Spilite from Kamešnica, Mt. Kalnik, NW Croatia

The results of microscopic and chemical investigation of spilites from the upper coarse of the stream Kamešnica and from iu tributary Kalnički potok on Mt. Kalnik (north-western Croatia) have been described. Spilites arc a result of postmagmatic hydrothermal alteration of the basic effusive rocks. They are of Upper Cretaceous age

UTJECAJ PETROGRAFSKIH OBILJEŽJA SILIKATNIH STIJENA NA KVALITETU AGREGATA

The mechanical properties of chrushed rock aggregates are greatly influenced by the petrographic characteristics of parent rock. The main objective of this study was to determine the relation between the petrographic characteristics of some volcanic and subvolcanic (silicate) rocks from Croatia, and the chrushing resistance of aggregates produced by their comminution. The aggregate resistance to chrusing was tested by means of the Los Angeles abrasion test. During this testing, an aggregate is subjected to dynamic load by impact and abrasion. The petrographic characteristics were examined with the petrographic and scanning electron microscope and by X-ray powder diffraction with CuKa (1,54 A) radiation. In order to obtain the most correct evaluation of aggregates chrushing resistance, four different values had been used - the recrushing index (Ir), the reduction ratio (RR), the Los Angeles abrasion value (LA) and the Los Angeles abrasion value residue (LAr). On the basis of the obtained results, the following petrographic factors have been revealed as the most important ones for rock aggregates resistance to crushing: a - the size of crystals, b - the form, arrangement and dimensions ratio of crystals, and, especially c - the presence of microfractures in parent rock.Petrografska obilježja ishodišne stijene bitno utječu na mehanička svojstva drobljenih kamenih agregata. Glavni cilj ovog rada bio je utvrditi odnose između petrografskih obilježja nekih vulkanskih i subvulkanskih (silikatnih) stijena i otpornosti prema drobljenju agregata dobivenih njihovih usitnjavanjem. Otpornost prema drobljenju ispitivana je metodom "Los Angeles". Tijekom ispitivanja agregat je izložen dinamičkim opterećenjima na udar i habanje. Mineralni sastav i druga petrografska obilježja određeni su petrografskim i elektronskim mikroskopom, te metodom rendgenske difrakcije na prahu vertikalnim rendgenskim goniometrom s CuKu (1,54 A) zračenjem. Kako bi se što točnije ocijenila otpornost prema drobljenju ispitivanih agregata korištena su četiri različita pokazatelja: koeficijent Los Angeles (LA), koeficijent Los Angeles ostatka (LAr), indeks pregranulacije (Ir) i stupanj usitnjavanja (PR). Na temelju dobivenih rezultata kao najvažnija petrografska obilježja kamenih agregata u pogledu otpornosti prema drobljenju izdvojeni su: a- veličina kristala; b- oblik, prostorni raspored i međusobni odnos veličine kristala; i, posebice c - prisustvo mikropukotina u ishodišnoj stijeni

OPTIMALNI POSTUPAK PRIPREME UZORAKA SILIKATNE STIJENE ZA ANALITIČKE SVRHE

The purpose of this study was to determine an optimal dissolution method for silicate rock samples for further analytical purposes. Analytical FAAS method of determining cobalt, chromium, copper, nickel, lead and zinc content in gabbro sample and geochemical standard AGV-1 has been applied for verification. Dissolution in mixtures of various inorganic acids has been tested, as well as Na2CO3 fusion technique. The results obtained by different methods have been compared and dissolution in the mixture of HNO3 + HF has been recommended as optimal.Svrha rada bila je utvrđivanje optimalnog postupka otapanja uzoraka silikatne stijene za dalje analitičke svrhe. Za verifikaciju je primijenjena analitička metoda FAAS određivanja udjela kobalta, kroma, bakra, nikla, olova i cinka u uzorku gabra i u geokemijskom standardu AGV-1. Istraženo je otapanje u smjesama različitih anorganskih kiselina kao i taljenje s Na2CO3. Uspoređeni su rezultati dobiveni različitim postupcima te se kao optimalni postupak preporuča otapanje u smjesi HNO3 + HF

"GUTTER CAST" TEXTURE AS POSSIBLE CORRELATIVE MARKER - EXAMPLE OF LOWER TRIASSIC SEDIMENTARY SEQUENCE PLAVNO AND STRMICA (CROATIA AND BOSNIA AND HERZEGOVINA)

Na profilima Plavno i Strmica u okolici Knina istraženi su sedimenti donjeg trijasa - skita koji u oba slijeda pokazuju iste litofacijesne značjke. Karakteristike Siliciklastičnog litofacijesa, koji odgovara sedimentima donjeg skita,te Muljnog i Siltozno-muljnog litofacijesa gornjeg skita odražavaju utjecaj oluja u plićim i dubljim dijelovima šelfa, kao i oscilacije razine mora koja se manifestira nizanjem ciklusa pretpostavljenog 5, 4. i 3. reda. Na otvorenim donjim slojnim plohama sedimenata Muljnog i Siltozno - muljnog litofacijesa uočena je "gutter crust" tekstura nastala uslijed helikoidalnog (vrtložnog) strujanja čija je os paralelna površini sedimenta. Takvo strujanje moguće je interpretirati kao posljedicu djelovanja jednosmjernih struja tijekom oluje. uslijed erozije vrtloženjem nastaju plitki dugački ravni ili prepleteni žljebovi. Tekstura je vezana uz sedimente vanjskog šelfa i predstavlja karakteristični, istovremeni olujni zapis na širem prostoru. Zahvaljujući ovoj teksturi i njenoj jednoobraznoj genezi sedimenti vertikalnog slijeda oba istaložena lokaliteta mogu se, u nedostatku drugog biostratigrafskog ili litostratigrafskog markera, međusobno korelirati. Kao osnova za korelaciju može poslužiti prva pojava "gutter cast" teksture vertikalno u slijedu sedimenata. Tako načinjena korelacija grupira "gutter cast-e" oba istražena slijeda u određeni vremenski (vertikalni) interval. "Gutter cast" tekstura predstavlja, u tom slučaju, kronostratigrafski marker. U slučaju takvog pristupa korelaciji razlika debljine litofacijesa pojedinih lokaliteta može se objasniti položajem u sedimentacijskom bazenu bliže ili dalje od obale. Korelacijski princip spajanja granice donjeg i gornjeg skita, što je uvriježeni princip korelacije, može se u tom slučaju isključiti kao neodgovarajući.Lower Triassic (Scythian) sedimentary sequence developed in similar lithofacies were studied at two sections in vicinity of Knin - Plavno (in Croatia) and Strmica (in Bosnia and Herzegovina). Characteristics of the Siliciclastic lithofacies, which corresponds to the Lower Scythian, Seis beds, and of the Mudstone and Siltstone - mudstone lithofacies of Upper Scythian, Campil beds, reflect the storm influence at the shallower and deeper parts of shelf, as well as the sea-level oscilations resulting in a presumed 5th, 4th and 3rd order cycles. Appearance of gutter casts exposed on lower bedding planes of sedimentary rocks in Mudstone and Siltstone-mudstone lithofacies has been considered as a consequence of bottom current flow component in the outer shelf area. This unidirectional current flow has a helicoidal component with horizontal axis parallel to the sediment surface. The flow generates characteristic storm imprint on the broad shelf area. Lacking any other types of either the biostratigraphic or litostratigraphic marker horizons, this structure, having only one way of formation, allows the improvement of chronostratigraphic correlation of the vertical sequence on both explored locations. The firs appearance of this structure in sediment successions of Plavno and Strmica, may serve as possible correlative marker. Using such a correlative principle gutter casts are in vertical succession grouped in interval, which signifies approximately penecontemporaneous events. Should the correlation be based on the gutter cast structure, the differences in thickness at both location can be explained by their more proximal or more distal position within the sedimentary basin. If this is true, the inveterate principle of correlating the contact between of Lower Scythian and Upper Scythian sediments as a contact between the red, dominantly clastic Seis beds and grey, dominantly calcareous Campil beds, is therefore found to be chronostratigraphically inadequate and can be excluded

RAZLIČITE GEOKEMIJSKE ZNAČAJKE RAZVIJENE U BAZIČNIM MAGMATSKIM STIJENAMA KALNIKA (SJEVERNA HRVATSKA)

Basic magmatic rocks of Mt. Kalnik experienced hydrothermal alteration and low grade metamorphism. In such circumstances the most useful tracers of their magma sources and tectonic settings are REE patterns and other normalized trace element abundance plots. Gabbro, basalt, diabase and two samples of metabasalts were investigated in this preliminary study. Geochemical signature of gabbro points to the mantle source of magma and those of metabasalts indicates continental crust source. According to its features basalt could have been derived from the same magma as gabbro by process of magmatic differentiation. The magma giving diabase arised most probably from mantle wedge enriched by hydrothermal fluids ascending from the subducting slab.Bazične magmatske stijene Kalnika su hidrotermalno alterirane i metamorfozirane do niskog stupnja. Za takve stijene najbolji pokazatelji izvora njihove magme i tektonskog položaja jesu obrasci elemenata rijetkih zemalja i drugi dijagrami normaliziranih elemenata u tragovima. U ovoj preliminarnoj studiji istraženi su gabro, bazalt, dijabaz i dva uzorka metabazalta. Geokemijske značajke gabra ukazuju na plaštni izvor magme, a one metabazalta ukazuju na kontinentalnu koru kao izvor. Prema svojim obilježjima bazalt je mogao nastati iz iste magme kao i gabro procesom magmatske diferencijacije. Magma iz koje je nastao dijabaz potječe najvjerojatnije iz omotačkog klina obogaćenoga hidrotermalnim fludima koji se dižu sa subducirajuće ploče

ODREĐIVANJE OTPONOSTI KAMENIH AGREGATA NA PREGRANULACIJU

The stone aggregates of dolomite, andesitic and spililized diabase were tested to estimate their response to abrasive-impact strain. Standardized and non-standardized estimation of recrushing action were utilized in the experiment. The focus of the study was to improve the estimation of resistance to the recrushing process. The assumption that there is a relationship between the degree of recrushing of the stone aggregates and the grain surface before recrushing was confirmed The investigation was performed by the use of the standardised method according to the HRN Standard (Los Angeles). For the complete evaluation of the aggregate several other methods in accordance to HRN were also applied. The values obtained are found to be the result of several factor which include structural, textural and mineral properties, as well as genesis, tectonics (postgenetic strain producing the micro-cleavage and cataclasis) and recrystallization. The influence of the size, shape together with the interrelationship of crystals and micro-blocks on the physical and mechanical properties were determined by electronic microscopy.Kameni agregati dolomita, andezita i spilitiziranog dijabaza podvrgnuti su ispitivanju na udarno huhajuća opterećenja. Korištene su normirane i nenormirane metode ocjene pregranulacijc. Posebna pažnja posvećena je poboljšanju ocjene otpornosti prema pregranulaciji. Potvrđene su pretpostavke da postoji ovisnost stupnja pregranulacije kamenih agregata o površini zrna agregata prije predrobljvanja. Ispitivanje je obavljeno normiranom metodom prema normativu HRN (LosAngeles). Za potpunu ocjenu agregata korištene su i druge metode ispitivanja prema HRN-u. Utvrđeno je da su dobivene vrijednosti posljedica strukturno-teksturnih i mineralnih značajki, geneze, tektonike (postgenetskih naprezanja koja uzrokuju mikroraspucanost i kataklaziranje) i rekristalizacije. Elektronskim je mikroskopom utvrđen utjecaj veličine, oblika i međusobne povezanosti kristala i mikroblokova na fizička i mehanička svojstva

CONTACT PHENOMENA IN THE ROCKS OF MT. KALNIK (NW CROATIA)

Na području Kalničkog gorja istraženi su malobrojni kontakti magmatskih i sedimentnih stijena. Neki kontakti imaju elemente tektonizacije. Primarni kontakti su ili bez kontaktnometamorfnih promjena, ili s izraženim promjenama. Na neke kontakte, uz prostorni odnos magmatske i sedimentne stijene, ukazuju i kontaktne pojave u sedimentnim stijenama. Magmatske stijene su u kontaktu sa šejlovima, vapnencima dolomitima i litičnim grauvakama. Među kontaktnim strukturno-teksturnim i kemijskim pojavama zapažene su izrazito jaka listatost sedimenata s prijelazom u škriljavost, kontaktne eruptivne breče, anklave vapnenaca, klinasto utiskivanje, raspucanost sedimenata, transformacija matriksa, sekundarni sastojci u žilicama i gnijezdima u sedimentnim stijenama, rekristalizacija, dolomitizacija, skarnska parageneza, silicifikacija, hematitizacija i pojava ferokalcita. Navedene pojave ukazuju na sinsedimentacijske i/ili postsedimentacijske višekratne efuzije i plitke intruzije bazične lave. Različitost kontaktnih pojava upućuje na različite brzine izlijevanja, količine i temperature lave i različiti stupanj konsolidiranosti sedimentnih stijena.Scarce contacts between magnetic and sedimentary rocks have been investigated on the Mt. Kalnik. Magmatic rocks are in contact with shales, limestones, dolomites, and lithic greywackes. Some contacts are characterized by the tectonic nature. The primary contacts are either without contact metamprphic changes, or with them, whereas some contacts are characterized by close space relationship between magmatic and sedimentary rocks and also with contact phenomena in sedimentary rocks. The observed textural and chemical contact phenomena are the pronounced schistosity of sediments grading to the cleavage, contact extrusive breccias, limestone enclaves,wedge shaped denting, cracked sediments, the transformation of matrix, secondary minerals in veinlets and nests in sedimentary rocks, recrystallization, dolomitization, skarn paragenesis, silification, hematitization and the occurrence of ferrocalcite. Mentioned phenomena point to the synsedimentary and/or postsedimentary repeated extrusions and shallow intrusions of basic lavas. The diversity of contact phenomena indicates variable rates of extrusion, quantity and temperatures of lavas as also different grade of consolidation of sedimentary rocks

MEĐUSOBNI ODNOSI MINERALA I NJIHOVA KEMIJA U NEKIM BAZIČNIM MAGMATSKIM STIJENAMA OFIOLITNOG KOMPLEKSA BANIJE, HRVATSKA

Mineral relationships and their chemistry were studied in some basic magmatic rocks of Banija ophiolite complex. On the basis of mineral and structural characteristics three kind of rocks are distinguished: metadiabase I (being characterized by secondary amphibole), metadiabase II (being characterized by secondary albite) and spilite. Detailed chemistry of all mineral phases, specially of zoned clinopyroxenes and zoned amphiboles is given. The black opaque phases consist of different Fe-Ti-Mn oxides (ilmenite, Mn-ilmenite, magnetite, Ti-magnetite, ferropseudobrookite) being often at the rims replaced by Al- and Fe-rich titanite. All rocks are hydrothermally metamorphosed whereby amphibole replaced partly or completely clinopyroxene and plagioclase was altered in albite, prehnite, pumpellyite and/or sericite. Secondary chlorite occurs too. The whole rock chemistry of each studied rock corresponds to tholeiitic basalts.Međusobni odnosi minerala i njihova kemija proučavani su u nekim bazičnim magmatskim stijenama ofiolitnog kompleksa Banije. Na temelju mineralnih i stukturnih karakteristika razlikuju se tri vrste stijena: metadijabazi I (karakterizirani sekundarnim amfibolom), metadijabazi II (karakterizirani sekundarnim albitom) i spilit. Dana je detaljna kemija svih mineralnih faza, osobito zoniranih klinopiroksena i zoniranih amfibola. Crne opâke faze sastoje se od različitih Fe-Ti-Mn oksida (ilmenit, Mn-ilmenit, magnetit, Ti-magnetit, Fe-pseudobrukit) koje su često na rubovima potisnute Al- i Fe-bogatim titanitom. Sve su stijene hidrotermalno metamorfozirane pri čemu je amfibol djelomično ili potpuno potisnuo klinopiroksen, a plagioklas je izmijenjen u albit, prehnit, pumpeliit i/ili sericit. Pojavljuje se također i sekundarni klorit. Ukupna kemijska analiza svake proučavane stijene odgovara toleitskom bazaltu

Utjecaj oktreotida na lučenje hormona rasta u bolesnika s akromegalijom

A majority of growth hormone secreting pituitary adenomas respond well to somatostatin and somatostatin analogues. The acute action of octreotide, a synthetic somatostatin analogue, on growth hormone secretion was assessed in 42 patients with clinically and laboratory verified acromegaly. Octreotide was administered subcutaneously in a dose of 50 mg. Blood sampling was performed at 1-hour intervals during 6 hours of testing. The mean basal values of growth hormone (c±SE) was 26.3±4.5 ng/ml (range 6.1-66.6 ng/ml), and of IGF-I 2940±171.7 IU/l (range 2350-4856 IU/l). Reduction in growth hormone values below 5 ng/ml was recorded in 31 (73.8%), suppression by more than 50% in 5 (11.9%) and by more than 45% in 3 (7.1%) patients. Maximal suppression was noticed in the first two hours of testing. In 3 (7.1%) patients, resistance to octreotide with no change in growth hormone values was observed. In conclusion, octreotide reduces growth hormone values in most acromegalic patients. A small proportion of acromegalic patients do not respond well to octreotide, probably due to the lack of somatostatin receptors on tumor cells. We consider the acute octreotide test as a very useful tool in triage of acromegalic patients eligible for medicamentous treatment.Većina adenoma hipofize koji luče hormon rasta zadrže osjetljivost na somatostatin i njegove analoge. Ispitivano je akutno djelovanje oktreotida, sintetskog oktapeptidnog analoga somatostatina, na razinu hormona rasta u 42 bolesnika s klinički i laboratorijski potvrđenom akromegalijom. Oktreotid je primijenjen supkutano u dozi od 50 mg. Uzorci krvi za određivanje hormona rasta uzimani su svakog sata u razdoblju od šest sati. Prosječna bazalna vrijednost hormona rasta bila je 26,3±4,5 c±SE) ng/ml (raspon 6,1-66,6 ng/ml), a IGF-I 2940,2±171,7 IJ/l (raspon 2350-4856 IJ/l). Nakon primjene oktreotida razina hormona rasta u serumu snizila se na normalne vrijednosti (<5 ng/ml) u 31 (73,8%) bolesnika, u 5 (11,9%) bolesnika nastupilo je sniženje za više od 50%, a u 3 (7,1%) za više od 45%. Maksimalno je sniženje u ovih bolesnika uslijedilo jedan do dva sata nakon početka testa. Troje (7,1%) bolesnika pokazalo je rezistenciju na oktreotid. Njihove vrijednosti hormona rasta ostale su gotovo jednake onima u bazalnim uvjetima. Zaključeno je da oktreotid normalizira razinu hormona rasta u većine akromegaličnih bolesnika, međutim, u nekih se ne postiže zadovoljavajući odgovor, vjerojatno zbog malog broja somatostatinskih receptora na membrani tumorskih stanica. Smatramo da je akutni test s oktreotidom koristan u odabiru akromegaličnih bolesnika za konzervativno liječenje analozima somatostatina

Recidivirajući hiperparatiroidizam: prikaz slučaja

A 57-year-old man with a history of primary hyperparathyroidism, consequential chronic renal failure and associated chronic Hashimoto.s thyroiditis presented with recurrent hypercalcemia. Hypercalcemia persisted despite three resections of enlarged parathyroid glands and multiple sclerosations of the remaining parathyroid tissue. The possible causes of persisting hypercalcemia include unrecognized asymmetric parathyroid hyperplasia, multiple parathyroid adenomas, however, parathyromatosis as a complication of parathyroid resection could not be ruled out. Dispersion of parathyroid tissue and growth of multiple parathyroid nodules could lead to primary hyperparathyroidism. With intermittent parenteral pamidronate normocalcemia was temporarily achieved, although fourth resection of parathyroid tissue and subtotal thyroidectomy eventually led to normocalcemia and normal parathyroid hormone levels in this patient.Prikazuje se 57-godišnji bolesnik s recidivirajućim primarnim hiperparatiroidizmom i posljedičnom kroničnom bubrežnom insuficijencijom.U tri navrata učinjena je ekstirpacija povećanih paratiroidnih žlijezda i višekratna sklerozacija preostalog paratiroidnog tkiva, uz i dalje prisutnu hiperkalcemiju. Moguća objašnjenja su da se kod bolesnika radilo o višestrukim adenomima paratiroidnih žlijezda koji su se razvili metakrono ili se od samog početka radilo o neprepoznatoj asimetričnoj hiperplaziji svih paratiroidnih žlijezda. Ne može se, međutim, isključiti niti paratiromatoza kao posljedica poslijeoperacijske rupture kapsule adenoma, što je dovelo do rasapa i ponovnog rasta višestrukih paratiroidnih čvorova i recidiva primarnog hiperparatiroidizma. Bolesnik je uz intermitentnu parenteralnu terapiju pamidronatom bio u prolaznoj normokalcemiji, a nakon ponovne pojave hiperparatiroidizma učinjena je radikalna disekcija paratiroidnog tkiva i subtotalnalna resekcija štitne žlijezde, čime je uspostavljena normokalcemija i postignuta uredna razina paratiroidnog hormona