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Phyllosilicate Minerals in the Hydrothermal Mafic–Ultramafic-Hosted Massive-Sulfide Deposit of Ivanovka

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Contrib Mineral Petrol (2004) 147: 363–383 DOI 10.1007/s00410-004-0565-3

ORIGINAL PAPER

Paolo Nimis Æ Svetlana G. Tesalina Æ Paolo Omenetto Paola Tartarotti Æ Catherine Lerouge

Phyllosilicate minerals in the hydrothermal mafic–ultramafic-hosted massive-sulfide deposit of Ivanovka (southern Urals): comparison with modern ocean seafloor analogues

Received: 15 August 2003 / Accepted: 9 February 2004 / Published online: 17 March 2004 Ó Springer-Verlag 2004

Abstract We have studied textural relationships and required a high contribution of Mg-rich seawater to the compositions of phyllosilicate minerals in the mafic– hydrothermal fluid, which could be achieved in a highly ultramafic-hosted massive-sulfide deposit of Ivanovka permeable, breccia-dominated seafloor. More evolved (Main Uralian Fault Zone, southern Urals). The main hydrothermal fluids produced addition of silica, carhydrothermal phyllosilicate minerals are Mg-rich chlo- bonates and further sulfides, and led to local developrite, variably ferroan talc, (Mg, Si)-rich and (Ca, Na, ment of saponite after chlorite and widespread K)-poor saponite (stevensite), and serpentine. These replacement of serpentine by talc. The Ivanovka deposit minerals occur both as alteration products after mafic shows many similarities with active and fossil hydrovolcanics and ultramafic protoliths and, except serpen- thermal sites on some modern oceanic spreading centers tine, as hydrothermal vein and seafloor mound-like characterized by highly permeable upflow zones. Howprecipitates associated with variable amounts of (Ca, ever, given the arc signature of the ore host rocks, the Mg, Fe)-carbonates, quartz and Fe and Cu (Co, Ni) most probable setting for the observed alteration–minsulfides. Brecciated mafic lithologies underwent perva- eralization patterns is in an early-arc or forearc seafloor– sive chloritization, while interlayered gabbro sills subseafloor environment, characterized by the presence underwent partial alteration to chlorite + illite actinolite saponite later localized deeper alteration to chlorite of abundant mafic–ultramafic breccias of tectonic and/ talc-bearing assemblages and or sedimentary origin. saponite.
Ultramafic and mixed ultramafic–mafic breccias were altered to talc-rich rocks with variable amounts of chlorite, carbonate and quartz. Chloritization, locally accompanied by formation of disseminated sulfides,

Introduction

Phyllosilicate minerals are a major constituent of lowgrade metamorphic and hydrothermally altered mafic– ultramafic rocks. Their association with massive sulfide deposits is well known both in modern ocean seafloor hydrothermal sites and in their ancient counterparts, and analogies between modern and ancient examples have been pointed out by several workers (e.g. Costa et al. 1983; Kranidiotis and MacLean 1987; Evans and Guggenheim 1988; Zierenberg et al. 1995). The nature and compositions of the phyllosilicate minerals can be used to discriminate between various metamorphic and hydrothermal environments (e.g. Shikazono and Kawahata 1987; Laird 1988), to gain an insight into hydrothermal processes at or near the seafloor (Aggarwal and Nesbitt 1984; Evans and Guggenheim 1988), as well as to estimate physical and chemical conditions extant during rock–fluid interaction and hydrothermal precipitation (e.g. Cathelineau and Nieva 1985; Cathelineau 1988; Zierenberg and Shanks 1988). Formation of phyllosilicate minerals during hydrothermal alteration is

Editorial responsibility: J. Hoefs P. Nimis (&) Æ S. G. Tesalina Æ P. Omenetto Dipartimento di Mineralogia e Petrologia, Universita degli Studi di Padova, C.so Garibaldi 37, 35137 Padova, Italy E-mail: [email protected] Tel.: +39-049-8272022 Fax: +39-049-8272010

P. Nimis Æ P. Omenetto Kroseven Services S.A.S., Padova, Italy

S. G. Tesalina Institute of Mineralogy, Uralian Division, Russian Academy of Sciences, 456301 Miass, Russia

P. Tartarotti Dipartimento di Scienze della Terra, Universita di Milano, Milano, Italy

C. Lerouge

  • BRGM, B.P. 6009, 45060 Orleans Cedex 2, France
  • ´

364

often associated with significant removal or uptake of marks the main suture that can be traced continuously metals and silica. These processes contribute to the along the Uralide Orogen (e.g. Puchkov 1997) (Fig. 1). compositional evolution of the hydrothermal fluids and The MUFZ is interpreted as the major damage zone that produce geochemical and mineralogical zoning within developed between an accretionary wedge to the west hydrothermal recharge and upflow zones (Alt 1995).
The results presented herewith form part of a com- nian arc–continent collision (Brown and Spadea 1999). prehensive study of mineralizations and ore–host rock It comprises a melange of dismembered mafic–ultraand a forearc basement to the east during Late Devo-
´relationships in mafic–ultramafic-hosted, massive sulfide mafic sheets made of serpentinites, gabbros, basalts, deposits in southern Urals. In this paper we describe dolerites, mingled with Mid-Ordovician to Mid-Devophyllosilicate mineralogy in a little known deposit from nian sedimentary rocks (e.g. Maslov et al. 1993; Seravthe Main Uralian Fault Zone, located near the village of kin et al. 2001). The sedimentary units include Ivanovka (Fig. 1). We will show that this deposit con- olistostromes which carry olistolites of volcanic and stitutes an example of fossil hydrothermal body in which intrusive igneous rocks and, sometimes, seafloor the original seafloor–subseafloor hydrothermal mineral hydrothermal mounds of carbonatic and carbonaticassemblages and textures have been extraordinarily well siliceous composition.

  • preserved. The compositions and paragenetic relations
  • In the southern Urals, important massive sulfide

of the Ivanovka phyllosilicates will be discussed through deposits belonging to the Cyprus, Besshi, Baimak comparisons with those reported for hydrothermal (Kuroko), and Uralian types are associated with Mid-

  • deposits on modern seafloor settings.
  • Palaeozoic ophiolitic and island-arc volcanic sequences

(Prokin and Buslaev 1999; Herrington et al. 2002). Mafic–ultramafic-hosted massive sulfide occurrences along the southern MUFZ (i.e. Ivanovka, Dergamish, and Ishkinino deposits) are represented by small-sized, at present subeconomic, Cu (Co, Au) deposits (Zaykov et al. 2000; Herrington et al. 2002). Sulfide mineralization in these deposits is traditionally thought to occur near or at the contact between variously metasomatized serpentinitic and basaltic units (e.g. Ismagilov 1962; Buchkovskiy 1970; Zakharov and Zakharova 1975; Zaykov et al. 2000). This idea may not be completely correct. Based on petrographic and geochemical analy-

ses (see Mineral textures and hydrothermal parageneses),

we believe that many ore-bearing rocks that have been described in the literature as ‘‘metasomatized serpentinite’’ (or ‘‘aposerpentinity’’ in the Russian lit.) actually

Geological outline

The Urals are a linear orogenic belt that resulted from the Late-Palaeozoic collision of the East European Platform with a Siberian–Kazakhian plate assemblage and interposed oceanic and island-arc terranes. The Main Uralian Fault Zone (hereafter MUFZ), a 2 to 10- km-wide (locally up to 25 km), east dipping fault system,

  • include a melange of hydrothermally altered mafic
  • ´

and ultramafic lithologies of both crustal and mantle derivation.

The Ivanovka deposit At Ivanovka, basalts of post-Silurian, possibly EarlyMid Devonian age (Seravkin et al. 2001) rest on an extensively metasomatized sequence of mafic–ultramafic rock breccias cross-cut by several pre-metasomatic gabbroic sills, decimetric to metric in thickness (Figs. 2 and 3). The mixed mafic–ultramafic rock sequence hosts the sulfide mineralization and lies on a serpentinite unit. Metamorphism, probably related at least in part to oceanic hydrothermal alteration, is mostly represented by serpentinization of former harzburgites and dunites, and by albite + chlorite + epidote + quartz greenschist-facies metamorphism of mafic rocks. The latter are well exposed on an escarpment along the Yangyz River, a few hundred meters north-east of the ore deposit.
The sulfide mineralization comprises massive, disseminated and stockwork ores which consist of dominant tabular, lamellar and granular pyrrhotite, with or

Fig. 1 Geological sketch-map of the southern Urals, with location of the Ivanovka ore field
365

portions of talc, (Ca, Mg, Fe)-carbonates, chlorite, saponite, and quartz (Zakharov and Zakharova 1975; and in-house unpublished data). The sulfide-rich levels are mainly (75%) restricted to chlorite-rich rocks after mafic protoliths, where also higher Cu (Co, As, Au) occur (ca. 1% Cu). Relatively high Ni contents (0.1– 0.2%), with low Cu (Co, As, Au), are mostly found in talc-rich, ultramafic-hosted mineralizations. Significant Au contents (up to 5.4 ppm) are found near the top of the ore-bearing sequence within pyrite + chalcopyrite + pyrrhotite-bearing assemblages.
The Ivanovka deposit differs from sulfide deposits within the Uralian back-arc and island-arc terranes by its extremely poor Zn grades (<to <<0.1%) and Co– As–Ni–Bi (Au) specialization (Tesalina et al. 2001). The aggregates of lamellar pyrrhotite that occur at the top of the deposits strictly resemble those found in some modern seafloor hydrothermal mounds (Peter and Scott 1988; Goodfellow and Franklin 1993; Turner et al. 1993; Zierenberg et al. 1993), suggesting formation near or at the seafloor. However, the presence of stockwork mineralizations, the widespread association of sulfides with alteration minerals, the presence of inclusions of relict chromite, as well as local replacement of alteration phyllosilicates by sulfides, indicate that the Ivanovka ores dominantly formed in the subsurface by cementation, replacement and veining.

Sample materials and analytical methods

Sample materials were mainly taken from a drill-core (DDH2T) obtained during the 1998 drilling campaign by Bashkirgeologia (Ufa). The drill-core is representative of the shallowest portions of the Ivanovka deposit and crosscuts several mineralized and barren levels. The uppermost portion is almost totally barren and represented by tectonic slices which were thrust over the main sulfide-bearing sequence. A detailed description of the drill-core stratigraphy is given in Fig. 3. Additional samples were taken from outcrops in the deposit’s nearest surroundings. In the following, notations of the type Iv36.0 will be used to indicate samples from the Ivanovka drill-core DDH2T taken from depths in meters as indicated by the numbers.
Polished thin sections of representative rock types, including both mineralized and barren lithologies, were prepared for optical and scanning-electron microscopy and electron microprobe analysis. In some cases, identification of mineral phases was aided by qualitative X-ray powder diffraction (XRD) of whole-rocks and separated mineral grains. In a few cases, XRD analysis was re-
Fig. 2 Geological section of the Ivanovka deposit (simplified after Buchkovskiy 1970)

without pyrite and chalcopyrite. Gangue minerals include Mg-rich chlorite, variably ferroan talc, Mg-rich saponite, quartz, and (Ca, Mg, Fe)-carbonates (mostly dolomite). The uppermost ore level is characterized by peculiar, open-latticework aggregates of lamellar pyr-

rhotite associated with chalcopyrite–cubanite inter- peated after saturation with ethylene glycol and after in-situ heating at 350 °C for 1.5 h.

growths and interstitial Mg-rich saponite, Mg-rich chlorite, or carbonates (Nimis et al. 2003) (Fig. 4). Accessory hydrothermal ore minerals are cobaltite, sphalerite, Co-rich pyrite, Co-rich pentlandite, Nirich glaucodot as well as traces of native gold, native bismuth and pilsenite (Bi-telluride) (Tesalina et al. 2001). In addition, the sulfides often include abundant (up to 3%) relict chromite crystals and fragments derived from the host rocks (Tesalina et al. 2003).

Chemical analyses of minerals (Tables 2 through 6) were carried out at the CNR-IGG–Dipartimento di Mineralogia e Petrologia, University of Padua, using a CAMECA ‘‘CAMEBAX’’ electron microprobe equipped with four vertical WDS spectrometers, operating at an accelerating voltage of 15 kV, beam current of 15 nA, counting time of 10 s for peak and 10 s for background, using a 1-lm beam. Some saponite analyses were replicated using a lower beam current (10 nA) and a defocused beam (5 lm) to minimize interlayer cation loss. Natural and synthetic minerals (wollastonite for Ca and Si, albite for Na, orthoclase for K) and pure oxides (for Al, Cr, Fe, and MnTi) were used as standards. The CAMECA-PAP program was used to convert X-ray counts into weight percent oxides. Reproducibility of analyses was found to be within 1–2% relative for major and within 2–5% relative for

The metal grades and the abundance of accessory sulfides appear to be controlled by the composition of the host rocks, which are altered to talc- or chlorite-rich metasomatic assemblages consisting of variable pro- minor oxides.

366
Scanning electron microscope (SEM) analyses were carried out Qualitative chemical microanalysis were carried out using an at the Dipartimento di Mineralogia e Petrologia, University of EDAX system with a ‘‘Sapphire’’ detector (LEAP + Si(Li) crysPadua, using a CamScan MX2500 microscope, equipped with a tal). The analytical conditions were: 20 kV accelerating voltage, tungsten cathode and a four-quadrant solid-state BSE detector. ꢀ160 lA filament emission, and 35 mm working distance.
367

b

Sequences (1) through (4) describe the alteration of olivine-rich (ca. 50 vol%) gabbroic rocks, which were tectonically superimposed on the main sulfide orebody and constitute a major portion of the shallow Ivanovka drill-core (32.0–64.7 m depth; Fig. 3). These rocks exhibit heteradcumulate texture, with completely altered euhedral olivine and poikilitic pyroxene crystals, com-

Fig. 3 Description of Ivanovka drill-core DDH2T (modified after Tesalina et al. 2003)

Six whole-rock samples representative of different alteration patterns and a talc concentrate were analyzed for oxygen isotopic composition by laser fluorination, following the procedure of Fouillac and Girard (1996). Isotopic data are reported in d units relative to V-SMOW. Reproducibility of d values was found to be pletely altered interstitial matrix (probably representing within 0.3&.

  • former intercumulus plagioclase
  • pyroxene), and

flakes of partially altered titanian phlogopite (Fig. 5a, b). In these rocks, serpentine of late hydrothermal derivation often occurs as fine-grained mixtures with Mg-rich saponite or Mg-rich chlorite. The strong alteration does not allow accurate classification of the protoliths and the general term melagabbroid will be used here according to standard criteria (Le Maitre et al. 1989).
Sequence (5) characterizes fine- to ultrafine-grained, almost monomineralic chloritites which probably developed after aphyric mafic protoliths. These chloritites, often occurring in brecciated form (former hyaloclastites?), are often associated with abundant pyrrhotite

Mineral textures and hydrothermal parageneses

The samples studied include extensively to completely altered mafic and ultramafic rocks, and associated orebearing hydrothermalites. Phyllosilicates occur in alteromorphs after olivine, pyroxenes, plagioclase and, probably, glass, and as major or minor constituents of veins and of interstitial matrix in the sulfide ores. Where relicts of the original pre-alteration textures or minerals are preserved, the alteration sequences listed in Table 1 and described below can be observed.

  • + chalcopyrite
  • cobaltite (Fig. 5c, d). A later chlorite,

characterized by anomalous ‘‘blue’’ interference colors and associated with Mg-rich saponite, may locally replace an earlier chlorite characterized by anomalous ‘‘olive-brown’’ interference colors.
Sequences (6) through (8) describe the progressive alteration of medium- to coarse-grained mafic rocks. Some of the medium-grained examples retain clear relicts of a magmatic intersertal texture, which suggests their derivation from highly phyric mafic protoliths such as subvolcanic dolerites or pillow cores. In such

Fig. 4 Back-scattered electron image showing a peculiar pyrrhotite

  • (Po) + Mg-saponite (Sap)
  • Mg-chlorite (Chl) association in a

sample from the top of the Ivanovka orebody (Iv80.5). A network of coarse (<1 mm) pyrrhotite lamellas in association with Mgsaponite, siderite (Sid) and chalcopyrite (Cp) is visible in the upper portion of the main picture. In the enlargement a concentric structure is shown, that is composed of an inner network of fine (<10 lm) lamellar pyrrhotite + Mg-saponite, an intermediate pyrrhotite + Mg-saponite + Mg-chlorite shell and an outer pyrite (Py) rim 368 Table 1 Recognized hydrothermal alteration sequences in the Ivanovka samples

  • Alteration sequence
  • Representative samples/intervals in drill-hole DDH2T

Iv30.0–64.7

Olivine-rich melagabbroids

(1) olivine fi talc + magnetite fi serpentine
Mg-saponite

magnetite ( fi talc) ( fi dolomite)
(2) pyroxene fi Mg-saponite chlorite magnetite fi serpentine

  • Mg-saponite
  • magnetite

(3) plagioclase fi chlorite + serpentine
Mg-saponite

(4) titanian phlogopite fi (chlorite) fi (serpentine)

Fine-grained chloritites (after basalts l.s.)

(5) basalt ( fi chlorite–smectite ? + rutile) fi chlorite + rutile
Iv80.5; Iv127.7; Iv132.7; Iv136.0; Iv166.2

( fi Mg-saponite

  • dolomite–ankerite
  • chlorite
  • quartz)

Gabbros and highly phyric basalts l.s.

  • (6) pyroxene fi chlorite actinolite
  • Mg-saponite ( fi talc) ( fi chlorite) Iv64.0; Iv65.2; Iv78.5; Iv174.7

Mg-saponite talc
Mg-saponite ( fi chlorite–smectite ?

dolomite–ankerite chlorite quartz)

a

(7) amphibole fi actinolite fi chlorite (8) plagioclase fi chlorite illite or Mg-saponite illite

Serpentinites (after peridotitic melting residua and cumulates)

(9) olivine orthopyroxene fi serpentineb Mg-saponite or talc carbonate
Iv14.0; Iv82.0–117.0; Iv155.0–177.3
( fi talc quartz)

Notations in parentheses indicate alteration assemblages that in aSequence represented only in gabbros some samples were apparently not developed or preserved Assemblages in italic were deduced from textural relations and alteration patterns (i.e. no relicts preserved) bProbably related to early oceanic alteration

chloritites, ‘‘blue’’ and ‘‘olive-brown’’ chlorites tend to hydrothermal alteration is testified by substitution of occupy texturally distinct sites, which can reasonably be serpentine by talc related to former clinopyroxene and plagioclase crystals, pentinite samples. respectively. Many of these medium-grained chloritites,
Mg-rich saponite in some ser-

c

which often occur in brecciated form, are host to

Fig. 5 Representative modes of occurrence of phyllosilicate minerals in samples from Ivanovka drill-core DDH2T. a Alteration patterns in an olivine-rich melagabbroic rock (#Iv44.0). A euhedral olivine crystal is altered to talc + magnetite and further altered to

abundant disseminated lamellar and massive granular pyrrhotite. Non-brecciated gabbroic levels, which probably represent sills intruded in the breccia sequence,

exhibit less extensive alteration, with preserved relicts of serpentine along fractures and rims. Matrix is a fine intergrowth of

  • Mg-chlorite + serpentine after interstitial plagioclase
  • pyroxene

minerals belonging to the original magmatic parageneses (e.g. slightly Na-enriched plagioclase, Ab43–70) or produced during incipient alteration processes (Fig. 5e). In these rocks the original magmatic amphibole and pyroxene have been completely transformed into actin-

(?). The dashed line contours a chlorite + serpentine + magnetite alteromorph after pyroxene (?). Flakes of largely unaltered titanian phlogopite ( Phl) are present. Plane polarized transmitted light. b Alteration patterns in an olivine-rich melagabbroic rock showing pervasive serpentinization and olivine cores replaced by Mgsaponite (#Iv36.0). A crystal of largely unaltered titanian phlogopite ( Phl) is shown in the upper right corner. Crossed polars, transmitted light. c, d Fissure cutting through massive pyrrhotite (Po). The fissure is filled by a microbreccia of fragments of finegrained chloritite ( Chl), partially altered to Mg-saponite ( Sap), and of pyrrhotite ore, set in a matrix made of (Fe, Mn)-bearing dolomite ( Dol), Mg-saponite, small euhedral cobaltite crystals and small chromite crystals and fragments (#Iv132.7). Plane polarized (c) and crossed polars ( d) transmitted light. e Partial alteration in a

  • olite and chlorite
  • actinolite
  • Mg-saponite, respec-

tively, during an early stage of alteration. Local further alteration to talc or chlorite of mafic minerals was accompanied by replacement of plagioclase by illite and/or chlorite cleavage planes.
Sequence (9) has produced mesh- and ribbon-tex-
Mg-saponite in patches and along

tured serpentinites after original peridotites (harzburg- gabbro sill (#Iv78.5). During an early stage of alteration, pyroxene was totally replaced by chlorite Mg-saponite ( Chl), while

ites, dunites and minor lherzolites). The habit of the relict chromian spinel allowed us to distinguish two groups of protoliths (cf. Tesalina et al. 2003). The first group includes residues after mantle partial melting, which are characterized by holly-leaf or amoeboid spinels. The second group includes magmatic protoliths of mantle and possibly lower-crust derivation, which are characterized by euhedral or subhedral spinels. The serpentinites are abundant in the deposit’s surroundings and often occur in the form of breccias of tectonic and, in part, possibly sedimentary origin. They are never associated with massive sulfides and their origin was

plagioclase ( Plag) underwent slight Na-enrichment (Ab43–70). Subsequently, talc ( Tc) and illite + chlorite ( IC) partly replaced the chloritized pyroxene and the plagioclase, respectively. Crossed polars, transmitted light. f Mantle spinel peridotite showing complete alteration of serpentinized (?) olivine to talc ( Tc) and an unaltered amoeboid chromite crystal ( Chr) (#Iv161.3). The rock

  • shown is a clast in a polygenic, talc
  • chlorite
  • carbonate-altered

mafic–ultramafic breccia with carbonate cement and stockwork sulfide mineralization. Crossed polars, transmitted light. g Breccia altered to talc ( Tc) and carbonate ( Cb), showing a probable pseudomorph after Ti-rich phlogopite, now replaced by Ti-rich and Ti-poor chlorite ( Ti-Chl) (#Iv176.2). Crossed polars, transmitted light. h Late, composite dolomite ( Dol)–quartz ( Qz)–chlorite (Chl) vein cutting through massive pyrrhotite (#Iv141.8). Plane polarized

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    Michigan Minerals Listed by Mineral Name Based on MI DEQ GSD Bulletin 6 “Mineralogy of Michigan” Actinolite, Dickinson, Gogebic, Gratiot, and Anthonyite, Houghton County Marquette counties Anthophyllite, Dickinson, and Marquette counties Aegirinaugite, Marquette County Antigorite, Dickinson, and Marquette counties Aegirine, Marquette County Apatite, Baraga, Dickinson, Houghton, Iron, Albite, Dickinson, Gratiot, Houghton, Keweenaw, Kalkaska, Keweenaw, Marquette, and Monroe and Marquette counties counties Algodonite, Baraga, Houghton, Keweenaw, and Aphrosiderite, Gogebic, Iron, and Marquette Ontonagon counties counties Allanite, Gogebic, Iron, and Marquette counties Apophyllite, Houghton, and Keweenaw counties Almandite, Dickinson, Keweenaw, and Marquette Aragonite, Gogebic, Iron, Jackson, Marquette, and counties Monroe counties Alunite, Iron County Arsenopyrite, Marquette, and Menominee counties Analcite, Houghton, Keweenaw, and Ontonagon counties Atacamite, Houghton, Keweenaw, and Ontonagon counties Anatase, Gratiot, Houghton, Keweenaw, Marquette, and Ontonagon counties Augite, Dickinson, Genesee, Gratiot, Houghton, Iron, Keweenaw, Marquette, and Ontonagon counties Andalusite, Iron, and Marquette counties Awarurite, Marquette County Andesine, Keweenaw County Axinite, Gogebic, and Marquette counties Andradite, Dickinson County Azurite, Dickinson, Keweenaw, Marquette, and Anglesite, Marquette County Ontonagon counties Anhydrite, Bay, Berrien, Gratiot, Houghton, Babingtonite, Keweenaw County Isabella, Kalamazoo, Kent, Keweenaw, Macomb, Manistee,
  • Mineralogical Constraints on the Paleoenvironments of The

    Mineralogical Constraints on the Paleoenvironments of The

    Supporting Information Bristow et al. 10.1073/pnas.0901080106 SI Text growth of stevensitic layers on preexisting phyllosilicate sheets Lithological Description of the Doushantuo Formation in Yangtze has been proposed as the transformation mechanism resulting in Gorges. Member 1 consists of the cap carbonate, typically 3 to 5 m Mg-smectites with saponitic compositions (8). Palygorskite and thick and in sharp lithological contact with underlying glacial sepiolite have chain structures and are readily distinguished from diamictite of the Nantuo Formation (1). Member 2 is Ϸ70 m sheet-like stevensite and saponite XRD analysis and by their thick and consists of calcareous mudstones and marls alternating fibrous fabrics. with parallel-laminated limestone and dolomite beds at scales of In subaqueous sedimentary settings the type of Mg-clay a few centimeters to several meters. Argillaceous member 2 forming is governed by chemical conditions and the availability gradually changes to carbonate-dominated member 3 that is of detrital Al-silicates. In Phanerozoic sedimentary deposits, characterized by cm-scale alternating limestone/dolostone rib- fibrous clays like palygorskite and sepiolite tend to form at bon rock and is approximately 70 m in thickness. Approximately moderate pH (ϳ8) and are found in peri-marine basins (3) and 10 m of organic-rich shales of member 4 contain decimeter-scale high-stand sediments of closed lake systems (9, 10). Thermody- oval limestone concretions and form a sharp lithological contact namic calculations indicate that fibrous clays are favored by high with the underlying ribbon rock. Ash layers, dated as 635.2 Ϯ 0.6 silica activities (11), but as pointed out in the main text, kinetic Ma and 632.5 Ϯ 0.5 Ma occur within the cap carbonate and controls are critical.
  • Urea-Assisted Synthesis and Characterization of Saponite with Different Octahedral (Mg, Zn, Ni, Co) and Tetrahedral Metals (Al, Ga, B), a Review

    Urea-Assisted Synthesis and Characterization of Saponite with Different Octahedral (Mg, Zn, Ni, Co) and Tetrahedral Metals (Al, Ga, B), a Review

    life Review Urea-Assisted Synthesis and Characterization of Saponite with Different Octahedral (Mg, Zn, Ni, Co) and Tetrahedral Metals (Al, Ga, B), a Review Concepcion P. Ponce 1 and J. Theo Kloprogge 1,2,* 1 Department of Chemistry, College of Arts and Sciences, University of the Philippines, Miag-ao, Iloilo 5023, Philippines; [email protected] 2 School of Earth and Environmental Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia * Correspondence: [email protected] Received: 10 August 2020; Accepted: 26 August 2020; Published: 28 August 2020 Abstract: Clay minerals surfaces potentially play a role in prebiotic synthesis through adsorption of organic monomers that give rise to highly concentrated systems; facilitate condensation and polymerization reactions, protection of early biomolecules from hydrolysis and photolysis, and surface-templating for specific adsorption and synthesis of organic molecules. This review presents processes of clay formation using saponite as a model clay mineral, since it has been shown to catalyze organic reactions, is easy to synthesize in large and pure form, and has tunable properties. In particular, a method involving urea is presented as a reasonable analog of natural processes. The method involves a two-step process: (1) formation of the precursor aluminosilicate gel and (2) hydrolysis of a divalent metal (Mg, Ni, Co, and Zn) by the slow release of ammonia from urea decomposition. The aluminosilicate gels in the first step forms a 4-fold-coordinated Al3+ similar to what is found in nature such as in volcanic glass. The use of urea, a compound figuring in many prebiotic model reactions, circumvents the formation of undesirable brucite, Mg(OH)2, in the final product, by slowly releasing ammonia thereby controlling the hydrolysis of magnesium.
  • Smectite-To-Chlorite Transformation in Thermally Metamorphosed Yolcanoclastic Rocks in the Kamikita Area, Northern Honshu, Japan

    Smectite-To-Chlorite Transformation in Thermally Metamorphosed Yolcanoclastic Rocks in the Kamikita Area, Northern Honshu, Japan

    American Mineralogist, Volume 76, pages 628-640, l99l Smectite-to-chloritetransformation in thermally metamorphosedyolcanoclastic rocks in the Kamikita area, northern Honshu, Japan Arsuyuxr lNour Geological Institute, Collegeof Ans and Sciences,Chiba University, Chiba 260, Japan MrNonu Uuoa. The University Museum, University of Tokyo, Tokyo I 13, Japan Ansrnlcr Miocene volcanoclastic rocks at Kamikita, northern Honshu, Japan, exhibit the effects of an intensive episodeof thermal metamorphism causedby a hornblende quartz diorite intrusion. Metamorphic zones with a total thickness of approximately 6 km are concen- trically developed around the diorite mass. The zones are defined by the sequential ap- pearanceof characteristicmineral assemblagesfrom smectite (Zane I), to smectite * heu- landite + stilbite (Zone II), to corrensite + laumontite (Zone III), to chlorite + epidote (Zone IV), and finally to biotite + actinolite (Zone V) with increasingmetamorphic grade. As smectite transforms to chlorite, the percentageof smectitelayers in interstraiified chlo- rite/smectite (C/S) (the intermediate products) decreasesdiscontinuously with increasing metamorphic grades,with stepsat 100-800/0,50-40o/o (corrensite), and 10-00/0.The trans- formation of smectiteto chlorite through corrensiteis characterizedchemically by decreas- es in Ca and Si, an increase in Al, and a constant Fel(Fe + Mg) ratio. The mineral paragenesis,structural variation, and compositions all support the hypothesisthat corren- site is a thermodynamically stable C/S phase.Corrensite formed at temperaturesbetween approximately 100 and 200 "C. The Kamikita metamorphic zonation was developed in responseto a thermal gradient of approximately 70 .C/km, and the secondaryminerals crystallized with near-equilibrium compositions. fNrnooucrroN rite transformation, e.g., from smectite to corrensite or from corrensite to smectite.
  • Adsorption Experiments of Ammonia and Clay Minerals to Understand Nitrogen Isotopic Fractionation in Molecular Clouds

    Adsorption Experiments of Ammonia and Clay Minerals to Understand Nitrogen Isotopic Fractionation in Molecular Clouds

    PPS24-10 Room:A02 Time:May 27 14:45-15:00 Adsorption experiments of ammonia and clay minerals to understand nitrogen isotopic fractionation in molecular clouds SUGAHARA, Haruna1¤ ; TAKANO, Yoshinori1 ; OGAWA, Nanako O.1 ; CHIKARAISHI, Yoshito1 ; OHKOUCHI, Naohiko1 1Japan Agency for Marine-Earth Science and Technology Nitrogen is the fifth abundant element in the universe and also essential component of organic molecules. Various nitrogen- containing organic compounds have been found by laboratory analysis of extraterrestrial materials. The stable isotopic composi- tion of nitrogen (15N/14N ratio) will give information about evolutionary history of the organic molecules. Primitive solar system materials such as chondrites, comets, and interplanetary dust particles (IDPs) show various degrees of 15N-enrichment compared to the solar system value of -400 ‰ [1]. They display up to +1500 ‰ in the bulk ±15N value (‰, normalized as vs. AIR) [2, 3]. Furthermore, anomalously high 15N-enrichments, as called hot spots, have been frequently found within a single material with the highest ±15N values reaching as high as +5000 ‰ [4]. These 15N-enrichments are considered to be originated in cold interstellar environments. However, the mechanisms of isotopic fractionation of nitrogen in the interstellar medium are not well understood and only a few models have been proposed [e.g., 5]. In this study, we focused on adsorption process of ammonia on grain surface of interstellar dusts as a potential mechanism for the extreme 15N-enrichment and its high-heterogeneity found in extraterrestrial materials. Ammonia is a primitive nitrogen- containing compound and also one of major molecules in molecular clouds. Since ammonia is a highly reactive chemical, it is a precursor for nitrogen-involving organic molecules.
  • Saponite Dissolution Experiments and Implications for Mars

    Saponite Dissolution Experiments and Implications for Mars

    50th Lunar and Planetary Science Conference 2019 (LPI Contrib. No. 2132) 1981.pdf SAPONITE DISSOLUTION EXPERIMENTS AND IMPLICATIONS FOR MARS. N. C. Luu1, E. M. Haus- rath1, A. M. Sanchez1, S. Gainey2, E. Rampe3, T. Peretyazhko3, O. Tschauner1, A. Lanzirotti4, C. Adcock1, and K. Leftwich5, 1Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, NV, USA ([email protected] vada.edu), 2College of Engineering, University of Nevada, Las Vegas, Las Vegas, NV, USA 3NASA Johnson Space Center, Houston, TX, USA 4Center for Advanced Radiation Sources, Univ. of Chicago, Chicago, IL, USA, 5Proto, Taylor, MI, USA. Introduction: Recent work suggests that the miner- then returned to the anoxic glovebox where the super- alogical sequence of the Murray formation at Gale natant is decanted and rinsed with deoxygenated 18.2 crater may have resulted from diagenetic alteration after ϺΩ deionized water. Rinsed samples are returned to the sedimentation [1], or deposition in a stratified lake with glove box, placed in an N2-filled desiccator, sealed, re- oxic surface and anoxic bottom waters [2]. Fe-contain- moved from the glovebox, and placed under vacuum un- ing clay minerals are common both at Gale crater, and til dried. Final material is returned to the glovebox throughout the Noachian-aged terrains on Mars. These where it is ground to a powder and stored until use. Syn- clay minerals are primarily ferric (Fe3+), and previous thesis of the pure Mg-saponite end-member followed work suggests that these ferric clay minerals may result the same methods as described above, but all steps were from alteration of ferrous (Fe2+) smectites that were ox- performed under ambient lab conditions since Mg is not idized after deposition [3].
  • Phyllosilicates and Sulfates on Mars

    Phyllosilicates and Sulfates on Mars

    Phyllosilicates and Sulfates on Mars Case Studies from Terra Cimmeria and Valles Marineris Inauguraldissertation zur Erlangung des Grades eines Doktors der Naturwissenschaften am Fachbereich Geowissenschaften der Freien Universität Berlin Vorgelegt von Lorenz Wendt Berlin, 2012 I Ersttgutachter: Prof. Dr. Ralf Jaumann Fachbereich Geowissenschaften Institut für Geologische Wissenschaften Fachrichtung Planetologie und Fernerkundung und Deutsches Zentrum für Luft- und Raumfahrt DLR Institut für Planetenforschung, Abteilung Planetologie Zweitgutachter: Prof. Dr. Stephan van Gasselt Freie Universität Berlin Fachbereich Geowissenschaften Institut für Geologische Wissenschaften Fachrichtung Planetologie und Fernerkundung Datum der Disputation: 13. Juli 2012 III Eidesstattliche Erklärung Hiermit erkläre ich, die vorliegende Arbeit selbständig und nur unter Verwendung der angegebenen Quellen und Hilfsmittel erstellt zu haben. Lorenz Wendt V Danksagung Ich möchte zuallererst Herrn Prof. Neukum meinen Dank aussprechen. Seine High Resolution Stereo Camera (HRSC), die er mit viel Durchhaltevermögen nach dem Absturz der Mars 96 Mission auf Mars Express auf die Reise schickte, gab mir überhaupt erst die Möglichkeit, mich an der Freien Universität Berlin mit der Geologie des Mars zu beschäftigen. Herr Prof. Neukum hat mir damit die Tür zur Planetenforschung geöffnet, und mir auch in vielerlei anderer Hinsicht Möglichkeiten zur wissenschaftlichen Weiterentwicklung eröffnet. Herrn Prof. van Gasselt danke ich für die Begutachtung der vorliegenden Arbeit, die fachlichen Diskussionen und die kritische Durchsicht meiner Manuskripte, sowie die menschliche Unterstützung an manch einem schwierigen Punkt, der sich im Lauf der Arbeit an dieser Dissertation ergab. Und natürlich danke ich ihm für die viele Mühe im Hintergrund, die er sich mit der Betreuung der wissenschaftlichen Anträge gemacht hat, aus denen viele meiner Kollegen und auch ich ihren Lebensunterhalt bestritten haben.
  • Saponite (Ca0:5; Na)0:3(Mg; Fe )3(Si; Al)4O10(OH)2 ² 4H2O C 2001 Mineral Data Publishing, Version 1.2 ° Crystal Data: Monoclinic

    Saponite (Ca0:5; Na)0:3(Mg; Fe )3(Si; Al)4O10(OH)2 ² 4H2O C 2001 Mineral Data Publishing, Version 1.2 ° Crystal Data: Monoclinic

    2+ Saponite (Ca0:5; Na)0:3(Mg; Fe )3(Si; Al)4O10(OH)2 ² 4H2O c 2001 Mineral Data Publishing, version 1.2 ° Crystal Data: Monoclinic. Point Group: n.d. Crystals minute, pseudohexagonal, tabular 001 ; bladed, ¯brous, °aky, or subparallel aggregates; nodular, ¯ne-grained, massive. k f g Physical Properties: Cleavage: 001 , perfect. Tenacity: Plastic when hydrated, brittle when dry. Hardness = < 1{2 D(mefas.)g= 2.24{2.30 D(calc.) = n.d. Positive identi¯cation of minerals in the smectite group may need data from DTA curves, dehydration curves, and X-ray powder patterns before and after treatment by heating and with organic liquids. Optical Properties: Translucent. Color: White, yellow, gray, blue, green, reddish, brown. Luster: Greasy. Optical Class: Biaxial ({). Pleochroism: X = colorless, light yellow to green-brown; Y = Z = colorless, greenish brown to dark brown. Orientation: X 001 ; Z elongation. Absorption: Y Z > X. ® = 1.48{1.54 ¯ = 1.50{1.58 ° = ?1.5f0{1.g58 2kV(meas.) = 0 {40 ' ± ± Cell Data: Space Group: n.d. a = 5.3 b = 9.14 c = 16.9 ¯ = 97 Z = n.d. » ± X-ray Powder Pattern: Synthetic Na0:33Mg3:00(Si0:67Al3:67)§=4:00O10(OH)2; glycolated; very close to stevensite. 17.0 (100), 3.37 (80), 1.535 (70), 8.5 (50), 4.58 (50), 5.69 (40), 2.58 (40) Chemistry: (1) (2) (1) (2) SiO2 40.46 51.26 MgO 20.71 23.54 TiO2 0.09 CaO 1.94 1.25 Al2O3 10.15 4.42 Na2O 0.25 1.14 Fe2O3 3.56 1.14 K2O 0.32 0.18 + FeO 4.89 H2O 4.24 6.58 MnO 0.24 0.03 H2O¡ 13.33 10.08 NiO 0.04 P2O5 0.14 Total 100.23 99.75 · 2+ (1) C¶aslav, Czech Republic; corresponds to (Ca0:16Mg0:05Na0:04K0:03)§=0:28(Mg2:37Fe0:32 3+ Fe0:21Al0:10)§=3:00(Si3:16Al0:84)§=4:00O10(OH)2 ² 0:98H2O: (2) Ballarat, California, USA; by XRF, 2+ Na by AA, H2O by TGA; corresponds to (Ca0:19Na0:16K0:02)§=0:37(Mg2:61Al0:15Fe0:06)§=2:82 (Si3:77Al0:23)§=4:00O10(OH)2 ² nH2O: Mineral Group: Smectite group.
  • Clay Minerals in Hydrothermal Systems

    Clay Minerals in Hydrothermal Systems

    minerals Review Clay Minerals in Hydrothermal Systems Paolo Fulignati Dipartimento di Scienze della Terra, University of Pisa, Via S. Maria 53, 56126 Pisa, Italy; [email protected] Received: 24 August 2020; Accepted: 14 October 2020; Published: 16 October 2020 Abstract: The study of active and fossil hydrothermal systems shows clay minerals to be a fundamental tool for the identification and characterization of hydrothermal alteration facies. The occurrence and composition of hydrothermal alteration facies could provide useful information on the physicochemical conditions of the hydrothermal activity affecting a rock volume. In particular, clay minerals (i.e., smectite group, chlorite, illite, kaoline group, pyrophyllite, biotite) are pivotal for extrapolating important parameters that strongly affect the development of water/rock interaction processes such as the temperature and pH of the hydrothermal environment. This work aims to give a general reference scheme concerning the occurrence of clay minerals in hydrothermal alteration paragenesis, their significance, and the information that can be deduced by their presence and chemical composition, with some examples from active and fossil hydrothermal systems around the world. The main mineralogical geothermometers based on chlorite and illite composition are presented, together with the use of hydrogen and oxygen isotope investigation of clay minerals in hydrothermal systems. These techniques provide a useful tool for the reconstruction of the origin and evolution of fluids involved in hydrothermal alteration. Finally, a list of oxygen and hydrogen fractionation factor equations between the main clay minerals and water is also provided. Keywords: clay minerals; hydrothermal alteration; hydrothermal mineralogical paragenesis; geothermometers 1. Introduction A volume of rock, when affected by hydrothermal fluid circulation, typically undergoes a variety of alteration processes.