Wayne C. Isphording

Discussion of the Occurrence and Origin of Sedimentary Palygorskite-Sepiolite Deposits

Marine and non-marine palygorskite-sepiolite deposits are found throughout the world and occur interbedded with chert, dolomite, limestone, phosphates and other non-detrital sedimentary rocks. The origin of these high-magnesium clays has long been attributed to either alteration of volcanic ash or the structural transformation of smectite clays. More recently, others have argued origin by direct crystallization (neo-formation). Recent laboratory studies support this latter concept, particularly in environments where the concentration of alumina is low, the silica concentration high, and the pH alkaline. Such an origin is proposed for the Georgia-Florida deposits in southeastern United States, since major obstacles exist against formation by alteration of volcanic ash or by transformation of smectites. Lateritic weathering during the Miocene would have favored direct precipitation of these clays in the shallow, marginal seas. The basinward increase in the MgO: Al2O3 ratio is further support.Deep weathering of crystalline rocks in northern British Honduras and Guatemala would have produced similar high silica, low alumina conditions on the adjacent submerged Yucatan Platform during the late Tertiary. The seaward increase in the MgO: A12O3 ratio, the lack of associated detrital constituents, and the absence of associated smectites strongly indicate a similar origin by direct crystallization of these Yucatan palygorskite-sepiolite clays.Some occurrences of palygorskite and sepiolite may well be related to the alteration of smectite clays or volcanic ash. However, many of the large sedimentary deposits are more probably the result of direct crystallization adjacent to areas undergoing tropical or subtropical weathering.RésuméLes dépôts marins et non marins de palygorskite-sépiolite existent partout dans le monde et se présentent en mélange avec des chailles, de la dolomite, du calcaire, des phosphates et d’autres roches sédimendaires non détritiques. L’origine de ces argiles à haute teneur en magnésium a longtemps été attribuée soit à l’altération de cendres volcaniques, soit à la transformation structurale de smectites. Plus récemment d’autres auteurs ont défendu l’hypothèse d’une origine par cristallisation directe (néoformation). Des travaux de laboratoire récents confirment ce dernier concept, notamment dans le cas des environnements à concentration en alumine basse, à concentration en silice élevée et à pH alcalin. Une telle origine est proposée pour les dépôts de Georgie et Floride dans le sud-est des Etats-Unis, puisque des obstacles majeurs s’y opposent à l’altération d’une cendre volcanique ou à la transformation de smectites. Une altération latéritique pendant le miocène aurait favorisé la précipitation de ces argiles dans des mers marginales peu profondes. L’augmentation du rapport MgO: A12O3 en allant vers la cuvette est un argument supplémentaire.L’altération profonde de roches cristallines dans le nord du Honduras britannique et au Gautemala aurait produit des conditions similaires—richesse en silice et pauvtreé en alumine—sur la plateforme voisine submergée du Yucatan pendant la fin du tertiaire. L’augmentation du rapport MgO: A12O3 en allant vers la mer, l’absence de constituants détritiques et de smectites associés indiquent avec force une origine comparable par cristallisation directe de ces palygorskites-sépiolites du Yucatan.Certains gisements de palygorskite et de sépiolite sont sans doute reliés à l’altération de smectites ou de cendres volcaniques. Cependant, la plupart des grands dépôts sédimentaires est beaucoup plus probablement le résultat d’une cristallisation directe adjacente à des zones ayant subi une altération tropicale ou subtropicale.KurzreferatMarine und nichtmarine Palygorskit-Sepiolit-Lagerstätten werden in der ganzen Welt gefunden und treten eingebettet in Quarzit, Dolomit, Kalkstein, Phosphate und andere nichtdetritische Sedimentgesteine auf. Die Entstehung dieser hochmagnesiumhaltigen Tone wurde lange entweder der Umbildung vulkanischer Aschen oder der Strukturumwandlung von Smectiten zugeschrieben. Neuerdings wurde von anderen Autoren eine Entstehung durch direkte Kristallisation (Neoformation) erörtert. Neuere Laboruntersuchungen stützen das letztgenannte Konzept besonders für Umweltbedingungen, in denen die Aluminiumkonzentration gering, die Kieselsäurekonzentration hoch ist und der pH-Wert im alkalischen Bereich liegt. Eine solche Entstehung wird für die Georgia-Florida-Lagerstätten in den südöstlichen Vereinigten Staaten vorgeschlagen, da hier einer Bildung durch Umsetzung vulkanischer Aschen oder durch Umwandlung von Smectiten größere Hindernisse entgegenstehen. Lateritische Verwitterung während des Miozäns würde in den flachen Randseen eine direkte Fällung dieser Tonminerale begünstigt haben. Der beckenwärts erfolgende Anstieg im MgO: Al2O3-Verhältnis ist eine weitere Stütze.Tiefgründige Verwitterung kristalliner Gesteine im nördlichen Britisch-Honduras und Guatemala würden während des späten Tertiärs ähnliche kieselsäurereiche, aluminiumarme Bedingungen in der benachbarten überschwemmten Yucatan-Plattform hervorgerufen haben. Der seewärts erfolgende Anstieg im Mg0:Al203-Verhältnis, das Fehlen von Beimengungen detritischer Bestandteile und die Abwesenheit von Smectit deuten stark darauf hin, daß diese Yukatan-Palygorskit-Sepiolit Tone in ähnlicher Weise durch direkte Kristallisation entstanden sind.Einige Vorkommen von Palygorskit und Sepiolit mögen wohl mit der Umwandlung von smectitischen und vulkanischen Aschen in Beziehung stehen, jedoch sind viele der großen sedimentären Lagerstätten mit großer Wahrscheinlichkeit das Ergebnis direkter Kristallisation in der Nachbarschaft von Gebieten, in denen tropische und subtropische Verwitterung ablief.РезюмеМорские и неморские отложения палыгорскита-сепиолита находят по всему свету и они встречаются залегающими между пластами кремнистого сланца, доломита, известняка, фосфора и других необломочных осадочных горных пород. Происхождение этих глин с высоким содержанием магния давно уже предписывалось или изменениям вулканического пепла или структурной трансформации смектитных глин. Недавно выдвинули мнение, что происхождение это является непосредственной кристаллизацией (новонаслоением). Современные лабораторные исследования подтверждают последнюю консепцию, особенно, если в окружающих условиях концентрация глинозема низка, а концентрация кварца высока и при этом рН щелочный. Считают, что отложения в Джорджии-Флорида в Южных Соединенных Штатах такого происхождения, так как существуют важные возражения против изменения вулканического пепла или трансформации смектитов. Латеритовое выветривание в период миоцена повело бы к непосредственному осаждению этих глин в мелководных побережных морях. Увеличение отношения МgО: А12O3 по направлению к бассейну является добавочным подтверждением.Глубокое выветривание кристаллических горных пород в Британских Гондурас и Гватемала создали бы такие условия высокого содержания кварца и низкого содержания глинозема на смежной погруженной платформе Юкатана во воремя позднего третичного периода. Повышение отношения МgO: А12Оз по направлению к морю, отсутствие ассоциированных наносных компонентов и отсутствие ассоциированных смектитов явно указывают на непосредственную кристаллизацию этих юкотанских палыгорских-сепиолитных глин.Иногда происхождение палыгорскита и сепиолита может быть связано с изменениями смектитных глин или вулканического пепла. Однако многие крупные осадочные отложения являются, наверно, результатом непосредственной кристаллизации рядом с областями подвергающихся тропическому или субтропическому выветриванию.

Heavy-Mineral Assemblages of Continental Margins as Indicators of Plate-Tectonic Environments

ABSTRACT Heavy-mineral analyses of fifty Quaternary sediments from the North Sea, Red Sea, East China Sea, South China Sea, and Vancouver Island area (western seaboard of Canada) supplemented by over 1000 published analyses of sediments from many other sites in the world define accessory clastic mineral assemblages indicative of the principal plate-tectonic settings (excluding transform plate boundaries) associated with continental margins. Assemblages of all continental margins studied differ significantly from those of the intraoceanic, island-arc, and deep marginal-sea assemblages by possessing relatively high contents of zircon, tourmaline, garnet, epidote, amphibole (as well as other less common minerals), derived chiefly from metamorphic and sialic intrusive rocks. This suite is accompan ed by olivine, iddingsite, and brown (titanium-rich) clinopyroxene in regions containing rifting-type volcaniclastic sediments (i.e., near divergent plate boundaries), and with orthopyroxene, green clinopyroxene, and green-brown hornblende in arc-type volcaniclastic deposits (areas near convergent plate boundaries). On passive continental margins, both volcaniclastic suites are absent or present in negligible amounts.

Age and Origin of the Citronelle Formation in Alabama

The sediments forming the Citronelle Formation occur as a nearly continuous blanket along the southern margin of the Coastal Plain and can be traced from Texas across the Gulf Coast into peninsular Florida. The lack of fossil evidence, however, has made this formation the subject of a heated age controversy since it was first described in 1916. At present, its age is given by various investigators as late Miocene, Pliocene, Plio-Pleistocene or Pleistocene. The recent discovery of abundant vertebrate fossils, at a site in northern Mobile County, Alabama, near the base of the formation, indicates that the maximum age of the Citronelle is mid-Pliocene (Hemphillian). Other evidence is present to indicate that the rocks of fossil zone represent a brackish estuary that was later filled by river encroachment, forming the overlying fluviatile sediments typical of the Citronelle Formation. Hence, the faunal evidence, coupled with existing pollen data from the upper sediments of the Citronelle in nearby Florida, now indicates that deposition of this formation began in the middle Pliocene and continued into the pre-Nebraskan Pleistocene.

Late Tertiary Paleoclimate of Eastern United States

Paleoclimatic information for the Miocene and Pliocene is scarce or lacking in eastern United States because of a general absence of fossils in the nonmarine upper Tertiary sedimentary rocks. Information previously available was based chiefly on floral evidence from a few widely scattered locations in the Atlantic and Gulf coastal plains, or represented extension of climatic zones which were determined from fossiliferous units in the Mid-Continent or Western Interior. X-ray and petrographic information from land-derived Miocene and Pliocene deposits in northeastern and southeastern United States clearly reflects climatic conditions during the late Tertiary and verifies the conclusion that subtropical conditions did prevail as far north as northern New Jersey during the Miocene and Pliocene. In addition, mineralogic evidence from Miocene sedimentary rocks in the Gulf Coast strongly indicates that the sediments deposited on the Florida platform were not derived from material eroded in the Rocky Mountain drainage basin, as previously has been proposed, but instead represent detritus carried southward by rivers from the southern Appalachians and Piedmont and distributed by longshore currents.

The right way and the wrong way of presenting statistical and geological evidence in a court of law (a little knowledge is a dangerous thing

Abstract On 21 March 1981 a young black male was abducted in Mobile, Alabama, and taken to a site across Mobile Bay where he was beaten and murdered. The act was in apparent revenge for the mis-trial of a black man accused of killing a white police officer from Birmingham, Alabama. Three members of the notorious Ku Klux Klan were apprehended and charged with murder. All were found guilty and the ringleader was executed in 1997; the others are now serving life sentences. Ironically, the perpetrators were successful in having evidence tying them to the crime scene completely discredited. Statistical evidence purporting to show similarities in soil chemistry from samples taken from the victim, the defendants, and the crime scene was totally invalidated because improper statistical analyses were used. Following completion of the trial, the defence’s expert witness was contacted by the district attorney and asked to describe the appropriate statistical tests that should have been offered and that would have supported his case. He was further able to take solace by learning that strong mineralogical evidence could also have been used. It simply had not been reviewed by anyone who possessed the proper expertise.

Heavy metals in red crabs, Chaceon quinquedens, from the Gulf of Mexico

The red crab, Chaceon quinquedens, is distributed in deep waters of the Gulf of Mexico (GOM) and is most abundant in an area associated with sediment deposition from the Mississippi River. Sediment geochemistry and biological and ecological traits of red crabs favor accumulation of contaminants. Red crabs, sediment, and bottom water samples were taken from three distinct geographic locations representing areas with differing exposure to contaminant laden effluents from the Mississippi River. Inductively coupled plasma spectrophotometry and atomic absorption spectrophotometry were employed to determine levels of heavy metals in red crab muscle tissue. Ion site partitioning was used to determine metal speciation in sediments. Red crabs showed evidence of heavy metal bioaccumulation in all sample areas with high variability in contaminant levels in individual crabs for some metals. Bioavailability of metals in sediment did not always result in accumulation in muscle tissue.

ORIGIN OF THE WOODSTOWN, NEW JERSEY, MACRO-KAOLINITE

A kaolin bed in which many of the individual kaolinite platelets exceed 0·2 mm in size occurs in the immediate vicinity of the base of the middle-Miocene Kirkwood Formation, near Woodstown, New Jersey. These platelets appear to have resulted from breakdown of pre-existing illite and montmorillonite coupled with concurrent epitaxial growth and diagenetic growth of primary kaolinite. The alteration of the clay minerals is thought to be a product of upward leaching (dialysis) by groundwaters in the underlying Vincentown Sand. This is further evidenced by abnormally high percentages of clay-size kaolinite in the clays that lie above the Vincentown Sand but beneath the macro-kaolinite horizon. Growth of the macro-kaolinite was facilitated by face-to-edge sedimentation and the resultant high permeability of the stratum.RésuméOn trouve un lit de kaolin dans lequel l’épaisseur de plusieurs plaquettes individuelles de kaolin est supérieure à 0,2 mm. dans la proximité immédiate de la base de la formation Kirkwood du miocène moyen, près de Woodstown, New Jersey. Les plaquettes semplent résulter de la désintégration d’illite et de montmorillonite préexistantes, et. simultanément, d’une croissance épetaxiale et d’une croissance diagénétique de kaolinite primaire. On attribue l’altération des minéraux d’argile à l’épuisement vers la haut (par dialyse) causé par les eaux souterraines d’une sous-couche de sable Vincentown. Les pourcentages anormalement élevés de kaolinite de taille d’argile dans les argiles qui se trouvent au-dessus du sable Vincentown mais sous l’horizon macro-kaolimique contribuent à prouver la véracité de cette thése. La croissance macro-kaolinitique a été facilitde par la s6dimentation de la face au bord et l’importance de la perméabilité de la strate qui l’a accompagnée.KurzreferatEine Kaolin Lagerstätte, in der die Grösse vieler der einzelnen Kaolinitplättchen einen Wert von 0,2mm übersteigt, befindet sich in der unmittelbaren Nachbarschaft des Sockels der Mittel-Miozän Kirkwood Formation in der Nähe von Woodstown, New Jersey. Diese Plättchen scheinen das Ergebnis eines Zerfalls von vorher vorhandenen Illit und Montmorillonit in Verbindung mit gleichzeitigen epitaxialem und diagenitischem Wachstum von Primärkaolinit zu sein. Die Umwandlung der Tonminerale wird einer nach oben gerichteten Auslaugung (Dialyse) durch Grundwasser im darunter befindlichen Vincentown Sand zugeschrieben. Ein weiterer Beweis hierfür sind die abnormal hohen Anteile der Kaolinite von Tongrösse in den oberhalb des Vincentown Sands, aber unterhalb des makro-kaolinitischem Horizonts gelegenen Tonarten. Das Wachstum des Makro-Kaolinits wurde durch die Fläche und Kante Ablagerung, und die sich daraus ergebende hohe Durchlässigkeit der Schicht, gefördert.РезюмеПласт каолина, в котором многие из отдельных каолинитовых листочков превышают 0,2 ц по размеру находится при самой подошве миоценовой формации Кирквуд, поблизости Вудстаун в штате Нью-Джерси (США). Листочки эти являются повидимому следствием разрушения исходно существующего иллита имонтмориллонита с одновременным эпитаксиальным и диагенетическим ростом первичного каолинита. Изменение в глинистых минералах считают следствием восходящего выщелачивания (диализа) грунтовой воды в лежащих под этим пластом песках Винсенттаун. Доказывается это также ненормально высоким процентным содержанием каолинита размера как глина в тех глинах, которые лежат над песками Винсен-таун, но под макро-каолинитовым горизонтом. Выращивание макро-каолинита облегчается осаждением поверхности к краю и последующей высокой проницаемостью пласта.

Chapter 38 Forensic Use of Heavy Minerals in Civil and Criminal Investigations

Abstract Extensive historic use has been made of heavy minerals in sedimentological and stratigraphic studies. More recently, heavy minerals have been utilised in a wide variety of forensic applications. Five examples are presented to show how heavy minerals have been used in a murder investigation, identify the source of groundwater contamination, quantify the volume of sediment deposited in a wetland area as a result of improper erosion control in an adjacent subdivision, identify the source and cause of the premature aircraft engine failure and in a case involving industrial sabotage. These examples illustrate well how a mineral component, which often comprises less than 1% of a typical sample, can provide the geoscientist with information that is critical in a wide variety of forensic investigations.

Using soil mineral signatures to confirm sources of industrial contaminant trespass

Abstract An accompanying consequence of new industrial operations, or the expansion and enlargement of existing facilities, is contaminant encroachment from these operations onto adjacent residential properties. This often results in a favourable jury decision for the plaintiffs, providing the case can be proven. While smokestack emissions or wind-blown debris from some manufacturing operations can be readily identified in samples obtained from nearby properties (e.g. coal fly ash and mine wastes), obtaining proof that a site, or individuals, have been impacted by emissions from other processes may pose a challenge for the expert witness. As an example of the former, a mineral phase universally present in electric arc furnace smokestack discharges by mini steel mills (now widespread throughout the United States) is magnetite (FeO · Fe2O3). When this mineral is present as non-detrital anthropogenic grains in dust and soil samples (and further identified by a manganese content three or more orders of magnitude greater than in detrital magnetite) its presence is conclusive evidence that airborne contamination from an anthropogenic source has taken place. A problem arises, however, when contaminants are emitted as a mixed gas–particulate phase whose particles are <2.5 µm in size. Emissions from paper mills may fall into this category, and invariably will contain hydrogen sulphide (H2S), sulphur dioxide (SO2) and sulphur trioxide (SO3) as gas phases. These rapidly combine with water vapour to form sulphuric acid. Dispersal can occur over a wide area as a toxic plume, and can cause a variety of acutely or chronically harmful medical problems, especially in young children and the elderly. Although acknowledged as present in stack emissions by the paper companies, evidence of the vapour phase is often difficult to find on surrounding residential properties (although its corrosive effects are invariably present). An associated particulate phase (calcite), which is used as a whitener in paper production, however, is emitted from a facility’s lime kiln and can often be used to show that contamination from a paper-manufacturing source has taken place.

Identification of Ancient Storm Events in Buried Gulf Coast Sediments

ABSTRACT Within the past 100 years, 25 hurricanes have struck the coast of the Gulf of Mexico in the area from the mouth of the Mississippi River to Apalachicola, Florida. During the passage of the storms, marginal coastal lowlands were often flooded, passes from coastal estuaries to the sea were heavily eroded, and the size and position of offshore barrier islands suffered significant modification. Not generally observed, however, were changes that took place in the submarine environment. These changes, from a geological standpoint, were equally impressive. Investigations have now confirmed that the passage of Hurricane Elena near Apalachicola Bay, Florida, in 1985, caused severe scouring of the bottom of the bay and also the resuspension and removal of over 80 million tons of sediment from the bay in a period of some 8 to 10 hours. Mobile Bay, similarly, was impacted by Hurricane Frederic, in 1979. The passage of this storm caused an overall deepening of the bay of approximately 1.5 feet and the removal of nearly 290 million tons of sediment in a period of 7 hours. This is especially striking when it is realized that this amount of sediment is nearly equivalent to that delivered by the Mississippi River to the Gulf of Mexico during one entire year! Obviously, such events also must have taken place in the geological past. While no unequivocal means probably exists to identify positively storm events in ancient sediments, detailed examination of sediment cores from Apalachicola Bay, Florida, strongly suggests that passage of major storms does leave a discernible imprint. Abrupt changes in particle median diameters, sorting coefficients, and percentages of sand-sized sediment, when viewed simultaneously, may offer such a possibility. When these parameters are determined and plotted for closely spaced samples from cores, and the cores are laid side-by-side, the simultaneous occurrence of abrupt changes in median diameter, sorting, and sand percent is strongly suspicious of a storm event. While such changes also might be explained by other causes, the likelihood of these is significantly lower than changes caused by major hurricanes, given the frequency of occurrence of storms in the Gulfs historical past.