James, Noel P.

English

University of New Brunswick: Centre for Digital Scholarship Journals

Geoscience Canada. Volume 3. Number 2. May. 1976 137 Possibly the most interesting and original paper (also the longest. . .30 pages) wasthat by G. M. Kaufman elal., "A Probabilistic Model of Oil and Gas Discovery". The authors present a statistical model based upon Alberta's oil andgas pools, and utilize Monte Carlo simulations to predict the size of pools discovered as the resource base is depleted. Other papers including those by such authors as H. D. Hedberg, M. T. Halbouty, K. 0. Emery and L. G. Weeks deal with a diversity of concepts relating to basin evaluation, entrapment factors. computer simulation studies and deep ocean sediments. Editor J. D. Haun has provided a good introductory summary paper. The volume is suitably indexed under author, sublect, and keyword, and is attractively bound in soft cover. Conferences, especially of this type. have may inherent limitations which make the original objectives difficult to achieve. It is therefore understandable that expediency and confidentiality result in only minor input from the major oil companies and little originality in many of the papers. Many oftheauthors have merely reiterated old ideas and some touch only on the peripheral aspects of the conference theme. However. despite such shortcomings. thls volume is deftnltely a good buy, and recommended readlng for any geologist who 1s concerned about the state of the artlscience for whlch geologists as a group are receiving much justiftable crltlclsm M~neral geologtsts may flnd some of the concepts adaptable In addillon, this book should be recommended reading for the lavman. Belize Shelf - Carbonate Sediments, Clastic Sedimentology, and Ecology Edtted by K F Wantland and W C Pusey Ill Amer~can Assocralron of Pelroleurn Geologrsls Sludres In Geology No 2 599 p , sol1 cover. 1975 SEPM and AAPG members $1 5 00. Others $19 00 Reviewed by Noel P. James Departmenl of Geology Mernor~al Un~vers~ly of Newfoundland 8. John's. Newfoundland In 1960, having completed the herculean task of describingthemodern carbonate sedimentson the Great Bahama Bank. E. G. Purdy turned his attention to the Bellze (British Honduras) continental shelf, a contrasting, reef- dominated area of both terrigenous- clastic and carbonate sedimentation. Over the next six years he, and ateam of graduate students from Rice University, studied the sedimentology of this complex. The result was nine PhD. dissertations focused on various aspects of sedimentation, carbonate diagenesls and benthic organism ecology T~me and circumstance have mit~gated against publication of all but two of these studies, and now,at last, the rest are combined between the pagesof this volume. The book contains nine papers: a succinct, well-written overview of the reglonal shelf attributes by Purdy and the The documentation of carbonate sediments in lagoons, on beaches and on tidal flats around the large island Ambergris Cay by Ebanks isanother addition to the growing literature on this topic. An important, andat thesametime disturbing conclusion resulting from analysis of coastal mangrove swamps along the landward margin of the shelf by High, isthat thesediment sin thiszone have no consistent relationship to environment of deposition. Perhaps the most significant contribution does not come from any one of these papers alone. but rather from the consistent picture of sedimentation during the Holocene transgression, obtained by all three workers from analysisof many sofi-sediment cores. Clay minerals, which comprise a significant part of lagoon sediments throughout, are thought by Scott to be detrital in origin and to reflect drainage from intensively leached, geologically varied terrane versus karsted carbonate terrane. Interestingly, she also feels that dispersal patterns of the clay minerals reflect, in part, the different settling tendencies of the various clays. Pleistocene carbonates are treated in two studies, one on the reef to shelf to mudbank transition on Ambergris Cay (Tebbutt) and one on the aeolianites of the Northeast Yucatan platform north of Belize (Ward). These studies confirm the now well-documented diagenetic processes that occur in the subaerial vadose zone and contain interesting tnformation on recrystallization of aragonite skeletons (to aragonite) and diagenesis related to plant roots, paleoexposure horizons and calcrete. Microfauna in the Holocene shelf - c j : ~ . ~ ~ n ~ r ~ n t  011 c a an,] po t c an or I r o  eo 101s scbcn papers on tne Be ~r menls arc oescr oeo n INO SO (1 anyotie concernco ~DIJJI tooay s or snc l uroper an0 one paper on lne st4d es, one on the ecology of oentn c 'cr. lLrrc .\ s crc'g, s..pp es a<!(] .all la5 of lnc n0rlneaStCrn Y~Calarl loram n lera ~Wan1lano)andtnc otner on venlnsula. MS recelved February 10. 1976. Sedlmentalion on dtfferent parts of the Belize shelf are detailed in three papers. The shallow northern shelf studied by Pusey, although reminiscent of Florida Bay. Shark Bay and parts of the Great Bahama Bank. is veneered with fine grained terrigenous clastic as well as carbonate sediments. Of particular interest are the two large mud banks at the entrance to Chetumal Bay, thought 10 result from the interplay of tidal currents and waves as opposed to binding andtrapptng by sea grasses. the taxonomy of ostracods (Teeter) and both convincingly illustrate the value of examining mlcrofauna together with sediments. This volume, along with earlier published studies on the shelf intertor lime muds (Matthews. Jour. Sed. Petrology, 1969: Scholle and Kling, Jour. Sed. Petrology. 1972): the morphology and fauna of some shallow reefs (Stoddart: Atoll. Res. Bull., 1962,1963) and the role of inherited topography in reef distribution and sedimentation (Purdy, SEPM Spec. Publ 18, 1974) combine to yield one of the most complete analyses of a modern reef complex, with the exception of thereefs. The fact that most studies were completed some eight years before publication is glaringly obvious both lrom the text and the referencesquoted. few of which are later than 1967. Eight years ago this would have been a major publication in the lield of carbonate sedimentology, today it isa solid addition to the literature; for the serious worker on carbonate sedimentology and paleoecology this book should be handy asa reference;for the worker on carbonate diagenesis ii can easily be reached in the nearby library. MS received March 1 .  1976. Neue Mbglichkeiten erdgeschichtlicher Forschung mlt Hilfe des Palaogeruches By W. A. Schnitzer and R. G. Schwab Erlanger Geol. Abh., Helf 10l ,20 Seilen. 1975. DM 8.00 (approx. $3.25). Revtewed by Anna-Stina Edhorn 582 Davenport Road Toronto, Ontar10 M5R 7 K9 New Porribilltler in Stratigraphic Research with the help of Paleosmell Paleosmell is the term used by Schntlzer and Schwab in their publication. Considered is the sensorial perception of smell from clays and its usefulness and tmporlance in stratigraphic geology. It is known that burnt clay is able to adsorb odorous substances from the atmosphere During fieldwork in India. Schnitzer came in contact wlth the manufacturer of an "earth parfum" "Matti- ka-attar" and he could follow the process of retrieving that odorous substance from its source. The substance is produced in the clay burnt by the sun in the hot summer months frDm April to June. I. J. Bear and R. GThomas. Melbourne. Australia have made de- tailed studies of the complex composl- tion of that "Matti-ka-attar". They introduced the term "petrichor" to describe the smell of clay and also the smell displayed by outcropping rockson earth. Schnitzer and Schwab speculated that shale and even other rocks from the past must have had the same ability to adsorb odorous substances. Hence the goal was to make use of this aSSumptlOn and to find methods to identify these odorous substances, which are of great vartety and discernible in moistened shales and rnarls. The two researchers establtshed a jolnt program, in which Schnitzer used thin-layer chromatography to graphically explain paleosmell. He gives a detailed descriplion of the procedures in his method as well as illustrations of the chromatograms received from the shales used in the experiments. He found that shalesol diflerent age and facies could be distinguished because of remarkable differences in smell ranging from musty to earthy and aromatic to burnt. This thin-layer chromatographic method has been successfully applied to the Upper Triassic shales of southern Germany From vertical sections without noticeable changes in facies, there Is evidence that isochronous strata are identical, whereas heterochronous sediments differ as far as thetr paleosmell is concerned. Over a studied area with a distanceof approximately 50 km, these observations proved to be correct Many other shale samples have been investigated. suchas Precambrian shales from Indla. Devonian ones from Spain and PliolPleistocene shales from western Germany. Chromatograms in this project are not interpreted in terms of the nature of the easily volatilized organic compounds. but are madetor visual comparison Only. to record which chromatograms are identical and wh~ch ave a diflerent configuration. A sertes of chromatographtc Identity cards have been comp~led for the Upper Triassic stratigraphic untts, representing 200 collected samples. Hopefully. these cards will serve as a comparative standard in the future Inlormation regarding the nature Of those organic compounds, which are volatile in water vapour and are the essence of paleosmell, IS given by Schwab in part II of tne reviewed publication He uses pulse- polarography to invest~gate various clay-stones and gives a description 01 h ~ s  method. Most of the samples investigated contained polarographically active compounds giving characteristic polarograms. These compounds being the source of the paleosmell apparently are aldehyds. ketones. terpene-aldehyds and terpen- ketones, possibly also aromates and heterocyclic compounds. The polarograms received proved to be identical wlthin the same stratum. A valuable potnt ts that Precambrian samples, asexpected, do give characteristic polarograms, which are quite dtfferent from the Mesozoic ones. Th~s may reveal what type of compounds existed in the Precambrian biology and in the primeval atmosphere. It may bring out such important information as when and where the first animals appeared and started to compete with the all dominating algae. 

Belize Shelf - Carbonate Sediments, Clastic Sedimentology, and Ecology

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Belize Shelf - Carbonate Sediments, Clastic Sedimentology, and Ecology

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