in some bleached subsoil horizons developed in poorly drained Madhupur clay deposits.

Mineralogy, provenance, and dispersal history of late Quaternary deep-sea sands in Cascadia Basin and Blanco fracture zone off Oregon

Abstract The mineralogy of sandy sediments deposited during the late Pleistocene and Holocene in southern Cascadia Basin and the adjoining Blanco Fracture Zone displays systematic regional and temporal trends. The light-mineral constituents of these sands are lithic, arkosic, or volcanic in composition. They are mainly derived from extrusive and intrusive basic igneous rocks. Four deep-sea heavy-mineral provinces (A, B, C, and D) are distinguishable in the area investigated. Province A lies in the Blanco Fracture Zone--Gorda Ridge transition area. Textural and mineralogical compositions of these deposits suggest local submarine volcanism. The volcanism may be associated with sea-floor spreading along the young crestal zone of Gorda Ridge. Province B is restricted to the late Pleistocene sediments of western Cascadia Abyssal Plain and Vancouver Valley; the most probable sediment source is Vancouver Island and vicinity. Sandy sediments from the island no longer reach the deep-sea environments, because they are presently being trapped behind the sills of the glacially-scoured inlets of the island. Province C includes the late Pleistocene and Holocene deposits in southeastern Cascadia Basin and Cascadia Channel; the sediments were derived from the Columbia River drainage. During Holocene time, the supply of coarse-grained detritals from the Columbia River diminished as sea level rose, and locally derived sediments from the metamorphic terrane of the Klamath Mountains were deposited at the base of the continental slope off southern Oregon and northern California (Province D), overriding the influence of the Columbia River sedimentation.

Recent Sedimentation on Southern Bering Shelf: ABSTRACT

A veneer of contemporary sediments covers the entire continental shelf in the Bristol Bay region of the southeast Bering Sea. This broad shelf, covering an area of 1.5 × 105 sq km has a relatively smooth bottom and gentle slope of about 1:4,000. Nearshore sediment is gravelly, coarse sand which grades to fine sand offshore. In general, the mean size of the sediment is related to the depth. The nearshore and offshore heterogenous sediments are very poorly sorted whereas homogeneous sand in the center is well sorted. The mineralogy of sand is diverse, reflecting the complex sources: sedimentary, metamorphic, and igneous terrane of the hinterland in the north and east, and typically volcanics from the Aleutian Islands in the End_Page 2503------------------------------ south. The general paucity of clay minerals and dominance of feldspars in size fraction The sediment character and distribution in Bristol Bay reflects two distinct sedimentary environments of deposition. Sediments on the shallow shelf are controlled by the storm-generated-wave drift currents, are moderately well sorted, and are devoid of silt and clay. In protected bays, and at water depths prohibiting elutriation by storm waves, the silt-clay content in sediments increases significantly. Local influences of fluvial, tidal, and wind-driven currents on sediments are also apparent. Long waves generated by frequent storms roil shelf sediments with a net seaward movement. The absence of silt and clay sediments and abundance of fine sand on the shelf and seaward prograding blankets of mud near the slope reflect midstage of shelf grading. Sedimentation in Bristol Bay shelf ma well be an analogue to the widespread, uniform epicontinental clastic deposits that were formed in the past. End_of_Article - Last_Page 2504------------

Mineralogy, Provenance, and Dispersal History of Late Quarternary Deep-Sea Sands in Cascadia Basin and Blanco Fracture Zone off Oregon

Mineralogy, Provenance, and Dispersal History of Late Quarternary Deep-Sea Sands in Cascadia Basin and Blanco Fracture Zone off Oregon

Evidence for the residual character of two soils, one on granite, the other on limestone in Peterborough County, Ontario

The morphology, particle size distribution, and clay mineralogy data of a Methuen soil derived from a granite and a Tweed soil derived from a crystalline limestone are interpreted as supporting the concept that these two soils are residual. Sand mineralogy and elemental analysis of mica support the residual hypothesis.

Occurrence of talc in clay fractions from beach sands of the Gulf of Mexico

The clay mineralogy of beach sands is in general similar to that of nearby samples from other environments except for the occurrence of the mineral talc in the <2mu fractions from some of the beach sands and from closely adjacent areas, but from no other bottom samples in the NE. Gulf of Mexico area. No conclusions are reached regarding the significance of the occurrence of talc in only the beach samples. The mineral usually is most abundant in samples which contain little clay matter, but this is apparently not a controlling factor. Possibly physical processes peculiar to the swash area such as sand flotation combined with the flaky habit and chemical resistance of talc produce the concentration noted in the beach material.

Weathering and soil formation on dolerite in Tasmania with particular reference to several trace elements

The mineralogy and chemistry of weathering and soil formation have been studied at 17 widely separated sites with contrasting climatic conditions on comparatively uniform dolerite in Tasmania. The clay and fine sand mineralogy of the soils has been related to their degree of weathering. These studies have shown large chemical and mineralogical changes accompanying the initial stages of weathering in some krasnozem soils. The reorganization of cobalt, zirconium, nickel, copper, molybdenum, manganese, and zinc during genesis of four soil groups has been considered in terms of the factors involved. Some of these results indicate that the clay horizon of the podzolic soils has probably been formed by weathering in situ. Seasonal waterlogging in certain horizons has strongly mfluenced the chemistry and mineralogy of weathering in many of these soils. This study has shown that the composition of the parent material has only influenced the geochemistry of trace elements in less weathered soils and that pedogenic factors assumed greater significance as the soils became more strongly weathered. Geomorphic processes had a marked influence on the geochemistry of some soils by the truncation of mature soil profiles.

Mineralogy and origin of the yellow-brown sands and related soils

Summary Soils formed from wind-blown sand are found throughout New Zealand. In order to study their genesis the mineralogy of a large number of these soils from the Manawatu, Waverley, Dargaville, Ruakaka, Ahipara and the Canterbury Plains has been examined. The Manawatu and Waverley soils were similar in clay mineralogy, the clay minerals being micas, hydrous micas and vermiculite, with traces of halloysite. The pattern of clay content was consistent with the theory that most of the clay in these soils is derived from loess-like material blown in from the beaches after being eroded from older soils in the vicinity. A similar picture was found in a sequence from Dargaville, for the younger soils which were clearly wind-blown and had a clay mineral distribution very like the Manawatu soils. The older soils, however, appeared to be derived from water-deposited rather than wind-blown sand, and contained kaolin and gibbsite, but these also were derived from the sediment and not formed in situ. The Ruakaka soi...

Texture and Mineralogy of the Recent Sands of the Gulf Coast

ABSTRACT The objectives of this investigation are to determine the major transportation paths for the Recent beach sands of the Gulf of Mexico and to relate the textures and mineralogy of the Recent sands to their depositional environments. Approximately two hundred Recent sand samples were collected from the rivers and beaches of the Gulf Coast states. Mechanical analyses were made to determine the grain size and sorting. Spectro-chemical methods were used to determine chemical composition, and thin-section Rosiwal analyses were used to determine mineralogical composition. The major conclusions of this investigation are as follows: 1.--The Recent beach sands east of the Mississippi River Delta are mature quartz sands which contain practically no feldspar and a mature heavy-mineral suite rich in staurolite and kyanite. The Recent beach sands west of the Mississippi River are feldspathic. The feldspar abundance of these sands decreases from the Mississippi Delta area westward in the direction of prevailing longshore currents, mainly by dilution. The heavy-mineral suite of the Recent beach sands from Louisiana and east Texas contains abundant unstable minerals; among the resistant heavy minerals, garnet predominates over staurolite and kyanite. 2.--The relative abundance of unstable heavy minerals which can easily be decomposed during weathering or by postdepositional changes is not a reliable criterion for paleogeographic interpretations. On the other hand, feldspar abundance and ratio of garnet to staurolite plus kyanite, can be used to recognize ancient petrologic provinces.

Size, Sorting, Mineralogy, and Chemical Composition of Recent Sands of Northern Gulf Coast: ABSTRACT

An investigation was completed to determine the origin and the major transportation paths for the Recent beach sands of the northern Gulf Coast and to relate the texture and mineralogy of the Recent sands to their depositional environments. About 200 Recent sand samples were collected from the rivers and beaches of the Gulf Coast states. Mechanical analyses were made to determine the grain size and sorting. Spectrochemical methods were used to determine chemical composition, and thin-section Rosiwal analyses for mineralogical composition. The major conclusions of this investigation follow. 1. The Recent beach sands east of the Mississippi River Delta are mature quartz sands, which contain practically no feldspar and which contain a mature heavy-mineral suite rich in staurolite and kyanite. The Recent beach sands west of the Mississippi River are feldsphatic. The feldspar abundance End_Page 2520------------------------------ of these sands decreases from about 20 per cent in the Mississippi Delta area to less than 10 per cent on the Texas Coast. The westward decrease of the feldspar abundance in the direction of prevailing longshore current can be attributed mainly to dilution. The heavy-mineral suite of the Recent beach sands from Louisiana and east Texas contains abundant unstable minerals; among the resistant heavy minerals garnet predominates over staurolite and kyanite. 2. The relative abundance of unstable heavy mineral which can be easily decomposed during weathering or by post-depositional changes is not a reliable criterion for paleogeographic interpretations. Feldspar abundance and ratio of garnet to staurolite plus kyanite, on the other hand, may be used to recognize ancient petrologic provinces. End_of_Article - Last_Page 2521------------

Petrology of Recent Sands of the Rhine and the Meuse in the Netherlands

ABSTRACT The sands which the Rhine deposited during the Pleistocene to Recent reflect the geological history of the river. The picture presented by the mineralogy of the Rhine sands is a chaotic one, due to the fact that sands of three sources occur side by side and are mixed. The Meuse-sands, too, show an entirely different picture from the one to be expected on general grounds. The southern part of the stream contains sand with a mineral association (Eysden-province) derived from the hinterland, the Ardennes. In the middle part of the stream this material is already getting into the background and is giving way to sand from the Pleistocene terraces belonging for the greater part to the Limburg-province. In the lower part of this river the Eysden-material has become very unimportant and the sand shows especially the characteristics of young-Pleistocene Rhine-sands, which correspond with the geological situation of the surroundings. The Netherland rivers transport no sand to sea, the estuaries sand up from the sea, and the river sand comes to rest about 30 km. from the coast.

The mineralogy and origin of the natural beach sand concentrates of New South Wales

The mineralogy and origin of the natural beach sand concentrates of New South Wales

Mineralogy of some black sands from Idaho, with a description of the methods used for their study

Mineralogy of some black sands from Idaho, with a description of the methods used for their study