Fossil Vood from Grua Canaria
Prrlimiriciry ?;vie
By Hans-Ulrich Schmincke
I.nb<irari>riiini für Sedinientforcch~ing. I\lineralogisch!:s !nstitut.
Universiiai Heide!berg (Alemania).
The iirst Possil plants from Gran Canaria and, as far as
is known from the entire Canarian Archlpelago were found
a) as exce1lcnt:y preserved stems and brailches of small
trees, some of them being severa1 drn long and more than 20
cm in diameter. They oceur at the base of the "Roqile Nublo
breccia" which fills a deep fossil valley carved out along the
caldera perimeter fault which separates the Mid - Miocene
alkali basalts from the trachytic-rhyolitic sills. ignimbrites
and phonolites in the northwest part of thr island
(SCHMIKCKE, 1967) ;
b) as carbonatized plant fragrnents along bedding pla-nes
in fluviatile volcaniclastic sandstones of the "Roque Nu-blo
breccia" on the east sidc! of Barranro de Hoya.
The plants have not been determined yet - so that their
stratigraphic value is still uncertain. However, they are of
some ecologic and paleozlimatologic impoitance because they
indicate a plant cover of the island at the beginning of Roque
Nublo time (possiMy Mid-Pliocene, i.e. about 5 million years
%o).
The first and main phase of the island's volcanic history
started abmt ??lid-?Ji<;cene time (ABEEL-MGNEM ct u!. in
SCHMINCKE 1967) with the building of a basaltic shield
volcano, ignimbrite effusion, caldera collapse, and construc-tion
of central volcanoes in the island's center (SCHMINCKE
1967). The culminating phonolite volcanism may have ended
about 9 million years ago (op. cit.).
Tile erlbuirig iong erosionaí perioa auring whicn the whc-le
island was worn down to a skeletal volcanic cdifice with
deep barrancos but with a total height we!l over thogsanci m+
tres, and during which a plant cover spread over thc valleys,
may have lasted several million years. The forests w x e cum-pletely
destroyed by f i r ~2n d the ~ x p l n i wbl asts f r ~ mde nre,
highly lava-charged, glowing civalanc'nes that burst fcrth
from the island's center and rapidly filled up the deep radial
barrancos with what is now known as the Ruque I\iub!o
breccia.
Acknowledg;;ients: A trax-€1 qant frcm the DEUT-SCHE
FORSCHLNGSGEMEITUSCH~~FiTs s r ~ t ~ f u l layrk -
nowledged.
Auf Grail Canaria . j , . ~ i r dg~11~t erhallcme tusi le Holzi'r
an der Basis und inncrhalb dci- Eoqile Nublo Srcccie .i wi i$7e- . sten der Insel gefunden. Sie sind dcr ercli 3;;: e:s a i ~
fossilen Pflanzendecke, rncgli:~herwcisc . i?; t t~! -~L.ix, Aal-
-. ters untl, neben mxinen, cpatrr~oz:~íicM,i n11: G ~ C . - I t r iC P I ~ I -
gen bisher von Gran Canaria bek,m:,teri k'?c;siiicn.
Se ha encontrado en Gran C:rnai-iit tla~io C':sl¿ dc l.: isiw, !:I\ pii;:ici-;i\ !ni:-,,-
tras de fósiles vegetales. indicaciíin y tesiimoiíio J c ; : n ~fo rii::ici/::i cic \ v z e l ~ i ~ i i >\!¡n-perior
durante una época gco!6gic:ii:icn;e rcii:ot<i. Se i:.,..,~ de Fi.:igixen;w, d. ti::nios !.
ramas de árboles (petrificados, otros c,irbonizuclo:i). ptli p r t e de iiiJs (ir ?O [:;tis. c:i:i-iiiciiu.
bii-11 prcservacios en ei esrr:iro de rocn conocido po:- "Koqtrc N~ihlo brcc!:i:i".
Dichos fragmentos se da una edad de t:pi-oxini~~d:inieiit:: 5 iniliones ik años, o iea tlc
la época dcl plioceno medio.
Estas muestras son cl prinier hallazgo clc flísiizs vegetales del Arctiipici:!:o C:I-nario.
donde sr coiiocíiiri mkrioriiiente sólo f5siles i!i;irinos :iiic~l:iscos iiiioccno~).
Las muestras fueron erivi:idas para su identific;iciJn sisteiiiáticn y p,ir:i c5t~idios pe-trográficos
y püleoclimatol6gicos.
L I T E R A T U R E
H.-U. SCHMINCKE: "Cone sheet swarm, resurgence of Tejeda CalJei-a, :inJ
the early geologic history of Gr an Canariaw.-Ortli. I'ii~c~ci~i~~3l 1o :~ i1~5~3-~ 1i6~2~:
1967.
