Citation:

dsdp.proc.72.135.1983

Name: (Table 1) Radiolarians in the Oligocene-Miocene at DSDP Hole 72-515B
Creator: David A Johnson
Published: 1983
License: https://creativecommons.org/licenses/by/3.0/

Always quote citation above when using data! You can download the citation in several formats below.

RIS Citation BibTeX Citation Text Citation Facebook TwitterShow Map Google Earth

Abstract:

The Neogene of the southwestern Atlantic is virtually barren of biogenic silica. Of the four sites drilled on Leg 72, only two contained identifiable radiolarian specimens. In the southwestern Brazil Basin (Site 515), radiolarians are present only from the upper Oligocene (Anomaly 8, about 28 Ma) to the middle Miocene (Zone NN8, about 11.5 Ma). On the Rio Grande Rise (Site 516), radiolarians are present only within a short interval of the lower Miocene (Zones N5-N6, about 18-20 Ma). The abrupt cessation of silica deposition in the upper middle Miocene is characteristic of many drill sites in the tropical and temperate Atlantic and implies that a major oceanographic "threshold" was exceeded at this time, allowing the Atlantic waters to become either less productive or relatively silica deficient. Siliceous microfossils are notably more abundant in Oligocene-Miocene sediments of deep regions where carbonate preservation is poor (Site 515) than in equivalent carbonate-rich strata nearby (Site 516). This discrepancy suggests that the presence of calcareous microfossils may act to enhance post-depositional dissolution of biogenic silica tests by elevating the pH of the surrounding pore waters. Carbonate-free clays, by contrast, may provide a more favorable chemical environment for silica preservation.

Project(s):

Deep Sea Drilling Project (DSDP)

Coverage:

Latitude: -26.238700 * Longitude: -36.503200

Date/Time Start: 1980-03-01T00:00:00 * Date/Time End: 1980-03-01T00:00:00

Minimum Elevation: -4252.0 m * Maximum Elevation: -4252.0 m

Event(s):

72-515B * Latitude: -26.238700 * Longitude: -36.503200 * Date/Time: 1980-03-01T00:00:00 * Elevation: -4252.0 m * Penetration: 636.4 m * Recovery: 428.6 m * Location: South Atlantic/BASIN * Campaign: * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 57 cores; 541.4 m cored; 94.9 m drilled; 79.2 % recovery

Comment:

A = abundant (>50 specimens per slide), C = common (15-50 specimens per slide), F = few (5-15 specimens per slide); R = rare (2-5 specimens per slide), + = trace (only one specimen per slide), - = absent (taxon was searched for, but was not found on any of the prepared slides), empty cells = no data.

Parameter(s):

#	Name	Short Name	Principal Investigator	Method/Device	Comment
1	Sample code/label	Sample label	Johnson, David A	DSDP/ODP/IODP sample designation
2	Radiolarian zone	Radiolarian zone	Johnson, David A
3	Radiolarians abundance	Rad abund	Johnson, David A
4	Radiolarian preservation	Rad preserv	Johnson, David A		E = excellent, G = good, M = moderate, P = poor
5	Artophormis gracilis	A. gracilis	Johnson, David A
6	Botryopyle dictyocephalus	B. dictyocephalus	Johnson, David A
7	Calocycletta cf. costata	C. cf. costata	Johnson, David A
8	Calocycletta robusta	C. robusta	Johnson, David A
9	Calocycletta virginis	C. virginis	Johnson, David A
10	Cannartus bassanii	C. bassanii	Johnson, David A
11	Cannartus prismaticus	C. prismaticus	Johnson, David A
12	Cannartus tubarius	C. tubarius	Johnson, David A
13	Carpocanopsis bramlettei	C. bramlettei	Johnson, David A
14	Carpocanopsis cristatatum	C. cristatatum	Johnson, David A
15	Carpocanopsis favosa	C. favosa	Johnson, David A
16	Centrobotrys petrushevskayae	C. petrushevskayae	Johnson, David A
17	Clathrocanium sphaerocephalum	C. sphaerocephalum	Johnson, David A
18	Cyclampterium leptetrum	C. leptetrum	Johnson, David A
19	Cyclampterium milowi	C. milowi	Johnson, David A		?
20	Cyclampterium pegetrum	C. pegetrum	Johnson, David A
21	Cyrtocapsella cornuta	C. cornuta	Johnson, David A
22	Cyrtocapsella elongata	C. elongata	Johnson, David A
23	Cyrtocapsella japonica	C. japonica	Johnson, David A
24	Cyrtocapsella tetrapera	C. tetrapera	Johnson, David A
25	Dendrospyris bursa	D. bursa	Johnson, David A
26	Dicolocapsa microcephala	D. microcephala	Johnson, David A
27	Dorcadospyris alata	D. alata	Johnson, David A
28	Dorcadospyris ateuchus	D. ateuchus	Johnson, David A
29	Dorcadospyris papilio	D. papilio	Johnson, David A
30	Dorcadospyris simplex	D. simplex	Johnson, David A
31	Dorcadospyris triceros	D. triceros	Johnson, David A
32	Eucyrtidium cienkowskii	E. cienkowskii	Johnson, David A
33	Eucyrtidium diaphanes	E. diaphanes	Johnson, David A
34	Eucyrtidium punctatum	E. punctatum	Johnson, David A
35	Gorgospyris schizopodia	G. schizopodia	Johnson, David A
36	Histiastrum martinianum	H. martinianum	Johnson, David A
37	Lychnocanoma elongata	L. elongata	Johnson, David A
38	Siphostichartus corona	S. corona	Johnson, David A
39	Stichocorys armata	S. armata	Johnson, David A
40	Stichocorys delmontensis	S. delmontensis	Johnson, David A
41	Stichocorys peregrina	S. peregrina	Johnson, David A
42	Stichocorys wolfii	S. wolfii	Johnson, David A
43	Theocorys spongoconum	T. spongoconum	Johnson, David A
44	Theocyrtis annosa	T. annosa	Johnson, David A

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

1451 data points

Download Data

Download dataset as tab-delimited text — use the following character encoding:

View dataset as HTML